nasl_packet_forgery.h File Reference

#include "nasl_lex_ctxt.h"

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Functions
tree_cell *	forge_ip_packet (lex_ctxt *)
	Forge an IP datagram. More...
tree_cell *	set_ip_elements (lex_ctxt *)
	Modify the fields of a datagram. More...
tree_cell *	get_ip_element (lex_ctxt *)
	Extracts a field from an IP datagram. More...
tree_cell *	dump_ip_packet (lex_ctxt *)
	Dump IP datagrams. More...
tree_cell *	insert_ip_options (lex_ctxt *)
	Add option datagram. More...
tree_cell *	forge_tcp_packet (lex_ctxt *)
	Fills an IP datagram with TCP data. Note that the ip_p field is not updated. It returns the modified IP datagram. Its arguments are: More...
tree_cell *	get_tcp_element (lex_ctxt *)
	Extracts TCP field from an IP datagram. More...
tree_cell *	get_tcp_option (lex_ctxt *)
	Get a TCP option from an IP datagram if present. Possible options are: TCPOPT_MAXSEG (2), values between 536 and 65535 TCPOPT_WINDOW (3), with values between 0 and 14 TCPOPT_SACK_PERMITTED (4), no value required. TCPOPT_TIMESTAMP (8), 8 bytes value for timestamp and echo timestamp, 4 bytes each one. More...
tree_cell *	set_tcp_elements (lex_ctxt *)
	Modify the TCP fields of a datagram. More...
tree_cell *	insert_tcp_options (lex_ctxt *)
	Add options to a TCP segment header. Possible options are: TCPOPT_MAXSEG (2), values between 536 and 65535 TCPOPT_WINDOW (3), with values between 0 and 14 TCPOPT_SACK_PERMITTED (4), no value required. TCPOPT_TIMESTAMP (8), 8 bytes value for timestamp and echo timestamp, 4 bytes each one. More...
tree_cell *	dump_tcp_packet (lex_ctxt *)
	Dump the TCP part of a IP Datagram. More...
tree_cell *	forge_udp_packet (lex_ctxt *)
	Fills an IP datagram with UDP data. Note that the ip_p field is not updated. It returns the modified IP datagram. Its arguments are: More...
tree_cell *	set_udp_elements (lex_ctxt *)
	Modify UDP fields of an IP datagram. More...
tree_cell *	dump_udp_packet (lex_ctxt *)
	Dump the UDP part of a IP Datagram. More...
tree_cell *	get_udp_element (lex_ctxt *)
	Get an UDP element from a IP datagram. More...
tree_cell *	forge_icmp_packet (lex_ctxt *)
	Fill an IP datagram with ICMP data. More...
tree_cell *	get_icmp_element (lex_ctxt *)
	Get an ICMP element from a IP datagram. More...
tree_cell *	dump_icmp_packet (lex_ctxt *)
	Dump the ICMP part of a IP Datagram. More...
tree_cell *	forge_igmp_packet (lex_ctxt *)
	Fills an IP datagram with IGMP data. More...
tree_cell *	nasl_tcp_ping (lex_ctxt *)
	Launches a “TCP ping” against the target host. More...
tree_cell *	nasl_send_packet (lex_ctxt *)
	Send a list of packets (passed as unnamed arguments) and listens to the answers. It returns a block made of all the sniffed “answers”. More...
tree_cell *	nasl_pcap_next (lex_ctxt *)
	Listen to one packet and return it. More...
tree_cell *	nasl_send_capture (lex_ctxt *)
	Send a capture. More...

Function Documentation

dump_icmp_packet()

tree_cell* dump_icmp_packet

(

lex_ctxt *

lexic

)

Dump the ICMP part of a IP Datagram.

Parameters

[in]	lexic	Lexical context of NASL interpreter.
[in]	...	IP datagrams to dump the ICMP part from.

Definition at line 1928 of file nasl_packet_forgery.c.

{
  int i = 0;
  u_char *pkt;
  while ((pkt = (u_char *) get_str_var_by_num (lexic, i++)) != NULL)
    {
      struct ip *ip = (struct ip *) pkt;
      struct icmp *icmp;
      icmp = (struct icmp *) (pkt + ip->ip_hl * 4);
      printf ("------\n");
      printf ("\ticmp_id    : %d\n", ntohs (icmp->icmp_id));
      printf ("\ticmp_code  : %d\n", icmp->icmp_code);
      printf ("\ticmp_type  : %u\n", icmp->icmp_type);
      printf ("\ticmp_seq   : %u\n", ntohs (icmp->icmp_seq));
      printf ("\ticmp_cksum : %d\n", ntohs (icmp->icmp_cksum));
      printf ("\tData       : %s\n", icmp->icmp_data);
      printf ("\n");
    }
  return NULL;
}

References get_str_var_by_num().

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dump_ip_packet()

tree_cell* dump_ip_packet

(

lex_ctxt *

lexic

)

Dump IP datagrams.

Parameters

[in]	lexic	Lexical context of NASL interpreter.
[in]	...	IP datagrams to dump.

Definition at line 434 of file nasl_packet_forgery.c.

{
  int i;
 
  for (i = 0;; i++)
    {
      struct ip *ip = (struct ip *) get_str_var_by_num (lexic, i);
      if (ip == NULL)
        break;
      else
        {
          printf ("------\n");
          printf ("\tip_hl  : %d\n", ip->ip_hl);
          printf ("\tip_v   : %d\n", ip->ip_v);
          printf ("\tip_tos : %d\n", ip->ip_tos);
          printf ("\tip_len : %d\n", UNFIX (ip->ip_len));
          printf ("\tip_id  : %d\n", ntohs (ip->ip_id));
          printf ("\tip_off : %d\n", UNFIX (ip->ip_off));
          printf ("\tip_ttl : %d\n", ip->ip_ttl);
          switch (ip->ip_p)
            {
            case IPPROTO_TCP:
              printf ("\tip_p   : IPPROTO_TCP (%d)\n", ip->ip_p);
              break;
            case IPPROTO_UDP:
              printf ("\tip_p   : IPPROTO_UDP (%d)\n", ip->ip_p);
              break;
            case IPPROTO_ICMP:
              printf ("\tip_p   : IPPROTO_ICMP (%d)\n", ip->ip_p);
              break;
            default:
              printf ("\tip_p   : %d\n", ip->ip_p);
              break;
            }
          printf ("\tip_sum : 0x%x\n", ntohs (ip->ip_sum));
          printf ("\tip_src : %s\n", inet_ntoa (ip->ip_src));
          printf ("\tip_dst : %s\n", inet_ntoa (ip->ip_dst));
          printf ("\n");
        }
    }
 
  return FAKE_CELL;
}

References FAKE_CELL, get_str_var_by_num(), and UNFIX.

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dump_tcp_packet()

tree_cell* dump_tcp_packet

(

lex_ctxt *

lexic

)

Dump the TCP part of a IP Datagram.

Parameters

[in]	lexic	Lexical context of NASL interpreter.
[in]	...	IP datagrams to dump the TCP part from.

Definition at line 1304 of file nasl_packet_forgery.c.

{
  int i = 0;
  u_char *pkt;
  while ((pkt = (u_char *) get_str_var_by_num (lexic, i++)) != NULL)
    {
      int a = 0;
      struct ip *ip = (struct ip *) pkt;
      struct tcphdr *tcp = (struct tcphdr *) (pkt + ip->ip_hl * 4);
      unsigned int j;
      unsigned int limit;
      char *c;
      limit = get_var_size_by_num (lexic, i - 1);
      printf ("------\n");
      printf ("\tth_sport : %d\n", ntohs (tcp->th_sport));
      printf ("\tth_dport : %d\n", ntohs (tcp->th_dport));
      printf ("\tth_seq   : %u\n", (unsigned int) ntohl (tcp->th_seq));
      printf ("\tth_ack   : %u\n", (unsigned int) ntohl (tcp->th_ack));
      printf ("\tth_x2    : %d\n", tcp->th_x2);
      printf ("\tth_off   : %d\n", tcp->th_off);
      printf ("\tth_flags : ");
      if (tcp->th_flags & TH_FIN)
        {
          printf ("TH_FIN");
          a++;
        }
      if (tcp->th_flags & TH_SYN)
        {
          if (a)
            printf ("|");
          printf ("TH_SYN");
          a++;
        }
      if (tcp->th_flags & TH_RST)
        {
          if (a)
            printf ("|");
          printf ("TH_RST");
          a++;
        }
      if (tcp->th_flags & TH_PUSH)
        {
          if (a)
            printf ("|");
          printf ("TH_PUSH");
          a++;
        }
      if (tcp->th_flags & TH_ACK)
        {
          if (a)
            printf ("|");
          printf ("TH_ACK");
          a++;
        }
      if (tcp->th_flags & TH_URG)
        {
          if (a)
            printf ("|");
          printf ("TH_URG");
          a++;
        }
      if (!a)
        printf ("0");
      else
        printf (" (%d)", tcp->th_flags);
      printf ("\n");
      printf ("\tth_win   : %d\n", ntohs (tcp->th_win));
      printf ("\tth_sum   : 0x%x\n", ntohs (tcp->th_sum));
      printf ("\tth_urp   : %d\n", ntohs (tcp->th_urp));
 
      if (tcp->th_off > 5) // Options present
        {
          char *options;
          struct tcp_options *tcp_all_options;
 
          options =
            (char *) g_malloc0 (sizeof (uint8_t) * 4 * (tcp->th_off - 5));
          memcpy (options, (char *) tcp + 20, (tcp->th_off - 5) * 4);
 
          tcp_all_options = g_malloc0 (sizeof (struct tcp_options));
          get_tcp_options (options, tcp_all_options);
          if (tcp_all_options != NULL)
            {
              printf ("\tTCP Options:\n");
              printf ("\t\tTCPOPT_MAXSEG: %u\n",
                      ntohs ((uint16_t) tcp_all_options->mss.mss));
              printf ("\t\tTCPOPT_WINDOW: %u\n",
                      tcp_all_options->wscale.wscale);
              printf ("\t\tTCPOPT_SACK_PERMITTED: %u\n",
                      tcp_all_options->sack_perm.kind ? 1 : 0);
              printf ("\t\tTCPOPT_TIMESTAMP TSval: %u\n",
                      ntohl ((uint32_t) tcp_all_options->tstamp.tstamp));
              printf ("\t\tTCPOPT_TIMESTAMP TSecr: %u\n",
                      ntohl ((uint32_t) tcp_all_options->tstamp.e_tstamp));
            }
          g_free (options);
          g_free (tcp_all_options);
        }
 
      printf ("\n\tData     : ");
      c = (char *) ((char *) tcp + sizeof (struct tcphdr)
                    + sizeof (uint8_t) * 4 * (tcp->th_off - 5));
      if (UNFIX (ip->ip_len) > (sizeof (struct ip) + sizeof (struct tcphdr)))
        for (j = 0; j < UNFIX (ip->ip_len) - sizeof (struct ip)
                          - sizeof (struct tcphdr)
                          - sizeof (uint8_t) * 4 * (tcp->th_off - 5)
                    && j < limit;
             j++)
          printf ("%c", isprint (c[j]) ? c[j] : '.');
      printf ("\n");
 
      printf ("\n");
    }
  return NULL;
}

References tcp_opt_tstamp::e_tstamp, get_str_var_by_num(), get_tcp_options(), get_var_size_by_num(), tcp_opt_sack_perm::kind, tcp_options::mss, tcp_opt_mss::mss, tcp_options::sack_perm, tcp_options::tstamp, tcp_opt_tstamp::tstamp, UNFIX, tcp_options::wscale, and tcp_opt_wscale::wscale.

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dump_udp_packet()

tree_cell* dump_udp_packet

(

lex_ctxt *

lexic

)

Dump the UDP part of a IP Datagram.

Parameters

[in]	lexic	Lexical context of NASL interpreter.
[in]	...	IP datagrams to dump the UDP part from.

Definition at line 1732 of file nasl_packet_forgery.c.

{
  int i = 0;
  u_char *pkt;
  while ((pkt = (u_char *) get_str_var_by_num (lexic, i++)) != NULL)
    {
      struct udphdr *udp = (struct udphdr *) (pkt + sizeof (struct ip));
      unsigned int j;
      char *c;
      unsigned int limit = get_var_size_by_num (lexic, i - 1);
      printf ("------\n");
      printf ("\tuh_sport : %d\n", ntohs (udp->uh_sport));
      printf ("\tuh_dport : %d\n", ntohs (udp->uh_dport));
      printf ("\tuh_sum   : 0x%x\n", udp->uh_sum);
      printf ("\tuh_ulen  : %d\n", ntohs (udp->uh_ulen));
      printf ("\tdata     : ");
      c = (char *) udp;
      if (udp->uh_ulen > sizeof (struct udphdr))
        for (j = sizeof (struct udphdr);
             j < (ntohs (udp->uh_ulen)) && j < limit; j++)
          printf ("%c", isprint (c[j]) ? c[j] : '.');
 
      printf ("\n");
    }
  return NULL;
}

References get_str_var_by_num(), and get_var_size_by_num().

