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Annotation of embedaddon/libnet/src/libnet_build_udp.c, revision 1.1.1.1

1.1       misho       1: /*
                      2:  *  $Id: libnet_build_udp.c,v 1.10 2004/01/21 19:01:29 mike 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 */