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qemu/slirp/ip_icmp.c

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/*
* Copyright (c) 1982, 1986, 1988, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)ip_icmp.c 8.2 (Berkeley) 1/4/94
* ip_icmp.c,v 1.7 1995/05/30 08:09:42 rgrimes Exp
*/
#include "slirp.h"
#include "ip_icmp.h"
#ifndef WITH_ICMP_ERROR_MSG
#define WITH_ICMP_ERROR_MSG 0
#endif
/* The message sent when emulating PING */
/* Be nice and tell them it's just a pseudo-ping packet */
static const char icmp_ping_msg[] = "This is a pseudo-PING packet used by Slirp to emulate ICMP ECHO-REQUEST packets.\n";
/* list of actions for icmp_send_error() on RX of an icmp message */
static const int icmp_flush[19] = {
/* ECHO REPLY (0) */ 0,
1,
1,
/* DEST UNREACH (3) */ 1,
/* SOURCE QUENCH (4)*/ 1,
/* REDIRECT (5) */ 1,
1,
1,
/* ECHO (8) */ 0,
/* ROUTERADVERT (9) */ 1,
/* ROUTERSOLICIT (10) */ 1,
/* TIME EXCEEDED (11) */ 1,
/* PARAMETER PROBLEM (12) */ 1,
/* TIMESTAMP (13) */ 0,
/* TIMESTAMP REPLY (14) */ 0,
/* INFO (15) */ 0,
/* INFO REPLY (16) */ 0,
/* ADDR MASK (17) */ 0,
/* ADDR MASK REPLY (18) */ 0
};
void icmp_init(Slirp *slirp)
{
slirp->icmp.so_next = slirp->icmp.so_prev = &slirp->icmp;
slirp->icmp_last_so = &slirp->icmp;
}
void icmp_cleanup(Slirp *slirp)
{
while (slirp->icmp.so_next != &slirp->icmp) {
icmp_detach(slirp->icmp.so_next);
}
}
static int icmp_send(struct socket *so, struct mbuf *m, int hlen)
{
struct ip *ip = mtod(m, struct ip *);
struct sockaddr_in addr;
so->s = slirp_socket(AF_INET, SOCK_DGRAM, IPPROTO_ICMP);
if (so->s == -1) {
return -1;
}
so->so_m = m;
so->so_faddr = ip->ip_dst;
so->so_laddr = ip->ip_src;
so->so_iptos = ip->ip_tos;
so->so_type = IPPROTO_ICMP;
so->so_state = SS_ISFCONNECTED;
so->so_expire = curtime + SO_EXPIRE;
addr.sin_family = AF_INET;
addr.sin_addr = so->so_faddr;
insque(so, &so->slirp->icmp);
if (sendto(so->s, m->m_data + hlen, m->m_len - hlen, 0,
(struct sockaddr *)&addr, sizeof(addr)) == -1) {
DEBUG_MISC("icmp_input icmp sendto tx errno = %d-%s",
errno, strerror(errno));
icmp_send_error(m, ICMP_UNREACH, ICMP_UNREACH_NET, 0, strerror(errno));
icmp_detach(so);
}
return 0;
}
void icmp_detach(struct socket *so)
{
so->slirp->cb->unregister_poll_fd(so->s, so->slirp->opaque);
closesocket(so->s);
sofree(so);
}
/*
* Process a received ICMP message.
*/
void
icmp_input(struct mbuf *m, int hlen)
{
register struct icmp *icp;
register struct ip *ip=mtod(m, struct ip *);
int icmplen=ip->ip_len;
Slirp *slirp = m->slirp;
DEBUG_CALL("icmp_input");
DEBUG_ARG("m = %p", m);
DEBUG_ARG("m_len = %d", m->m_len);
/*
* Locate icmp structure in mbuf, and check
* that its not corrupted and of at least minimum length.