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forge_icmp_packet()

tree_cell* forge_icmp_packet

(

lex_ctxt *

lexic

)

Fill an IP datagram with ICMP data.

Parameters

[in]	lexic	Lexical context of NASL interpreter.
[in]	ip	IP datagram that is updated.
[in]	data	Payload.
[in]	icmp_cksum	Checksum, computed by default.
[in]	icmp_code	ICMP code. 0 by default.
[in]	icmp_id	ICMP ID. 0 by default.
[in]	icmp_seq	ICMP sequence number.
[in]	icmp_type	ICMP type. 0 by default.
[in]	update_ip_len	Flag (TRUE by default). If set, NASL will recompute the size field of the IP datagram.

Returns

Modified IP datagram.

Definition at line 1778 of file nasl_packet_forgery.c.

{
  tree_cell *retc = NULL;
  struct ip *ip;
  struct ip *ip_icmp;
  int ip_sz;
  struct icmp *icmp;
  char *data, *p;
  int len;
  u_char *pkt;
  int t;
 
  ip = (struct ip *) get_str_var_by_name (lexic, "ip");
  ip_sz = get_var_size_by_name (lexic, "ip");
  if (ip != NULL)
    {
      data = get_str_var_by_name (lexic, "data");
      len = data == NULL ? 0 : get_var_size_by_name (lexic, "data");
 
      t = get_int_var_by_name (lexic, "icmp_type", 0);
      if (t == 13 || t == 14)
        len += 3 * sizeof (time_t);
 
      if (ip->ip_hl * 4 > ip_sz)
        return NULL;
 
      pkt = g_malloc0 (sizeof (struct icmp) + ip_sz + len);
      ip_icmp = (struct ip *) pkt;
 
      bcopy (ip, ip_icmp, ip_sz);
      if (UNFIX (ip_icmp->ip_len) <= (ip_icmp->ip_hl * 4))
        {
          if (get_int_var_by_name (lexic, "update_ip_len", 1) != 0)
            {
              ip_icmp->ip_len = FIX (ip->ip_hl * 4 + 8 + len);
              ip_icmp->ip_sum = 0;
              ip_icmp->ip_sum =
                np_in_cksum ((u_short *) ip_icmp, ip->ip_hl * 4);
            }
        }
      p = (char *) (pkt + (ip->ip_hl * 4));
      icmp = (struct icmp *) p;
 
      icmp->icmp_code = get_int_var_by_name (lexic, "icmp_code", 0);
      icmp->icmp_type = t;
      icmp->icmp_seq = htons (get_int_var_by_name (lexic, "icmp_seq", 0));
      icmp->icmp_id = htons (get_int_var_by_name (lexic, "icmp_id", 0));
 
      if (data != NULL)
        bcopy (data, &(p[8]), len);
 
      if (get_int_var_by_name (lexic, "icmp_cksum", -1) == -1)
        icmp->icmp_cksum = np_in_cksum ((u_short *) icmp, len + 8);
      else
        icmp->icmp_cksum = htons (get_int_var_by_name (lexic, "icmp_cksum", 0));
 
      retc = alloc_typed_cell (CONST_DATA);
      retc->x.str_val = (char *) pkt;
      retc->size = ip_sz + len + 8;
    }
  else
    nasl_perror (lexic, "forge_icmp_packet: missing 'ip' parameter\n");
 
  return retc;
}

References alloc_typed_cell(), CONST_DATA, FIX, get_int_var_by_name(), get_str_var_by_name(), get_var_size_by_name(), len, nasl_perror(), np_in_cksum(), TC::size, TC::str_val, UNFIX, and TC::x.

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forge_igmp_packet()

tree_cell* forge_igmp_packet

(

lex_ctxt *

lexic

)

Fills an IP datagram with IGMP data.

Parameters

[in]	lexic	Lexical context of NASL interpreter.
[in]	ip	IP datagram that is updated.
[in]	code	0 by default.
[in]	data
[in]	group
[in]	type	0 by default.
[in]	update_ip_len	Flag (TRUE by default). If set, NASL will recompute the size field of the IP datagram.

Returns

Modified IP datagram.

Definition at line 1974 of file nasl_packet_forgery.c.

{
  struct ip *ip = (struct ip *) get_str_var_by_name (lexic, "ip");
 
  if (ip != NULL)
    {
      char *data = get_str_var_by_name (lexic, "data");
      int len = data ? get_var_size_by_name (lexic, "data") : 0;
      u_char *pkt = g_malloc0 (sizeof (struct igmp) + ip->ip_hl * 4 + len);
      struct ip *ip_igmp = (struct ip *) pkt;
      struct igmp *igmp;
      char *p;
      char *grp;
      tree_cell *retc;
      int ipsz = get_var_size_by_name (lexic, "ip");
 
      bcopy (ip, ip_igmp, ipsz);
 
      if (UNFIX (ip_igmp->ip_len) <= ip_igmp->ip_hl * 4)
        {
          int v = get_int_var_by_name (lexic, "update_ip_len", 1);
          if (v != 0)
            {
              ip_igmp->ip_len =
                FIX (ip->ip_hl * 4 + sizeof (struct igmp) + len);
              ip_igmp->ip_sum = 0;
              ip_igmp->ip_sum =
                np_in_cksum ((u_short *) ip_igmp, ip->ip_hl * 4);
            }
        }
      p = (char *) (pkt + ip_igmp->ip_hl * 4);
      igmp = (struct igmp *) p;
 
      igmp->code = get_int_var_by_name (lexic, "code", 0);
      igmp->type = get_int_var_by_name (lexic, "type", 0);
      grp = get_str_var_by_name (lexic, "group");
 
      if (grp != NULL)
        {
          inet_aton (grp, &igmp->group);
        }
 
      igmp->cksum = np_in_cksum ((u_short *) igmp, sizeof (struct igmp));
      if (data != NULL)
        {
          char *ptmp = (char *) (pkt + ip->ip_hl * 4 + sizeof (struct igmp));
          bcopy (ptmp, data, len);
        }
      retc = alloc_typed_cell (CONST_DATA);
      retc->x.str_val = (char *) pkt;
      retc->size = ip->ip_hl * 4 + sizeof (struct igmp) + len;
      return retc;
    }
  else
    nasl_perror (lexic, "forge_igmp_packet: missing 'ip' parameter\n");
 
  return NULL;
}

References alloc_typed_cell(), igmp::cksum, igmp::code, CONST_DATA, FIX, get_int_var_by_name(), get_str_var_by_name(), get_var_size_by_name(), igmp::group, len, nasl_perror(), np_in_cksum(), TC::size, TC::str_val, igmp::type, UNFIX, and TC::x.

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forge_ip_packet()

tree_cell* forge_ip_packet

(

lex_ctxt *

lexic

)

Forge an IP datagram.

Parameters

[in]	lexic	Lexical context of NASL interpreter.
[in]	data	Payload.
[in]	ip_hl	IP header length in 32 bits words. 5 by default.
[in]	ip_id	Datagram ID. Random by default.
[in]	ip_len	Length of the datagram. 20 plus the length of the data field by default.
[in]	ip_off	Fragment offset in 64 bits words. 0 by default.
[in]	ip_p	IP protocol. 0 by default.
[in]	ip_src	Source address in ASCII. NASL will convert it into an integer in network order.
[in]	ip_dst	Destination address in ASCII. NASL will convert it into an integer in network order. Uses the target ip of the current plugin by default.
[in]	ip_sum	Packet header checksum. It will be computed by default.
[in]	ip_tos	Type of service field. 0 by default
[in]	ip_ttl	Time To Live field. 64 by default.
[in]	ip_v	IP version. 4 by default.

Returns

The forged IP packet.

Definition at line 104 of file nasl_packet_forgery.c.

{
  tree_cell *retc;
  struct ip *pkt;
  char *s;
  struct script_infos *script_infos = lexic->script_infos;
  struct in6_addr *dst_addr;
  char *data;
  int data_len;
 
  dst_addr = plug_get_host_ip (script_infos);
 
  if (dst_addr == NULL || (IN6_IS_ADDR_V4MAPPED (dst_addr) != 1))
    {
      nasl_perror (lexic, "forge_ip_packet: No valid dst_addr could be "
                          "determined via call to plug_get_host_ip().\n");
      return NULL;
    }
 
  data = get_str_var_by_name (lexic, "data");
  data_len = get_var_size_by_name (lexic, "data");
 
  retc = alloc_typed_cell (CONST_DATA);
  retc->size = sizeof (struct ip) + data_len;
 
  pkt = (struct ip *) g_malloc0 (sizeof (struct ip) + data_len);
  retc->x.str_val = (char *) pkt;
 
  pkt->ip_hl = get_int_var_by_name (lexic, "ip_hl", 5);
  pkt->ip_v = get_int_var_by_name (lexic, "ip_v", 4);
  pkt->ip_tos = get_int_var_by_name (lexic, "ip_tos", 0);
  /* pkt->ip_len = FIX(get_int_var_by_name(lexic, "ip_len", 20 + data_len)); */
 
  pkt->ip_len = FIX (20 + data_len);
 
  pkt->ip_id = htons (get_int_var_by_name (lexic, "ip_id", rand ()));
  pkt->ip_off = get_int_var_by_name (lexic, "ip_off", 0);
  pkt->ip_off = FIX (pkt->ip_off);
  pkt->ip_ttl = get_int_var_by_name (lexic, "ip_ttl", 64);
  pkt->ip_p = get_int_var_by_name (lexic, "ip_p", 0);
  pkt->ip_sum = htons (get_int_var_by_name (lexic, "ip_sum", 0));
  /* source */
  s = get_str_var_by_name (lexic, "ip_src");
  if (s != NULL)
    inet_aton (s, &pkt->ip_src);
  /* else this host address? */
 
  /* I know that this feature looks dangerous, but anybody can edit an IP
   * packet with the string functions */
  s = get_str_var_by_name (lexic, "ip_dst");
  if (s != NULL)
    inet_aton (s, &pkt->ip_dst);
  else
    pkt->ip_dst.s_addr = dst_addr->s6_addr32[3];
 
  if (data != NULL)
    {
      bcopy (data, retc->x.str_val + sizeof (struct ip), data_len);
    }
 
  if (!pkt->ip_sum)
    {
      if (get_int_var_by_name (lexic, "ip_sum", -1) < 0)
        pkt->ip_sum = np_in_cksum ((u_short *) pkt, sizeof (struct ip));
    }
 
  return retc;
}

References alloc_typed_cell(), CONST_DATA, FIX, get_int_var_by_name(), get_str_var_by_name(), get_var_size_by_name(), nasl_perror(), np_in_cksum(), plug_get_host_ip(), struct_lex_ctxt::script_infos, TC::size, TC::str_val, and TC::x.

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forge_tcp_packet()

tree_cell* forge_tcp_packet

(

lex_ctxt *

lexic

)

Fills an IP datagram with TCP data. Note that the ip_p field is not updated. It returns the modified IP datagram. Its arguments are:

Parameters

[in]	ip	IP datagram to be filled.
[in]	data	TCP data payload.
[in]	th_ack	Acknowledge number. NASL will convert it into network order if necessary. 0 by default.
[in]	th_dport	Destination port. NASL will convert it into network order if necessary. 0 by default.
[in]	th_flags	TCP flags. 0 by default.
[in]	th_off	Size of the TCP header in 32 bits words. By default, 5.
[in]	th_seq	TCP sequence number. NASL will convert it into network order if necessary. Random by default.
[in]	th_sport	Source port. NASL will convert it into network order if necessary. 0 by default.
[in]	th_sum	TCP checksum. Right value is computed by default.
[in]	th_urp	Urgent pointer. 0 by default.
[in]	th_win	TCP window size. NASL will convert it into network order if necessary. 0 by default.
[in]	th_x2	Is a reserved field and should probably be left unchanged. 0 by default.
[in]	update_ip_len	Flag (TRUE by default). If set, NASL will recompute the size field of the IP datagram.

Returns

Modified IP datagram.

Definition at line 555 of file nasl_packet_forgery.c.

