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 <slirp.h>
25 #include "helper.h"
26
27 /* XXX: only DHCP is supported */
28
29 #define NB_ADDR 16
30
31 #define START_ADDR 15
32
33 #define LEASE_TIME (24 * 3600)
34
35 typedef struct {
36 uint8_t allocated;
37 uint8_t macaddr[6];
38 } BOOTPClient;
39
40 static BOOTPClient bootp_clients[NB_ADDR];
41
42 const char *bootp_filename;
43
44 static const uint8_t rfc1533_cookie[] = { RFC1533_COOKIE };
45
46 #ifdef DEBUG
47 #define dprintf(fmt, ...) \
48 if (slirp_debug & DBG_CALL) { fprintf(dfd, fmt, ## __VA_ARGS__); fflush(dfd); }
49 #else
50 #define dprintf(fmt, ...)
51 #endif
52
get_new_addr(SockAddress * paddr,const uint8_t * macaddr)53 static BOOTPClient *get_new_addr(SockAddress* paddr,
54 const uint8_t *macaddr)
55 {
56 BOOTPClient *bc;
57 int i;
58
59 for(i = 0; i < NB_ADDR; i++) {
60 bc = &bootp_clients[i];
61 if (!bc->allocated || !memcmp(macaddr, bc->macaddr, 6))
62 goto found;
63 }
64 return NULL;
65 found:
66 bc = &bootp_clients[i];
67 bc->allocated = 1;
68 sock_address_init_inet( paddr,
69 special_addr_ip | (i+START_ADDR),
70 BOOTP_CLIENT );
71 return bc;
72 }
73
request_addr(const ipaddr_t * paddr,const uint8_t * macaddr)74 static BOOTPClient *request_addr(const ipaddr_t *paddr,
75 const uint8_t *macaddr)
76 {
77 uint32_t req_addr = ip_geth(*paddr);
78 uint32_t spec_addr = special_addr_ip;
79 BOOTPClient *bc;
80
81 if (req_addr >= (spec_addr | START_ADDR) &&
82 req_addr < (spec_addr | (NB_ADDR + START_ADDR))) {
83 bc = &bootp_clients[(req_addr & 0xff) - START_ADDR];
84 if (!bc->allocated || !memcmp(macaddr, bc->macaddr, 6)) {
85 bc->allocated = 1;
86 return bc;
87 }
88 }
89 return NULL;
90 }
91
find_addr(SockAddress * paddr,const uint8_t * macaddr)92 static BOOTPClient *find_addr(SockAddress *paddr, const uint8_t *macaddr)
93 {
94 BOOTPClient *bc;
95 int i;
96
97 for(i = 0; i < NB_ADDR; i++) {
98 if (!memcmp(macaddr, bootp_clients[i].macaddr, 6))
99 goto found;
100 }
101 return NULL;
102 found:
103 bc = &bootp_clients[i];
104 bc->allocated = 1;
105 sock_address_init_inet( paddr,
106 special_addr_ip | (i + START_ADDR),
107 BOOTP_CLIENT );
108 return bc;
109 }
110
dhcp_decode(const struct bootp_t * bp,int * pmsg_type,const ipaddr_t ** preq_addr)111 static void dhcp_decode(const struct bootp_t *bp, int *pmsg_type,
112 const ipaddr_t **preq_addr)
113 {
114 const uint8_t *p, *p_end;
115 int len, tag;
116
117 *pmsg_type = 0;
118 *preq_addr = NULL;
119
120 p = bp->bp_vend;
121 p_end = p + DHCP_OPT_LEN;
122 if (memcmp(p, rfc1533_cookie, 4) != 0)
123 return;
124 p += 4;
125 while (p < p_end) {
126 tag = p[0];
127 if (tag == RFC1533_PAD) {
128 p++;
129 } else if (tag == RFC1533_END) {
130 break;
131 } else {
132 p++;
133 if (p >= p_end)
134 break;
135 len = *p++;
136 dprintf("dhcp: tag=%d len=%d\n", tag, len);
137
138 switch(tag) {
139 case RFC2132_MSG_TYPE:
140 if (len >= 1)
141 *pmsg_type = p[0];
142 break;
143 case RFC2132_REQ_ADDR:
144 if (len >= 4)
145 *preq_addr = (const ipaddr_t *)p;
146 break;
147 default:
148 break;
149 }
150 p += len;
151 }
152 }
153 if (*pmsg_type == DHCPREQUEST && !*preq_addr && bp->bp_ciaddr) {
154 *preq_addr = (const ipaddr_t*)&bp->bp_ciaddr;
155 }
156 }
157
bootp_reply(const struct bootp_t * bp)158 static void bootp_reply(const struct bootp_t *bp)
159 {
160 BOOTPClient *bc = NULL;
161 struct mbuf *m;
162 struct bootp_t *rbp;
163 SockAddress saddr, daddr;
164 uint32_t dns_addr;
165 const ipaddr_t *preq_addr;
166 int dhcp_msg_type, val;
167 uint8_t *q;
168
169 /* extract exact DHCP msg type */
170 dhcp_decode(bp, &dhcp_msg_type, &preq_addr);
171 dprintf("bootp packet op=%d msgtype=%d", bp->bp_op, dhcp_msg_type);
172 if (preq_addr) {
173 dprintf(" req_addr=%08x\n", ntohl(*(uint32_t*)preq_addr));
174 } else {
175 dprintf("\n");
176 }
177 if (dhcp_msg_type == 0)
