vde-2/src/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 #include <config.h>
  27 #include <vde.h>
  28 #include <vdecommon.h>
  29
  30 /* XXX: only DHCP is supported */
  31
  32 #define NB_ADDR 16
  33
  34 #define START_ADDR 15
  35
  36 #define LEASE_TIME (120)
  37
  38 typedef struct {
  39     uint8_t allocated;
  40     uint8_t macaddr[6];
  41     int time;
  42 } BOOTPClient;
  43
  44 BOOTPClient bootp_clients[NB_ADDR];
  45
  46 static const uint8_t rfc1533_cookie[] = { RFC1533_COOKIE };
  47
  48 #ifdef DEBUG
  49 #define dprintf(fmt, args...) \
  50 if (slirp_debug & DBG_CALL) { fprintf(dfd, fmt, ## args); fflush(dfd); }
  51 #else
  52 #define dprintf(fmt, args...)
  53 #endif
  54
  55 static BOOTPClient *get_new_addr(struct in_addr *paddr)
  56 {
  57     BOOTPClient *bc;
  58     int i;
  59     int now=time(NULL);
  60
  61     for(i = 0; i < NB_ADDR; i++) {
  62         if (!bootp_clients[i].allocated)
  63             goto found;
  64     }
  65     for(i = 0; i < NB_ADDR; i++) {
  66         if (now-bootp_clients[i].time > 3*LEASE_TIME)
  67             goto found;
  68     }
  69     return NULL;
  70  found:
  71     bc = &bootp_clients[i];
  72     paddr->s_addr = htonl(ntohl(special_addr.s_addr) | (i + START_ADDR));
  73     return bc;
  74 }
  75
  76 static BOOTPClient *find_addr(struct in_addr *paddr, const uint8_t *macaddr)
  77 {
  78     BOOTPClient *bc;
  79     int i;
  80
  81     for(i = 0; i < NB_ADDR; i++) {
  82         if (!memcmp(macaddr, bootp_clients[i].macaddr, 6))
  83             goto found;
  84     }
  85     return NULL;
  86  found:
  87     bc = &bootp_clients[i];
  88     paddr->s_addr = htonl(ntohl(special_addr.s_addr) | (i + START_ADDR));
  89     return bc;
  90 }
  91
  92 static BOOTPClient *find_reqaddr(struct in_addr *paddr, struct in_addr *reqaddr, const uint8_t *macaddr)
  93 {
  94     BOOTPClient *bc=NULL;
  95     int i;
  96     /*check the net prefix*/
  97     if ((ntohl(reqaddr->s_addr) & 0xffffff00) ==
  98                     (ntohl(special_addr.s_addr) & 0xffffff00)) {
  99             i=(ntohl(reqaddr->s_addr) & 0xff) - START_ADDR;
 100             if (i>=0 && i< NB_ADDR) {
 101                     bc = &bootp_clients[i];
 102                     if (bc->allocated &&
 103                                     (memcmp(macaddr, bootp_clients[i].macaddr, 6)==0)) {
 104                             paddr->s_addr = reqaddr->s_addr;
 105                             return bc;
 106                     }
 107                     else
 108                             bc=NULL;
 109             }
 110     }
 111     return bc;
 112 }
 113
 114 static void dhcp_decode(const uint8_t *buf, int size,
 115                         int *pmsg_type, struct sockaddr_in *preqaddr)
 116 {
 117     const uint8_t *p, *p_end;
 118     int len, tag;
 119
 120     *pmsg_type = 0;
 121     preqaddr->sin_addr.s_addr=htonl(0L);
 122
 123     p = buf;
 124     p_end = buf + size;
 125     if (size < 5)
 126         return;
 127     if (memcmp(p, rfc1533_cookie, 4) != 0)
 128         return;
 129     p += 4;
 130     while (p < p_end) {
 131         tag = p[0];
 132         if (tag == RFC1533_PAD) {
 133             p++;
 134         } else if (tag == RFC1533_END) {
 135             break;
 136         } else {
 137             p++;
 138             if (p >= p_end)
 139                 break;
 140             len = *p++;
 141             dprintf("dhcp: tag=0x%02x len=%d\n", tag, len);
 142
 143             switch(tag) {
 144             case RFC2132_MSG_TYPE:
 145                 if (len >= 1)
 146                     *pmsg_type = p[0];
 147                 break;
 148             case RFC2132_REQ_ADDR:
 149                 if (len == 4) {
 150                         memcpy(&(preqaddr->sin_addr),p,4);
 151                 }
 152             default:
 153                 break;
 154             }
 155             p += len;
 156         }
 157     }
 158 }
 159