{
  tree_cell *retc;
  char *data;
  int len;
  struct ip *ip, *tcp_packet;
  struct tcphdr *tcp;
  int ipsz;
 
  ip = (struct ip *) get_str_var_by_name (lexic, "ip");
  if (ip == NULL)
    {
      nasl_perror (lexic,
                   "forge_tcp_packet: You must supply the 'ip' argument\n");
      return NULL;
    }
 
  ipsz = get_var_size_by_name (lexic, "ip");
  if (ipsz > ip->ip_hl * 4)
    ipsz = ip->ip_hl * 4;
 
  data = get_str_var_by_name (lexic, "data");
  len = data == NULL ? 0 : get_var_size_by_name (lexic, "data");
 
  retc = alloc_typed_cell (CONST_DATA);
  tcp_packet = (struct ip *) g_malloc0 (ipsz + sizeof (struct tcphdr) + len);
  retc->x.str_val = (char *) tcp_packet;
 
  bcopy (ip, tcp_packet, ipsz);
  /* recompute the ip checksum, because the ip length changed */
  if (UNFIX (tcp_packet->ip_len) <= tcp_packet->ip_hl * 4)
    {
      if (get_int_var_by_name (lexic, "update_ip_len", 1))
        {
          tcp_packet->ip_len =
            FIX (tcp_packet->ip_hl * 4 + sizeof (struct tcphdr) + len);
          tcp_packet->ip_sum = 0;
          tcp_packet->ip_sum =
            np_in_cksum ((u_short *) tcp_packet, sizeof (struct ip));
        }
    }
  tcp = (struct tcphdr *) ((char *) tcp_packet + tcp_packet->ip_hl * 4);
 
  tcp->th_sport = ntohs (get_int_var_by_name (lexic, "th_sport", 0));
  tcp->th_dport = ntohs (get_int_var_by_name (lexic, "th_dport", 0));
  tcp->th_seq = htonl (get_int_var_by_name (lexic, "th_seq", rand ()));
  tcp->th_ack = htonl (get_int_var_by_name (lexic, "th_ack", 0));
  tcp->th_x2 = get_int_var_by_name (lexic, "th_x2", 0);
  tcp->th_off = get_int_var_by_name (lexic, "th_off", 5);
  tcp->th_flags = get_int_var_by_name (lexic, "th_flags", 0);
  tcp->th_win = htons (get_int_var_by_name (lexic, "th_win", 0));
  tcp->th_sum = get_int_var_by_name (lexic, "th_sum", 0);
  tcp->th_urp = get_int_var_by_name (lexic, "th_urp", 0);
 
  if (data != NULL)
    bcopy (data, (char *) tcp + sizeof (struct tcphdr), len);
 
  if (!tcp->th_sum)
    {
      struct pseudohdr pseudoheader;
      char *tcpsumdata = g_malloc0 (sizeof (struct pseudohdr) + len + 1);
      struct in_addr source, dest;
 
      source.s_addr = ip->ip_src.s_addr;
      dest.s_addr = ip->ip_dst.s_addr;
 
      bzero (&pseudoheader, 12 + sizeof (struct tcphdr));
      pseudoheader.saddr.s_addr = source.s_addr;
      pseudoheader.daddr.s_addr = dest.s_addr;
 
      pseudoheader.protocol = IPPROTO_TCP;
      pseudoheader.length = htons (sizeof (struct tcphdr) + len);
      bcopy ((char *) tcp, (char *) &pseudoheader.tcpheader,
             sizeof (struct tcphdr));
      /* fill tcpsumdata with data to checksum */
      bcopy ((char *) &pseudoheader, tcpsumdata, sizeof (struct pseudohdr));
      if (data != NULL)
        bcopy ((char *) data, tcpsumdata + sizeof (struct pseudohdr), len);
      tcp->th_sum = np_in_cksum ((unsigned short *) tcpsumdata,
                                 12 + sizeof (struct tcphdr) + len);
      g_free (tcpsumdata);
    }
 
  retc->size = ipsz + sizeof (struct tcphdr) + len;
  return retc;
}

References alloc_typed_cell(), CONST_DATA, pseudohdr::daddr, FIX, get_int_var_by_name(), get_str_var_by_name(), get_var_size_by_name(), len, pseudohdr::length, nasl_perror(), np_in_cksum(), pseudohdr::protocol, pseudohdr::saddr, TC::size, TC::str_val, pseudohdr::tcpheader, UNFIX, and TC::x.

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forge_udp_packet()

tree_cell* forge_udp_packet

(

lex_ctxt *

lexic

)

Fills an IP datagram with UDP data. Note that the ip_p field is not updated. It returns the modified IP datagram. Its arguments are:

Parameters

[in]	ip	IP datagram to be filled.
[in]	data	Payload.
[in]	uh_dport	Destination port. NASL will convert it into network order if necessary. 0 by default.
[in]	uh_sport	Source port. NASL will convert it into network order if necessary. 0 by default.
[in]	uh_sum	UDP checksum. Although it is not compulsory, the right value is computed by default.
[in]	uh_ulen	Data length. By default it is set to the length of the data argument plus the size of the UDP header.
[in]	update_ip_len	Flag (TRUE by default). If set, NASL will recompute the size field of the IP datagram.

Returns

Modified IP datagram.

Definition at line 1451 of file nasl_packet_forgery.c.

{
  tree_cell *retc;
  struct ip *ip = (struct ip *) get_str_var_by_name (lexic, "ip");
 
  if (ip != NULL)
    {
      char *data = get_str_var_by_name (lexic, "data");
      int data_len = get_var_size_by_name (lexic, "data");
      u_char *pkt;
      struct ip *udp_packet;
      struct udphdr *udp;
 
      pkt = g_malloc0 (sizeof (struct udphdr) + ip->ip_hl * 4
                       + sizeof (struct udphdr) + data_len);
 
      udp_packet = (struct ip *) pkt;
      udp = (struct udphdr *) (pkt + ip->ip_hl * 4);
 
      udp->uh_sport = htons (get_int_var_by_name (lexic, "uh_sport", 0));
      udp->uh_dport = htons (get_int_var_by_name (lexic, "uh_dport", 0));
      udp->uh_ulen = htons (get_int_var_by_name (
        lexic, "uh_ulen", data_len + sizeof (struct udphdr)));
 
      /* printf("len : %d %s\n", len, data); */
      if (data_len != 0 && data != NULL)
        bcopy (data, (pkt + ip->ip_hl * 4 + sizeof (struct udphdr)), data_len);
 
      udp->uh_sum = get_int_var_by_name (lexic, "uh_sum", 0);
      bcopy ((char *) ip, pkt, ip->ip_hl * 4);
      if (udp->uh_sum == 0)
        {
          struct pseudo_udp_hdr pseudohdr;
          struct in_addr source, dest;
          char *udpsumdata =
            g_malloc0 (sizeof (struct pseudo_udp_hdr) + data_len + 1);
 
          source.s_addr = ip->ip_src.s_addr;
          dest.s_addr = ip->ip_dst.s_addr;
 
          bzero (&pseudohdr, sizeof (struct pseudo_udp_hdr));
          pseudohdr.saddr.s_addr = source.s_addr;
          pseudohdr.daddr.s_addr = dest.s_addr;
 
          pseudohdr.proto = IPPROTO_UDP;
          pseudohdr.len = htons (sizeof (struct udphdr) + data_len);
          bcopy ((char *) udp, (char *) &pseudohdr.udpheader,
                 sizeof (struct udphdr));
          bcopy ((char *) &pseudohdr, udpsumdata, sizeof (pseudohdr));
          if (data != NULL)
            {
              bcopy ((char *) data, udpsumdata + sizeof (pseudohdr), data_len);
            }
          udp->uh_sum = np_in_cksum ((unsigned short *) udpsumdata,
                                     12 + sizeof (struct udphdr) + data_len);
          g_free (udpsumdata);
        }
 
      if (UNFIX (udp_packet->ip_len) <= udp_packet->ip_hl * 4)
        {
          int v = get_int_var_by_name (lexic, "update_ip_len", 1);
          if (v != 0)
            {
              udp_packet->ip_len =
                FIX (ntohs (udp->uh_ulen) + (udp_packet->ip_hl * 4));
              udp_packet->ip_sum = 0;
              udp_packet->ip_sum =
                np_in_cksum ((u_short *) udp_packet, udp_packet->ip_hl * 4);
            }
        }
 
      retc = alloc_typed_cell (CONST_DATA);
      retc->x.str_val = (char *) pkt;
      retc->size = 8 + ip->ip_hl * 4 + data_len;
      return retc;
    }
  else
    nasl_perror (lexic,
                 "forge_udp_packet: Invalid value for the argument 'ip'\n");
 
  return NULL;
}

References alloc_typed_cell(), CONST_DATA, pseudohdr::daddr, FIX, get_int_var_by_name(), get_str_var_by_name(), get_var_size_by_name(), nasl_perror(), np_in_cksum(), pseudohdr::saddr, TC::size, TC::str_val, UNFIX, and TC::x.

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get_icmp_element()

tree_cell* get_icmp_element

(

lex_ctxt *

lexic

)

Get an ICMP element from a IP datagram.

Parameters

[in]	lexic	Lexical context of NASL interpreter.
[in]	icmp	Full IP datagram (IP + ICMP).
[in]	element	Name of the TCP field (see forge_tcp_packet()).

Returns

Data block or an integer, according to the type of the element.

Definition at line 1854 of file nasl_packet_forgery.c.

{
  struct icmp *icmp;
  char *p;
 
  if ((p = get_str_var_by_name (lexic, "icmp")) != NULL)
    {
      char *elem = get_str_var_by_name (lexic, "element");
      int value;
      struct ip *ip = (struct ip *) p;
      tree_cell *retc;
 
      icmp = (struct icmp *) (p + ip->ip_hl * 4);
 
      if (elem == NULL)
        {
          nasl_perror (lexic,
                       "get_icmp_element: missing 'element' parameter\n");
          return NULL;
        }
 
      if (!strcmp (elem, "icmp_id"))
        value = ntohs (icmp->icmp_id);
      else if (!strcmp (elem, "icmp_code"))
        value = icmp->icmp_code;
      else if (!strcmp (elem, "icmp_type"))
        value = icmp->icmp_type;
      else if (!strcmp (elem, "icmp_seq"))
        value = ntohs (icmp->icmp_seq);
      else if (!strcmp (elem, "icmp_cksum"))
        value = ntohs (icmp->icmp_cksum);
      else if (!strcmp (elem, "data"))
        {
          retc = alloc_typed_cell (CONST_DATA);
          retc->size =
            get_var_size_by_name (lexic, "icmp") - (ip->ip_hl * 4) - 8;
          if (retc->size > 0)
            {
              retc->x.str_val = g_malloc0 (retc->size + 1);
              memcpy (retc->x.str_val, &(p[ip->ip_hl * 4 + 8]), retc->size + 1);
            }
          else
            {
              retc->x.str_val = NULL;
              retc->size = 0;
            }
          return retc;
        }
      else
        {
          nasl_perror (
            lexic,
            "get_icmp_element: Element '%s' is not a valid element to get.\n",
            elem);
          return NULL;
        }
 
      retc = alloc_typed_cell (CONST_INT);
      retc->x.i_val = value;
      return retc;
    }
  else
    nasl_perror (lexic, "get_icmp_element: missing 'icmp' parameter\n");
 
  return NULL;
}

References alloc_typed_cell(), CONST_DATA, CONST_INT, get_str_var_by_name(), get_var_size_by_name(), TC::i_val, nasl_perror(), TC::size, TC::str_val, and TC::x.

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get_ip_element()

tree_cell* get_ip_element

(

lex_ctxt *

lexic

)

Extracts a field from an IP datagram.

Parameters

[in]	lexic	Lexical context of NASL interpreter.
[in]	element	Name of the field, e.g. "ip_len" or "ip_src".
[in]	ip	IP datagram or fragment.

Returns

integer or a string, depending on the type of the element.

Definition at line 183 of file nasl_packet_forgery.c.

