slirp: correct size computation while concatenating mbuf
[qemu.git] / slirp / bootp.c
1 /*
2 * QEMU BOOTP/DHCP server
3 *
4 * Copyright (c) 2004 Fabrice Bellard
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a copy
7 * of this software and associated documentation files (the "Software"), to deal
8 * in the Software without restriction, including without limitation the rights
9 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
10 * copies of the Software, and to permit persons to whom the Software is
11 * furnished to do so, subject to the following conditions:
12 *
13 * The above copyright notice and this permission notice shall be included in
14 * all copies or substantial portions of the Software.
15 *
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
19 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
22 * THE SOFTWARE.
23 */
24 #include "qemu/osdep.h"
25 #include "slirp.h"
26
27 #if defined(_WIN32)
28 /* Windows ntohl() returns an u_long value.
29 * Add a type cast to match the format strings. */
30 # define ntohl(n) ((uint32_t)ntohl(n))
31 #endif
32
33 /* XXX: only DHCP is supported */
34
35 #define LEASE_TIME (24 * 3600)
36
37 static const uint8_t rfc1533_cookie[] = { RFC1533_COOKIE };
38
39 #ifdef DEBUG
40 #define DPRINTF(fmt, ...) \
41 do if (slirp_debug & DBG_CALL) { fprintf(dfd, fmt, ## __VA_ARGS__); fflush(dfd); } while (0)
42 #else
43 #define DPRINTF(fmt, ...) do{}while(0)
44 #endif
45
46 static BOOTPClient *get_new_addr(Slirp *slirp, struct in_addr *paddr,
47 const uint8_t *macaddr)
48 {
49 BOOTPClient *bc;
50 int i;
51
52 for(i = 0; i < NB_BOOTP_CLIENTS; i++) {
53 bc = &slirp->bootp_clients[i];
54 if (!bc->allocated || !memcmp(macaddr, bc->macaddr, 6))
55 goto found;
56 }
57 return NULL;
58 found:
59 bc = &slirp->bootp_clients[i];
60 bc->allocated = 1;
61 paddr->s_addr = slirp->vdhcp_startaddr.s_addr + htonl(i);
62 return bc;
63 }
64
65 static BOOTPClient *request_addr(Slirp *slirp, const struct in_addr *paddr,
66 const uint8_t *macaddr)
67 {
68 uint32_t req_addr = ntohl(paddr->s_addr);
69 uint32_t dhcp_addr = ntohl(slirp->vdhcp_startaddr.s_addr);
70 BOOTPClient *bc;
71
72 if (req_addr >= dhcp_addr &&
73 req_addr < (dhcp_addr + NB_BOOTP_CLIENTS)) {
74 bc = &slirp->bootp_clients[req_addr - dhcp_addr];
75 if (!bc->allocated || !memcmp(macaddr, bc->macaddr, 6)) {
76 bc->allocated = 1;
77 return bc;
78 }
79 }
80 return NULL;
81 }
82
83 static BOOTPClient *find_addr(Slirp *slirp, struct in_addr *paddr,
84 const uint8_t *macaddr)
85 {
86 BOOTPClient *bc;
87 int i;
88
89 for(i = 0; i < NB_BOOTP_CLIENTS; i++) {
90 if (!memcmp(macaddr, slirp->bootp_clients[i].macaddr, 6))
91 goto found;
92 }
93 return NULL;
94 found:
95 bc = &slirp->bootp_clients[i];
96 bc->allocated = 1;
97 paddr->s_addr = slirp->vdhcp_startaddr.s_addr + htonl(i);
98 return bc;
99 }
100
101 static void dhcp_decode(const struct bootp_t *bp, int *pmsg_type,
102 struct in_addr *preq_addr)
103 {
104 const uint8_t *p, *p_end;
105 int len, tag;
106
107 *pmsg_type = 0;
