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1 | /* |
2 | * $Id: libnet_build_udp.c,v 1.20 2005/11/29 22:30:13 carlosc 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 */ |