{
  tree_cell *retc;
  struct ip *ip = (struct ip *) get_str_var_by_name (lexic, "ip");
  char *element = get_str_var_by_name (lexic, "element");
  char ret_ascii[32];
  int ret_int = 0;
  int flag = 0;
 
  if (ip == NULL)
    {
      nasl_perror (lexic, "get_ip_element: no valid 'ip' argument\n");
      return NULL;
    }
 
  if (element == NULL)
    {
      nasl_perror (lexic, "get_ip_element: no valid 'element' argument\n");
      return NULL;
    }
 
  if (!strcmp (element, "ip_v"))
    {
      ret_int = ip->ip_v;
      flag++;
    }
  else if (!strcmp (element, "ip_id"))
    {
      ret_int = UNFIX (ip->ip_id);
      flag++;
    }
  else if (!strcmp (element, "ip_hl"))
    {
      ret_int = ip->ip_hl;
      flag++;
    }
  else if (!strcmp (element, "ip_tos"))
    {
      ret_int = ip->ip_tos;
      flag++;
    }
  else if (!strcmp (element, "ip_len"))
    {
      ret_int = UNFIX (ip->ip_len);
      flag++;
    }
  else if (!strcmp (element, "ip_off"))
    {
      ret_int = UNFIX (ip->ip_off);
      flag++;
    }
  else if (!strcmp (element, "ip_ttl"))
    {
      ret_int = ip->ip_ttl;
      flag++;
    }
  else if (!strcmp (element, "ip_p"))
    {
      ret_int = ip->ip_p;
      flag++;
    }
  else if (!strcmp (element, "ip_sum"))
    {
      ret_int = UNFIX (ip->ip_sum);
      flag++;
    }
 
  if (flag != 0)
    {
      retc = alloc_typed_cell (CONST_INT);
      retc->x.i_val = ret_int;
      return retc;
    }
 
  if (!strcmp (element, "ip_src"))
    {
      snprintf (ret_ascii, sizeof (ret_ascii), "%s", inet_ntoa (ip->ip_src));
      flag++;
    }
  else if (!strcmp (element, "ip_dst"))
    {
      snprintf (ret_ascii, sizeof (ret_ascii), "%s", inet_ntoa (ip->ip_dst));
      flag++;
    }
 
  if (flag == 0)
    {
      nasl_perror (lexic, "%s: unknown element '%s'\n", __func__, element);
      return NULL;
    }
 
  retc = alloc_typed_cell (CONST_DATA);
  retc->size = strlen (ret_ascii);
  retc->x.str_val = g_strdup (ret_ascii);
 
  return retc;
}

References alloc_typed_cell(), CONST_DATA, CONST_INT, get_str_var_by_name(), TC::i_val, nasl_perror(), TC::size, TC::str_val, UNFIX, and TC::x.

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get_tcp_element()

tree_cell* get_tcp_element

(

lex_ctxt *

lexic

)

Extracts TCP field from an IP datagram.

Parameters

[in]	lexic	Lexical context of NASL interpreter.
[in]	element	Name of the the TCP field. See forge_tcp_packet().
[in]	tcp	The full IP datagram (IP + TCP).

Returns

Data block or an integer, according to the type of the element.

Definition at line 652 of file nasl_packet_forgery.c.

{
  u_char *packet = (u_char *) get_str_var_by_name (lexic, "tcp");
  struct ip *ip;
  int ipsz;
  struct tcphdr *tcp;
  char *element;
  int ret;
  tree_cell *retc;
 
  ipsz = get_var_size_by_name (lexic, "tcp");
 
  if (packet == NULL)
    {
      nasl_perror (lexic, "get_tcp_element: No valid 'tcp' argument\n");
      return NULL;
    }
 
  ip = (struct ip *) packet;
 
  if (ip->ip_hl * 4 > ipsz)
    return NULL; /* Invalid packet */
 
  if (UNFIX (ip->ip_len) > ipsz)
    return NULL; /* Invalid packet */
 
  tcp = (struct tcphdr *) (packet + ip->ip_hl * 4);
 
  element = get_str_var_by_name (lexic, "element");
  if (!element)
    {
      nasl_perror (lexic, "get_tcp_element: No valid 'element' argument\n");
      return NULL;
    }
 
  if (!strcmp (element, "th_sport"))
    ret = ntohs (tcp->th_sport);
  else if (!strcmp (element, "th_dsport"))
    ret = ntohs (tcp->th_dport);
  else if (!strcmp (element, "th_seq"))
    ret = ntohl (tcp->th_seq);
  else if (!strcmp (element, "th_ack"))
    ret = ntohl (tcp->th_ack);
  else if (!strcmp (element, "th_x2"))
    ret = tcp->th_x2;
  else if (!strcmp (element, "th_off"))
    ret = tcp->th_off;
  else if (!strcmp (element, "th_flags"))
    ret = tcp->th_flags;
  else if (!strcmp (element, "th_win"))
    ret = ntohs (tcp->th_win);
  else if (!strcmp (element, "th_sum"))
    ret = tcp->th_sum;
  else if (!strcmp (element, "th_urp"))
    ret = tcp->th_urp;
  else if (!strcmp (element, "data"))
    {
      retc = alloc_typed_cell (CONST_DATA);
      retc->size = UNFIX (ip->ip_len) - (tcp->th_off + ip->ip_hl) * 4;
      retc->x.str_val = g_malloc0 (retc->size);
      bcopy ((char *) tcp + tcp->th_off * 4, retc->x.str_val, retc->size);
      return retc;
    }
  else
    {
      nasl_perror (lexic, "get_tcp_element: Unknown tcp field %s\n", element);
      return NULL;
    }
 
  retc = alloc_typed_cell (CONST_INT);
  retc->x.i_val = ret;
  return retc;
}

References alloc_typed_cell(), CONST_DATA, CONST_INT, get_str_var_by_name(), get_var_size_by_name(), TC::i_val, nasl_perror(), TC::size, TC::str_val, UNFIX, and TC::x.

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get_tcp_option()

tree_cell* get_tcp_option

(

lex_ctxt *

lexic

)

Get a TCP option from an IP datagram if present. Possible options are: TCPOPT_MAXSEG (2), values between 536 and 65535 TCPOPT_WINDOW (3), with values between 0 and 14 TCPOPT_SACK_PERMITTED (4), no value required. TCPOPT_TIMESTAMP (8), 8 bytes value for timestamp and echo timestamp, 4 bytes each one.

Parameters

[in]	lexic	Lexical context of NASL interpreter.
[in]	tcp	The full IP datagram (IP + TCP).
[in]	option	Option to get.

Returns

Integer or array given the case.

Definition at line 802 of file nasl_packet_forgery.c.

{
  u_char *packet = (u_char *) get_str_var_by_name (lexic, "tcp");
  struct ip *ip;
  int ipsz;
  struct tcphdr *tcp;
  char *options;
  int opt;
  tree_cell *retc;
  nasl_array *arr;
  anon_nasl_var v;
 
  struct tcp_options *tcp_all_options = NULL;
 
  if (packet == NULL)
    {
      nasl_perror (lexic, "%s: No valid 'tcp' argument passed.\n", __func__);
      return NULL;
    }
 
  opt = get_int_var_by_name (lexic, "option", -1);
  if (opt < 0)
    {
      nasl_perror (lexic,
                   "%s: No options\n."
                   "Usage: %s(tcp:<tcp>, option:<TCPOPT>)",
                   __func__, __func__);
      return NULL;
    }
 
  ip = (struct ip *) packet;
 
  ipsz = get_var_size_by_name (lexic, "tcp");
  if (ip->ip_hl * 4 > ipsz)
    return NULL; /* Invalid packet */
 
  if (UNFIX (ip->ip_len) > ipsz)
    return NULL; /* Invalid packet */
 
  tcp = (struct tcphdr *) (packet + ip->ip_hl * 4);
 
  if (tcp->th_off <= 5)
    return NULL;
 
  // Get options from the segment
  options = (char *) g_malloc0 (sizeof (uint8_t) * 4 * (tcp->th_off - 5));
  memcpy (options, (char *) tcp + 20, (tcp->th_off - 5) * 4);
 
  tcp_all_options = g_malloc0 (sizeof (struct tcp_options));
  get_tcp_options (options, tcp_all_options);
  if (tcp_all_options == NULL)
    {
      nasl_perror (lexic, "%s: No TCP options found in passed TCP packet.\n",
                   __func__);
 
      g_free (options);
      return NULL;
    }
 
  opt = get_int_var_by_name (lexic, "option", -1);
  retc = NULL;
  switch (opt)
    {
    case TCPOPT_MAXSEG:
      retc = alloc_typed_cell (CONST_INT);
      retc->x.i_val = ntohs ((uint16_t) tcp_all_options->mss.mss);
      break;
    case TCPOPT_WINDOW:
      retc = alloc_typed_cell (CONST_INT);
      retc->x.i_val = tcp_all_options->wscale.wscale;
      break;
    case TCPOPT_SACK_PERMITTED:
      retc = alloc_typed_cell (CONST_INT);
      retc->x.i_val = tcp_all_options->sack_perm.kind ? 1 : 0;
      break;
    case TCPOPT_TIMESTAMP:
      retc = alloc_typed_cell (DYN_ARRAY);
      retc->x.ref_val = arr = g_malloc0 (sizeof (nasl_array));
 
      memset (&v, 0, sizeof (v));
      v.var_type = VAR2_INT;
      v.v.v_int = ntohl ((uint32_t) tcp_all_options->tstamp.tstamp);
      add_var_to_array (arr, "timestamp", &v);
 
      memset (&v, 0, sizeof (v));
      v.var_type = VAR2_INT;
      v.v.v_int = ntohl ((uint32_t) tcp_all_options->tstamp.e_tstamp);
      add_var_to_array (arr, "echo_timestamp", &v);
      break;
    default:
      nasl_perror (lexic, "%s: Invalid TCP option passed.\n", __func__);
      break;
    }
 
  g_free (tcp_all_options);
  g_free (options);
  return retc;
}

References add_var_to_array(), alloc_typed_cell(), CONST_INT, DYN_ARRAY, tcp_opt_tstamp::e_tstamp, get_int_var_by_name(), get_str_var_by_name(), get_tcp_options(), get_var_size_by_name(), TC::i_val, tcp_opt_sack_perm::kind, tcp_options::mss, tcp_opt_mss::mss, nasl_perror(), TC::ref_val, tcp_options::sack_perm, tcp_options::tstamp, tcp_opt_tstamp::tstamp, UNFIX, st_a_nasl_var::v, st_a_nasl_var::v_int, VAR2_INT, st_a_nasl_var::var_type, tcp_options::wscale, tcp_opt_wscale::wscale, and TC::x.

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get_udp_element()

tree_cell* get_udp_element

(

lex_ctxt *

lexic

)

Get an UDP element from a IP datagram.

Parameters

[in]	lexic	Lexical context of NASL interpreter.
[in]	udp	The full IP datagram (IP + UDP).
[in]	element	Name of the UDP field (see forge_udp_packet()).

Returns

Data block or an integer, according to the type of the element.

Definition at line 1544 of file nasl_packet_forgery.c.

{
  tree_cell *retc;
  char *udp;
  char *element;
  struct ip *ip;
  unsigned int ipsz;
  struct udphdr *udphdr;
  int ret;
 
  udp = get_str_var_by_name (lexic, "udp");
  ipsz = get_var_size_by_name (lexic, "udp");
 
  element = get_str_var_by_name (lexic, "element");
  if (udp == NULL || element == NULL)
    {
      nasl_perror (lexic, "get_udp_element: usage :\nelement = "
                          "get_udp_element(udp:<udp>,element:<element>\n");
      return NULL;
    }
  ip = (struct ip *) udp;
 
  if (ip->ip_hl * 4 + sizeof (struct udphdr) > ipsz)
    return NULL;
 
  udphdr = (struct udphdr *) (udp + ip->ip_hl * 4);
  if (!strcmp (element, "uh_sport"))
    ret = ntohs (udphdr->uh_sport);
  else if (!strcmp (element, "uh_dport"))
    ret = ntohs (udphdr->uh_dport);
  else if (!strcmp (element, "uh_ulen"))
    ret = ntohs (udphdr->uh_ulen);
  else if (!strcmp (element, "uh_sum"))
    ret = ntohs (udphdr->uh_sum);
  else if (!strcmp (element, "data"))
    {
      int sz;
      retc = alloc_typed_cell (CONST_DATA);
      sz = ntohs (udphdr->uh_ulen) - sizeof (struct udphdr);
 
      if (ntohs (udphdr->uh_ulen) - ip->ip_hl * 4 - sizeof (struct udphdr)
          > ipsz)
        sz = ipsz - ip->ip_hl * 4 - sizeof (struct udphdr);
 
      retc->x.str_val = g_malloc0 (sz);
      retc->size = sz;
      bcopy (udp + ip->ip_hl * 4 + sizeof (struct udphdr), retc->x.str_val, sz);
      return retc;
    }
  else
    {
      nasl_perror (lexic, "%s: '%s' is not a value of a udp packet\n", __func__,
                   element);
      return NULL;
    }
 
  retc = alloc_typed_cell (CONST_INT);
  retc->x.i_val = ret;
  return retc;
}

References alloc_typed_cell(), CONST_DATA, CONST_INT, get_str_var_by_name(), get_var_size_by_name(), TC::i_val, nasl_perror(), TC::size, TC::str_val, and TC::x.

