Annotation of qemu/slirp/bootp.c, revision 1.1.1.5

1.1       root        1: /*
                      2:  * QEMU BOOTP/DHCP server
1.1.1.3   root        3:  *
1.1       root        4:  * Copyright (c) 2004 Fabrice Bellard
1.1.1.3   root        5:  *
1.1       root        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
1.1.1.5 ! root       33: #define dprintf(fmt, ...) \
        !            34: do if (slirp_debug & DBG_CALL) { fprintf(dfd, fmt, ##  __VA_ARGS__); fflush(dfd); } while (0)
1.1       root       35: #else
1.1.1.5 ! root       36: #define dprintf(fmt, ...)
1.1       root       37: #endif
                     38: 
1.1.1.5 ! root       39: static BOOTPClient *get_new_addr(Slirp *slirp, struct in_addr *paddr,
        !            40:                                  const uint8_t *macaddr)
1.1       root       41: {
                     42:     BOOTPClient *bc;
                     43:     int i;
                     44: 
1.1.1.5 ! root       45:     for(i = 0; i < NB_BOOTP_CLIENTS; i++) {
        !            46:         bc = &slirp->bootp_clients[i];
        !            47:         if (!bc->allocated || !memcmp(macaddr, bc->macaddr, 6))
1.1       root       48:             goto found;
                     49:     }
                     50:     return NULL;
                     51:  found:
1.1.1.5 ! root       52:     bc = &slirp->bootp_clients[i];
1.1       root       53:     bc->allocated = 1;
1.1.1.5 ! root       54:     paddr->s_addr = slirp->vdhcp_startaddr.s_addr + htonl(i);
1.1       root       55:     return bc;
                     56: }
                     57: 
1.1.1.5 ! root       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)
1.1       root       78: {
                     79:     BOOTPClient *bc;
                     80:     int i;
                     81: 
1.1.1.5 ! root       82:     for(i = 0; i < NB_BOOTP_CLIENTS; i++) {
        !            83:         if (!memcmp(macaddr, slirp->bootp_clients[i].macaddr, 6))
1.1       root       84:             goto found;
                     85:     }
                     86:     return NULL;
                     87:  found:
1.1.1.5 ! root       88:     bc = &slirp->bootp_clients[i];
1.1       root       89:     bc->allocated = 1;
1.1.1.5 ! root       90:     paddr->s_addr = slirp->vdhcp_startaddr.s_addr + htonl(i);
1.1       root       91:     return bc;
                     92: }
                     93: 
1.1.1.5 ! root       94: static void dhcp_decode(const struct bootp_t *bp, int *pmsg_type,
        !            95:                         const struct in_addr **preq_addr)
1.1       root       96: {
                     97:     const uint8_t *p, *p_end;
                     98:     int len, tag;
                     99: 
1.1.1.3   root      100:     *pmsg_type = 0;
1.1.1.5 ! root      101:     *preq_addr = NULL;
1.1       root      102: 
1.1.1.5 ! root      103:     p = bp->bp_vend;
        !           104:     p_end = p + DHCP_OPT_LEN;
1.1       root      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) {
1.1.1.3   root      111:             p++;
1.1       root      112:         } else if (tag == RFC1533_END) {
                    113:             break;
                    114:         } else {
                    115:             p++;
                    116:             if (p >= p_end)
                    117:                 break;
                    118:             len = *p++;
1.1.1.5 ! root      119:             dprintf("dhcp: tag=%d len=%d\n", tag, len);
1.1       root      120: 
                    121:             switch(tag) {
                    122:             case RFC2132_MSG_TYPE:
                    123:                 if (len >= 1)
                    124:                     *pmsg_type = p[0];
                    125:                 break;
1.1.1.5 ! root      126:             case RFC2132_REQ_ADDR:
        !           127:                 if (len >= 4)
        !           128:                     *preq_addr = (struct in_addr *)p;
        !           129:                 break;
1.1       root      130:             default:
                    131:                 break;
                    132:             }
                    133:             p += len;
                    134:         }
                    135:     }
1.1.1.5 ! root      136:     if (*pmsg_type == DHCPREQUEST && !*preq_addr && bp->bp_ciaddr.s_addr) {
        !           137:         *preq_addr = &bp->bp_ciaddr;
        !           138:     }
1.1       root      139: }
                    140: 