108 preq_addr->s_addr = htonl(0L);
109
110 p = bp->bp_vend;
111 p_end = p + DHCP_OPT_LEN;
112 if (memcmp(p, rfc1533_cookie, 4) != 0)
113 return;
114 p += 4;
115 while (p < p_end) {
116 tag = p[0];
117 if (tag == RFC1533_PAD) {
118 p++;
119 } else if (tag == RFC1533_END) {
120 break;
121 } else {
122 p++;
123 if (p >= p_end)
124 break;
125 len = *p++;
126 if (p + len > p_end) {
127 break;
128 }
129 DPRINTF("dhcp: tag=%d len=%d\n", tag, len);
130
131 switch(tag) {
132 case RFC2132_MSG_TYPE:
133 if (len >= 1)
134 *pmsg_type = p[0];
135 break;
136 case RFC2132_REQ_ADDR:
137 if (len >= 4) {
138 memcpy(&(preq_addr->s_addr), p, 4);
139 }
140 break;
141 default:
142 break;
143 }
144 p += len;
145 }
146 }
147 if (*pmsg_type == DHCPREQUEST && preq_addr->s_addr == htonl(0L) &&
148 bp->bp_ciaddr.s_addr) {
149 memcpy(&(preq_addr->s_addr), &bp->bp_ciaddr, 4);
150 }
151 }
152
153 static void bootp_reply(Slirp *slirp, const struct bootp_t *bp)
154 {
155 BOOTPClient *bc = NULL;
156 struct mbuf *m;
157 struct bootp_t *rbp;
158 struct sockaddr_in saddr, daddr;
159 struct in_addr preq_addr;
160 int dhcp_msg_type, val;
161 uint8_t *q;
162 uint8_t client_ethaddr[ETH_ALEN];
163
164 /* extract exact DHCP msg type */
165 dhcp_decode(bp, &dhcp_msg_type, &preq_addr);
166 DPRINTF("bootp packet op=%d msgtype=%d", bp->bp_op, dhcp_msg_type);
167 if (preq_addr.s_addr != htonl(0L))
168 DPRINTF(" req_addr=%08" PRIx32 "\n", ntohl(preq_addr.s_addr));
169 else
170 DPRINTF("\n");
171
172 if (dhcp_msg_type == 0)
173 dhcp_msg_type = DHCPREQUEST; /* Force reply for old BOOTP clients */
174
175 if (dhcp_msg_type != DHCPDISCOVER &&
176 dhcp_msg_type != DHCPREQUEST)
177 return;
178
179 /* Get client's hardware address from bootp request */
180 memcpy(client_ethaddr, bp->bp_hwaddr, ETH_ALEN);
181
182 m = m_get(slirp);
183 if (!m) {
184 return;
185 }
186 m->m_data += IF_MAXLINKHDR;
187 rbp = (struct bootp_t *)m->m_data;
188 m->m_data += sizeof(struct udpiphdr);
189 memset(rbp, 0, sizeof(struct bootp_t));
190
191 if (dhcp_msg_type == DHCPDISCOVER) {
192 if (preq_addr.s_addr != htonl(0L)) {
193 bc = request_addr(slirp, &preq_addr, client_ethaddr);
194 if (bc) {
195 daddr.sin_addr = preq_addr;
196 }
197 }
198 if (!bc) {
199 new_addr:
200 bc = get_new_addr(slirp, &daddr.sin_addr, client_ethaddr);
201 if (!bc) {
202 DPRINTF("no address left\n");
203 return;
204 }
205 }
206 memcpy(bc->macaddr, client_ethaddr, ETH_ALEN);
207 } else if (preq_addr.s_addr != htonl(0L)) {
208 bc = request_addr(slirp, &preq_addr, client_ethaddr);
209 if (bc) {
210 daddr.sin_addr = preq_addr;
211 memcpy(bc->macaddr, client_ethaddr, ETH_ALEN);
212 } else {
213 /* DHCPNAKs should be sent to broadcast */
214 daddr.sin_addr.s_addr = 0xffffffff;
215 }
216 } else {
217 bc = find_addr(slirp, &daddr.sin_addr, bp->bp_hwaddr);
218 if (!bc) {
219 /* if never assigned, behaves as if it was already
220 assigned (windows fix because it remembers its address) */
221 goto new_addr;
222 }
223 }
224
225 /* Update ARP table for this IP address */
