1 /*
2 * $Id: insert_ipo.c,v 1.2 1999/09/21 15:47:33 dugsong Exp $
3 *
4 * libnet
5 * insert_ipo.c - inserts IP options into a prebuilt IP packet
6 *
7 * Copyright (c) 1998, 1999 Mike D. Schiffman <mike@infonexus.com>
8 * route|daemon9 <route@infonexus.com>
9 * All rights reserved.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 * notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in the
18 * documentation and/or other materials provided with the distribution.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 *
32 */
33
34 #if (HAVE_CONFIG_H)
35 #include "../include/config.h"
36 #endif
37 #include "../include/libnet.h"
38
39 int
insert_ipo(struct ipoption * opt,u_char opt_len,u_char * buf)40 insert_ipo(struct ipoption *opt, u_char opt_len, u_char *buf)
41 {
42 struct ip *ip_hdr;
43 u_short s, ip_hl, pad;
44 u_char *p;
45
46 assert(buf);
47
48 ip_hdr = (struct ip *)(buf);
49 ip_hl = ip_hdr->ip_hl * 4;
50
51 s = ntohs(ip_hdr->ip_len);
52
53 /* See how much to pad options out (always terminating with EOL). */
54 pad = 4 - (((ip_hl - IP_H) + opt_len) & 3);
55
56 if ((s + opt_len + pad) > IP_MAXPACKET)
57 {
58 /* Nope. Too big. */
59 #if (__DEBUG)
60 fprintf(stderr,
61 "insert_ipo: options list would result in too large of a packet\n");
62 #endif
63 return (-1);
64 }
65
66 /* Do we have more then just an IP header? */
67 if (s > ip_hl)
68 {
69 /* Move over whatever's in the way. */
70 memmove(buf + ip_hl + opt_len + pad, buf + ip_hl, opt_len + pad);
71 }
72
73 /*
74 * Copy over option list. We rely on the programmer having been
75 * smart enough to allocate enough heap memory here. Uh oh.
76 */
77 p = buf + ip_hl;
78 memcpy(p, opt->ipopt_list, opt_len);
79
80 /* XXX - this should be 1 if more options are to follow. */
81 memset(p + opt_len, 0, pad);
82
83 ip_hdr->ip_hl += (opt_len + pad) / 4;
84 ip_hdr->ip_len = htons(s + opt_len + pad);
85
86 return (1);
87 }
88
89 /* EOF */
90