File:  [Qemu by Fabrice Bellard] / qemu / slirp / bootp.c
Revision 1.1.1.10 (vendor branch): download - view: text, annotated - select for diffs
Tue Apr 24 19:51:42 2018 UTC (3 years, 3 months ago) by root
Branches: qemu, MAIN
CVS tags: qemu1101, HEAD
qemu 1.1.1

    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 LEASE_TIME (24 * 3600)
   29: 
   30: static const uint8_t rfc1533_cookie[] = { RFC1533_COOKIE };
   31: 
   32: #ifdef DEBUG
   33: #define DPRINTF(fmt, ...) \
   34: do if (slirp_debug & DBG_CALL) { fprintf(dfd, fmt, ##  __VA_ARGS__); fflush(dfd); } while (0)
   35: #else
   36: #define DPRINTF(fmt, ...) do{}while(0)
   37: #endif
   38: 
   39: static BOOTPClient *get_new_addr(Slirp *slirp, struct in_addr *paddr,
   40:                                  const uint8_t *macaddr)
   41: {
   42:     BOOTPClient *bc;
   43:     int i;
   44: 
   45:     for(i = 0; i < NB_BOOTP_CLIENTS; i++) {
   46:         bc = &slirp->bootp_clients[i];
   47:         if (!bc->allocated || !memcmp(macaddr, bc->macaddr, 6))
   48:             goto found;
   49:     }
   50:     return NULL;
   51:  found:
   52:     bc = &slirp->bootp_clients[i];
   53:     bc->allocated = 1;
   54:     paddr->s_addr = slirp->vdhcp_startaddr.s_addr + htonl(i);
   55:     return bc;
   56: }
   57: 
   58: static BOOTPClient *request_addr(Slirp *slirp, const struct in_addr *paddr,
   59:                                  const uint8_t *macaddr)
   60: {
   61:     uint32_t req_addr = ntohl(paddr->s_addr);
   62:     uint32_t dhcp_addr = ntohl(slirp->vdhcp_startaddr.s_addr);
   63:     BOOTPClient *bc;
   64: 
   65:     if (req_addr >= dhcp_addr &&
   66:         req_addr < (dhcp_addr + NB_BOOTP_CLIENTS)) {
   67:         bc = &slirp->bootp_clients[req_addr - dhcp_addr];
   68:         if (!bc->allocated || !memcmp(macaddr, bc->macaddr, 6)) {
   69:             bc->allocated = 1;
   70:             return bc;
   71:         }
   72:     }
   73:     return NULL;
   74: }
   75: 
   76: static BOOTPClient *find_addr(Slirp *slirp, struct in_addr *paddr,
   77:                               const uint8_t *macaddr)
   78: {
   79:     BOOTPClient *bc;
   80:     int i;
   81: 
   82:     for(i = 0; i < NB_BOOTP_CLIENTS; i++) {
   83:         if (!memcmp(macaddr, slirp->bootp_clients[i].macaddr, 6))
   84:             goto found;
   85:     }
   86:     return NULL;
   87:  found:
   88:     bc = &slirp->bootp_clients[i];
   89:     bc->allocated = 1;
   90:     paddr->s_addr = slirp->vdhcp_startaddr.s_addr + htonl(i);
   91:     return bc;
   92: }
   93: 
   94: static void dhcp_decode(const struct bootp_t *bp, int *pmsg_type,
   95:                         struct in_addr *preq_addr)
   96: {
   97:     const uint8_t *p, *p_end;
   98:     int len, tag;
   99: 
  100:     *pmsg_type = 0;
  101:     preq_addr->s_addr = htonl(0L);
  102: 
  103:     p = bp->bp_vend;
  104:     p_end = p + DHCP_OPT_LEN;
  105:     if (memcmp(p, rfc1533_cookie, 4) != 0)
  106:         return;
  107:     p += 4;
  108:     while (p < p_end) {
  109:         tag = p[0];
  110:         if (tag == RFC1533_PAD) {
  111:             p++;
  112:         } else if (tag == RFC1533_END) {
  113:             break;
  114:         } else {
  115:             p++;
  116:             if (p >= p_end)
  117:                 break;
  118:             len = *p++;
  119:             DPRINTF("dhcp: tag=%d len=%d\n", tag, len);
  120: 
  121:             switch(tag) {
  122:             case RFC2132_MSG_TYPE:
  123:                 if (len >= 1)
  124:                     *pmsg_type = p[0];
  125:                 break;
  126:             case RFC2132_REQ_ADDR:
  127:                 if (len >= 4) {
  128:                     memcpy(&(preq_addr->s_addr), p, 4);
  129:                 }
  130:                 break;
  131:             default:
  132:                 break;
  133:             }
  134:             p += len;
  135:         }
  136:     }
  137:     if (*pmsg_type == DHCPREQUEST && preq_addr->s_addr == htonl(0L) &&
  138:         bp->bp_ciaddr.s_addr) {
  139:         memcpy(&(preq_addr->s_addr), &bp->bp_ciaddr, 4);
  140:     }
  141: }
  142: 
  143: static void bootp_reply(Slirp *slirp, const struct bootp_t *bp)
  144: {
  145:     BOOTPClient *bc = NULL;
  146:     struct mbuf *m;
  147:     struct bootp_t *rbp;
  148:     struct sockaddr_in saddr, daddr;
  149:     struct in_addr preq_addr;
  150:     int dhcp_msg_type, val;
  151:     uint8_t *q;
  152:     uint8_t client_ethaddr[ETH_ALEN];
  153: 
  154:     /* extract exact DHCP msg type */
  155:     dhcp_decode(bp, &dhcp_msg_type, &preq_addr);
  156:     DPRINTF("bootp packet op=%d msgtype=%d", bp->bp_op, dhcp_msg_type);
  157:     if (preq_addr.s_addr != htonl(0L))
  158:         DPRINTF(" req_addr=%08x\n", ntohl(preq_addr.s_addr));
  159:     else
  160:         DPRINTF("\n");
  161: 
  162:     if (dhcp_msg_type == 0)
  163:         dhcp_msg_type = DHCPREQUEST; /* Force reply for old BOOTP clients */
  164: 
  165:     if (dhcp_msg_type != DHCPDISCOVER &&
  166:         dhcp_msg_type != DHCPREQUEST)
  167:         return;
  168: 
  169:     /* Get client's hardware address from bootp request */
  170:     memcpy(client_ethaddr, bp->bp_hwaddr, ETH_ALEN);
  171: 
  172:     m = m_get(slirp);
  173:     if (!m) {
  174:         return;
  175:     }
  176:     m->m_data += IF_MAXLINKHDR;
  177:     rbp = (struct bootp_t *)m->m_data;
  178:     m->m_data += sizeof(struct udpiphdr);
  179:     memset(rbp, 0, sizeof(struct bootp_t));
  180: 
  181:     if (dhcp_msg_type == DHCPDISCOVER) {
  182:         if (preq_addr.s_addr != htonl(0L)) {
  183:             bc = request_addr(slirp, &preq_addr, client_ethaddr);
  184:             if (bc) {
  185:                 daddr.sin_addr = preq_addr;
  186:             }
  187:         }
  188:         if (!bc) {
  189:          new_addr:
  190:             bc = get_new_addr(slirp, &daddr.sin_addr, client_ethaddr);
  191:             if (!bc) {
  192:                 DPRINTF("no address left\n");
  193:                 return;
  194:             }
  195:         }
  196:         memcpy(bc->macaddr, client_ethaddr, ETH_ALEN);
  197:     } else if (preq_addr.s_addr != htonl(0L)) {
  198:         bc = request_addr(slirp, &preq_addr, client_ethaddr);
  199:         if (bc) {
  200:             daddr.sin_addr = preq_addr;
  201:             memcpy(bc->macaddr, client_ethaddr, ETH_ALEN);
  202:         } else {
  203:             /* DHCPNAKs should be sent to broadcast */
  204:             daddr.sin_addr.s_addr = 0xffffffff;
  205:         }
  206:     } else {
  207:         bc = find_addr(slirp, &daddr.sin_addr, bp->bp_hwaddr);
  208:         if (!bc) {
  209:             /* if never assigned, behaves as if it was already
  210:                assigned (windows fix because it remembers its address) */
  211:             goto new_addr;
  212:         }
  213:     }
  214: 
  215:     /* Update ARP table for this IP address */
  216:     arp_table_add(slirp, daddr.sin_addr.s_addr, client_ethaddr);
