vde/slirpvde/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 <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 (120)
  33
  34 typedef struct {
  35     uint8_t allocated;
  36     uint8_t macaddr[6];
  37     int time;
  38 } BOOTPClient;
  39
  40 BOOTPClient bootp_clients[NB_ADDR];
  41
  42 static const uint8_t rfc1533_cookie[] = { RFC1533_COOKIE };
  43
  44 #ifdef DEBUG
  45 #define dprintf(fmt, args...) \
  46 if (slirp_debug & DBG_CALL) { fprintf(dfd, fmt, ## args); fflush(dfd); }
  47 #else
  48 #define dprintf(fmt, args...)
  49 #endif
  50
  51 static BOOTPClient *get_new_addr(struct in_addr *paddr)
  52 {
  53     BOOTPClient *bc;
  54     int i;
  55     int now=time(NULL);
  56
  57     for(i = 0; i < NB_ADDR; i++) {
  58         if (!bootp_clients[i].allocated)
  59             goto found;
  60     }
  61     for(i = 0; i < NB_ADDR; i++) {
  62         if (now-bootp_clients[i].time > 3*LEASE_TIME)
  63             goto found;
  64     }
  65     return NULL;
  66  found:
  67     bc = &bootp_clients[i];
  68     paddr->s_addr = htonl(ntohl(special_addr.s_addr) | (i + START_ADDR));
  69     return bc;
  70 }
  71
  72 static BOOTPClient *find_addr(struct in_addr *paddr, const uint8_t *macaddr)
  73 {
  74     BOOTPClient *bc;
  75     int i;
  76
  77     for(i = 0; i < NB_ADDR; i++) {
  78         if (!memcmp(macaddr, bootp_clients[i].macaddr, 6))
  79             goto found;
  80     }
  81     return NULL;
  82  found:
  83     bc = &bootp_clients[i];
  84     paddr->s_addr = htonl(ntohl(special_addr.s_addr) | (i + START_ADDR));
  85     return bc;
  86 }
  87
  88 static BOOTPClient *find_reqaddr(struct in_addr *paddr, struct in_addr *reqaddr, const uint8_t *macaddr)
  89 {
  90     BOOTPClient *bc=NULL;
  91     int i;
  92     /*check the net prefix*/
  93     if ((ntohl(reqaddr->s_addr) & 0xffffff00) ==
  94                     (ntohl(special_addr.s_addr) & 0xffffff00)) {
  95             i=(ntohl(reqaddr->s_addr) & 0xff) - START_ADDR;
  96             if (i>=0 && i< NB_ADDR) {
  97                     bc = &bootp_clients[i];
  98                     if (bc->allocated &&
  99                                     (memcmp(macaddr, bootp_clients[i].macaddr, 6)==0)) {
 100                             paddr->s_addr = reqaddr->s_addr;
 101                             return bc;
 102                     }
 103                     else
 104                             bc=NULL;
 105             }
 106     }
 107     return bc;
 108 }
 109
 110 static void dhcp_decode(const uint8_t *buf, int size,
 111                         int *pmsg_type, struct sockaddr_in *preqaddr)
 112 {
 113     const uint8_t *p, *p_end;
 114     int len, tag;
 115
 116     *pmsg_type = 0;
 117     preqaddr->sin_addr.s_addr=htonl(0L);
 118
 119     p = buf;
 120     p_end = buf + size;
 121     if (size < 5)
 122         return;
 123     if (memcmp(p, rfc1533_cookie, 4) != 0)
 124         return;
 125     p += 4;
 126     while (p < p_end) {
 127         tag = p[0];
 128         if (tag == RFC1533_PAD) {
 129             p++;
 130         } else if (tag == RFC1533_END) {
 131             break;
 132         } else {
 133             p++;
 134             if (p >= p_end)
 135                 break;
 136             len = *p++;
 137             dprintf("dhcp: tag=0x%02x len=%d\n", tag, len);
 138
 139             switch(tag) {
 140             case RFC2132_MSG_TYPE:
 141                 if (len >= 1)
 142                     *pmsg_type = p[0];
 143                 break;
 144             case RFC2132_REQ_ADDR:
 145                 if (len == 4) {
 146                         memcpy(&(preqaddr->sin_addr),p,4);
 147                 }
 148             default:
 149                 break;
 150             }
 151             p += len;
 152         }
 153     }