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insert_ip_options()

tree_cell* insert_ip_options

(

lex_ctxt *

lexic

)

Add option datagram.

Parameters

[in]	lexic	Lexical context of NASL interpreter.
[in]	ip	IP datagram to add the option to.
[in]	code	Number of the option.
[in]	length	Length of the option data.
[in]	value	Option data.

Returns

The modified IP datagram.

Definition at line 357 of file nasl_packet_forgery.c.

{
  struct ip *ip = (struct ip *) get_str_var_by_name (lexic, "ip");
  int code = get_int_var_by_name (lexic, "code", 0);
  int len = get_int_var_by_name (lexic, "length", 0);
  char *value = get_str_var_by_name (lexic, "value");
  int value_size = get_var_size_by_name (lexic, "value");
  tree_cell *retc;
  struct ip *new_packet;
  char *p;
  int size = get_var_size_by_name (lexic, "ip");
  u_char uc_code, uc_len;
  int pad_len;
  char zero = '0';
  int i;
  int hl;
 
  if (ip == NULL)
    {
      nasl_perror (lexic, "Usage : insert_ip_options(ip:<ip>, code:<code>, "
                          "length:<len>, value:<value>\n");
      return NULL;
    }
 
  pad_len = 4 - ((sizeof (uc_code) + sizeof (uc_len) + value_size) % 4);
  if (pad_len == 4)
    pad_len = 0;
 
  hl = ip->ip_hl * 4 < UNFIX (ip->ip_len) ? ip->ip_hl * 4 : UNFIX (ip->ip_len);
  new_packet = g_malloc0 (size + 4 + value_size + pad_len);
  bcopy (ip, new_packet, hl);
 
  uc_code = (u_char) code;
  uc_len = (u_char) len;
 
  p = (char *) new_packet;
  bcopy (&uc_code, p + hl, sizeof (uc_code));
  bcopy (&uc_len, p + hl + sizeof (uc_code), sizeof (uc_len));
  bcopy (value, p + hl + sizeof (uc_code) + sizeof (uc_len), value_size);
 
  zero = 0;
  for (i = 0; i < pad_len; i++)
    {
      bcopy (&zero,
             p + hl + sizeof (uc_code) + sizeof (uc_len) + value_size + i, 1);
    }
 
  p = (char *) ip;
  bcopy (p + hl,
         new_packet
           + (sizeof (uc_code) + sizeof (uc_len) + value_size + pad_len) + hl,
         size - hl);
 
  new_packet->ip_hl =
    (hl + (sizeof (uc_code) + sizeof (uc_len) + value_size + pad_len)) / 4;
  new_packet->ip_len =
    FIX (size + sizeof (uc_code) + sizeof (uc_len) + value_size + pad_len);
  new_packet->ip_sum = 0;
  new_packet->ip_sum = np_in_cksum (
    (u_short *) new_packet, new_packet->ip_hl * 4 > UNFIX (new_packet->ip_len)
                              ? UNFIX (new_packet->ip_len)
                              : new_packet->ip_hl * 4);
 
  retc = alloc_typed_cell (CONST_DATA);
  retc->size = size + value_size + sizeof (uc_code) + sizeof (uc_len) + pad_len;
  retc->x.str_val = (char *) new_packet;
 
  return retc;
}

References alloc_typed_cell(), code, CONST_DATA, FIX, get_int_var_by_name(), get_str_var_by_name(), get_var_size_by_name(), len, nasl_perror(), np_in_cksum(), TC::size, TC::str_val, UNFIX, TC::x, and zero.

Here is the call graph for this function:

insert_tcp_options()

tree_cell* insert_tcp_options

(

lex_ctxt *

lexic

)

Add options to a TCP segment header. Possible options are: TCPOPT_MAXSEG (2), values between 536 and 65535 TCPOPT_WINDOW (3), with values between 0 and 14 TCPOPT_SACK_PERMITTED (4), no value required. TCPOPT_TIMESTAMP (8), 8 bytes value for timestamp and echo timestamp, 4 bytes each one.

Parameters

[in]	lexic	Lexical context of NASL interpreter.
[in]	tcp	IP datagram.
[in]	data	(optional) TCP data payload.
[in]	unnamed	option.
[in]	Value	for unnamed option if required.

Returns

The modified IP datagram.

Definition at line 1042 of file nasl_packet_forgery.c.

{
  char *pkt = get_str_var_by_name (lexic, "tcp");
  struct ip *ip = (struct ip *) pkt;
  int pktsz = get_var_size_by_name (lexic, "tcp");
  struct tcphdr *tcp;
  tree_cell *retc;
  char *data = get_str_var_by_name (lexic, "data");
  int data_len = get_var_size_by_name (lexic, "data");
  char *npkt;
  int tcp_opt, tcp_opt_val, tcp_opt_val2;
  int current_opt_len, total_opt_len, opt_size_allocated;
  char *opts, *ptr_opts_pos;
  uint8_t eol, nop;
  int i;
 
  struct tcp_opt_mss *opt_mss;
  struct tcp_opt_wscale *opt_wscale;
  struct tcp_opt_sack_perm *opt_sack_perm;
  struct tcp_opt_tstamp *opt_tstamp;
 
  if (!ip)
    {
      nasl_perror (lexic, "%s: Invalid value for the argument 'tcp'\n",
                   __func__);
      return NULL;
    }
 
  opts = g_malloc0 (sizeof (char) * 4);
  ptr_opts_pos = opts;
  opt_size_allocated = 4; // 4 bytes
  total_opt_len = 0;
  for (i = 0;; i++)
    {
      tcp_opt = get_int_var_by_num (lexic, i, -1);
      current_opt_len = total_opt_len;
 
      if (tcp_opt == -1)
        break;
 
      switch (tcp_opt)
        {
        case TCPOPT_MAXSEG:
          tcp_opt_val = get_int_var_by_num (lexic, i + 1, -1);
          i++;
          if (tcp_opt_val < (int) TCP_MSS_DEFAULT || tcp_opt_val > 65535)
            {
              nasl_perror (lexic, "%s: Invalid value for TCP option MSS\n",
                           __func__);
              break;
            }
          opt_mss = g_malloc0 (sizeof (struct tcp_opt_mss));
          total_opt_len += TCPOLEN_MAXSEG;
          opt_mss->kind = TCPOPT_MAXSEG;
          opt_mss->len = TCPOLEN_MAXSEG;
          opt_mss->mss = FIX (tcp_opt_val);
 
          // Need reallocated memory because options requires it.
          if (total_opt_len > opt_size_allocated)
            {
              opt_size_allocated = ((total_opt_len / 4) + 1) * 4;
              opts = g_realloc (opts, sizeof (char) * opt_size_allocated);
              ptr_opts_pos = opts + current_opt_len;
            }
 
          memcpy (ptr_opts_pos, (u_char *) opt_mss,
                  sizeof (struct tcp_opt_mss));
          ptr_opts_pos = ptr_opts_pos + sizeof (struct tcp_opt_mss);
          g_free (opt_mss);
          break;
        case TCPOPT_WINDOW:
          tcp_opt_val = get_int_var_by_num (lexic, i + 1, -1);
          i++;
          if (tcp_opt_val < 0 || tcp_opt_val > 14)
            {
              nasl_perror (lexic, "%s: Invalid value for TCP option WScale\n",
                           __func__);
              break;
            }
          opt_wscale = g_malloc0 (sizeof (struct tcp_opt_wscale));
          total_opt_len += TCPOLEN_WINDOW;
          opt_wscale->kind = TCPOPT_WINDOW;
          opt_wscale->len = TCPOLEN_WINDOW;
          opt_wscale->wscale = tcp_opt_val;
 
          // Need reallocated memory because options requires it.
          if (total_opt_len > opt_size_allocated)
            {
              opt_size_allocated = ((total_opt_len / 4) + 1) * 4;
              opts = g_realloc (opts, sizeof (char) * opt_size_allocated);
              ptr_opts_pos = opts + current_opt_len;
            }
 
          memcpy (ptr_opts_pos, (u_char *) opt_wscale,
                  sizeof (struct tcp_opt_wscale));
          ptr_opts_pos = ptr_opts_pos + sizeof (struct tcp_opt_wscale);
          g_free (opt_wscale);
          break;
        case TCPOPT_SACK_PERMITTED:
          opt_sack_perm = g_malloc0 (sizeof (struct tcp_opt_sack_perm));
          total_opt_len += TCPOLEN_SACK_PERMITTED;
          opt_sack_perm->kind = TCPOPT_SACK_PERMITTED;
          opt_sack_perm->len = TCPOLEN_SACK_PERMITTED;
 
          // Need reallocated memory because options requires it.
          if (total_opt_len > opt_size_allocated)
            {
              opt_size_allocated = ((total_opt_len / 4) + 1) * 4;
              opts = g_realloc (opts, sizeof (char) * opt_size_allocated);
              ptr_opts_pos = opts + current_opt_len;
            }
 
          memcpy (ptr_opts_pos, (u_char *) opt_sack_perm,
                  sizeof (struct tcp_opt_sack_perm));
          ptr_opts_pos = ptr_opts_pos + sizeof (struct tcp_opt_sack_perm);
          g_free (opt_sack_perm);
          break;
        case TCPOPT_TIMESTAMP:
          tcp_opt_val = get_int_var_by_num (lexic, i + 1, -1);
          tcp_opt_val2 = get_int_var_by_num (lexic, i + 2, -1);
          i = i + 2;
          if (tcp_opt_val < 0)
            nasl_perror (lexic, "%s: Invalid value for TCP option Timestamp\n",
                         __func__);
          opt_tstamp = g_malloc0 (sizeof (struct tcp_opt_tstamp));
          total_opt_len += TCPOLEN_TIMESTAMP;
          opt_tstamp->kind = TCPOPT_TIMESTAMP;
          opt_tstamp->len = TCPOLEN_TIMESTAMP;
          opt_tstamp->tstamp = htonl (tcp_opt_val);
          opt_tstamp->e_tstamp = htonl (tcp_opt_val2);
 
          // Need reallocated memory because options requires it.
          if (total_opt_len > opt_size_allocated)
            {
              opt_size_allocated = ((total_opt_len / 4) + 1) * 4;
              opts = g_realloc (opts, sizeof (char) * opt_size_allocated);
              ptr_opts_pos = opts + current_opt_len;
            }
 
          memcpy (ptr_opts_pos, (u_char *) opt_tstamp,
                  sizeof (struct tcp_opt_tstamp));
          ptr_opts_pos = ptr_opts_pos + sizeof (struct tcp_opt_tstamp);
          g_free (opt_tstamp);
          break;
        case TCPOPT_NOP:
        case TCPOPT_EOL:
        case TCPOPT_SACK: /* Experimental, not supported */
        default:
          nasl_perror (lexic, "%s: TCP option %d not supported\n", __func__,
                       tcp_opt);
          break;
        }
    }
 
  // Add NOP padding and End Of Option list kinds.
  current_opt_len = total_opt_len;
  eol = TCPOPT_EOL;
  nop = TCPOPT_NOP;
  if (total_opt_len % 4 == 0)
    {
      opt_size_allocated = opt_size_allocated + 4;
      opts = g_realloc (opts, sizeof (char) * opt_size_allocated);
      ptr_opts_pos = opts + total_opt_len;
    }
  if (current_opt_len < opt_size_allocated - 1)
    {
      // Add NOPs
      for (i = current_opt_len; i < opt_size_allocated - 1; i++)
        {
          memcpy (ptr_opts_pos, &nop, 1);
          total_opt_len++;
          ptr_opts_pos++;
        }
    }
  // Add EOL
  memcpy (ptr_opts_pos, &eol, 1);
 
  if (ip->ip_hl * 4 > pktsz)
    // ip->ip_hl is bogus, we work around that
    tcp = (struct tcphdr *) (pkt + 20);
  else
    tcp = (struct tcphdr *) (pkt + ip->ip_hl * 4);
 
  if (pktsz < UNFIX (ip->ip_len))
    {
      g_free (opts);
      return NULL;
    }
 
  if (data_len == 0)
    {
      data_len = UNFIX (ip->ip_len) - (ip->ip_hl * 4) - (tcp->th_off * 4);
      data = (char *) ((char *) tcp + tcp->th_off * 4);
    }
 