*/
if (icmplen < ICMP_MINLEN) { /* min 8 bytes payload */
freeit:
m_free(m);
goto end_error;
}
m->m_len -= hlen;
m->m_data += hlen;
icp = mtod(m, struct icmp *);
if (cksum(m, icmplen)) {
goto freeit;
}
m->m_len += hlen;
m->m_data -= hlen;
DEBUG_ARG("icmp_type = %d", icp->icmp_type);
switch (icp->icmp_type) {
case ICMP_ECHO:
ip->ip_len += hlen; /* since ip_input subtracts this */
if (ip->ip_dst.s_addr == slirp->vhost_addr.s_addr ||
ip->ip_dst.s_addr == slirp->vnameserver_addr.s_addr) {
icmp_reflect(m);
} else if (slirp->restricted) {
goto freeit;
} else {
struct socket *so;
struct sockaddr_storage addr;
so = socreate(slirp);
if (icmp_send(so, m, hlen) == 0) {
return;
}
if (udp_attach(so, AF_INET) == -1) {
DEBUG_MISC("icmp_input udp_attach errno = %d-%s",
errno,strerror(errno));
sofree(so);
m_free(m);
goto end_error;
}
so->so_m = m;
so->so_ffamily = AF_INET;
so->so_faddr = ip->ip_dst;
so->so_fport = htons(7);
so->so_lfamily = AF_INET;
so->so_laddr = ip->ip_src;
so->so_lport = htons(9);
so->so_iptos = ip->ip_tos;
so->so_type = IPPROTO_ICMP;
so->so_state = SS_ISFCONNECTED;
/* Send the packet */
addr = so->fhost.ss;
sotranslate_out(so, &addr);
if(sendto(so->s, icmp_ping_msg, strlen(icmp_ping_msg), 0,
(struct sockaddr *)&addr, sockaddr_size(&addr)) == -1) {
DEBUG_MISC("icmp_input udp sendto tx errno = %d-%s",
errno,strerror(errno));
icmp_send_error(m, ICMP_UNREACH, ICMP_UNREACH_NET, 0, strerror(errno));
udp_detach(so);
}
} /* if ip->ip_dst.s_addr == alias_addr.s_addr */
break;
case ICMP_UNREACH:
/* XXX? report error? close socket? */
case ICMP_TIMXCEED:
case ICMP_PARAMPROB:
case ICMP_SOURCEQUENCH:
case ICMP_TSTAMP:
case ICMP_MASKREQ:
case ICMP_REDIRECT:
m_free(m);
break;
default:
m_free(m);
} /* swith */
end_error:
/* m is m_free()'d xor put in a socket xor or given to ip_send */
return;
}
/*
* Send an ICMP message in response to a situation
*
* RFC 1122: 3.2.2 MUST send at least the IP header and 8 bytes of header. MAY send more (we do).
* MUST NOT change this header information.
* MUST NOT reply to a multicast/broadcast IP address.
* MUST NOT reply to a multicast/broadcast MAC address.
* MUST reply to only the first fragment.
*/
/*
* Send ICMP_UNREACH back to the source regarding msrc.
* mbuf *msrc is used as a template, but is NOT m_free()'d.
* It is reported as the bad ip packet. The header should
* be fully correct and in host byte order.
* ICMP fragmentation is illegal. All machines must accept 576 bytes in one
* packet. The maximum payload is 576-20(ip hdr)-8(icmp hdr)=548
*/
#define ICMP_MAXDATALEN (IP_MSS-28)
void
icmp_send_error(struct mbuf *msrc, uint8_t type, uint8_t code, int minsize,
const char *message)
{
unsigned hlen, shlen, s_ip_len;
register struct ip *ip;
register struct icmp *icp;
register struct mbuf *m;
DEBUG_CALL("icmp_send_error");
DEBUG_ARG("msrc = %p", msrc);
DEBUG_ARG("msrc_len = %d", msrc->m_len);
if(type!=ICMP_UNREACH && type!=ICMP_TIMXCEED) goto end_error;
/* check msrc */
if(!msrc) goto end_error;
ip = mtod(msrc, struct ip *);
if (slirp_debug & DBG_MISC) {
char bufa[20], bufb[20];
strcpy(bufa, inet_ntoa(ip->ip_src));
strcpy(bufb, inet_ntoa(ip->ip_dst));
DEBUG_MISC(" %.16s to %.16s", bufa, bufb);
}
if(ip->ip_off & IP_OFFMASK) goto end_error; /* Only reply to fragment 0 */
/* Do not reply to source-only IPs */
if ((ip->ip_src.s_addr & htonl(~(0xf << 28))) == 0) {
goto end_error;
}
shlen=ip->ip_hl << 2;
s_ip_len=ip->ip_len;
if(ip->ip_p == IPPROTO_ICMP) {
icp = (struct icmp *)((char *)ip + shlen);
/*
* Assume any unknown ICMP type is an error. This isn't
* specified by the RFC, but think about it..
