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1.1 root 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:
26: /* XXX: only DHCP is supported */
27:
28: #define NB_ADDR 16
29:
30: #define START_ADDR 15
31:
32: #define LEASE_TIME (24 * 3600)
33:
34: typedef struct {
35: uint8_t allocated;
36: uint8_t macaddr[6];
37: } BOOTPClient;
38:
39: BOOTPClient bootp_clients[NB_ADDR];
40:
41: static const uint8_t rfc1533_cookie[] = { RFC1533_COOKIE };
42: #if BOOTP_VEND_NEXT
43: static const uint8_t magic_next[] = {'N','e','X','T'};
44: #endif
45:
46:
47: static BOOTPClient *get_new_addr(struct in_addr *paddr)
48: {
49: BOOTPClient *bc;
50: int i;
51:
52: for(i = 0; i < NB_ADDR; i++) {
53: if (!bootp_clients[i].allocated)
54: goto found;
55: }
56: return NULL;
57: found:
58: bc = &bootp_clients[i];
59: bc->allocated = 1;
60: paddr->s_addr = htonl(ntohl(special_addr.s_addr) | (i + START_ADDR));
61: return bc;
62: }
63:
64: static BOOTPClient *find_addr(struct in_addr *paddr, const uint8_t *macaddr)
65: {
66: BOOTPClient *bc;
67: int i;
68:
69: for(i = 0; i < NB_ADDR; i++) {
70: if (!memcmp(macaddr, bootp_clients[i].macaddr, 6))
71: goto found;
72: }
73: return NULL;
74: found:
75: bc = &bootp_clients[i];
76: bc->allocated = 1;
77: paddr->s_addr = htonl(ntohl(special_addr.s_addr) | (i + START_ADDR));
78: return bc;
79: }
80:
81: static void dhcp_decode(const uint8_t *buf, int size,
82: int *pmsg_type)
83: {
84: const uint8_t *p, *p_end;
85: int len, tag;
86:
87: *pmsg_type = 0;
88:
89: p = buf;
90: p_end = buf + size;
91: if (size < 5)
92: return;
93: if (memcmp(p, rfc1533_cookie, 4) != 0)
94: return;
95: p += 4;
96: while (p < p_end) {
97: tag = p[0];
98: if (tag == RFC1533_PAD) {
99: p++;
100: } else if (tag == RFC1533_END) {
101: break;
102: } else {
103: p++;
104: if (p >= p_end)
105: break;
106: len = *p++;
107:
108: switch(tag) {
109: case RFC2132_MSG_TYPE:
110: if (len >= 1)
111: *pmsg_type = p[0];
112: break;
113: default:
114: break;
115: }
116: p += len;
117: }
118: }
119: }
120:
121: static void bootp_reply(struct bootp_t *bp)
122: {
123: BOOTPClient *bc;
124: struct mbuf *m;
125: struct bootp_t *rbp;
126: struct sockaddr_in saddr, daddr;
127: struct in_addr dns_addr;
128: int dhcp_msg_type, val;
129: uint8_t *q;
130:
131: /* extract exact DHCP msg type */
132: dhcp_decode(bp->bp_vend, DHCP_OPT_LEN, &dhcp_msg_type);
133:
134: if (dhcp_msg_type == 0)
135: dhcp_msg_type = DHCPREQUEST; /* Force reply for old BOOTP clients */
136:
137: if (dhcp_msg_type != DHCPDISCOVER &&
138: dhcp_msg_type != DHCPREQUEST)
139: return;
140: /* XXX: this is a hack to get the client mac address */
141: memcpy(client_ethaddr, bp->bp_hwaddr, 6);
142:
143: if ((m = m_get()) == NULL)
144: return;
145: m->m_data += if_maxlinkhdr;
