File:  [Qemu by Fabrice Bellard] / qemu / slirp / bootp.c
Revision 1.1.1.3 (vendor branch): download - view: text, annotated - select for diffs
Tue Apr 24 16:49:22 2018 UTC (3 years, 7 months ago) by root
Branches: qemu, MAIN
CVS tags: qemu0091, HEAD
qemu 0.9.1

    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 NB_ADDR 16
   29: 
   30: #define START_ADDR 15
   31: 
   32: #define LEASE_TIME (24 * 3600)
   33: 
   34: typedef struct {
   35:     uint8_t allocated;
   36:     uint8_t macaddr[6];
   37: } BOOTPClient;
   38: 
   39: BOOTPClient bootp_clients[NB_ADDR];
   40: 
   41: const char *bootp_filename;
   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: 
   57:     for(i = 0; i < NB_ADDR; i++) {
   58:         if (!bootp_clients[i].allocated)
   59:             goto found;
   60:     }
   61:     return NULL;
   62:  found:
   63:     bc = &bootp_clients[i];
   64:     bc->allocated = 1;
   65:     paddr->s_addr = htonl(ntohl(special_addr.s_addr) | (i + START_ADDR));
   66:     return bc;
   67: }
   68: 
   69: static BOOTPClient *find_addr(struct in_addr *paddr, const uint8_t *macaddr)
   70: {
   71:     BOOTPClient *bc;
   72:     int i;
   73: 
   74:     for(i = 0; i < NB_ADDR; i++) {
   75:         if (!memcmp(macaddr, bootp_clients[i].macaddr, 6))
   76:             goto found;
   77:     }
   78:     return NULL;
   79:  found:
   80:     bc = &bootp_clients[i];
   81:     bc->allocated = 1;
   82:     paddr->s_addr = htonl(ntohl(special_addr.s_addr) | (i + START_ADDR));
   83:     return bc;
   84: }
   85: 
   86: static void dhcp_decode(const uint8_t *buf, int size,
   87:                         int *pmsg_type)
   88: {
   89:     const uint8_t *p, *p_end;
   90:     int len, tag;
   91: 
   92:     *pmsg_type = 0;
   93: 
   94:     p = buf;
   95:     p_end = buf + size;
   96:     if (size < 5)
   97:         return;
   98:     if (memcmp(p, rfc1533_cookie, 4) != 0)
   99:         return;
  100:     p += 4;
  101:     while (p < p_end) {
  102:         tag = p[0];
  103:         if (tag == RFC1533_PAD) {
  104:             p++;
  105:         } else if (tag == RFC1533_END) {
  106:             break;
  107:         } else {
  108:             p++;
  109:             if (p >= p_end)
  110:                 break;
  111:             len = *p++;
  112:             dprintf("dhcp: tag=0x%02x len=%d\n", tag, len);
  113: 
  114:             switch(tag) {
  115:             case RFC2132_MSG_TYPE:
  116:                 if (len >= 1)
  117:                     *pmsg_type = p[0];
  118:                 break;
  119:             default:
  120:                 break;
  121:             }
  122:             p += len;
  123:         }
  124:     }
  125: }
  126: 
  127: static void bootp_reply(struct bootp_t *bp)
  128: {
  129:     BOOTPClient *bc;
  130:     struct mbuf *m;
  131:     struct bootp_t *rbp;
  132:     struct sockaddr_in saddr, daddr;
  133:     struct in_addr dns_addr;
  134:     int dhcp_msg_type, val;
  135:     uint8_t *q;
  136: 
  137:     /* extract exact DHCP msg type */
  138:     dhcp_decode(bp->bp_vend, DHCP_OPT_LEN, &dhcp_msg_type);
  139:     dprintf("bootp packet op=%d msgtype=%d\n", bp->bp_op, dhcp_msg_type);
  140: 
  141:     if (dhcp_msg_type == 0)
  142:         dhcp_msg_type = DHCPREQUEST; /* Force reply for old BOOTP clients */
  143: 
  144:     if (dhcp_msg_type != DHCPDISCOVER &&
  145:         dhcp_msg_type != DHCPREQUEST)
  146:         return;
  147:     /* XXX: this is a hack to get the client mac address */
  148:     memcpy(client_ethaddr, bp->bp_hwaddr, 6);
  149: 
  150:     if ((m = m_get()) == NULL)
  151:         return;