*/
if(icp->icmp_type>18 || icmp_flush[icp->icmp_type]) goto end_error;
}
/* make a copy */
m = m_get(msrc->slirp);
if (!m) {
goto end_error;
}
{ int new_m_size;
new_m_size=sizeof(struct ip )+ICMP_MINLEN+msrc->m_len+ICMP_MAXDATALEN;
if(new_m_size>m->m_size) m_inc(m, new_m_size);
}
memcpy(m->m_data, msrc->m_data, msrc->m_len);
m->m_len = msrc->m_len; /* copy msrc to m */
/* make the header of the reply packet */
ip = mtod(m, struct ip *);
hlen= sizeof(struct ip ); /* no options in reply */
/* fill in icmp */
m->m_data += hlen;
m->m_len -= hlen;
icp = mtod(m, struct icmp *);
if(minsize) s_ip_len=shlen+ICMP_MINLEN; /* return header+8b only */
else if(s_ip_len>ICMP_MAXDATALEN) /* maximum size */
s_ip_len=ICMP_MAXDATALEN;
m->m_len=ICMP_MINLEN+s_ip_len; /* 8 bytes ICMP header */
/* min. size = 8+sizeof(struct ip)+8 */
icp->icmp_type = type;
icp->icmp_code = code;
icp->icmp_id = 0;
icp->icmp_seq = 0;
memcpy(&icp->icmp_ip, msrc->m_data, s_ip_len); /* report the ip packet */
HTONS(icp->icmp_ip.ip_len);
HTONS(icp->icmp_ip.ip_id);
HTONS(icp->icmp_ip.ip_off);
if (message && WITH_ICMP_ERROR_MSG) { /* append message to ICMP packet */
int message_len;
char *cpnt;
message_len=strlen(message);
if(message_len>ICMP_MAXDATALEN) message_len=ICMP_MAXDATALEN;
cpnt=(char *)m->m_data+m->m_len;
memcpy(cpnt, message, message_len);
m->m_len+=message_len;
}
icp->icmp_cksum = 0;
icp->icmp_cksum = cksum(m, m->m_len);
m->m_data -= hlen;
m->m_len += hlen;
/* fill in ip */
ip->ip_hl = hlen >> 2;
ip->ip_len = m->m_len;
ip->ip_tos=((ip->ip_tos & 0x1E) | 0xC0); /* high priority for errors */
ip->ip_ttl = MAXTTL;
ip->ip_p = IPPROTO_ICMP;
ip->ip_dst = ip->ip_src; /* ip addresses */
ip->ip_src = m->slirp->vhost_addr;
(void ) ip_output((struct socket *)NULL, m);
end_error:
return;
}
#undef ICMP_MAXDATALEN
/*
* Reflect the ip packet back to the source
*/
void
icmp_reflect(struct mbuf *m)
{
register struct ip *ip = mtod(m, struct ip *);
int hlen = ip->ip_hl << 2;
int optlen = hlen - sizeof(struct ip );
register struct icmp *icp;
/*
* Send an icmp packet back to the ip level,
* after supplying a checksum.
*/
m->m_data += hlen;
m->m_len -= hlen;
icp = mtod(m, struct icmp *);
icp->icmp_type = ICMP_ECHOREPLY;
icp->icmp_cksum = 0;
icp->icmp_cksum = cksum(m, ip->ip_len - hlen);
m->m_data -= hlen;
m->m_len += hlen;
/* fill in ip */
if (optlen > 0) {
/*
* Strip out original options by copying rest of first
* mbuf's data back, and adjust the IP length.
*/
memmove((char *)(ip + 1), (char *)ip + hlen,
(unsigned )(m->m_len - hlen));
hlen -= optlen;
ip->ip_hl = hlen >> 2;
ip->ip_len -= optlen;
m->m_len -= optlen;
}
ip->ip_ttl = MAXTTL;
{ /* swap */
struct in_addr icmp_dst;
icmp_dst = ip->ip_dst;
ip->ip_dst = ip->ip_src;
ip->ip_src = icmp_dst;
}
(void ) ip_output((struct socket *)NULL, m);
}
void icmp_receive(struct socket *so)
{
struct mbuf *m = so->so_m;
struct ip *ip = mtod(m, struct ip *);
int hlen = ip->ip_hl << 2;
uint8_t error_code;
struct icmp *icp;
int id, len;
m->m_data += hlen;
m->m_len -= hlen;
icp = mtod(m, struct icmp *);
id = icp->icmp_id;
len = recv(so->s, icp, M_ROOM(m), 0);
/*
* The behavior of reading SOCK_DGRAM+IPPROTO_ICMP sockets is inconsistent
* between host OSes. On Linux, only the ICMP header and payload is
* included. On macOS/Darwin, the socket acts like a raw socket and
* includes the IP header as well. On other BSDs, SOCK_DGRAM+IPPROTO_ICMP
* sockets aren't supported at all, so we treat them like raw sockets. It
* isn't possible to detect this difference at runtime, so we must use an
* #ifdef to determine if we need to remove the IP header.
*/
#ifdef CONFIG_BSD
if (len >= sizeof(struct ip)) {
struct ip *inner_ip = mtod(m, struct ip *);
int inner_hlen = inner_ip->ip_hl << 2;
if (inner_hlen > len) {
len = -1;
errno = -EINVAL;
} else {
len -= inner_hlen;
memmove(icp, (unsigned char *)icp + inner_hlen, len);
}
} else {
len = -1;
errno = -EINVAL;
}
#endif
icp->icmp_id = id;
m->m_data -= hlen;
m->m_len += hlen;
if (len == -1 || len == 0) {
if (errno == ENETUNREACH) {
error_code = ICMP_UNREACH_NET;
} else {
error_code = ICMP_UNREACH_HOST;
}
DEBUG_MISC(" udp icmp rx errno = %d-%s", errno,
strerror(errno));
icmp_send_error(so->so_m, ICMP_UNREACH, error_code, 0, strerror(errno));
} else {
icmp_reflect(so->so_m);
so->so_m = NULL; /* Don't m_free() it again! */
}
icmp_detach(so);
}
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