  217: 
  218:     saddr.sin_addr = slirp->vhost_addr;
  219:     saddr.sin_port = htons(BOOTP_SERVER);
  220: 
  221:     daddr.sin_port = htons(BOOTP_CLIENT);
  222: 
  223:     rbp->bp_op = BOOTP_REPLY;
  224:     rbp->bp_xid = bp->bp_xid;
  225:     rbp->bp_htype = 1;
  226:     rbp->bp_hlen = 6;
  227:     memcpy(rbp->bp_hwaddr, bp->bp_hwaddr, ETH_ALEN);
  228: 
  229:     rbp->bp_yiaddr = daddr.sin_addr; /* Client IP address */
  230:     rbp->bp_siaddr = saddr.sin_addr; /* Server IP address */
  231: 
  232:     q = rbp->bp_vend;
  233:     memcpy(q, rfc1533_cookie, 4);
  234:     q += 4;
  235: 
  236:     if (bc) {
  237:         DPRINTF("%s addr=%08x\n",
  238:                 (dhcp_msg_type == DHCPDISCOVER) ? "offered" : "ack'ed",
  239:                 ntohl(daddr.sin_addr.s_addr));
  240: 
  241:         if (dhcp_msg_type == DHCPDISCOVER) {
  242:             *q++ = RFC2132_MSG_TYPE;
  243:             *q++ = 1;
  244:             *q++ = DHCPOFFER;
  245:         } else /* DHCPREQUEST */ {
  246:             *q++ = RFC2132_MSG_TYPE;
  247:             *q++ = 1;
  248:             *q++ = DHCPACK;
  249:         }
  250: 
  251:         if (slirp->bootp_filename)
  252:             snprintf((char *)rbp->bp_file, sizeof(rbp->bp_file), "%s",
  253:                      slirp->bootp_filename);
  254: 
  255:         *q++ = RFC2132_SRV_ID;
  256:         *q++ = 4;
  257:         memcpy(q, &saddr.sin_addr, 4);
  258:         q += 4;
  259: 
  260:         *q++ = RFC1533_NETMASK;
  261:         *q++ = 4;
  262:         memcpy(q, &slirp->vnetwork_mask, 4);
  263:         q += 4;
  264: 
  265:         if (!slirp->restricted) {
  266:             *q++ = RFC1533_GATEWAY;
  267:             *q++ = 4;
  268:             memcpy(q, &saddr.sin_addr, 4);
  269:             q += 4;
  270: 
  271:             *q++ = RFC1533_DNS;
  272:             *q++ = 4;
  273:             memcpy(q, &slirp->vnameserver_addr, 4);
  274:             q += 4;
  275:         }
  276: 
  277:         *q++ = RFC2132_LEASE_TIME;
  278:         *q++ = 4;
  279:         val = htonl(LEASE_TIME);
  280:         memcpy(q, &val, 4);
  281:         q += 4;
  282: 
  283:         if (*slirp->client_hostname) {
  284:             val = strlen(slirp->client_hostname);
  285:             *q++ = RFC1533_HOSTNAME;
  286:             *q++ = val;
  287:             memcpy(q, slirp->client_hostname, val);
  288:             q += val;
  289:         }
  290:     } else {
  291:         static const char nak_msg[] = "requested address not available";
  292: 
  293:         DPRINTF("nak'ed addr=%08x\n", ntohl(preq_addr.s_addr));
  294: 
  295:         *q++ = RFC2132_MSG_TYPE;
  296:         *q++ = 1;
  297:         *q++ = DHCPNAK;
  298: 
  299:         *q++ = RFC2132_MESSAGE;
  300:         *q++ = sizeof(nak_msg) - 1;
  301:         memcpy(q, nak_msg, sizeof(nak_msg) - 1);
  302:         q += sizeof(nak_msg) - 1;
  303:     }
  304:     *q = RFC1533_END;
  305: 
  306:     daddr.sin_addr.s_addr = 0xffffffffu;
  307: 
  308:     m->m_len = sizeof(struct bootp_t) -
  309:         sizeof(struct ip) - sizeof(struct udphdr);
  310:     udp_output2(NULL, m, &saddr, &daddr, IPTOS_LOWDELAY);
  311: }
  312: 
  313: void bootp_input(struct mbuf *m)
  314: {
  315:     struct bootp_t *bp = mtod(m, struct bootp_t *);
  316: 
  317:     if (bp->bp_op == BOOTP_REQUEST) {
  318:         bootp_reply(m->slirp, bp);
  319:     }
  320: }

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