1.1.1.5 ! root      141: static void bootp_reply(Slirp *slirp, const struct bootp_t *bp)
1.1       root      142: {
1.1.1.5 ! root      143:     BOOTPClient *bc = NULL;
1.1       root      144:     struct mbuf *m;
                    145:     struct bootp_t *rbp;
                    146:     struct sockaddr_in saddr, daddr;
1.1.1.5 ! root      147:     const struct in_addr *preq_addr;
1.1       root      148:     int dhcp_msg_type, val;
                    149:     uint8_t *q;
                    150: 
                    151:     /* extract exact DHCP msg type */
1.1.1.5 ! root      152:     dhcp_decode(bp, &dhcp_msg_type, &preq_addr);
        !           153:     dprintf("bootp packet op=%d msgtype=%d", bp->bp_op, dhcp_msg_type);
        !           154:     if (preq_addr)
        !           155:         dprintf(" req_addr=%08x\n", ntohl(preq_addr->s_addr));
        !           156:     else
        !           157:         dprintf("\n");
1.1.1.3   root      158: 
1.1       root      159:     if (dhcp_msg_type == 0)
                    160:         dhcp_msg_type = DHCPREQUEST; /* Force reply for old BOOTP clients */
1.1.1.3   root      161: 
                    162:     if (dhcp_msg_type != DHCPDISCOVER &&
1.1       root      163:         dhcp_msg_type != DHCPREQUEST)
                    164:         return;
                    165:     /* XXX: this is a hack to get the client mac address */
1.1.1.5 ! root      166:     memcpy(slirp->client_ethaddr, bp->bp_hwaddr, 6);
1.1.1.3   root      167: 
1.1.1.5 ! root      168:     m = m_get(slirp);
        !           169:     if (!m) {
1.1       root      170:         return;
1.1.1.5 ! root      171:     }
1.1.1.3   root      172:     m->m_data += IF_MAXLINKHDR;
1.1       root      173:     rbp = (struct bootp_t *)m->m_data;
                    174:     m->m_data += sizeof(struct udpiphdr);
                    175:     memset(rbp, 0, sizeof(struct bootp_t));
                    176: 
                    177:     if (dhcp_msg_type == DHCPDISCOVER) {
1.1.1.5 ! root      178:         if (preq_addr) {
        !           179:             bc = request_addr(slirp, preq_addr, slirp->client_ethaddr);
        !           180:             if (bc) {
        !           181:                 daddr.sin_addr = *preq_addr;
        !           182:             }
        !           183:         }
1.1       root      184:         if (!bc) {
1.1.1.5 ! root      185:          new_addr:
        !           186:             bc = get_new_addr(slirp, &daddr.sin_addr, slirp->client_ethaddr);
        !           187:             if (!bc) {
        !           188:                 dprintf("no address left\n");
        !           189:                 return;
        !           190:             }
        !           191:         }
        !           192:         memcpy(bc->macaddr, slirp->client_ethaddr, 6);
        !           193:     } else if (preq_addr) {
        !           194:         bc = request_addr(slirp, preq_addr, slirp->client_ethaddr);
        !           195:         if (bc) {
        !           196:             daddr.sin_addr = *preq_addr;
        !           197:             memcpy(bc->macaddr, slirp->client_ethaddr, 6);
        !           198:         } else {
        !           199:             daddr.sin_addr.s_addr = 0;
1.1       root      200:         }
                    201:     } else {
1.1.1.5 ! root      202:         bc = find_addr(slirp, &daddr.sin_addr, bp->bp_hwaddr);
1.1       root      203:         if (!bc) {
                    204:             /* if never assigned, behaves as if it was already
                    205:                assigned (windows fix because it remembers its address) */
                    206:             goto new_addr;
                    207:         }
                    208:     }
1.1.1.3   root      209: 
1.1.1.5 ! root      210:     saddr.sin_addr = slirp->vhost_addr;
1.1       root      211:     saddr.sin_port = htons(BOOTP_SERVER);
                    212: 
                    213:     daddr.sin_port = htons(BOOTP_CLIENT);
                    214: 
                    215:     rbp->bp_op = BOOTP_REPLY;
                    216:     rbp->bp_xid = bp->bp_xid;
                    217:     rbp->bp_htype = 1;
                    218:     rbp->bp_hlen = 6;
                    219:     memcpy(rbp->bp_hwaddr, bp->bp_hwaddr, 6);
                    220: 
                    221:     rbp->bp_yiaddr = daddr.sin_addr; /* Client IP address */
                    222:     rbp->bp_siaddr = saddr.sin_addr; /* Server IP address */
                    223: 