146: rbp = (struct bootp_t *)m->m_data;
147: m->m_data += sizeof(struct udpiphdr);
148: memset(rbp, 0, sizeof(struct bootp_t));
149:
150: if (dhcp_msg_type == DHCPDISCOVER) {
151: new_addr:
152: bc = get_new_addr(&daddr.sin_addr);
153: if (!bc)
154: return;
155: memcpy(bc->macaddr, client_ethaddr, 6);
156: } else {
157: bc = find_addr(&daddr.sin_addr, bp->bp_hwaddr);
158: if (!bc) {
159: /* if never assigned, behaves as if it was already
160: assigned (windows fix because it remembers its address) */
161: goto new_addr;
162: }
163: }
164:
165: saddr.sin_addr.s_addr = htonl(ntohl(special_addr.s_addr) | CTL_ALIAS);
166: saddr.sin_port = htons(BOOTP_SERVER);
167:
168: daddr.sin_port = htons(BOOTP_CLIENT);
169:
170: rbp->bp_op = BOOTP_REPLY;
171: rbp->bp_xid = bp->bp_xid;
172: rbp->bp_htype = 1;
173: rbp->bp_hlen = 6;
174: memcpy(rbp->bp_hwaddr, bp->bp_hwaddr, 6);
175:
176: rbp->bp_yiaddr = daddr.sin_addr; /* Client IP address */
177: rbp->bp_siaddr = saddr.sin_addr; /* Server IP address */
178:
179: q = rbp->bp_vend;
180: #if BOOTP_VEND_NEXT
181: memcpy(q, magic_next, 4);
182: q += 4;
183: *q++ = 1;
184: *q++ = 0;
185: *q++ = 0;
186: memset(q, 0, 56);
187: q += 56;
188: *q++ = 0;
189: #else
190: memcpy(q, rfc1533_cookie, 4);
191: q += 4;
192: if (dhcp_msg_type == DHCPDISCOVER) {
193: *q++ = RFC2132_MSG_TYPE;
194: *q++ = 1;
195: *q++ = DHCPOFFER;
196: } else if (dhcp_msg_type == DHCPREQUEST) {
197: *q++ = RFC2132_MSG_TYPE;
198: *q++ = 1;
199: *q++ = DHCPACK;
200: }
201:
202: if (dhcp_msg_type == DHCPDISCOVER ||
203: dhcp_msg_type == DHCPREQUEST) {
204: *q++ = RFC2132_SRV_ID;
205: *q++ = 4;
206: memcpy(q, &saddr.sin_addr, 4);
207: q += 4;
208:
209: *q++ = RFC1533_NETMASK;
210: *q++ = 4;
211: *q++ = 0xff;
212: *q++ = 0xff;
213: *q++ = 0xff;
214: *q++ = 0x00;
215:
216: *q++ = RFC1533_GATEWAY;
217: *q++ = 4;
218: memcpy(q, &saddr.sin_addr, 4);
219: q += 4;
220:
221: *q++ = RFC1533_DNS;
222: *q++ = 4;
223: dns_addr.s_addr = htonl(ntohl(special_addr.s_addr) | CTL_DNS);
224: memcpy(q, &dns_addr, 4);
225: q += 4;
226:
227: *q++ = RFC2132_LEASE_TIME;
228: *q++ = 4;
229: val = htonl(LEASE_TIME);
230: memcpy(q, &val, 4);
231: q += 4;
232:
233: if (*slirp_hostname) {
234: val = strlen(slirp_hostname);
235: *q++ = RFC1533_HOSTNAME;
236: *q++ = val;
237: memcpy(q, slirp_hostname, val);
238: q += val;
239: }
240: }
241: *q++ = RFC1533_END;
242: #endif
243: m->m_len = sizeof(struct bootp_t) -
244: sizeof(struct ip) - sizeof(struct udphdr);
245: udp_output2(NULL, m, &saddr, &daddr, IPTOS_LOWDELAY);
246: }
247:
248: void bootp_input(struct mbuf *m)
249: {
250: struct bootp_t *bp = mtod(m, struct bootp_t *);
251:
252: if (bp->bp_op == BOOTP_REQUEST) {
253: bootp_reply(bp);
254: }
255: }
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