226 arp_table_add(slirp, daddr.sin_addr.s_addr, client_ethaddr);
227
228 saddr.sin_addr = slirp->vhost_addr;
229 saddr.sin_port = htons(BOOTP_SERVER);
230
231 daddr.sin_port = htons(BOOTP_CLIENT);
232
233 rbp->bp_op = BOOTP_REPLY;
234 rbp->bp_xid = bp->bp_xid;
235 rbp->bp_htype = 1;
236 rbp->bp_hlen = 6;
237 memcpy(rbp->bp_hwaddr, bp->bp_hwaddr, ETH_ALEN);
238
239 rbp->bp_yiaddr = daddr.sin_addr; /* Client IP address */
240 rbp->bp_siaddr = saddr.sin_addr; /* Server IP address */
241
242 q = rbp->bp_vend;
243 memcpy(q, rfc1533_cookie, 4);
244 q += 4;
245
246 if (bc) {
247 DPRINTF("%s addr=%08" PRIx32 "\n",
248 (dhcp_msg_type == DHCPDISCOVER) ? "offered" : "ack'ed",
249 ntohl(daddr.sin_addr.s_addr));
250
251 if (dhcp_msg_type == DHCPDISCOVER) {
252 *q++ = RFC2132_MSG_TYPE;
253 *q++ = 1;
254 *q++ = DHCPOFFER;
255 } else /* DHCPREQUEST */ {
256 *q++ = RFC2132_MSG_TYPE;
257 *q++ = 1;
258 *q++ = DHCPACK;
259 }
260
261 if (slirp->bootp_filename)
262 snprintf((char *)rbp->bp_file, sizeof(rbp->bp_file), "%s",
263 slirp->bootp_filename);
264
265 *q++ = RFC2132_SRV_ID;
266 *q++ = 4;
267 memcpy(q, &saddr.sin_addr, 4);
268 q += 4;
269
270 *q++ = RFC1533_NETMASK;
271 *q++ = 4;
272 memcpy(q, &slirp->vnetwork_mask, 4);
273 q += 4;
274
275 if (!slirp->restricted) {
276 *q++ = RFC1533_GATEWAY;
277 *q++ = 4;
278 memcpy(q, &saddr.sin_addr, 4);
279 q += 4;
280
281 *q++ = RFC1533_DNS;
282 *q++ = 4;
283 memcpy(q, &slirp->vnameserver_addr, 4);
284 q += 4;
285 }
286
287 *q++ = RFC2132_LEASE_TIME;
288 *q++ = 4;
289 val = htonl(LEASE_TIME);
290 memcpy(q, &val, 4);
291 q += 4;
292
293 if (*slirp->client_hostname) {
294 val = strlen(slirp->client_hostname);
295 *q++ = RFC1533_HOSTNAME;
296 *q++ = val;
297 memcpy(q, slirp->client_hostname, val);
298 q += val;
299 }
300
301 if (slirp->vdomainname) {
302 val = strlen(slirp->vdomainname);
303 *q++ = RFC1533_DOMAINNAME;
304 *q++ = val;
305 memcpy(q, slirp->vdomainname, val);
306 q += val;
307 }
308
309 if (slirp->vdnssearch) {
310 size_t spaceleft = sizeof(rbp->bp_vend) - (q - rbp->bp_vend);
311 val = slirp->vdnssearch_len;
312 if (val + 1 > spaceleft) {
313 g_warning("DHCP packet size exceeded, "
314 "omitting domain-search option.");
315 } else {
316 memcpy(q, slirp->vdnssearch, val);
317 q += val;
318 }
319 }
320 } else {
321 static const char nak_msg[] = "requested address not available";
322
323 DPRINTF("nak'ed addr=%08" PRIx32 "\n", ntohl(preq_addr.s_addr));
324
325 *q++ = RFC2132_MSG_TYPE;
326 *q++ = 1;
327 *q++ = DHCPNAK;
328
329 *q++ = RFC2132_MESSAGE;
330 *q++ = sizeof(nak_msg) - 1;
331 memcpy(q, nak_msg, sizeof(nak_msg) - 1);
332 q += sizeof(nak_msg) - 1;
333 }
334 *q = RFC1533_END;
335
336 daddr.sin_addr.s_addr = 0xffffffffu;
337
338 m->m_len = sizeof(struct bootp_t) -
339 sizeof(struct ip) - sizeof(struct udphdr);
340 udp_output(NULL, m, &saddr, &daddr, IPTOS_LOWDELAY);
341 }
342
343 void bootp_input(struct mbuf *m)
344 {
345 struct bootp_t *bp = mtod(m, struct bootp_t *);
346
347 if (bp->bp_op == BOOTP_REQUEST) {
348 bootp_reply(m->slirp, bp);
349 }
350 }