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