| /* SPDX-License-Identifier: MIT */ |
| /* |
| * 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" |
| |
| #if defined(_WIN32) |
| /* Windows ntohl() returns an u_long value. |
| * Add a type cast to match the format strings. */ |
| #define ntohl(n) ((uint32_t)ntohl(n)) |
| #endif |
| |
| /* XXX: only DHCP is supported */ |
| |
| #define LEASE_TIME (24 * 3600) |
| |
| static const uint8_t rfc1533_cookie[] = { RFC1533_COOKIE }; |
| |
| #define DPRINTF(fmt, ...) DEBUG_CALL(fmt, ##__VA_ARGS__) |
| |
| 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++; |
| if (p + len > p_end) { |
| break; |
| } |
| 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 *end; |
| 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=%08" PRIx32 "\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; |
| end = (uint8_t *)&rbp[1]; |
| memcpy(q, rfc1533_cookie, 4); |
| q += 4; |
| |
| if (bc) { |
| DPRINTF("%s addr=%08" PRIx32 "\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) { |
| g_assert(strlen(slirp->bootp_filename) < sizeof(rbp->bp_file)); |
| strcpy(rbp->bp_file, 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); |
| if (q + val + 2 >= end) { |
| g_warning("DHCP packet size exceeded, " |
| "omitting host name option."); |
| } else { |
| *q++ = RFC1533_HOSTNAME; |
| *q++ = val; |
| memcpy(q, slirp->client_hostname, val); |
| q += val; |
| } |
| } |
| |
| if (slirp->vdomainname) { |
| val = strlen(slirp->vdomainname); |
| if (q + val + 2 >= end) { |
| g_warning("DHCP packet size exceeded, " |
| "omitting domain name option."); |
| } else { |
| *q++ = RFC1533_DOMAINNAME; |
| *q++ = val; |
| memcpy(q, slirp->vdomainname, val); |
| q += val; |
| } |
| } |
| |
| if (slirp->tftp_server_name) { |
| val = strlen(slirp->tftp_server_name); |
| if (q + val + 2 >= end) { |
| g_warning("DHCP packet size exceeded, " |
| "omitting tftp-server-name option."); |
| } else { |
| *q++ = RFC2132_TFTP_SERVER_NAME; |
| *q++ = val; |
| memcpy(q, slirp->tftp_server_name, val); |
| q += val; |
| } |
| } |
| |
| if (slirp->vdnssearch) { |
| val = slirp->vdnssearch_len; |
| if (q + val >= end) { |
| 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=%08" PRIx32 "\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; |
| } |
| assert(q < end); |
| *q = RFC1533_END; |
| |
| daddr.sin_addr.s_addr = 0xffffffffu; |
| |
| m->m_len = sizeof(struct bootp_t) - sizeof(struct ip) - sizeof(struct udphdr); |
| udp_output(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); |
| } |
| } |