 154 }
 155
 156 static void bootp_reply(struct bootp_t *bp)
 157 {
 158     BOOTPClient *bc;
 159     struct mbuf *m;
 160     struct bootp_t *rbp;
 161     struct sockaddr_in saddr, daddr, reqaddr;
 162     struct in_addr dns_addr;
 163     int dhcp_msg_type, val;
 164     uint8_t *q,replytype;
 165
 166     /* extract exact DHCP msg type */
 167     dhcp_decode(bp->bp_vend, DHCP_OPT_LEN, &dhcp_msg_type,&reqaddr);
 168     dprintf("bootp packet op=%d msgtype=%d reqaddr=%x\n", bp->bp_op, dhcp_msg_type,ntohl(reqaddr.sin_addr.s_addr));
 169
 170     if (dhcp_msg_type != DHCPDISCOVER &&
 171         dhcp_msg_type != DHCPREQUEST)
 172         return;
 173     /* XXX: this is a hack to get the client mac address */
 174     memcpy(client_ethaddr, bp->bp_hwaddr, 6);
 175
 176     if ((m = m_get()) == NULL)
 177         return;
 178     m->m_data += if_maxlinkhdr;
 179     rbp = (struct bootp_t *)m->m_data;
 180     m->m_data += sizeof(struct udpiphdr);
 181     memset(rbp, 0, sizeof(struct bootp_t));
 182
 183     bc=NULL;
 184     daddr.sin_addr.s_addr=htonl(0L);
 185     if (dhcp_msg_type == DHCPREQUEST) {
 186             if (reqaddr.sin_addr.s_addr != htonl(0L))
 187                     bc = find_reqaddr(&daddr.sin_addr, &reqaddr.sin_addr, bp->bp_hwaddr);
 188             else
 189                     bc = find_addr(&daddr.sin_addr, bp->bp_hwaddr);
 190     }
 191     else if (dhcp_msg_type == DHCPDISCOVER) {
 192             bc = find_addr(&daddr.sin_addr, bp->bp_hwaddr);
 193             if (!bc)
 194                 bc = get_new_addr(&daddr.sin_addr);
 195     }
 196
 197     dprintf("offered addr=%08x\n", ntohl(daddr.sin_addr.s_addr));
 198
 199     saddr.sin_addr.s_addr = htonl(ntohl(special_addr.s_addr) | CTL_ALIAS);
 200     saddr.sin_port = htons(BOOTP_SERVER);
 201
 202     daddr.sin_port = htons(BOOTP_CLIENT);
 203
 204     rbp->bp_op = BOOTP_REPLY;
 205     rbp->bp_xid = bp->bp_xid;
 206     rbp->bp_htype = 1;
 207     rbp->bp_hlen = 6;
 208     memcpy(rbp->bp_hwaddr, bp->bp_hwaddr, 6);
 209
 210     rbp->bp_yiaddr = daddr.sin_addr; /* IP address */
 211
 212     q = rbp->bp_vend;
 213     memcpy(q, rfc1533_cookie, 4);
 214     q += 4;
 215
 216     if (bc != NULL) {
 217         memcpy(bc->macaddr, client_ethaddr, 6);
 218         bc->allocated = 1;
 219         bc->time = time(NULL);
 220         replytype=(dhcp_msg_type == DHCPDISCOVER)?DHCPOFFER:DHCPACK;
 221     }
 222     else
 223         replytype=DHCPNACK;
 224
 225     *q++ = RFC2132_MSG_TYPE;
 226     *q++ = 1;
 227     *q++ = replytype;
 228
 229     if ((dhcp_msg_type == DHCPDISCOVER ||
 230         dhcp_msg_type == DHCPREQUEST) && replytype!=DHCPNACK) {
 231         *q++ = RFC2132_SRV_ID;
 232         *q++ = 4;
 233         memcpy(q, &saddr.sin_addr, 4);
 234         q += 4;
 235
 236         *q++ = RFC1533_NETMASK;
 237         *q++ = 4;
 238         *q++ = 0xff;
 239         *q++ = 0xff;
 240         *q++ = 0xff;
 241         *q++ = 0x00;
 242
 243         *q++ = RFC1533_GATEWAY;
 244         *q++ = 4;
 245         memcpy(q, &saddr.sin_addr, 4);
 246         q += 4;
 247
 248         *q++ = RFC1533_DNS;
 249         *q++ = 4;
 250         dns_addr.s_addr = htonl(ntohl(special_addr.s_addr) | CTL_DNS);
 251         memcpy(q, &dns_addr, 4);
 252         q += 4;
 253
 254         *q++ = RFC2132_LEASE_TIME;
 255         *q++ = 4;
 256         val = htonl(LEASE_TIME);
 257         memcpy(q, &val, 4);
 258         q += 4;
 259     }
 260     *q++ = RFC1533_END;
 261
 262     m->m_len = sizeof(struct bootp_t);
 263     udp_output2(NULL, m, &saddr, &daddr, IPTOS_LOWDELAY);
 264 }
 265
 266 void bootp_input(struct mbuf *m)
 267 {
 268     struct bootp_t *bp = (struct bootp_t *)m->m_data;
 269
 270     if (bp->bp_op == BOOTP_REQUEST) {
 271         bootp_reply(bp);
 272     }
 273 }