  // Alloc enough memory to hold the options
  npkt =
    g_malloc0 (ip->ip_hl * 4 + tcp->th_off * 4 + opt_size_allocated + data_len);
  memcpy (npkt, pkt, UNFIX (ip->ip_len));
  ip = (struct ip *) (npkt);
  tcp = (struct tcphdr *) (npkt + ip->ip_hl * 4);
 
  // copy options
  memcpy ((char *) tcp + tcp->th_off * 4, opts, opt_size_allocated);
 
  tcp->th_off = tcp->th_off + (opt_size_allocated / 4);
  memcpy ((char *) tcp + tcp->th_off * 4, data, data_len);
 
  // Update ip_len and calculate ip checksum
  ip->ip_len = FIX (ip->ip_hl * 4 + tcp->th_off * 4 + data_len);
  ip->ip_sum = 0;
  ip->ip_sum = np_in_cksum ((u_short *) npkt, ip->ip_hl * 4);
 
  // Calculate tcp header with options checksum
  struct pseudohdr pseudoheader;
  char *tcpsumdata =
    g_malloc0 (sizeof (struct pseudohdr) + opt_size_allocated + data_len + 1);
  struct in_addr source, dest;
 
  source.s_addr = ip->ip_src.s_addr;
  dest.s_addr = ip->ip_dst.s_addr;
 
  memset (&pseudoheader, 0, sizeof (struct pseudohdr));
  pseudoheader.saddr.s_addr = source.s_addr;
  pseudoheader.daddr.s_addr = dest.s_addr;
 
  pseudoheader.protocol = IPPROTO_TCP;
  // TCP length is tcpheader + options + data
  pseudoheader.length =
    htons (sizeof (struct tcphdr) + opt_size_allocated + data_len);
 
  // Set th_sum to Zero, necessary for the new checksum calculation
  tcp->th_sum = 0;
 
  memcpy ((char *) &pseudoheader.tcpheader, (char *) tcp,
          sizeof (struct tcphdr));
 
  /* fill tcpsumdata with data to checksum */
  memcpy (tcpsumdata, (char *) &pseudoheader, sizeof (struct pseudohdr));
  memcpy (tcpsumdata + sizeof (struct pseudohdr), (char *) opts,
          opt_size_allocated);
  memcpy (tcpsumdata + sizeof (struct pseudohdr) + opt_size_allocated,
          (char *) data, data_len);
  tcp->th_sum =
    np_in_cksum ((unsigned short *) tcpsumdata,
                 sizeof (struct pseudohdr) + opt_size_allocated + data_len);
  g_free (opts);
  g_free (tcpsumdata);
 
  retc = alloc_typed_cell (CONST_DATA);
  retc->size = (ip->ip_hl * 4) + (tcp->th_off * 4) + data_len;
  retc->x.str_val = npkt;
  return retc;
}

References alloc_typed_cell(), CONST_DATA, pseudohdr::daddr, tcp_opt_tstamp::e_tstamp, FIX, get_int_var_by_num(), get_str_var_by_name(), get_var_size_by_name(), tcp_opt_mss::kind, tcp_opt_wscale::kind, tcp_opt_sack_perm::kind, tcp_opt_tstamp::kind, tcp_opt_mss::len, tcp_opt_wscale::len, tcp_opt_sack_perm::len, tcp_opt_tstamp::len, pseudohdr::length, tcp_opt_mss::mss, nasl_perror(), np_in_cksum(), pseudohdr::protocol, pseudohdr::saddr, TC::size, TC::str_val, pseudohdr::tcpheader, tcp_opt_tstamp::tstamp, UNFIX, tcp_opt_wscale::wscale, and TC::x.

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nasl_pcap_next()

tree_cell* nasl_pcap_next

(

lex_ctxt *

lexic

)

Listen to one packet and return it.

Parameters

[in]	lexic	Lexical context of NASL interpreter.
[in]	interface	Network interface name. By default, NASL will try to find the best one.
[in]	pcap_filter	BPF filter. By default, it listens to everything.
[in]	timeout	5 seconds by default.

Returns

Packet which was captured.

Definition at line 2338 of file nasl_packet_forgery.c.

{
  char *interface = get_str_var_by_name (lexic, "interface");
  int bpf = -1;
  static char errbuf[PCAP_ERRBUF_SIZE];
  int is_ip = 0;
  struct ip *ret = NULL;
  struct ip6_hdr *ret6 = NULL;
  char *filter = get_str_var_by_name (lexic, "pcap_filter");
  pcap_if_t *alldevsp = NULL; /* list of capture devices */
  int timeout = get_int_var_by_name (lexic, "timeout", 5);
  tree_cell *retc;
  int sz;
  struct in6_addr *dst = plug_get_host_ip (lexic->script_infos);
  struct in_addr inaddr;
 
  if (dst == NULL)
    {
      return NULL;
    }
  int v4_addr = IN6_IS_ADDR_V4MAPPED (dst);
  if (interface == NULL)
    {
      if (v4_addr)
        {
          struct in_addr src;
          bzero (&src, sizeof (src));
          inaddr.s_addr = dst->s6_addr32[3];
          interface = routethrough (&inaddr, &src);
        }
      else
        {
          struct in6_addr src;
          bzero (&src, sizeof (src));
          interface = v6_routethrough (dst, &src);
        }
      if (interface == NULL)
        {
          if (pcap_findalldevs (&alldevsp, errbuf) < 0)
            g_message ("Error for pcap_findalldevs(): %s", errbuf);
          if (alldevsp != NULL)
            interface = alldevsp->name;
        }
    }
 
  if (interface != NULL)
    {
      bpf = bpf_open_live (interface, filter);
    }
 
  if (bpf < 0)
    {
      nasl_perror (lexic, "pcap_next: Could not get a bpf\n");
      return NULL;
    }
  else
    {
      int len;
      int dl_len = get_datalink_size (bpf_datalink (bpf));
      char *packet;
      struct timeval then, now;
 
      gettimeofday (&then, NULL);
      for (;;)
        {
          packet = (char *) bpf_next (bpf, &len);
 
          if (packet != NULL)
            break;
 
          if (timeout != 0)
            {
              gettimeofday (&now, NULL);
              if (now.tv_sec - then.tv_sec >= timeout)
                {
                  break;
                }
            }
        }
 
      if (packet)
        {
          if (v4_addr)
            {
              struct ip *ip;
              ip = (struct ip *) (packet + dl_len);
              sz = UNFIX (ip->ip_len);
              ret = g_malloc0 (sz);
 
              is_ip = (ip->ip_v == 4);
 
              if (is_ip)
                {
                  bcopy (ip, ret, sz);
                }
              else
                {
                  sz = len - dl_len;
                  bcopy (ip, ret, sz);
                }
            }
          else
            {
              struct ip6_hdr *ip;
              ip = (struct ip6_hdr *) (packet + dl_len);
              sz = UNFIX (ip->ip6_plen);
              ret6 = g_malloc0 (sz);
 
              is_ip = ((ip->ip6_flow & 0x3ffff) == 96);
              if (is_ip)
                {
                  bcopy (ip, ret6, sz);
                }
              else
                {
                  sz = len - dl_len;
                  bcopy (ip, ret6, sz);
                }
            }
        }
      else
        {
          bpf_close (bpf);
          return NULL;
        }
    }
  bpf_close (bpf);
  retc = alloc_typed_cell (CONST_DATA);
  if (v4_addr)
    retc->x.str_val = (char *) ret;
  else
    retc->x.str_val = (char *) ret6;
  retc->size = sz;
 
  if (alldevsp != NULL)
    pcap_freealldevs (alldevsp);
 
  return retc;
}

References alloc_typed_cell(), bpf_close(), bpf_datalink(), bpf_next(), bpf_open_live(), CONST_DATA, get_datalink_size(), get_int_var_by_name(), get_str_var_by_name(), len, name, nasl_perror(), plug_get_host_ip(), routethrough(), TC::size, TC::str_val, timeval(), UNFIX, v6_routethrough(), and TC::x.

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nasl_send_capture()

tree_cell* nasl_send_capture

(

lex_ctxt *

lexic

)

Send a capture.

Parameters

[in]	interface	string
[in]	pcap	filter string
[in]	timeout	integer

Returns

Packet which was captured.

Definition at line 2488 of file nasl_packet_forgery.c.

{
  char *interface = get_str_var_by_name (lexic, "interface");
  int bpf = -1;
  static char errbuf[PCAP_ERRBUF_SIZE];
  int is_ip = 0;
  struct ip *ret = NULL;
  struct ip6_hdr *ret6 = NULL;
  char *filter = get_str_var_by_name (lexic, "pcap_filter");
  pcap_if_t *alldevsp = NULL; /* list of capture devices */
  int timeout = get_int_var_by_name (lexic, "timeout", 5);
  tree_cell *retc;
  int sz;
  struct in6_addr *dst = plug_get_host_ip (lexic->script_infos);
  struct in_addr inaddr;
 
  if (dst == NULL)
    return NULL;
 
  int v4_addr = IN6_IS_ADDR_V4MAPPED (dst);
  if (interface == NULL)
    {
      if (v4_addr)
        {
          struct in_addr src;
          bzero (&src, sizeof (src));
          inaddr.s_addr = dst->s6_addr32[3];
          interface = routethrough (&inaddr, &src);
        }
      else
        {
          struct in6_addr src;
          bzero (&src, sizeof (src));
          interface = v6_routethrough (dst, &src);
        }
      if (interface == NULL)
        {
          if (pcap_findalldevs (&alldevsp, errbuf) < 0)
            g_message ("Error for pcap_findalldevs(): %s", errbuf);
          if (alldevsp != NULL)
            interface = alldevsp->name;
        }
    }
 
  if (interface != NULL)
    bpf = bpf_open_live (interface, filter);
 
  if (bpf < 0)
    {
      nasl_perror (lexic, "pcap_next: Could not get a bpf\n");
      if (alldevsp != NULL)
        pcap_freealldevs (alldevsp);
      return NULL;
    }
  else
    {
      int len;
      int dl_len = get_datalink_size (bpf_datalink (bpf));
      char *packet;
      struct timeval then, now;
 
      retc = nasl_send (lexic);
      g_free (retc);
 
      gettimeofday (&then, NULL);
      for (;;)
        {
          packet = (char *) bpf_next (bpf, &len);
 
          if (packet != NULL)
            break;
 
          if (timeout != 0)
            {
              gettimeofday (&now, NULL);
              if (now.tv_sec - then.tv_sec >= timeout)
                break;
            }
        }
 
      if (packet)
        {
          if (v4_addr)
            {
              struct ip *ip;
              ip = (struct ip *) (packet + dl_len);
              sz = UNFIX (ip->ip_len);
              ret = g_malloc0 (sz);
 
              is_ip = (ip->ip_v == 4);
              if (is_ip)
                {
                  bcopy (ip, ret, sz);
                }
              else
                {
                  sz = len - dl_len;
                  bcopy (ip, ret, sz);
                }
            }
          else
            {
              struct ip6_hdr *ip;
              ip = (struct ip6_hdr *) (packet + dl_len);
              sz = UNFIX (ip->ip6_plen);
              ret6 = g_malloc0 (sz);
              is_ip = ((ip->ip6_flow & 0x3ffff) == 96);
              if (is_ip)
                {
                  bcopy (ip, ret6, sz);
                }
              else
                {
                  sz = len - dl_len;
                  bcopy (ip, ret6, sz);
                }
            }
        }
      else
        {
          if (alldevsp != NULL)
            pcap_freealldevs (alldevsp);
          bpf_close (bpf);
          return NULL;
        }
    }
  bpf_close (bpf);
  retc = alloc_typed_cell (CONST_DATA);
  if (v4_addr)
    retc->x.str_val = (char *) ret;
  else
    retc->x.str_val = (char *) ret6;
  retc->size = sz;
 
  if (alldevsp != NULL)
    pcap_freealldevs (alldevsp);
 
  return retc;
}

References alloc_typed_cell(), bpf_close(), bpf_datalink(), bpf_next(), bpf_open_live(), CONST_DATA, get_datalink_size(), get_int_var_by_name(), get_str_var_by_name(), len, name, nasl_perror(), nasl_send(), plug_get_host_ip(), routethrough(), TC::size, TC::str_val, timeval(), UNFIX, v6_routethrough(), and TC::x.

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nasl_send_packet()

tree_cell* nasl_send_packet

(

lex_ctxt *

lexic

)

Send a list of packets (passed as unnamed arguments) and listens to the answers. It returns a block made of all the sniffed “answers”.

