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qemu-e2k/slirp/bootp.c
Jan Kiszka 0928a95ffe slirp: Reassign same address to same DHCP client 
In case a client restarts a DHCP recovery without releasing its old
address, reassign the same address to prevent consuming free addresses
and moving away from the standard client address.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
2009-05-22 10:50:34 -05:00

327 lines
8.9 KiB
C
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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, ...) \
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,
const uint8_t *macaddr)
{
BOOTPClient *bc;
int i;
for(i = 0; i < NB_ADDR; i++) {
bc = &bootp_clients[i];
if (!bc->allocated || !memcmp(macaddr, bc->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 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, client_ethaddr);
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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