1 /* $NetBSD: ip.c,v 1.5 2022/07/08 07:02:47 skrll Exp $ */
2
3 /*
4 * Copyright (c) 1992 Regents of the University of California.
5 * Copyright (c) 2010 Zoltan Arnold NAGY
6 * All rights reserved.
7 *
8 * This software was developed by the Computer Systems Engineering group
9 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
10 * contributed to Berkeley.
11 *
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
14 * are met:
15 * 1. Redistributions of source code must retain the above copyright
16 * notice, this list of conditions and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 * notice, this list of conditions and the following disclaimer in the
19 * documentation and/or other materials provided with the distribution.
20 * 3. All advertising materials mentioning features or use of this software
21 * must display the following acknowledgement:
22 * This product includes software developed by the University of
23 * California, Lawrence Berkeley Laboratory and its contributors.
24 * 4. Neither the name of the University nor the names of its contributors
25 * may be used to endorse or promote products derived from this software
26 * without specific prior written permission.
27 *
28 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
29 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
30 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
31 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
32 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
33 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
34 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
35 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
37 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
38 * SUCH DAMAGE.
39 */
40
41 #include <sys/param.h>
42 #include <sys/socket.h>
43 #include <net/if.h>
44 #include <net/if_ether.h>
45 #include <netinet/in.h>
46 #include <netinet/in_systm.h>
47 #include <netinet/ip.h>
48 #include <netinet/ip_var.h>
49 #include <netinet/udp.h>
50 #include <netinet/udp_var.h>
51
52 #ifdef _STANDALONE
53 #include <lib/libkern/libkern.h>
54 #else
55 #include <string.h>
56 #endif
57
58 #include "stand.h"
59 #include "net.h"
60
61 /*
62 * sends an IP packet, if it's already constructed
63 */
64 static ssize_t
_sendip(struct iodesc * d,struct ip * ip,size_t len)65 _sendip(struct iodesc *d, struct ip *ip, size_t len)
66 {
67 u_char *ea;
68
69 if (ip->ip_dst.s_addr == INADDR_BROADCAST || ip->ip_src.s_addr == 0 ||
70 netmask == 0 || SAMENET(ip->ip_src, ip->ip_dst, netmask)) {
71 ea = arpwhohas(d, ip->ip_dst);
72 } else {
73 ea = arpwhohas(d, gateip);
74 }
75
76 return sendether(d, ip, len, ea, ETHERTYPE_IP);
77 }
78
79 /*
80 * fills out the IP header
81 * Caller must leave room for ethernet, ip and udp headers in front!
82 */
83 ssize_t
sendip(struct iodesc * d,void * pkt,size_t len,u_int8_t proto)84 sendip(struct iodesc *d, void *pkt, size_t len, u_int8_t proto)
85 {
86 ssize_t cc;
87 struct ip *ip;
88
89 ip = (struct ip *)pkt - 1;
90 len += sizeof(*ip);
91
92 memset(ip, 0, sizeof(*ip));
93
94 ip->ip_v = IPVERSION;
95 ip->ip_hl = sizeof(*ip) >> 2;
96 ip->ip_len = htons(len);
97 ip->ip_p = proto;
98 ip->ip_ttl = IPDEFTTL;
99 ip->ip_src = d->myip;
100 ip->ip_dst = d->destip;
101 ip->ip_sum = ip_cksum(ip, sizeof(*ip));
102
103 cc = _sendip(d, ip, len);
104
105 if (cc == -1)
106 return -1;
107 if ((size_t)cc != len)
108 panic("%s: bad write (%zd != %zu)", __func__, cc, len);
109 return (cc - (sizeof(*ip)));
110 }
111
112 /*
113 * reads an IP packet
114 * WARNING: the old version stripped the IP options, if there were
115 * any. Because we have absolutely no idea if the upper layer needs
116 * these or not, it's best to leave them there.
117 *
118 * The size returned is the size indicated in the header.
119 */
120 ssize_t
readip(struct iodesc * d,void * pkt,size_t len,time_t tleft,u_int8_t proto)121 readip(struct iodesc *d, void *pkt, size_t len, time_t tleft, u_int8_t proto)
122 {
123 ssize_t n;
124 size_t hlen;
125 struct ip *ip;
126 u_int16_t etype;
127
128 ip = (struct ip *)pkt - 1;
129
130 n = readether(d, ip, len + sizeof(*ip), tleft, &etype);
131 if (n == -1 || (size_t)n < sizeof(*ip))
132 return -1;
133
134 if (etype == ETHERTYPE_ARP) {
135 struct arphdr *ah = (void *)ip;
136 if (n < (ssize_t)(sizeof(*ah) + 2 * (ah->ar_hln + ah->ar_pln))) {
137 return -1;
138 }
139 if (ah->ar_op == htons(ARPOP_REQUEST)) {
140 /* Send ARP reply */
141 arp_reply(d, ah);
142 }
143 return -1;
144 }
145 if (etype != ETHERTYPE_IP) {
146 return -1;
147 }
148
149 if (ip->ip_v != IPVERSION || ip->ip_p != proto) {
150 return -1;
151 }
152
153 hlen = ip->ip_hl << 2;
154 if (hlen != sizeof(*ip) || ip_cksum(ip, hlen) != 0) {
155 return -1;
156 }
157 if (ntohs(ip->ip_len) < hlen) {
158 return -1;
159 }
160 if (n < ntohs(ip->ip_len)) {
161 return -1;
162 }
163 if (d->myip.s_addr && ip->ip_dst.s_addr != d->myip.s_addr) {
164 return -1;
165 }
166
167 return (ntohs(ip->ip_len) - hlen);
168 }
169