/* * 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 NB_ADDR 16 #define START_ADDR 15 #define LEASE_TIME (24 * 3600) typedef struct { uint8_t allocated; uint8_t macaddr[6]; } BOOTPClient; static BOOTPClient bootp_clients[NB_ADDR]; const char *bootp_filename; static const uint8_t rfc1533_cookie[] = { RFC1533_COOKIE }; #ifdef DEBUG #define dprintf(fmt, ...) \ if (slirp_debug & DBG_CALL) { fprintf(dfd, fmt, ## __VA_ARGS__); fflush(dfd); } #else #define dprintf(fmt, ...) #endif static BOOTPClient *get_new_addr(struct in_addr *paddr) { BOOTPClient *bc; int i; for(i = 0; i < NB_ADDR; i++) { if (!bootp_clients[i].allocated) goto found; } return NULL; found: bc = &bootp_clients[i]; bc->allocated = 1; paddr->s_addr = htonl(ntohl(special_addr.s_addr) | (i + START_ADDR)); return bc; } static BOOTPClient *request_addr(const struct in_addr *paddr, const uint8_t *macaddr) { uint32_t req_addr = ntohl(paddr->s_addr); uint32_t spec_addr = ntohl(special_addr.s_addr); BOOTPClient *bc; if (req_addr >= (spec_addr | START_ADDR) && req_addr < (spec_addr | (NB_ADDR + START_ADDR))) { bc = &bootp_clients[(req_addr & 0xff) - START_ADDR]; if (!bc->allocated || !memcmp(macaddr, bc->macaddr, 6)) { bc->allocated = 1; return bc; } } return NULL; } static BOOTPClient *find_addr(struct in_addr *paddr, const uint8_t *macaddr) { BOOTPClient *bc; int i; for(i = 0; i < NB_ADDR; i++) { if (!memcmp(macaddr, bootp_clients[i].macaddr, 6)) goto found; } return NULL; found: bc = &bootp_clients[i]; bc->allocated = 1; paddr->s_addr = htonl(ntohl(special_addr.s_addr) | (i + START_ADDR)); return bc; } static void dhcp_decode(const struct bootp_t *bp, int *pmsg_type, const struct in_addr **preq_addr) { const uint8_t *p, *p_end; int len, tag; *pmsg_type = 0; *preq_addr = NULL; 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) *preq_addr = (struct in_addr *)p; break; default: break; } p += len; } } if (*pmsg_type == DHCPREQUEST && !*preq_addr && bp->bp_ciaddr.s_addr) { *preq_addr = &bp->bp_ciaddr; } } static void bootp_reply(const struct bootp_t *bp) { BOOTPClient *bc = NULL; struct mbuf *m; struct bootp_t *rbp; struct sockaddr_in saddr, daddr; struct in_addr dns_addr; const struct in_addr *preq_addr; int dhcp_msg_type, val; uint8_t *q; /* 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) 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; /* XXX: this is a hack to get the client mac address */ memcpy(client_ethaddr, bp->bp_hwaddr, 6); if ((m = m_get()) == NULL) 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) { bc = request_addr(preq_addr, client_ethaddr); if (bc) { daddr.sin_addr = *preq_addr; } } if (!bc) { new_addr: bc = get_new_addr(&daddr.sin_addr); if (!bc) { dprintf("no address left\n"); return; } } memcpy(bc->macaddr, client_ethaddr, 6); } else if (preq_addr) { bc = request_addr(preq_addr, client_ethaddr); if (bc) { daddr.sin_addr = *preq_addr; memcpy(bc->macaddr, client_ethaddr, 6); } else { daddr.sin_addr.s_addr = 0; } } else { bc = find_addr(&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; } } saddr.sin_addr.s_addr = htonl(ntohl(special_addr.s_addr) | CTL_ALIAS); 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, 6); 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 (bootp_filename) snprintf((char *)rbp->bp_file, sizeof(rbp->bp_file), "%s", bootp_filename); *q++ = RFC2132_SRV_ID; *q++ = 4; memcpy(q, &saddr.sin_addr, 4); q += 4; *q++ = RFC1533_NETMASK; *q++ = 4; *q++ = 0xff; *q++ = 0xff; *q++ = 0xff; *q++ = 0x00; if (!slirp_restrict) { *q++ = RFC1533_GATEWAY; *q++ = 4; memcpy(q, &saddr.sin_addr, 4); q += 4; *q++ = RFC1533_DNS; *q++ = 4; dns_addr.s_addr = htonl(ntohl(special_addr.s_addr) | CTL_DNS); memcpy(q, &dns_addr, 4); q += 4; } *q++ = RFC2132_LEASE_TIME; *q++ = 4; val = htonl(LEASE_TIME); memcpy(q, &val, 4); q += 4; if (*slirp_hostname) { val = strlen(slirp_hostname); *q++ = RFC1533_HOSTNAME; *q++ = val; memcpy(q, slirp_hostname, 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(bp); } }