vde-2/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 <config.h>
  25 #include <slirp.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 (120)
  34
  35 typedef struct {
  36     uint8_t allocated;
  37     uint8_t macaddr[6];
  38     int time;
  39 } BOOTPClient;
  40
  41 BOOTPClient bootp_clients[NB_ADDR];
  42
  43 static const uint8_t rfc1533_cookie[] = { RFC1533_COOKIE };
  44
  45 #ifdef DEBUG
  46 #define dprintf(fmt, args...) \
  47 if (slirp_debug & DBG_CALL) { fprintf(dfd, fmt, ## args); fflush(dfd); }
  48 #else
  49 #define dprintf(fmt, args...)
  50 #endif
  51
  52 static BOOTPClient *get_new_addr(struct in_addr *paddr)
  53 {
  54     BOOTPClient *bc;
  55     int i;
  56     int now=time(NULL);
  57
  58     for(i = 0; i < NB_ADDR; i++) {
  59         if (!bootp_clients[i].allocated)
  60             goto found;
  61     }
  62     for(i = 0; i < NB_ADDR; i++) {
  63         if (now-bootp_clients[i].time > 3*LEASE_TIME)
  64             goto found;
  65     }
  66     return NULL;
  67  found:
  68     bc = &bootp_clients[i];
  69     paddr->s_addr = htonl(ntohl(special_addr.s_addr) | (i + START_ADDR));
  70     return bc;
  71 }
  72
  73 static BOOTPClient *find_addr(struct in_addr *paddr, const uint8_t *macaddr)
  74 {
  75     BOOTPClient *bc;
  76     int i;
  77
  78     for(i = 0; i < NB_ADDR; i++) {
  79         if (!memcmp(macaddr, bootp_clients[i].macaddr, 6))
  80             goto found;
  81     }
  82     return NULL;
  83  found:
  84     bc = &bootp_clients[i];
  85     paddr->s_addr = htonl(ntohl(special_addr.s_addr) | (i + START_ADDR));
  86     return bc;
  87 }
  88
  89 static BOOTPClient *find_reqaddr(struct in_addr *paddr, struct in_addr *reqaddr, const uint8_t *macaddr)
  90 {
  91     BOOTPClient *bc=NULL;
  92     int i;
  93     /*check the net prefix*/
  94     if ((ntohl(reqaddr->s_addr) & 0xffffff00) ==
  95                     (ntohl(special_addr.s_addr) & 0xffffff00)) {
  96             i=(ntohl(reqaddr->s_addr) & 0xff) - START_ADDR;
  97             if (i>=0 && i< NB_ADDR) {
  98                     bc = &bootp_clients[i];
  99                     if (bc->allocated &&
 100                                     (memcmp(macaddr, bootp_clients[i].macaddr, 6)==0)) {
 101                             paddr->s_addr = reqaddr->s_addr;
 102                             return bc;
 103                     }
 104                     else
 105                             bc=NULL;
 106             }
 107     }
 108     return bc;
 109 }
 110
 111 static void dhcp_decode(const uint8_t *buf, int size,
 112                         int *pmsg_type, struct sockaddr_in *preqaddr)
 113 {
 114     const uint8_t *p, *p_end;
 115     int len, tag;
 116
 117     *pmsg_type = 0;
 118     preqaddr->sin_addr.s_addr=htonl(0L);
 119
 120     p = buf;
 121     p_end = buf + size;
 122     if (size < 5)
 123         return;
 124     if (memcmp(p, rfc1533_cookie, 4) != 0)
 125         return;
 126     p += 4;
 127     while (p < p_end) {
 128         tag = p[0];
 129         if (tag == RFC1533_PAD) {
 130             p++;
 131         } else if (tag == RFC1533_END) {
 132             break;
 133         } else {
 134             p++;
 135             if (p >= p_end)
 136                 break;
 137             len = *p++;
 138             dprintf("dhcp: tag=0x%02x len=%d\n", tag, len);
 139
 140             switch(tag) {
 141             case RFC2132_MSG_TYPE:
 142                 if (len >= 1)
 143                     *pmsg_type = p[0];
 144                 break;
 145             case RFC2132_REQ_ADDR:
 146                 if (len == 4) {
 147                         memcpy(&(preqaddr->sin_addr),p,4);
 148                 }
 149             default:
 150                 break;
 151             }
 152             p += len;
 153         }
 154     }
 155 }
 156
 157 static void bootp_reply(struct bootp_t *bp)
 158 {
 159     BOOTPClient *bc;
