1/* Taken from $NetBSD: net.c,v 1.20 1997/12/26 22:41:30 scottr Exp $	*/
2
3/*
4 * Copyright (c) 1992 Regents of the University of California.
5 * All rights reserved.
6 *
7 * This software was developed by the Computer Systems Engineering group
8 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
9 * contributed to Berkeley.
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 * 4. Neither the name of the University nor the names of its contributors
20 *    may be used to endorse or promote products derived from this software
21 *    without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 *
35 * @(#) Header: net.c,v 1.9 93/08/06 19:32:15 leres Exp  (LBL)
36 */
37
38#include <sys/cdefs.h>
39__FBSDID("$FreeBSD$");
40
41#include <sys/param.h>
42#include <sys/socket.h>
43
44#include <string.h>
45
46#include <net/if.h>
47#include <netinet/in.h>
48#include <netinet/if_ether.h>
49#include <netinet/in_systm.h>
50
51#include <netinet/in_pcb.h>
52#include <netinet/ip.h>
53#include <netinet/ip_var.h>
54#include <netinet/udp.h>
55#include <netinet/udp_var.h>
56
57#include "stand.h"
58#include "net.h"
59
60/* Caller must leave room for ethernet, ip and udp headers in front!! */
61ssize_t
62sendudp(d, pkt, len)
63	struct iodesc *d;
64	void *pkt;
65	size_t len;
66{
67	ssize_t cc;
68	struct ip *ip;
69	struct udphdr *uh;
70	u_char *ea;
71
72#ifdef NET_DEBUG
73 	if (debug) {
74		printf("sendudp: d=%lx called.\n", (long)d);
75		if (d) {
76			printf("saddr: %s:%d",
77			    inet_ntoa(d->myip), ntohs(d->myport));
78			printf(" daddr: %s:%d\n",
79			    inet_ntoa(d->destip), ntohs(d->destport));
80		}
81	}
82#endif
83
84	uh = (struct udphdr *)pkt - 1;
85	ip = (struct ip *)uh - 1;
86	len += sizeof(*ip) + sizeof(*uh);
87
88	bzero(ip, sizeof(*ip) + sizeof(*uh));
89
90	ip->ip_v = IPVERSION;			/* half-char */
91	ip->ip_hl = sizeof(*ip) >> 2;		/* half-char */
92	ip->ip_len = htons(len);
93	ip->ip_p = IPPROTO_UDP;			/* char */
94	ip->ip_ttl = IPDEFTTL;			/* char */
95	ip->ip_src = d->myip;
96	ip->ip_dst = d->destip;
97	ip->ip_sum = in_cksum(ip, sizeof(*ip));	 /* short, but special */
98
99	uh->uh_sport = d->myport;
100	uh->uh_dport = d->destport;
101	uh->uh_ulen = htons(len - sizeof(*ip));
102
103#ifndef UDP_NO_CKSUM
104	{
105		struct udpiphdr *ui;
106		struct ip tip;
107
108		/* Calculate checksum (must save and restore ip header) */
109		tip = *ip;
110		ui = (struct udpiphdr *)ip;
111		bzero(&ui->ui_x1, sizeof(ui->ui_x1));
112		ui->ui_len = uh->uh_ulen;
113		uh->uh_sum = in_cksum(ui, len);
114		*ip = tip;
115	}
116#endif
117
118	if (ip->ip_dst.s_addr == INADDR_BROADCAST || ip->ip_src.s_addr == 0 ||
119	    netmask == 0 || SAMENET(ip->ip_src, ip->ip_dst, netmask))
120		ea = arpwhohas(d, ip->ip_dst);
121	else
122		ea = arpwhohas(d, gateip);
123
124	cc = sendether(d, ip, len, ea, ETHERTYPE_IP);
125	if (cc == -1)
126		return (-1);
127	if (cc != len)
128		panic("sendudp: bad write (%zd != %zd)", cc, len);
129	return (cc - (sizeof(*ip) + sizeof(*uh)));
130}
131
132/*
133 * Receive a UDP packet and validate it is for us.