Parameters

[in]	lexic	Lexical context of NASL interpreter.
[in]	...	Packets to send.
[in]	length	Length of each packet by default.
[in]	pcap_active	TRUE by default. Otherwise, NASL does not listen for the answers.
[in]	pcap_filter	BPF filter.
[in]	pcap_timeout	Capture timeout. 5 by default.
[in]	allow_broadcast	Default 0.

Returns

block made of all the sniffed “answers”.

Definition at line 2202 of file nasl_packet_forgery.c.

{
  tree_cell *retc = FAKE_CELL;
  int bpf = -1;
  u_char *answer;
  int answer_sz;
  struct sockaddr_in sockaddr;
  char *ip = NULL;
  struct ip *sip = NULL;
  int vi = 0, b, len = 0;
  int soc;
  int use_pcap = get_int_var_by_name (lexic, "pcap_active", 1);
  int to = get_int_var_by_name (lexic, "pcap_timeout", 5);
  char *filter = get_str_var_by_name (lexic, "pcap_filter");
  int dfl_len = get_int_var_by_name (lexic, "length", -1);
  int opt_on = 1;
  struct script_infos *script_infos = lexic->script_infos;
  struct in6_addr *dstip = plug_get_host_ip (script_infos);
  struct in_addr inaddr;
  int allow_broadcast = 0;
 
  if (dstip == NULL || (IN6_IS_ADDR_V4MAPPED (dstip) != 1))
    return NULL;
  inaddr.s_addr = dstip->s6_addr32[3];
  soc = socket (AF_INET, SOCK_RAW, IPPROTO_RAW);
  if (soc < 0)
    return NULL;
  if (setsockopt (soc, IPPROTO_IP, IP_HDRINCL, (char *) &opt_on,
                  sizeof (opt_on))
      < 0)
    perror ("setsockopt ");
 
  while ((ip = get_str_var_by_num (lexic, vi)) != NULL)
    {
      allow_broadcast = get_int_var_by_name (lexic, "allow_broadcast", 0);
      int sz = get_var_size_by_num (lexic, vi);
      vi++;
 
      if ((unsigned int) sz < sizeof (struct ip))
        {
          nasl_perror (lexic, "send_packet: packet is too short\n");
          continue;
        }
 
      sip = (struct ip *) ip;
      if (use_pcap != 0 && bpf < 0)
        bpf = init_capture_device (sip->ip_dst, sip->ip_src, filter);
 
      bzero (&sockaddr, sizeof (struct sockaddr_in));
      sockaddr.sin_family = AF_INET;
      sockaddr.sin_addr = sip->ip_dst;
 
      if (allow_broadcast)
        {
          if (setsockopt (soc, SOL_SOCKET, SO_BROADCAST, &opt_on,
                          sizeof (opt_on))
              < 0)
            perror ("setsockopt ");
          if (sockaddr.sin_addr.s_addr != INADDR_BROADCAST)
            allow_broadcast = 0;
        }
 
      if (sockaddr.sin_addr.s_addr != inaddr.s_addr && !allow_broadcast)
        {
          char txt1[64], txt2[64];
          strncpy (txt1, inet_ntoa (sockaddr.sin_addr), sizeof (txt1));
          txt1[sizeof (txt1) - 1] = '\0';
          strncpy (txt2, inet_ntoa (inaddr), sizeof (txt2));
          txt2[sizeof (txt2) - 1] = '\0';
          nasl_perror (lexic,
                       "send_packet: malicious or buggy script is trying to "
                       "send packet to %s instead of designated target %s\n",
                       txt1, txt2);
#if 1
          if (bpf >= 0)
            bpf_close (bpf);
          close (soc);
          return NULL;
#else
          sip->ip_dst = inaddr;
          sip->ip_sum = np_in_cksum ((u_short *) sip, sizeof (struct ip));
#endif
        }
 
      if (dfl_len > 0 && dfl_len < sz)
        len = dfl_len;
      else
        len = sz;
 
      b = sendto (soc, (u_char *) ip, len, 0, (struct sockaddr *) &sockaddr,
                  sizeof (sockaddr));
      /* if(b < 0) perror("sendto "); */
      if (b >= 0 && use_pcap != 0 && bpf >= 0)
        {
          if (islocalhost (&sip->ip_dst))
            {
              answer = (u_char *) capture_next_packet (bpf, to, &answer_sz);
              while (answer != NULL
                     && (!memcmp (answer, (char *) ip, sizeof (struct ip))))
                {
                  g_free (answer);
                  answer = (u_char *) capture_next_packet (bpf, to, &answer_sz);
                }
            }
          else
            answer = (u_char *) capture_next_packet (bpf, to, &answer_sz);
 
          if (answer)
            {
              retc = alloc_typed_cell (CONST_DATA);
              retc->x.str_val = (char *) answer;
              retc->size = answer_sz;
              break;
            }
        }
    }
  if (bpf >= 0)
    bpf_close (bpf);
  close (soc);
  return retc;
}

References alloc_typed_cell(), bpf_close(), capture_next_packet(), CONST_DATA, FAKE_CELL, get_int_var_by_name(), get_str_var_by_name(), get_str_var_by_num(), get_var_size_by_num(), init_capture_device(), islocalhost(), len, nasl_perror(), np_in_cksum(), plug_get_host_ip(), struct_lex_ctxt::script_infos, TC::size, TC::str_val, and TC::x.

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nasl_tcp_ping()

tree_cell* nasl_tcp_ping

(

lex_ctxt *

lexic

)

Launches a “TCP ping” against the target host.

Tries to open a TCP connection and sees if anything comes back (SYN/ACK or RST).

Parameters

[in]	lexic	Lexical context of NASL interpreter.
[in]	port	Port to ping. Internal list of common ports is used as default.

Returns

1 if Ping was successful, 0 else.

Definition at line 2048 of file nasl_packet_forgery.c.

{
  struct script_infos *script_infos = lexic->script_infos;
  struct in6_addr *dst = plug_get_host_ip (script_infos);
  if (IN6_IS_ADDR_V4MAPPED (dst) != 1)
    {
      tree_cell *retc = nasl_tcp_v6_ping (lexic);
      return retc;
    }
  int port;
  u_char packet[sizeof (struct ip) + sizeof (struct tcphdr)];
  int soc;
  struct ip *ip = (struct ip *) packet;
  struct tcphdr *tcp = (struct tcphdr *) (packet + sizeof (struct ip));
  struct in_addr src;
  struct sockaddr_in soca;
  int flag = 0;
  unsigned int i = 0;
  int bpf;
  char filter[255];
  tree_cell *retc;
  int opt = 1;
  struct timeval tv;
  int len;
#define rnd_tcp_port() (rand () % 65535 + 1024)
  int sports[] = {0, 0, 0, 0, 0, 1023, 0, 0, 0,  0, 0,  0, 0, 0, 0,
                  0, 0, 0, 0, 0, 53,   0, 0, 20, 0, 25, 0, 0, 0};
  int ports[] = {139, 135, 445,  80,    22,   515, 23,  21,  6000, 1025,
                 25,  111, 1028, 9100,  1029, 79,  497, 548, 5000, 1917,
                 53,  161, 9001, 65535, 443,  113, 993, 8080};
  struct in_addr inaddr;
 
  if (dst == NULL || (IN6_IS_ADDR_V4MAPPED (dst) != 1))
    return NULL;
  inaddr.s_addr = dst->s6_addr32[3];
  for (i = 0; i < sizeof (sports) / sizeof (int); i++)
    {
      if (sports[i] == 0)
        sports[i] = rnd_tcp_port ();
    }
 
  soc = socket (AF_INET, SOCK_RAW, IPPROTO_RAW);
  if (soc < 0)
    return NULL;
  if (setsockopt (soc, IPPROTO_IP, IP_HDRINCL, (char *) &opt, sizeof (opt)) < 0)
    perror ("setsockopt ");
 
  port = get_int_var_by_name (lexic, "port", -1);
  if (port == -1)
    port = plug_get_host_open_port (script_infos);
 
  if (islocalhost (&inaddr) > 0)
    src.s_addr = dst->s6_addr32[3];
  else
    {
      bzero (&src, sizeof (src));
      routethrough (&inaddr, &src);
    }
 
  snprintf (filter, sizeof (filter), "ip and src host %s", inet_ntoa (inaddr));
  bpf = init_capture_device (inaddr, src, filter);
 
  if (islocalhost (&inaddr) != 0)
    flag++;
  else
    {
      for (i = 0; i < sizeof (sports) / sizeof (int) && !flag; i++)
        {
          bzero (packet, sizeof (packet));
          /* IP */
          ip->ip_hl = 5;
          ip->ip_off = FIX (0);
          ip->ip_v = 4;
          ip->ip_len = FIX (40);
          ip->ip_tos = 0;
          ip->ip_p = IPPROTO_TCP;
          ip->ip_id = rand ();
          ip->ip_ttl = 0x40;
          ip->ip_src = src;
          ip->ip_dst = inaddr;
          ip->ip_sum = 0;
          ip->ip_sum = np_in_cksum ((u_short *) ip, 20);
 
          /* TCP */
          tcp->th_sport = port ? htons (rnd_tcp_port ()) : htons (sports[i]);
          tcp->th_flags = TH_SYN;
          tcp->th_dport = port ? htons (port) : htons (ports[i]);
          tcp->th_seq = rand ();
          tcp->th_ack = 0;
          tcp->th_x2 = 0;
          tcp->th_off = 5;
          tcp->th_win = 2048;
          tcp->th_urp = 0;
          tcp->th_sum = 0;
 
          /* CKsum */
          {
            struct in_addr source, dest;
            struct pseudohdr pseudoheader;
            source.s_addr = ip->ip_src.s_addr;
            dest.s_addr = ip->ip_dst.s_addr;
 
            bzero (&pseudoheader, 12 + sizeof (struct tcphdr));
            pseudoheader.saddr.s_addr = source.s_addr;
            pseudoheader.daddr.s_addr = dest.s_addr;
 
            pseudoheader.protocol = 6;
            pseudoheader.length = htons (sizeof (struct tcphdr));
            bcopy ((char *) tcp, (char *) &pseudoheader.tcpheader,
                   sizeof (struct tcphdr));
            tcp->th_sum = np_in_cksum ((unsigned short *) &pseudoheader,
                                       12 + sizeof (struct tcphdr));
          }
 
          bzero (&soca, sizeof (soca));
          soca.sin_family = AF_INET;
          soca.sin_addr = ip->ip_dst;
          if (sendto (soc, (const void *) ip, 40, 0, (struct sockaddr *) &soca,
                      sizeof (soca))
              < 0)
            g_warning ("sendto: %s", strerror (errno));
          tv.tv_sec = 0;
          tv.tv_usec = 100000;
          if (bpf >= 0 && bpf_next_tv (bpf, &len, &tv))
            flag++;
        }
    }
 
  retc = alloc_typed_cell (CONST_INT);
  retc->x.i_val = flag;
  if (bpf >= 0)
    bpf_close (bpf);
  close (soc);
  return retc;
}

References alloc_typed_cell(), bpf_close(), bpf_next_tv(), CONST_INT, pseudohdr::daddr, FIX, get_int_var_by_name(), TC::i_val, init_capture_device(), islocalhost(), len, pseudohdr::length, nasl_tcp_v6_ping(), np_in_cksum(), plug_get_host_ip(), plug_get_host_open_port(), pseudohdr::protocol, rnd_tcp_port, routethrough(), pseudohdr::saddr, struct_lex_ctxt::script_infos, pseudohdr::tcpheader, timeval(), and TC::x.

Referenced by nasl_end_denial(), and nasl_start_denial().

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set_ip_elements()

tree_cell* set_ip_elements

(

lex_ctxt *

lexic

)

Modify the fields of a datagram.

Parameters

[in]	lexic	Lexical context of NASL interpreter.
[in]	ip	IP datagram to set fields on.
[in]	ip_hl	IP header length in 32 bits words. 5 by default.
[in]	ip_id	Datagram ID. Random by default.
[in]	ip_len	Length of the datagram. 20 plus the length of the data field by default.
[in]	ip_off	Fragment offset in 64 bits words. 0 by default.
[in]	ip_p	IP protocol. 0 by default.
[in]	ip_src	Source address in ASCII. NASL will convert it into an integer in network order.
[in]	ip_sum	Packet header checksum. It will be computed by default.
[in]	ip_tos	Type of service field. 0 by default
[in]	ip_ttl	Time To Live field. 64 by default.
[in]	ip_v	IP version. 4 by default.

Returns

The modified IP datagram.

Definition at line 302 of file nasl_packet_forgery.c.