 160 static void bootp_reply(struct bootp_t *bp)
 161 {
 162     BOOTPClient *bc;
 163     struct mbuf *m;
 164     struct bootp_t *rbp;
 165     struct sockaddr_in saddr, daddr, reqaddr;
 166     struct in_addr dns_addr;
 167     int dhcp_msg_type, val;
 168     uint8_t *q,replytype;
 169     uint8_t client_ethaddr[6];
 170
 171     /* extract exact DHCP msg type */
 172     dhcp_decode(bp->bp_vend, DHCP_OPT_LEN, &dhcp_msg_type,&reqaddr);
 173     dprintf("bootp packet op=%d msgtype=%d reqaddr=%x\n", bp->bp_op, dhcp_msg_type,ntohl(reqaddr.sin_addr.s_addr));
 174
 175     if (dhcp_msg_type != DHCPDISCOVER &&
 176         dhcp_msg_type != DHCPREQUEST)
 177         return;
 178     /* XXX: this is a hack to get the client mac address */
 179     memcpy(client_ethaddr, bp->bp_hwaddr, 6);
 180
 181     if ((m = m_get()) == NULL)
 182         return;
 183     m->m_data += if_maxlinkhdr;
 184     rbp = (struct bootp_t *)m->m_data;
 185     m->m_data += sizeof(struct udpiphdr);
 186     memset(rbp, 0, sizeof(struct bootp_t));
 187
 188     bc=NULL;
 189     daddr.sin_addr.s_addr=htonl(0L);
 190     if (dhcp_msg_type == DHCPREQUEST) {
 191             if (reqaddr.sin_addr.s_addr != htonl(0L))
 192                     bc = find_reqaddr(&daddr.sin_addr, &reqaddr.sin_addr, bp->bp_hwaddr);
 193             else
 194                     bc = find_addr(&daddr.sin_addr, bp->bp_hwaddr);
 195     }
 196     else if (dhcp_msg_type == DHCPDISCOVER) {
 197             bc = find_addr(&daddr.sin_addr, bp->bp_hwaddr);
 198             if (!bc)
 199                 bc = get_new_addr(&daddr.sin_addr);
 200     }
 201
 202     dprintf("offered addr=%08x\n", ntohl(daddr.sin_addr.s_addr));
 203
 204     saddr.sin_addr.s_addr = htonl(ntohl(special_addr.s_addr) | CTL_ALIAS);
 205     saddr.sin_port = htons(BOOTP_SERVER);
 206
 207     daddr.sin_port = htons(BOOTP_CLIENT);
 208
 209     rbp->bp_op = BOOTP_REPLY;
 210     rbp->bp_xid = bp->bp_xid;
 211     rbp->bp_htype = 1;
 212     rbp->bp_hlen = 6;
 213     memcpy(rbp->bp_hwaddr, bp->bp_hwaddr, 6);
 214
 215     rbp->bp_yiaddr = daddr.sin_addr; /* IP address */
 216     rbp->bp_siaddr = saddr.sin_addr; /* IP address */
 217
 218     q = rbp->bp_vend;
 219     memcpy(q, rfc1533_cookie, 4);
 220     q += 4;
 221
 222     if (bc != NULL) {
 223         memcpy(bc->macaddr, client_ethaddr, 6);
 224         bc->allocated = 1;
 225         bc->time = time(NULL);
 226         replytype=(dhcp_msg_type == DHCPDISCOVER)?DHCPOFFER:DHCPACK;
 227     }
 228     else
 229         replytype=DHCPNACK;
 230
 231     *q++ = RFC2132_MSG_TYPE;
 232     *q++ = 1;
 233     *q++ = replytype;
 234
 235     if ((dhcp_msg_type == DHCPDISCOVER ||
 236         dhcp_msg_type == DHCPREQUEST) && replytype!=DHCPNACK) {
 237         *q++ = RFC2132_SRV_ID;
 238         *q++ = 4;
 239         memcpy(q, &saddr.sin_addr, 4);
 240         q += 4;
 241
 242         *q++ = RFC1533_NETMASK;
 243         *q++ = 4;
 244         *q++ = 0xff;
 245         *q++ = 0xff;
 246         *q++ = 0xff;
 247         *q++ = 0x00;
 248
 249         *q++ = RFC1533_GATEWAY;
 250         *q++ = 4;
 251         memcpy(q, &saddr.sin_addr, 4);
 252         q += 4;
 253
 254         *q++ = RFC1533_DNS;
 255         *q++ = 4;
 256         dns_addr.s_addr = htonl(ntohl(special_addr.s_addr) | CTL_DNS);
 257         memcpy(q, &dns_addr, 4);
 258         q += 4;
 259
 260         *q++ = RFC2132_LEASE_TIME;
 261         *q++ = 4;
 262         val = htonl(LEASE_TIME);
 263         memcpy(q, &val, 4);
 264         q += 4;
 265     }
 266     *q++ = RFC1533_END;
 267
 268     //m->m_len = sizeof(struct bootp_t);
 269     m->m_len = q - (uint8_t *) (m->m_data);
 270                 client_eth_register(client_ethaddr,&daddr.sin_addr);
 271     udp_output2(NULL, m, &saddr, &daddr, IPTOS_LOWDELAY);
 272 }
 273
 274 void bootp_input(struct mbuf *m)
 275 {
 276     struct bootp_t *bp = (struct bootp_t *)m->m_data;
 277
 278     if (bp->bp_op == BOOTP_REQUEST) {
 279         bootp_reply(bp);
 280     }
 281 }