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Version 1.2p1

    1: /*
    2:  *  $Id: libnet_build_udp.c,v 1.1.1.3 2023/09/27 11:11:38 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: #include "common.h"
   34: 
   35: libnet_ptag_t
   36: libnet_build_udp(uint16_t sp, uint16_t dp, uint16_t len, uint16_t sum,
   37: const uint8_t *payload, uint32_t payload_s, libnet_t *l, libnet_ptag_t ptag)
   38: {
   39:     uint32_t n;
   40:     libnet_pblock_t *p;
   41:     struct libnet_udp_hdr udp_hdr;
   42: 
   43:     if (l == NULL)
   44:     { 
   45:         return (-1);
   46:     } 
   47: 
   48:     n = LIBNET_UDP_H + payload_s;               /* size of memory block */
   49: 
   50:     /*
   51:      *  Find the existing protocol block if a ptag is specified, or create
   52:      *  a new one.
   53:      */
   54:     p = libnet_pblock_probe(l, ptag, n, LIBNET_PBLOCK_UDP_H);
   55:     if (p == NULL)
   56:     {
   57:         return (-1);
   58:     }
   59: 
   60:     memset(&udp_hdr, 0, sizeof(udp_hdr));
   61:     udp_hdr.uh_sport   = htons(sp);             /* source port */
   62:     udp_hdr.uh_dport   = htons(dp);             /* destination port */
   63:     udp_hdr.uh_ulen    = htons(len);            /* total length of UDP packet*/
   64:     udp_hdr.uh_sum     = (sum ? htons(sum) : 0);/* checksum */
   65: 
   66:     n = libnet_pblock_append(l, p, (uint8_t *)&udp_hdr, LIBNET_UDP_H);
   67:     if (n == -1)
   68:     {
   69:         goto bad;
   70:     }
   71: 
   72:     /* boilerplate payload sanity check / append macro */
   73:     LIBNET_DO_PAYLOAD(l, p);
   74:  
   75:     if (sum == 0)
   76:     {
   77:         /*
   78:          *  If checksum is zero, by default libnet will compute a checksum
   79:          *  for the user.  The programmer can override this by calling
   80:          *  libnet_toggle_checksum(l, ptag, 1);
   81:          */
   82:         libnet_pblock_setflags(p, LIBNET_PBLOCK_DO_CHECKSUM);
   83:     }
   84:     return (ptag ? ptag : libnet_pblock_update(l, p, len, LIBNET_PBLOCK_UDP_H));
   85: bad:
   86:     libnet_pblock_delete(l, p);
   87:     return (-1);
   88: }
   89: 
   90: /**
   91:  * Local Variables:
   92:  *  indent-tabs-mode: nil
   93:  *  c-file-style: "stroustrup"
   94:  * End:
   95:  */