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qemu/slirp/bootp.c
Jan Kiszka a13a4126c8 slirp: Rework internal configuration 
The user mode IP stack is currently only minimally configurable /wrt to
its virtual IP addresses. This is unfortunate if some guest has a fixed
idea of which IP addresses to use.

Therefore this patch prepares the stack for fully configurable IP
addresses and masks. The user interface and default addresses remain
untouched in this step, they will be enhanced in the following patch.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2009-06-29 08:52:45 -05:00

321 lines
8.6 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 LEASE_TIME (24 * 3600)
typedef struct {
uint8_t allocated;
uint8_t macaddr[6];
} BOOTPClient;
static BOOTPClient bootp_clients[NB_ADDR];
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 = vdhcp_startaddr.s_addr + htonl(i);
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 dhcp_addr = ntohl(vdhcp_startaddr.s_addr);
BOOTPClient *bc;
if (req_addr >= dhcp_addr &&
req_addr < (dhcp_addr + NB_ADDR)) {
bc = &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(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 = vdhcp_startaddr.s_addr + htonl(i);
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;
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 = 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, 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;
memcpy(q, &vnetwork_mask, 4);
q += 4;
if (!slirp_restrict) {
*q++ = RFC1533_GATEWAY;
*q++ = 4;
memcpy(q, &saddr.sin_addr, 4);
q += 4;
*q++ = RFC1533_DNS;
*q++ = 4;
memcpy(q, &vnameserver_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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