134 * Caller leaves room for the headers (Ether, IP, UDP)
135 */
136ssize_t
137readudp(d, pkt, len, tleft)
138	struct iodesc *d;
139	void *pkt;
140	size_t len;
141	time_t tleft;
142{
143	ssize_t n;
144	size_t hlen;
145	struct ip *ip;
146	struct udphdr *uh;
147	u_int16_t etype;	/* host order */
148
149#ifdef NET_DEBUG
150	if (debug)
151		printf("readudp: called\n");
152#endif
153
154	uh = (struct udphdr *)pkt - 1;
155	ip = (struct ip *)uh - 1;
156
157	n = readether(d, ip, len + sizeof(*ip) + sizeof(*uh), tleft, &etype);
158	if (n == -1 || n < sizeof(*ip) + sizeof(*uh))
159		return -1;
160
161	/* Ethernet address checks now in readether() */
162
163	/* Need to respond to ARP requests. */
164	if (etype == ETHERTYPE_ARP) {
165		struct arphdr *ah = (void *)ip;
166		if (ah->ar_op == htons(ARPOP_REQUEST)) {
167			/* Send ARP reply */
168			arp_reply(d, ah);
169		}
170		return -1;
171	}
172
173	if (etype != ETHERTYPE_IP) {
174#ifdef NET_DEBUG
175		if (debug)
176			printf("readudp: not IP. ether_type=%x\n", etype);
177#endif
178		return -1;
179	}
180
181	/* Check ip header */
182	if (ip->ip_v != IPVERSION ||
183	    ip->ip_p != IPPROTO_UDP) {	/* half char */
184#ifdef NET_DEBUG
185		if (debug)
186			printf("readudp: IP version or not UDP. ip_v=%d ip_p=%d\n", ip->ip_v, ip->ip_p);
187#endif
188		return -1;
189	}
190
191	hlen = ip->ip_hl << 2;
192	if (hlen < sizeof(*ip) ||
193	    in_cksum(ip, hlen) != 0) {
194#ifdef NET_DEBUG
195		if (debug)
196			printf("readudp: short hdr or bad cksum.\n");
197#endif
198		return -1;
199	}
200	if (n < ntohs(ip->ip_len)) {
201#ifdef NET_DEBUG
202		if (debug)
203			printf("readudp: bad length %d < %d.\n",
204			       (int)n, ntohs(ip->ip_len));
205#endif
206		return -1;
207	}
208	if (d->myip.s_addr && ip->ip_dst.s_addr != d->myip.s_addr) {
209#ifdef NET_DEBUG
210		if (debug) {
211			printf("readudp: bad saddr %s != ", inet_ntoa(d->myip));
212			printf("%s\n", inet_ntoa(ip->ip_dst));
213		}
214#endif
215		return -1;
216	}
217
218	/* If there were ip options, make them go away */
219	if (hlen != sizeof(*ip)) {
220		bcopy(((u_char *)ip) + hlen, uh, len - hlen);
221		ip->ip_len = htons(sizeof(*ip));
222		n -= hlen - sizeof(*ip);
223	}
224	if (uh->uh_dport != d->myport) {
225#ifdef NET_DEBUG
226		if (debug)
227			printf("readudp: bad dport %d != %d\n",
228				d->myport, ntohs(uh->uh_dport));
229#endif
230		return -1;
231	}
232
233#ifndef UDP_NO_CKSUM
234	if (uh->uh_sum) {
235		struct udpiphdr *ui;
236		struct ip tip;
237
238		n = ntohs(uh->uh_ulen) + sizeof(*ip);
239		if (n > RECV_SIZE - ETHER_SIZE) {
240			printf("readudp: huge packet, udp len %d\n", (int)n);
241			return -1;
242		}
243
244		/* Check checksum (must save and restore ip header) */
245		tip = *ip;
246		ui = (struct udpiphdr *)ip;
247		bzero(&ui->ui_x1, sizeof(ui->ui_x1));
248		ui->ui_len = uh->uh_ulen;
249		if (in_cksum(ui, n) != 0) {
250#ifdef NET_DEBUG
251			if (debug)
252				printf("readudp: bad cksum\n");
253#endif
254			*ip = tip;
255			return -1;
256		}
257		*ip = tip;
258	}
259#endif
260	if (ntohs(uh->uh_ulen) < sizeof(*uh)) {
261#ifdef NET_DEBUG
262		if (debug)
263			printf("readudp: bad udp len %d < %d\n",
264				ntohs(uh->uh_ulen), (int)sizeof(*uh));
265#endif
266		return -1;
267	}
268
269	n = (n > (ntohs(uh->uh_ulen) - sizeof(*uh))) ?
270	    ntohs(uh->uh_ulen) - sizeof(*uh) : n;
271	return (n);
272}
273