 160     struct mbuf *m;
 161     struct bootp_t *rbp;
 162     struct sockaddr_in saddr, daddr, reqaddr;
 163     struct in_addr dns_addr;
 164     int dhcp_msg_type, val;
 165     uint8_t *q,replytype;
 166     uint8_t client_ethaddr[6];
 167
 168     /* extract exact DHCP msg type */
 169     dhcp_decode(bp->bp_vend, DHCP_OPT_LEN, &dhcp_msg_type,&reqaddr);
 170     dprintf("bootp packet op=%d msgtype=%d reqaddr=%x\n", bp->bp_op, dhcp_msg_type,ntohl(reqaddr.sin_addr.s_addr));
 171
 172     if (dhcp_msg_type != DHCPDISCOVER &&
 173         dhcp_msg_type != DHCPREQUEST)
 174         return;
 175     /* XXX: this is a hack to get the client mac address */
 176     memcpy(client_ethaddr, bp->bp_hwaddr, 6);
 177
 178     if ((m = m_get()) == NULL)
 179         return;
 180     m->m_data += if_maxlinkhdr;
 181     rbp = (struct bootp_t *)m->m_data;
 182     m->m_data += sizeof(struct udpiphdr);
 183     memset(rbp, 0, sizeof(struct bootp_t));
 184
 185     bc=NULL;
 186     daddr.sin_addr.s_addr=htonl(0L);
 187     if (dhcp_msg_type == DHCPREQUEST) {
 188             if (reqaddr.sin_addr.s_addr != htonl(0L))
 189                     bc = find_reqaddr(&daddr.sin_addr, &reqaddr.sin_addr, bp->bp_hwaddr);
 190             else
 191                     bc = find_addr(&daddr.sin_addr, bp->bp_hwaddr);
 192     }
 193     else if (dhcp_msg_type == DHCPDISCOVER) {
 194             bc = find_addr(&daddr.sin_addr, bp->bp_hwaddr);
 195             if (!bc)
 196                 bc = get_new_addr(&daddr.sin_addr);
 197     }
 198
 199     dprintf("offered addr=%08x\n", ntohl(daddr.sin_addr.s_addr));
 200
 201     saddr.sin_addr.s_addr = htonl(ntohl(special_addr.s_addr) | CTL_ALIAS);
 202     saddr.sin_port = htons(BOOTP_SERVER);
 203
 204     daddr.sin_port = htons(BOOTP_CLIENT);
 205
 206     rbp->bp_op = BOOTP_REPLY;
 207     rbp->bp_xid = bp->bp_xid;
 208     rbp->bp_htype = 1;
 209     rbp->bp_hlen = 6;
 210     memcpy(rbp->bp_hwaddr, bp->bp_hwaddr, 6);
 211
 212     rbp->bp_yiaddr = daddr.sin_addr; /* IP address */
 213     rbp->bp_siaddr = saddr.sin_addr; /* IP address */
 214
 215     q = rbp->bp_vend;
 216     memcpy(q, rfc1533_cookie, 4);
 217     q += 4;
 218
 219     if (bc != NULL) {
 220         memcpy(bc->macaddr, client_ethaddr, 6);
 221         bc->allocated = 1;
 222         bc->time = time(NULL);
 223         replytype=(dhcp_msg_type == DHCPDISCOVER)?DHCPOFFER:DHCPACK;
 224     }
 225     else
 226         replytype=DHCPNACK;
 227
 228     *q++ = RFC2132_MSG_TYPE;
 229     *q++ = 1;
 230     *q++ = replytype;
 231
 232     if ((dhcp_msg_type == DHCPDISCOVER ||
 233         dhcp_msg_type == DHCPREQUEST) && replytype!=DHCPNACK) {
 234         *q++ = RFC2132_SRV_ID;
 235         *q++ = 4;
 236         memcpy(q, &saddr.sin_addr, 4);
 237         q += 4;
 238
 239         *q++ = RFC1533_NETMASK;
 240         *q++ = 4;
 241         *q++ = 0xff;
 242         *q++ = 0xff;
 243         *q++ = 0xff;
 244         *q++ = 0x00;
 245
 246         *q++ = RFC1533_GATEWAY;
 247         *q++ = 4;
 248         memcpy(q, &saddr.sin_addr, 4);
 249         q += 4;
 250
 251         *q++ = RFC1533_DNS;
 252         *q++ = 4;
 253         dns_addr.s_addr = htonl(ntohl(special_addr.s_addr) | CTL_DNS);
 254         memcpy(q, &dns_addr, 4);
 255         q += 4;
 256
 257         *q++ = RFC2132_LEASE_TIME;
 258         *q++ = 4;
 259         val = htonl(LEASE_TIME);
 260         memcpy(q, &val, 4);
 261         q += 4;
 262     }
 263     *q++ = RFC1533_END;
 264
 265     //m->m_len = sizeof(struct bootp_t);
 266     m->m_len = q - (uint8_t *) (m->m_data);
 267                 client_eth_register(client_ethaddr,&daddr.sin_addr);
 268     udp_output2(NULL, m, &saddr, &daddr, IPTOS_LOWDELAY);
 269 }
 270
 271 void bootp_input(struct mbuf *m)
 272 {
 273     struct bootp_t *bp = (struct bootp_t *)m->m_data;
 274
 275     if (bp->bp_op == BOOTP_REQUEST) {
 276         bootp_reply(bp);
 277     }
 278 }