178 dhcp_msg_type = DHCPREQUEST; /* Force reply for old BOOTP clients */
179
180 if (dhcp_msg_type != DHCPDISCOVER &&
181 dhcp_msg_type != DHCPREQUEST)
182 return;
183 /* XXX: this is a hack to get the client mac address */
184 memcpy(client_ethaddr, bp->bp_hwaddr, 6);
185
186 if ((m = m_get()) == NULL)
187 return;
188 m->m_data += IF_MAXLINKHDR;
189 rbp = (struct bootp_t *)m->m_data;
190 m->m_data += sizeof(struct udpiphdr);
191 memset(rbp, 0, sizeof(struct bootp_t));
192
193 if (dhcp_msg_type == DHCPDISCOVER) {
194 if (preq_addr) {
195 bc = request_addr(preq_addr, client_ethaddr);
196 if (bc) {
197 sock_address_init_inet(&daddr, ip_geth(*preq_addr), BOOTP_CLIENT);
198 }
199 }
200 if (!bc) {
201 new_addr:
202 bc = get_new_addr(&daddr, client_ethaddr);
203 if (!bc) {
204 dprintf("no address left\n");
205 return;
206 }
207 }
208 memcpy(bc->macaddr, client_ethaddr, 6);
209 } else if (preq_addr) {
210 bc = request_addr(preq_addr, client_ethaddr);
211 if (bc) {
212 sock_address_init_inet(&daddr, ip_geth(*preq_addr), BOOTP_CLIENT);
213 memcpy(bc->macaddr, client_ethaddr, 6);
214 } else {
215 sock_address_init_inet(&daddr, 0, BOOTP_CLIENT);
216 }
217 } else {
218 bc = find_addr(&daddr, bp->bp_hwaddr);
219 if (!bc) {
220 /* if never assigned, behaves as if it was already
221 assigned (windows fix because it remembers its address) */
222 goto new_addr;
223 }
224 }
225
226 sock_address_init_inet( &saddr, special_addr_ip | CTL_ALIAS,
227 BOOTP_SERVER );
228
229 rbp->bp_op = BOOTP_REPLY;
230 rbp->bp_xid = bp->bp_xid;
231 rbp->bp_htype = 1;
232 rbp->bp_hlen = 6;
233 memcpy(rbp->bp_hwaddr, bp->bp_hwaddr, 6);
234
235 rbp->bp_yiaddr = htonl(sock_address_get_ip(&daddr)); /* Client IP address */
236 rbp->bp_siaddr = htonl(sock_address_get_ip(&saddr)); /* Server IP address */
237
238 q = rbp->bp_vend;
239 memcpy(q, rfc1533_cookie, 4);
240 q += 4;
241
242 if (bc) {
243 uint32_t saddr_ip = htonl(sock_address_get_ip(&saddr));
244 dprintf("%s addr=%08x\n",
245 (dhcp_msg_type == DHCPDISCOVER) ? "offered" : "ack'ed",
246 sock_address_get_ip(&daddr));
247
248 if (dhcp_msg_type == DHCPDISCOVER) {
249 *q++ = RFC2132_MSG_TYPE;
250 *q++ = 1;
251 *q++ = DHCPOFFER;
252 } else /* DHCPREQUEST */ {
253 *q++ = RFC2132_MSG_TYPE;
254 *q++ = 1;
255 *q++ = DHCPACK;
256 }
257
258 if (bootp_filename)
259 snprintf((char *)rbp->bp_file, sizeof(rbp->bp_file), "%s",
260 bootp_filename);
261
262 *q++ = RFC2132_SRV_ID;
263 *q++ = 4;
264 memcpy(q, &saddr_ip, 4);
265 q += 4;
266
267 *q++ = RFC1533_NETMASK;
268 *q++ = 4;
269 *q++ = 0xff;
270 *q++ = 0xff;
271 *q++ = 0xff;
272 *q++ = 0x00;
273
274 if (!slirp_restrict) {
275 *q++ = RFC1533_GATEWAY;
276 *q++ = 4;
277 memcpy(q, &saddr_ip, 4);
278 q += 4;
279
280 *q++ = RFC1533_DNS;
281 *q++ = 4;
282 dns_addr = htonl(special_addr_ip | CTL_DNS);
283 memcpy(q, &dns_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_hostname) {
294 val = strlen(slirp_hostname);
295 *q++ = RFC1533_HOSTNAME;
296 *q++ = val;
297 memcpy(q, slirp_hostname, val);
298 q += val;
299 }
300 } else {
301 static const char nak_msg[] = "requested address not available";
302
303 dprintf("nak'ed addr=%08x\n", ip_geth(*preq_addr));
304
305 *q++ = RFC2132_MSG_TYPE;
306 *q++ = 1;
307 *q++ = DHCPNAK;
308
309 *q++ = RFC2132_MESSAGE;
310 *q++ = sizeof(nak_msg) - 1;
311 memcpy(q, nak_msg, sizeof(nak_msg) - 1);
312 q += sizeof(nak_msg) - 1;
313 }
314 *q++ = RFC1533_END;
315
316 sock_address_init_inet(&daddr, 0xffffffffu, BOOTP_CLIENT);
317
318 m->m_len = sizeof(struct bootp_t) -
319 sizeof(struct ip) - sizeof(struct udphdr);
320 udp_output2_(NULL, m, &saddr, &daddr, IPTOS_LOWDELAY);
321 }
322
bootp_input(struct mbuf * m)323 void bootp_input(struct mbuf *m)
324 {
325 struct bootp_t *bp = mtod(m, struct bootp_t *);
326
327 if (bp->bp_op == BOOTP_REQUEST) {
328 bootp_reply(bp);
329 }
330 }
331