  152:     m->m_data += IF_MAXLINKHDR;
  153:     rbp = (struct bootp_t *)m->m_data;
  154:     m->m_data += sizeof(struct udpiphdr);
  155:     memset(rbp, 0, sizeof(struct bootp_t));
  156: 
  157:     if (dhcp_msg_type == DHCPDISCOVER) {
  158:     new_addr:
  159:         bc = get_new_addr(&daddr.sin_addr);
  160:         if (!bc) {
  161:             dprintf("no address left\n");
  162:             return;
  163:         }
  164:         memcpy(bc->macaddr, client_ethaddr, 6);
  165:     } else {
  166:         bc = find_addr(&daddr.sin_addr, bp->bp_hwaddr);
  167:         if (!bc) {
  168:             /* if never assigned, behaves as if it was already
  169:                assigned (windows fix because it remembers its address) */
  170:             goto new_addr;
  171:         }
  172:     }
  173: 
  174:     if (bootp_filename)
  175:         snprintf(rbp->bp_file, sizeof(rbp->bp_file), "%s", bootp_filename);
  176: 
  177:     dprintf("offered addr=%08x\n", ntohl(daddr.sin_addr.s_addr));
  178: 
  179:     saddr.sin_addr.s_addr = htonl(ntohl(special_addr.s_addr) | CTL_ALIAS);
  180:     saddr.sin_port = htons(BOOTP_SERVER);
  181: 
  182:     daddr.sin_port = htons(BOOTP_CLIENT);
  183: 
  184:     rbp->bp_op = BOOTP_REPLY;
  185:     rbp->bp_xid = bp->bp_xid;
  186:     rbp->bp_htype = 1;
  187:     rbp->bp_hlen = 6;
  188:     memcpy(rbp->bp_hwaddr, bp->bp_hwaddr, 6);
  189: 
  190:     rbp->bp_yiaddr = daddr.sin_addr; /* Client IP address */
  191:     rbp->bp_siaddr = saddr.sin_addr; /* Server IP address */
  192: 
  193:     q = rbp->bp_vend;
  194:     memcpy(q, rfc1533_cookie, 4);
  195:     q += 4;
  196: 
  197:     if (dhcp_msg_type == DHCPDISCOVER) {
  198:         *q++ = RFC2132_MSG_TYPE;
  199:         *q++ = 1;
  200:         *q++ = DHCPOFFER;
  201:     } else if (dhcp_msg_type == DHCPREQUEST) {
  202:         *q++ = RFC2132_MSG_TYPE;
  203:         *q++ = 1;
  204:         *q++ = DHCPACK;
  205:     }
  206: 
  207:     if (dhcp_msg_type == DHCPDISCOVER ||
  208:         dhcp_msg_type == DHCPREQUEST) {
  209:         *q++ = RFC2132_SRV_ID;
  210:         *q++ = 4;
  211:         memcpy(q, &saddr.sin_addr, 4);
  212:         q += 4;
  213: 
  214:         *q++ = RFC1533_NETMASK;
  215:         *q++ = 4;
  216:         *q++ = 0xff;
  217:         *q++ = 0xff;
  218:         *q++ = 0xff;
  219:         *q++ = 0x00;
  220: 
  221:         *q++ = RFC1533_GATEWAY;
  222:         *q++ = 4;
  223:         memcpy(q, &saddr.sin_addr, 4);
  224:         q += 4;
  225: 
  226:         *q++ = RFC1533_DNS;
  227:         *q++ = 4;
  228:         dns_addr.s_addr = htonl(ntohl(special_addr.s_addr) | CTL_DNS);
  229:         memcpy(q, &dns_addr, 4);
  230:         q += 4;
  231: 
  232:         *q++ = RFC2132_LEASE_TIME;
  233:         *q++ = 4;
  234:         val = htonl(LEASE_TIME);
  235:         memcpy(q, &val, 4);
  236:         q += 4;
  237: 
  238:         if (*slirp_hostname) {
  239:             val = strlen(slirp_hostname);
  240:             *q++ = RFC1533_HOSTNAME;
  241:             *q++ = val;
  242:             memcpy(q, slirp_hostname, val);
  243:             q += val;
  244:         }
  245:     }
  246:     *q++ = RFC1533_END;
  247: 
  248:     m->m_len = sizeof(struct bootp_t) -
  249:         sizeof(struct ip) - sizeof(struct udphdr);
  250:     udp_output2(NULL, m, &saddr, &daddr, IPTOS_LOWDELAY);
  251: }
  252: 
  253: void bootp_input(struct mbuf *m)
  254: {
  255:     struct bootp_t *bp = mtod(m, struct bootp_t *);
  256: 
  257:     if (bp->bp_op == BOOTP_REQUEST) {
  258:         bootp_reply(bp);
  259:     }
  260: }

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