/* * QEMU BOOTP/DHCP server * * Copyright (c) 2004 Fabrice Bellard * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN * THE SOFTWARE. */ #include <slirp.h> /* XXX: only DHCP is supported */ #define LEASE_TIME (24 * 3600) static const uint8_t rfc1533_cookie[] = { RFC1533_COOKIE }; #ifdef DEBUG #define DPRINTF(fmt, ...) \ do if (slirp_debug & DBG_CALL) { fprintf(dfd, fmt, ## __VA_ARGS__); fflush(dfd); } while (0) #else #define DPRINTF(fmt, ...) do{}while(0) #endif static BOOTPClient *get_new_addr(Slirp *slirp, struct in_addr *paddr, const uint8_t *macaddr) { BOOTPClient *bc; int i; for(i = 0; i < NB_BOOTP_CLIENTS; i++) { bc = &slirp->bootp_clients[i]; if (!bc->allocated || !memcmp(macaddr, bc->macaddr, 6)) goto found; } return NULL; found: bc = &slirp->bootp_clients[i]; bc->allocated = 1; paddr->s_addr = slirp->vdhcp_startaddr.s_addr + htonl(i); return bc; } static BOOTPClient *request_addr(Slirp *slirp, const struct in_addr *paddr, const uint8_t *macaddr) { uint32_t req_addr = ntohl(paddr->s_addr); uint32_t dhcp_addr = ntohl(slirp->vdhcp_startaddr.s_addr); BOOTPClient *bc; if (req_addr >= dhcp_addr && req_addr < (dhcp_addr + NB_BOOTP_CLIENTS)) { bc = &slirp->bootp_clients[req_addr - dhcp_addr]; if (!bc->allocated || !memcmp(macaddr, bc->macaddr, 6)) { bc->allocated = 1; return bc; } } return NULL; } static BOOTPClient *find_addr(Slirp *slirp, struct in_addr *paddr, const uint8_t *macaddr) { BOOTPClient *bc; int i; for(i = 0; i < NB_BOOTP_CLIENTS; i++) { if (!memcmp(macaddr, slirp->bootp_clients[i].macaddr, 6)) goto found; } return NULL; found: bc = &slirp->bootp_clients[i]; bc->allocated = 1; paddr->s_addr = slirp->vdhcp_startaddr.s_addr + htonl(i); return bc; } static void dhcp_decode(const struct bootp_t *bp, int *pmsg_type, struct in_addr *preq_addr) { const uint8_t *p, *p_end; int len, tag; *pmsg_type = 0; preq_addr->s_addr = htonl(0L); p = bp->bp_vend; p_end = p + DHCP_OPT_LEN; if (memcmp(p, rfc1533_cookie, 4) != 0) return; p += 4; while (p < p_end) { tag = p[0]; if (tag == RFC1533_PAD) { p++; } else if (tag == RFC1533_END) { break; } else { p++; if (p >= p_end) break; len = *p++; DPRINTF("dhcp: tag=%d len=%d\n", tag, len); switch(tag) { case RFC2132_MSG_TYPE: if (len >= 1) *pmsg_type = p[0]; break; case RFC2132_REQ_ADDR: if (len >= 4) { memcpy(&(preq_addr->s_addr), p, 4); } break; default: break; } p += len; } } if (*pmsg_type == DHCPREQUEST && preq_addr->s_addr == htonl(0L) && bp->bp_ciaddr.s_addr) { memcpy(&(preq_addr->s_addr), &bp->bp_ciaddr, 4); } } static void bootp_reply(Slirp *slirp, const struct bootp_t *bp) { BOOTPClient *bc = NULL; struct mbuf *m; struct bootp_t *rbp; struct sockaddr_in saddr, daddr; struct in_addr preq_addr; int dhcp_msg_type, val; uint8_t *q; uint8_t client_ethaddr[ETH_ALEN]; /* extract exact DHCP msg type */ dhcp_decode(bp, &dhcp_msg_type, &preq_addr); DPRINTF("bootp packet op=%d msgtype=%d", bp->bp_op, dhcp_msg_type); if (preq_addr.s_addr != htonl(0L)) DPRINTF(" req_addr=%08x\n", ntohl(preq_addr.s_addr)); else DPRINTF("\n"); if (dhcp_msg_type == 0) dhcp_msg_type = DHCPREQUEST; /* Force reply for old BOOTP clients */ if (dhcp_msg_type != DHCPDISCOVER && dhcp_msg_type != DHCPREQUEST) return; /* Get client's hardware address from bootp request */ memcpy(client_ethaddr, bp->bp_hwaddr, ETH_ALEN); m = m_get(slirp); if (!m) { return; } m->m_data += IF_MAXLINKHDR; rbp = (struct bootp_t *)m->m_data; m->m_data += sizeof(struct udpiphdr); memset(rbp, 0, sizeof(struct bootp_t)); if (dhcp_msg_type == DHCPDISCOVER) { if (preq_addr.s_addr != htonl(0L)) { bc = request_addr(slirp, &preq_addr, client_ethaddr); if (bc) { daddr.sin_addr = preq_addr; } } if (!bc) { new_addr: bc = get_new_addr(slirp, &daddr.sin_addr, client_ethaddr); if (!bc) { DPRINTF("no address left\n"); return; } } memcpy(bc->macaddr, client_ethaddr, ETH_ALEN); } else if (preq_addr.s_addr != htonl(0L)) { bc = request_addr(slirp, &preq_addr, client_ethaddr); if (bc) { daddr.sin_addr = preq_addr; memcpy(bc->macaddr, client_ethaddr, ETH_ALEN); } else { /* DHCPNAKs should be sent to broadcast */ daddr.sin_addr.s_addr = 0xffffffff; } } else { bc = find_addr(slirp, &daddr.sin_addr, bp->bp_hwaddr); if (!bc) { /* if never assigned, behaves as if it was already assigned (windows fix because it remembers its address) */ goto new_addr; } } /* Update ARP table for this IP address */ arp_table_add(slirp, daddr.sin_addr.s_addr, client_ethaddr); saddr.sin_addr = slirp->vhost_addr; saddr.sin_port = htons(BOOTP_SERVER); daddr.sin_port = htons(BOOTP_CLIENT); rbp->bp_op = BOOTP_REPLY; rbp->bp_xid = bp->bp_xid; rbp->bp_htype = 1; rbp->bp_hlen = 6; memcpy(rbp->bp_hwaddr, bp->bp_hwaddr, ETH_ALEN); rbp->bp_yiaddr = daddr.sin_addr; /* Client IP address */ rbp->bp_siaddr = saddr.sin_addr; /* Server IP address */ q = rbp->bp_vend; memcpy(q, rfc1533_cookie, 4); q += 4; if (bc) { DPRINTF("%s addr=%08x\n", (dhcp_msg_type == DHCPDISCOVER) ? "offered" : "ack'ed", ntohl(daddr.sin_addr.s_addr)); if (dhcp_msg_type == DHCPDISCOVER) { *q++ = RFC2132_MSG_TYPE; *q++ = 1; *q++ = DHCPOFFER; } else /* DHCPREQUEST */ { *q++ = RFC2132_MSG_TYPE; *q++ = 1; *q++ = DHCPACK; } if (slirp->bootp_filename) snprintf((char *)rbp->bp_file, sizeof(rbp->bp_file), "%s", slirp->bootp_filename); *q++ = RFC2132_SRV_ID; *q++ = 4; memcpy(q, &saddr.sin_addr, 4); q += 4; *q++ = RFC1533_NETMASK; *q++ = 4; memcpy(q, &slirp->vnetwork_mask, 4); q += 4; if (!slirp->restricted) { *q++ = RFC1533_GATEWAY; *q++ = 4; memcpy(q, &saddr.sin_addr, 4); q += 4; *q++ = RFC1533_DNS; *q++ = 4; memcpy(q, &slirp->vnameserver_addr, 4); q += 4; } *q++ = RFC2132_LEASE_TIME; *q++ = 4; val = htonl(LEASE_TIME); memcpy(q, &val, 4); q += 4; if (*slirp->client_hostname) { val = strlen(slirp->client_hostname); *q++ = RFC1533_HOSTNAME; *q++ = val; memcpy(q, slirp->client_hostname, val); q += val; } if (slirp->vdnssearch) { size_t spaceleft = sizeof(rbp->bp_vend) - (q - rbp->bp_vend); val = slirp->vdnssearch_len; if (val + 1 > spaceleft) { g_warning("DHCP packet size exceeded, " "omitting domain-search option."); } else { memcpy(q, slirp->vdnssearch, val); q += val; } } } else { static const char nak_msg[] = "requested address not available"; DPRINTF("nak'ed addr=%08x\n", ntohl(preq_addr.s_addr)); *q++ = RFC2132_MSG_TYPE; *q++ = 1; *q++ = DHCPNAK; *q++ = RFC2132_MESSAGE; *q++ = sizeof(nak_msg) - 1; memcpy(q, nak_msg, sizeof(nak_msg) - 1); q += sizeof(nak_msg) - 1; } *q = RFC1533_END; daddr.sin_addr.s_addr = 0xffffffffu; m->m_len = sizeof(struct bootp_t) - sizeof(struct ip) - sizeof(struct udphdr); udp_output2(NULL, m, &saddr, &daddr, IPTOS_LOWDELAY); } void bootp_input(struct mbuf *m) { struct bootp_t *bp = mtod(m, struct bootp_t *); if (bp->bp_op == BOOTP_REQUEST) { bootp_reply(m->slirp, bp); } }