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libnet

    1: /*
    2:  *  $Id: libnet_build_udp.c,v 1.1.1.1 2012/02/21 22:14:23 misho Exp $
    3:  *
    4:  *  libnet
    5:  *  libnet_build_udp.c - UDP packet assembler
    6:  *
    7:  *  Copyright (c) 1998 - 2004 Mike D. Schiffman <mike@infonexus.com>
    8:  *  All rights reserved.
    9:  *
   10:  * Redistribution and use in source and binary forms, with or without
   11:  * modification, are permitted provided that the following conditions
   12:  * are met:
   13:  * 1. Redistributions of source code must retain the above copyright
   14:  *    notice, this list of conditions and the following disclaimer.
   15:  * 2. Redistributions in binary form must reproduce the above copyright
   16:  *    notice, this list of conditions and the following disclaimer in the
   17:  *    documentation and/or other materials provided with the distribution.
   18:  *
   19:  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   20:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   21:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   22:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   23:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   24:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   25:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   26:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   27:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   28:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   29:  * SUCH DAMAGE.
   30:  *
   31:  */
   32: 
   33: #if (HAVE_CONFIG_H)
   34: #include "../include/config.h"
   35: #endif
   36: #if (!(_WIN32) || (__CYGWIN__)) 
   37: #include "../include/libnet.h"
   38: #else
   39: #include "../include/win32/libnet.h"
   40: #endif
   41: 
   42: libnet_ptag_t
   43: libnet_build_udp(u_int16_t sp, u_int16_t dp, u_int16_t len, u_int16_t sum,
   44: u_int8_t *payload, u_int32_t payload_s, libnet_t *l, libnet_ptag_t ptag)
   45: {
   46:     u_int32_t n, h;
   47:     libnet_pblock_t *p;
   48:     struct libnet_udp_hdr udp_hdr;
   49: 
   50:     if (l == NULL)
   51:     { 
   52:         return (-1);
   53:     } 
   54: 
   55:     n = LIBNET_UDP_H + payload_s;               /* size of memory block */
   56:     h = len;                                    /* header length (for cksum) */
   57: 
   58:     /*
   59:      *  Find the existing protocol block if a ptag is specified, or create
   60:      *  a new one.
   61:      */
   62:     p = libnet_pblock_probe(l, ptag, n, LIBNET_PBLOCK_UDP_H);
   63:     if (p == NULL)
   64:     {
   65:         return (-1);
   66:     }
   67: 
   68:     memset(&udp_hdr, 0, sizeof(udp_hdr));
   69:     udp_hdr.uh_sport   = htons(sp);             /* source port */
   70:     udp_hdr.uh_dport   = htons(dp);             /* destination port */
   71:     udp_hdr.uh_ulen    = htons(h);              /* total length of UDP packet*/
   72:     udp_hdr.uh_sum     = (sum ? htons(sum) : 0);/* checksum */
   73: 
   74:     n = libnet_pblock_append(l, p, (u_int8_t *)&udp_hdr, LIBNET_UDP_H);
   75:     if (n == -1)
   76:     {
   77:         goto bad;
   78:     }
   79: 
   80:     if ((payload && !payload_s) || (!payload && payload_s))
   81:     {
   82:         snprintf(l->err_buf, LIBNET_ERRBUF_SIZE,
   83: 			    "%s(): payload inconsistency\n", __func__);
   84:         goto bad;
   85:     }
   86:  
   87:     if (payload && payload_s)
   88:     {
   89:         n = libnet_pblock_append(l, p, payload, payload_s);
   90:         if (n == -1)
   91:         {
   92:             goto bad;
   93:         }
   94:     }
   95:  
   96:     if (sum == 0)
   97:     {
   98:         /*
   99:          *  If checksum is zero, by default libnet will compute a checksum
  100:          *  for the user.  The programmer can override this by calling
  101:          *  libnet_toggle_checksum(l, ptag, 1);
  102:          */
  103:         libnet_pblock_setflags(p, LIBNET_PBLOCK_DO_CHECKSUM);
  104:     }
  105:     return (ptag ? ptag : libnet_pblock_update(l, p, h, LIBNET_PBLOCK_UDP_H));
  106: bad:
  107:     libnet_pblock_delete(l, p);
  108:     return (-1);
  109: }
  110: 
  111: /* EOF */