1 /* SPDX-License-Identifier: BSD-3-Clause */
2 /*
3 * Copyright (c) 1982, 1986, 1988, 1990, 1993
4 * The Regents of the University of California. All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 * 3. Neither the name of the University nor the names of its contributors
15 * may be used to endorse or promote products derived from this software
16 * without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGE.
29 *
30 * @(#)ip_output.c 8.3 (Berkeley) 1/21/94
31 * ip_output.c,v 1.9 1994/11/16 10:17:10 jkh Exp
32 */
33
34 /*
35 * Changes and additions relating to SLiRP are
36 * Copyright (c) 1995 Danny Gasparovski.
37 */
38
39 #include "slirp.h"
40
41 /* Number of packets queued before we start sending
42 * (to prevent allocing too many mbufs) */
43 #define IF_THRESH 10
44
45 /*
46 * IP output. The packet in mbuf chain m contains a skeletal IP
47 * header (with len, off, ttl, proto, tos, src, dst).
48 * The mbuf chain containing the packet will be freed.
49 * The mbuf opt, if present, will not be freed.
50 */
ip_output(struct socket * so,struct mbuf * m0)51 int ip_output(struct socket *so, struct mbuf *m0)
52 {
53 Slirp *slirp = m0->slirp;
54 register struct ip *ip;
55 register struct mbuf *m = m0;
56 register int hlen = sizeof(struct ip);
57 int len, off, error = 0;
58
59 DEBUG_CALL("ip_output");
60 DEBUG_ARG("so = %p", so);
61 DEBUG_ARG("m0 = %p", m0);
62
63 ip = mtod(m, struct ip *);
64 /*
65 * Fill in IP header.
66 */
67 ip->ip_v = IPVERSION;
68 ip->ip_off &= IP_DF;
69 ip->ip_id = htons(slirp->ip_id++);
70 ip->ip_hl = hlen >> 2;
71
72 /*
73 * If small enough for interface, can just send directly.
74 */
75 if ((uint16_t)ip->ip_len <= slirp->if_mtu) {
76 ip->ip_len = htons((uint16_t)ip->ip_len);
77 ip->ip_off = htons((uint16_t)ip->ip_off);
78 ip->ip_sum = 0;
79 ip->ip_sum = cksum(m, hlen);
80
81 if_output(so, m);
82 goto done;
83 }
84
85 /*
86 * Too large for interface; fragment if possible.
87 * Must be able to put at least 8 bytes per fragment.
88 */
89 if (ip->ip_off & IP_DF) {
90 error = -1;
91 goto bad;
92 }
93
94 len = (slirp->if_mtu - hlen) & ~7; /* ip databytes per packet */
95 if (len < 8) {
96 error = -1;
97 goto bad;
98 }
99
100 {
101 int mhlen, firstlen = len;
102 struct mbuf **mnext = &m->m_nextpkt;
103
104 /*
105 * Loop through length of segment after first fragment,
106 * make new header and copy data of each part and link onto chain.
107 */
108 m0 = m;
109 mhlen = sizeof(struct ip);
110 for (off = hlen + len; off < (uint16_t)ip->ip_len; off += len) {
111 register struct ip *mhip;
112 m = m_get(slirp);
113 if (m == NULL) {
114 error = -1;
115 goto sendorfree;
116 }
117 m->m_data += IF_MAXLINKHDR;
118 mhip = mtod(m, struct ip *);
119 *mhip = *ip;
120
121 m->m_len = mhlen;
122 mhip->ip_off = ((off - hlen) >> 3) + (ip->ip_off & ~IP_MF);
123 if (ip->ip_off & IP_MF)
124 mhip->ip_off |= IP_MF;
125 if (off + len >= (uint16_t)ip->ip_len)
126 len = (uint16_t)ip->ip_len - off;
127 else
128 mhip->ip_off |= IP_MF;
129 mhip->ip_len = htons((uint16_t)(len + mhlen));
130
131 if (m_copy(m, m0, off, len) < 0) {
132 error = -1;
133 goto sendorfree;
134 }
135
136 mhip->ip_off = htons((uint16_t)mhip->ip_off);
137 mhip->ip_sum = 0;
138 mhip->ip_sum = cksum(m, mhlen);
139 *mnext = m;
140 mnext = &m->m_nextpkt;
141 }
142 /*
143 * Update first fragment by trimming what's been copied out
144 * and updating header, then send each fragment (in order).
145 */
146 m = m0;
147 m_adj(m, hlen + firstlen - (uint16_t)ip->ip_len);
148 ip->ip_len = htons((uint16_t)m->m_len);
149 ip->ip_off = htons((uint16_t)(ip->ip_off | IP_MF));
150 ip->ip_sum = 0;
151 ip->ip_sum = cksum(m, hlen);
152 sendorfree:
153 for (m = m0; m; m = m0) {
154 m0 = m->m_nextpkt;
155 m->m_nextpkt = NULL;
156 if (error == 0)
157 if_output(so, m);
158 else
159 m_free(m);
160 }
161 }
162
163 done:
164 return (error);
165
166 bad:
167 m_free(m0);
168 goto done;
169 }
170