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qemu-e2k/slirp/bootp.c
aliguori b63c7f6b77 slirp: Handle DHCP requests for specific IP (Jan Kiszka) 
This adds proper handling of the ciaddr field as well as the "Requested
IP Address" option to slirp's DHCP server. If the client requests an
invalid or used IP, a NAK reply is sent, if it requests a specific but
valid IP, this is now respected.

NAK'ing invalid IPs is specifically useful when changing the slirp IP
range via '-net user,ip=...' while the client saved its previously used
address and tries to reacquire it. Now this will be NAK'ed and the
client will start a new discovery round.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>


git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@7198 c046a42c-6fe2-441c-8c8c-71466251a162
2009-04-21 19:56:20 +00:00

325 lines
8.8 KiB
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/*
* 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, args...) \
if (slirp_debug & DBG_CALL) { fprintf(dfd, fmt, ## args); fflush(dfd); }
#else
#define dprintf(fmt, args...)
#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);
}
}
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