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/* $OpenBSD: socket.c,v 1.5 2002/06/07 03:32:04 itojun Exp $ */
/*
* This module determines the type of socket (datagram, stream), the client
* socket address and port, the server socket address and port. In addition,
* it provides methods to map a transport address to a printable host name
* or address. Socket address information results are in static memory.
*
* The result from the hostname lookup method is STRING_PARANOID when a host
* pretends to have someone elses name, or when a host name is available but
* could not be verified.
*
* When lookup or conversion fails the result is set to STRING_UNKNOWN.
*
* Diagnostics are reported through syslog(3).
*
* Author: Wietse Venema, Eindhoven University of Technology, The Netherlands.
*/
#ifndef lint
#if 0
static char sccsid[] = "@(#) socket.c 1.15 97/03/21 19:27:24";
#else
static char rcsid[] = "$OpenBSD: socket.c,v 1.5 2002/06/07 03:32:04 itojun Exp $";
#endif
#endif
/* System libraries. */
#include <sys/types.h>
#include <sys/param.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <stdio.h>
#include <syslog.h>
#include <string.h>
/* Local stuff. */
#include "tcpd.h"
/* Forward declarations. */
#ifdef APPEND_DOT
static const char *append_dot(const char *);
#endif
static void sock_sink(int);
#ifdef APPEND_DOT
/*
* Speed up DNS lookups by terminating the host name with a dot. Should be
* done with care. The speedup can give problems with lookups from sources
* that lack DNS-style trailing dot magic, such as local files or NIS maps.
*/
static const char *
append_dot(name)
const char *name;
{
static char hbuf[MAXHOSTNAMELEN + 1];
/*
* Don't append dots to unqualified names. Such names are likely to come
* from local hosts files or from NIS.
*/
if (strchr(name, '.') == 0 || strlen(name) + 2 > sizeof(hbuf))
strlcpy(hbuf, name, sizeof(hbuf));
else
snprintf(hbuf, sizeof(hbuf), "%s.", name);
return hbuf;
}
#endif
/* sock_host - look up endpoint addresses and install conversion methods */
void sock_host(request)
struct request_info *request;
{
static struct sockaddr_storage client;
static struct sockaddr_storage server;
int len;
char buf[BUFSIZ];
int fd = request->fd;
sock_methods(request);
/*
* Look up the client host address. Hal R. Brand <BRAND@addvax.llnl.gov>
* suggested how to get the client host info in case of UDP connections:
* peek at the first message without actually looking at its contents. We
* really should verify that client.sin_family gets the value AF_INET,
* but this program has already caused too much grief on systems with
* broken library code.
*
* XXX the last sentence is untrue as we support AF_INET6 as well :-)
*/
len = sizeof(client);
if (getpeername(fd, (struct sockaddr *) & client, &len) < 0) {
request->sink = sock_sink;
len = sizeof(client);
if (recvfrom(fd, buf, sizeof(buf), MSG_PEEK,
(struct sockaddr *) & client, &len) < 0) {
tcpd_warn("can't get client address: %m");
return; /* give up */
}
#ifdef really_paranoid
memset(buf, 0 sizeof(buf));
#endif
}
request->client->sin = (struct sockaddr *)&client;
/*
* Determine the server binding. This is used for client username
* lookups, and for access control rules that trigger on the server
* address or name.