                    224:     q = rbp->bp_vend;
                    225:     memcpy(q, rfc1533_cookie, 4);
                    226:     q += 4;
                    227: 
1.1.1.5 ! root      228:     if (bc) {
        !           229:         dprintf("%s addr=%08x\n",
        !           230:                 (dhcp_msg_type == DHCPDISCOVER) ? "offered" : "ack'ed",
        !           231:                 ntohl(daddr.sin_addr.s_addr));
        !           232: 
        !           233:         if (dhcp_msg_type == DHCPDISCOVER) {
        !           234:             *q++ = RFC2132_MSG_TYPE;
        !           235:             *q++ = 1;
        !           236:             *q++ = DHCPOFFER;
        !           237:         } else /* DHCPREQUEST */ {
        !           238:             *q++ = RFC2132_MSG_TYPE;
        !           239:             *q++ = 1;
        !           240:             *q++ = DHCPACK;
        !           241:         }
        !           242: 
        !           243:         if (slirp->bootp_filename)
        !           244:             snprintf((char *)rbp->bp_file, sizeof(rbp->bp_file), "%s",
        !           245:                      slirp->bootp_filename);
1.1.1.3   root      246: 
1.1       root      247:         *q++ = RFC2132_SRV_ID;
                    248:         *q++ = 4;
                    249:         memcpy(q, &saddr.sin_addr, 4);
                    250:         q += 4;
                    251: 
                    252:         *q++ = RFC1533_NETMASK;
                    253:         *q++ = 4;
1.1.1.5 ! root      254:         memcpy(q, &slirp->vnetwork_mask, 4);
        !           255:         q += 4;
1.1.1.3   root      256: 
1.1.1.5 ! root      257:         if (!slirp->restricted) {
1.1.1.4   root      258:             *q++ = RFC1533_GATEWAY;
                    259:             *q++ = 4;
                    260:             memcpy(q, &saddr.sin_addr, 4);
                    261:             q += 4;
                    262: 
                    263:             *q++ = RFC1533_DNS;
                    264:             *q++ = 4;
1.1.1.5 ! root      265:             memcpy(q, &slirp->vnameserver_addr, 4);
1.1.1.4   root      266:             q += 4;
                    267:         }
1.1       root      268: 
                    269:         *q++ = RFC2132_LEASE_TIME;
                    270:         *q++ = 4;
                    271:         val = htonl(LEASE_TIME);
                    272:         memcpy(q, &val, 4);
                    273:         q += 4;
1.1.1.2   root      274: 
1.1.1.5 ! root      275:         if (*slirp->client_hostname) {
        !           276:             val = strlen(slirp->client_hostname);
1.1.1.2   root      277:             *q++ = RFC1533_HOSTNAME;
                    278:             *q++ = val;
1.1.1.5 ! root      279:             memcpy(q, slirp->client_hostname, val);
1.1.1.2   root      280:             q += val;
                    281:         }
1.1.1.5 ! root      282:     } else {
        !           283:         static const char nak_msg[] = "requested address not available";
        !           284: 
        !           285:         dprintf("nak'ed addr=%08x\n", ntohl(preq_addr->s_addr));
        !           286: 
        !           287:         *q++ = RFC2132_MSG_TYPE;
        !           288:         *q++ = 1;
        !           289:         *q++ = DHCPNAK;
        !           290: 
        !           291:         *q++ = RFC2132_MESSAGE;
        !           292:         *q++ = sizeof(nak_msg) - 1;
        !           293:         memcpy(q, nak_msg, sizeof(nak_msg) - 1);
        !           294:         q += sizeof(nak_msg) - 1;
1.1       root      295:     }
                    296:     *q++ = RFC1533_END;
1.1.1.3   root      297: 
1.1.1.5 ! root      298:     daddr.sin_addr.s_addr = 0xffffffffu;
        !           299: 
1.1.1.3   root      300:     m->m_len = sizeof(struct bootp_t) -
1.1       root      301:         sizeof(struct ip) - sizeof(struct udphdr);
                    302:     udp_output2(NULL, m, &saddr, &daddr, IPTOS_LOWDELAY);
                    303: }
                    304: 
                    305: void bootp_input(struct mbuf *m)
                    306: {
                    307:     struct bootp_t *bp = mtod(m, struct bootp_t *);
                    308: 
                    309:     if (bp->bp_op == BOOTP_REQUEST) {
1.1.1.5 ! root      310:         bootp_reply(m->slirp, bp);
1.1       root      311:     }
                    312: }

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