9pfs: fix crash when fsdev is missing
[qemu.git] / slirp / ip_output.c
1 /*
2 * Copyright (c) 1982, 1986, 1988, 1990, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. Neither the name of the University nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 * @(#)ip_output.c 8.3 (Berkeley) 1/21/94
30 * ip_output.c,v 1.9 1994/11/16 10:17:10 jkh Exp
31 */
32
33 /*
34 * Changes and additions relating to SLiRP are
35 * Copyright (c) 1995 Danny Gasparovski.
36 *
37 * Please read the file COPYRIGHT for the
38 * terms and conditions of the copyright.
39 */
40
41 #include "qemu/osdep.h"
42 #include "slirp.h"
43
44 /* Number of packets queued before we start sending
45 * (to prevent allocing too many mbufs) */
46 #define IF_THRESH 10
47
48 /*
49 * IP output. The packet in mbuf chain m contains a skeletal IP
50 * header (with len, off, ttl, proto, tos, src, dst).
51 * The mbuf chain containing the packet will be freed.
52 * The mbuf opt, if present, will not be freed.
53 */
54 int
55 ip_output(struct socket *so, struct mbuf *m0)
56 {
57 Slirp *slirp = m0->slirp;
58 register struct ip *ip;
59 register struct mbuf *m = m0;
60 register int hlen = sizeof(struct ip );
61 int len, off, error = 0;
62
63 DEBUG_CALL("ip_output");
64 DEBUG_ARG("so = %p", so);
65 DEBUG_ARG("m0 = %p", m0);
66
67 ip = mtod(m, struct ip *);
68 /*
69 * Fill in IP header.
70 */
71 ip->ip_v = IPVERSION;
72 ip->ip_off &= IP_DF;
73 ip->ip_id = htons(slirp->ip_id++);
74 ip->ip_hl = hlen >> 2;
75
76 /*
77 * If small enough for interface, can just send directly.
78 */
79 if ((uint16_t)ip->ip_len <= IF_MTU) {
80 ip->ip_len = htons((uint16_t)ip->ip_len);
81 ip->ip_off = htons((uint16_t)ip->ip_off);
82 ip->ip_sum = 0;
83 ip->ip_sum = cksum(m, hlen);
84
85 if_output(so, m);
86 goto done;
87 }
88
89 /*
90 * Too large for interface; fragment if possible.
91 * Must be able to put at least 8 bytes per fragment.
92 */
93 if (ip->ip_off & IP_DF) {
94 error = -1;
95 goto bad;
96 }
97
98 len = (IF_MTU - hlen) &~ 7; /* ip databytes per packet */
99 if (len < 8) {
100 error = -1;
101 goto bad;
102 }
103
104 {
105 int mhlen, firstlen = len;
106 struct mbuf **mnext = &m->m_nextpkt;
107
108 /*
109 * Loop through length of segment after first fragment,
110 * make new header and copy data of each part and link onto chain.
111 */
112 m0 = m;
113 mhlen = sizeof (struct ip);
114 for (off = hlen + len; off < (uint16_t)ip->ip_len; off += len) {
115 register struct ip *mhip;
116 m = m_get(slirp);
117 if (m == NULL) {
118 error = -1;
119 goto sendorfree;
120 }
121 m->m_data += IF_MAXLINKHDR;
122 mhip = mtod(m, struct ip *);
123 *mhip = *ip;
124
125 m->m_len = mhlen;
126 mhip->ip_off = ((off - hlen) >> 3) + (ip->ip_off & ~IP_MF);
127 if (ip->ip_off & IP_MF)
128 mhip->ip_off |= IP_MF;
129 if (off + len >= (uint16_t)ip->ip_len)
130 len = (uint16_t)ip->ip_len - off;
131 else
132 mhip->ip_off |= IP_MF;
133 mhip->ip_len = htons((uint16_t)(len + mhlen));
134
135 if (m_copy(m, m0, off, len) < 0) {
136 error = -1;
137 goto sendorfree;
138 }
139
140 mhip->ip_off = htons((uint16_t)mhip->ip_off);
141 mhip->ip_sum = 0;
142 mhip->ip_sum = cksum(m, mhlen);
143 *mnext = m;
144 mnext = &m->m_nextpkt;
145 }
146 /*
147 * Update first fragment by trimming what's been copied out
148 * and updating header, then send each fragment (in order).
149 */
150 m = m0;
151 m_adj(m, hlen + firstlen - (uint16_t)ip->ip_len);
152 ip->ip_len = htons((uint16_t)m->m_len);
153 ip->ip_off = htons((uint16_t)(ip->ip_off | IP_MF));
154 ip->ip_sum = 0;
155 ip->ip_sum = cksum(m, hlen);
156 sendorfree:
157 for (m = m0; m; m = m0) {
158 m0 = m->m_nextpkt;
159 m->m_nextpkt = NULL;
160 if (error == 0)
161 if_output(so, m);
162 else
163 m_free(m);
164 }
165 }
166
167 done:
168 return (error);
169
170 bad:
171 m_free(m0);
172 goto done;
173 }