*/
len = sizeof(server);
if (getsockname(fd, (struct sockaddr *) & server, &len) < 0) {
tcpd_warn("getsockname: %m");
return;
}
request->server->sin = (struct sockaddr *)&server;
}
/* sock_hostaddr - map endpoint address to printable form */
void sock_hostaddr(host)
struct host_info *host;
{
struct sockaddr *sa = host->sin;
if (!sa)
return;
host->addr[0] = '\0';
getnameinfo(sa, sa->sa_len, host->addr, sizeof(host->addr),
NULL, 0, NI_NUMERICHOST);
}
/* sock_hostname - map endpoint address to host name */
void sock_hostname(host)
struct host_info *host;
{
struct sockaddr *sa = host->sin;
char h1[NI_MAXHOST], h2[NI_MAXHOST];
struct addrinfo hints, *res, *res0;
#ifdef INET6
struct sockaddr_in tmp;
#endif
if (!sa)
return;
#ifdef INET6
/* special case on reverse lookup: mapped addr. I hate it */
if (sa->sa_family == AF_INET6 &&
IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)sa)->sin6_addr)) {
memset(&tmp, 0, sizeof(tmp));
tmp.sin_family = AF_INET;
tmp.sin_len = sizeof(struct sockaddr_in);
memcpy(&tmp.sin_addr,
&((struct sockaddr_in6 *)sa)->sin6_addr.s6_addr[12], 4);
sa = (struct sockaddr *)&tmp;
}
#endif
if (getnameinfo(sa, sa->sa_len, h1, sizeof(h1), NULL, 0,
NI_NUMERICHOST) != 0) {
return;
}
if (getnameinfo(sa, sa->sa_len, host->name, sizeof(host->name), NULL, 0,
NI_NAMEREQD) == 0) {
/*
* Verify that the address is a member of the address list returned
* by getaddrinfo(hostname).
*
* Verify also that getnameinfo() and getaddrinfo() return the same
* hostname, or rshd and rlogind may still end up being spoofed.
*
* On some sites, getaddrinfo("localhost") returns "localhost.domain".
* This is a DNS artefact. We treat it as a special case. When we
* can't believe the address list from getaddrinfo("localhost")
* we're in big trouble anyway.
*/
memset(&hints, 0, sizeof(hints));
hints.ai_family = sa->sa_family;
hints.ai_socktype = SOCK_DGRAM; /*dummy*/
hints.ai_flags = AI_CANONNAME;
#ifdef APPEND_DOT
if (getaddrinfo(append_dot(host->name), "0", &hints, &res0) != 0)
#else
if (getaddrinfo(host->name, "0", &hints, &res0) != 0)
#endif
{
/*
* Unable to verify that the host name matches the address. This
* may be a transient problem or a botched name server setup.
*/
tcpd_warn("can't verify hostname: getaddrinfo(%s, %d) failed",
host->name, hints.ai_family);
} else if (res0->ai_canonname &&
STR_NE(host->name, res0->ai_canonname) &&
STR_NE(host->name, "localhost")) {
/*
* The getnameinfo() and getaddrinfo() calls did not return
* the same hostname. This could be a nameserver configuration
* problem. It could also be that someone is trying to spoof us.
*/
tcpd_warn("host name/name mismatch: %s != %s",
host->name, res0->ai_canonname);
freeaddrinfo(res0);
} else {
/*
* The address should be a member of the address list returned by
* getaddrinfo().
*/
for (res = res0; res; res = res->ai_next) {
if (getnameinfo(res->ai_addr, res->ai_addrlen, h2, sizeof(h2),
NULL, 0, NI_NUMERICHOST) != 0) {
continue;
}
if (STR_EQ(h1, h2)) {
freeaddrinfo(res0);
return;
}
}
/*
* The host name does not map to the initial address. Perhaps
* someone has messed up. Perhaps someone compromised a name
* server.
*/
tcpd_warn("host name/address mismatch: %s != %s", h1,
res0->ai_canonname ? res0->ai_canonname : "?");
freeaddrinfo(res0);
}
/* name is bad, clobber it */
strlcpy(host->name, paranoid, sizeof(host->name));
}
}
/* sock_sink - absorb unreceived IP datagram */
static void sock_sink(fd)
int fd;
{
char buf[BUFSIZ];
struct sockaddr_storage ss;
int size = sizeof(ss);
/*
* Eat up the not-yet received datagram. Some systems insist on a
* non-zero source address argument in the recvfrom() call below.
*/
(void) recvfrom(fd, buf, sizeof(buf), 0, (struct sockaddr *) & ss, &size);
}
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