{
  struct ip *o_pkt = (struct ip *) get_str_var_by_name (lexic, "ip");
  int size = get_var_size_by_name (lexic, "ip");
  tree_cell *retc;
  struct ip *pkt;
  char *s;
 
  if (o_pkt == NULL)
    {
      nasl_perror (lexic, "set_ip_elements: missing <ip> field\n");
      return NULL;
    }
 
  pkt = (struct ip *) g_malloc0 (size);
  bcopy (o_pkt, pkt, size);
 
  pkt->ip_hl = get_int_var_by_name (lexic, "ip_hl", pkt->ip_hl);
  pkt->ip_v = get_int_var_by_name (lexic, "ip_v", pkt->ip_v);
  pkt->ip_tos = get_int_var_by_name (lexic, "ip_tos", pkt->ip_tos);
  pkt->ip_len =
    FIX (get_int_var_by_name (lexic, "ip_len", UNFIX (pkt->ip_len)));
  pkt->ip_id = htons (get_int_var_by_name (lexic, "ip_id", pkt->ip_id));
  pkt->ip_off =
    FIX (get_int_var_by_name (lexic, "ip_off", UNFIX (pkt->ip_off)));
  pkt->ip_ttl = get_int_var_by_name (lexic, "ip_ttl", pkt->ip_ttl);
  pkt->ip_p = get_int_var_by_name (lexic, "ip_p", pkt->ip_p);
 
  s = get_str_var_by_name (lexic, "ip_src");
  if (s != NULL)
    inet_aton (s, &pkt->ip_src);
 
  pkt->ip_sum = htons (get_int_var_by_name (lexic, "ip_sum", 0));
  if (pkt->ip_sum == 0)
    pkt->ip_sum = np_in_cksum ((u_short *) pkt, sizeof (struct ip));
 
  retc = alloc_typed_cell (CONST_DATA);
  retc->size = size;
  retc->x.str_val = (char *) pkt;
 
  return retc;
}

References alloc_typed_cell(), CONST_DATA, FIX, get_int_var_by_name(), get_str_var_by_name(), get_var_size_by_name(), nasl_perror(), np_in_cksum(), TC::size, TC::str_val, UNFIX, and TC::x.

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set_tcp_elements()

tree_cell* set_tcp_elements

(

lex_ctxt *

lexic

)

Modify the TCP fields of a datagram.

Parameters

[in]	lexic	Lexical context of NASL interpreter.
[in]	tcp	IP datagram.
[in]	data	TCP data payload.
[in]	th_ack	Acknowledge number. NASL will convert it into network order if necessary.
[in]	th_dport	Destination port. NASL will convert it into network order if necessary.
[in]	th_flags	TCP flags.
[in]	th_off	Size of the TCP header in 32 bits words.
[in]	th_seq	TCP sequence number. NASL will convert it into network order if necessary.
[in]	th_sport	Source port. NASL will convert it into network order if necessary.
[in]	th_sum	TCP checksum.
[in]	th_urp	Urgent pointer.
[in]	th_win	TCP window size. NASL will convert it into network order if necessary.
[in]	th_x2	Is a reserved field and should probably be left unchanged.
[in]	update_ip_len	Flag (TRUE by default). If set, NASL will recompute the size field of the IP datagram.

Returns

The modified IP datagram.

Definition at line 929 of file nasl_packet_forgery.c.

{
  char *pkt = get_str_var_by_name (lexic, "tcp");
  struct ip *ip = (struct ip *) pkt;
  int pktsz = get_var_size_by_name (lexic, "tcp");
  struct tcphdr *tcp;
  tree_cell *retc;
  char *data = get_str_var_by_name (lexic, "data");
  int data_len = get_var_size_by_name (lexic, "data");
  char *npkt;
 
  if (!ip)
    {
      nasl_perror (lexic,
                   "set_tcp_elements: Invalid value for the argument 'tcp'\n");
      return NULL;
    }
 
  if (ip->ip_hl * 4 > pktsz)
    tcp =
      (struct tcphdr *) (pkt
                         + 20); /* ip->ip_hl is bogus, we work around that */
  else
    tcp = (struct tcphdr *) (pkt + ip->ip_hl * 4);
 
  if (pktsz < UNFIX (ip->ip_len))
    return NULL;
 
  if (data_len == 0)
    {
      data_len = UNFIX (ip->ip_len) - (ip->ip_hl * 4) - (tcp->th_off * 4);
      data = (char *) ((char *) tcp + tcp->th_off * 4);
    }
 
  npkt = g_malloc0 (ip->ip_hl * 4 + tcp->th_off * 4 + data_len);
  bcopy (pkt, npkt, UNFIX (ip->ip_len));
 
  ip = (struct ip *) (npkt);
  tcp = (struct tcphdr *) (npkt + ip->ip_hl * 4);
 
  tcp->th_sport =
    htons (get_int_var_by_name (lexic, "th_sport", ntohs (tcp->th_sport)));
  tcp->th_dport =
    htons (get_int_var_by_name (lexic, "th_dport", ntohs (tcp->th_dport)));
  tcp->th_seq =
    htonl (get_int_var_by_name (lexic, "th_seq", ntohl (tcp->th_seq)));
  tcp->th_ack =
    htonl (get_int_var_by_name (lexic, "th_ack", ntohl (tcp->th_ack)));
  tcp->th_x2 = get_int_var_by_name (lexic, "th_x2", tcp->th_x2);
  tcp->th_off = get_int_var_by_name (lexic, "th_off", tcp->th_off);
  tcp->th_flags = get_int_var_by_name (lexic, "th_flags", tcp->th_flags);
  tcp->th_win =
    htons (get_int_var_by_name (lexic, "th_win", ntohs (tcp->th_win)));
  tcp->th_sum = get_int_var_by_name (lexic, "th_sum", 0);
  tcp->th_urp = get_int_var_by_name (lexic, "th_urp", tcp->th_urp);
  bcopy (data, (char *) tcp + tcp->th_off * 4, data_len);
 
  if (get_int_var_by_name (lexic, "update_ip_len", 1) != 0)
    {
      ip->ip_len = ip->ip_hl * 4 + tcp->th_off * 4 + data_len;
      ip->ip_sum = 0;
      ip->ip_sum = np_in_cksum ((u_short *) pkt, ip->ip_hl * 4);
    }
 
  if (tcp->th_sum == 0)
    {
      struct pseudohdr pseudoheader;
      char *tcpsumdata = g_malloc0 (sizeof (struct pseudohdr) + data_len + 1);
      struct in_addr source, dest;
 
      source.s_addr = ip->ip_src.s_addr;
      dest.s_addr = ip->ip_dst.s_addr;
 
      bzero (&pseudoheader, sizeof (pseudoheader));
      pseudoheader.saddr.s_addr = source.s_addr;
      pseudoheader.daddr.s_addr = dest.s_addr;
 
      pseudoheader.protocol = IPPROTO_TCP;
      pseudoheader.length = htons (sizeof (struct tcphdr) + data_len);
      bcopy ((char *) tcp, (char *) &pseudoheader.tcpheader,
             sizeof (struct tcphdr));
      /* fill tcpsumdata with data to checksum */
      bcopy ((char *) &pseudoheader, tcpsumdata, sizeof (struct pseudohdr));
      bcopy ((char *) data, tcpsumdata + sizeof (struct pseudohdr), data_len);
      tcp->th_sum = np_in_cksum ((unsigned short *) tcpsumdata,
                                 sizeof (pseudoheader) + data_len);
      g_free (tcpsumdata);
    }
 
  retc = alloc_typed_cell (CONST_DATA);
  retc->size = (ip->ip_hl * 4) + (tcp->th_off * 4) + data_len;
  retc->x.str_val = npkt;
  return retc;
}

References alloc_typed_cell(), CONST_DATA, pseudohdr::daddr, get_int_var_by_name(), get_str_var_by_name(), get_var_size_by_name(), pseudohdr::length, nasl_perror(), np_in_cksum(), pseudohdr::protocol, pseudohdr::saddr, TC::size, TC::str_val, pseudohdr::tcpheader, UNFIX, and TC::x.

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set_udp_elements()

tree_cell* set_udp_elements

(

lex_ctxt *

lexic

)

Modify UDP fields of an IP datagram.

Parameters

[in]	udp	IP datagram to modify.
[in]	data	Payload.
[in]	uh_dport	Destination port. NASL will convert it into network order if necessary.
[in]	uh_sport	Source port. NASL will convert it into network order if necessary.
[in]	uh_sum	UDP checksum.
[in]	uh_ulen	Data length.

Returns

Modified IP datagram.

Definition at line 1620 of file nasl_packet_forgery.c.

{
  struct ip *ip = (struct ip *) get_str_var_by_name (lexic, "udp");
  unsigned int sz = get_var_size_by_name (lexic, "udp");
  char *data = get_str_var_by_name (lexic, "data");
  int data_len = get_var_size_by_name (lexic, "data");
 
  if (ip != NULL)
    {
      char *pkt;
      struct udphdr *udp;
      tree_cell *retc;
      int old_len;
 
      if (ip->ip_hl * 4 + sizeof (struct udphdr) > sz)
        return NULL;
 
      if (data != NULL)
        {
          sz = ip->ip_hl * 4 + sizeof (struct udphdr) + data_len;
          pkt = g_malloc0 (sz);
          bcopy (ip, pkt, ip->ip_hl * 4 + sizeof (struct udphdr));
        }
      else
        {
          pkt = g_malloc0 (sz);
          bcopy (ip, pkt, sz);
        }
 
      ip = (struct ip *) pkt;
      if (data != NULL)
        {
          ip->ip_len = FIX (sz);
          ip->ip_sum = 0;
          ip->ip_sum = np_in_cksum ((u_short *) ip, ip->ip_hl * 4);
        }
      udp = (struct udphdr *) (pkt + ip->ip_hl * 4);
 
      udp->uh_sport =
        htons (get_int_var_by_name (lexic, "uh_sport", ntohs (udp->uh_sport)));
      udp->uh_dport =
        htons (get_int_var_by_name (lexic, "uh_dport", ntohs (udp->uh_dport)));
      old_len = ntohs (udp->uh_ulen);
      udp->uh_ulen =
        htons (get_int_var_by_name (lexic, "uh_ulen", ntohs (udp->uh_ulen)));
      udp->uh_sum = get_int_var_by_name (lexic, "uh_sum", 0);
 
      if (data != NULL)
        {
          bcopy (data, pkt + ip->ip_hl * 4 + sizeof (struct udphdr), data_len);
          udp->uh_ulen = htons (sizeof (struct udphdr) + data_len);
        }
 
      if (udp->uh_sum == 0)
        {
          struct pseudo_udp_hdr pseudohdr;
          struct in_addr source, dest;
          int len = old_len - sizeof (struct udphdr);
          char *udpsumdata;
          char *ptr = NULL;
 
          if (data != NULL)
            {
              len = data_len;
            }
 
          if (len > 0)
            {
              ptr = (char *) udp + sizeof (struct udphdr);
            }
 
          udpsumdata = g_malloc0 (sizeof (struct pseudo_udp_hdr) + len + 1);
 
          source.s_addr = ip->ip_src.s_addr;
          dest.s_addr = ip->ip_dst.s_addr;
 
          bzero (&pseudohdr, sizeof (struct pseudo_udp_hdr));
          pseudohdr.saddr.s_addr = source.s_addr;
          pseudohdr.daddr.s_addr = dest.s_addr;
 
          pseudohdr.proto = IPPROTO_UDP;
          pseudohdr.len = htons (sizeof (struct udphdr) + len);
          bcopy ((char *) udp, (char *) &pseudohdr.udpheader,
                 sizeof (struct udphdr));
          bcopy ((char *) &pseudohdr, udpsumdata, sizeof (pseudohdr));
          if (ptr != NULL)
            {
              bcopy ((char *) ptr, udpsumdata + sizeof (pseudohdr), len);
            }
          udp->uh_sum = np_in_cksum ((unsigned short *) udpsumdata,
                                     12 + sizeof (struct udphdr) + len);
          g_free (udpsumdata);
        }
      retc = alloc_typed_cell (CONST_DATA);
      retc->size = sz;
      retc->x.str_val = pkt;
      return retc;
    }
  else
    nasl_perror (lexic,
                 "set_udp_elements:  Invalid value for the argument 'udp'.");
 
  return NULL;
}

References alloc_typed_cell(), CONST_DATA, pseudohdr::daddr, FIX, get_int_var_by_name(), get_str_var_by_name(), get_var_size_by_name(), len, nasl_perror(), np_in_cksum(), pseudohdr::saddr, TC::size, TC::str_val, and TC::x.

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