/* $NetBSD: socket.c,v 1.17 2003/05/26 10:05:07 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. */ #include #ifndef lint #if 0 static char sccsid[] = "@(#) socket.c 1.15 97/03/21 19:27:24"; #else __RCSID("$NetBSD: socket.c,v 1.17 2003/05/26 10:05:07 itojun Exp $"); #endif #endif /* System libraries. */ #include #include #include #include #include #include #include #include #include /* Local stuff. */ #include "tcpd.h" /* Forward declarations. */ #ifdef APPEND_DOT static const char *append_dot __P((const char *)); #endif static void sock_sink __P((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 (void)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 * 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 :-) */ if (request->client->sin == NULL) { 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. */ if (request->server->sin == NULL) { 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) { /* * if reverse lookup result looks like a numeric hostname, * someone is trying to trick us by PTR record like following: * 1.1.1.10.in-addr.arpa. IN PTR 2.3.4.5 */ memset(&hints, 0, sizeof(hints)); hints.ai_socktype = SOCK_DGRAM; /*dummy*/ hints.ai_flags = AI_NUMERICHOST; #ifdef APPEND_DOT if (getaddrinfo(append_dot(host->name), "0", &hints, &res0) == 0) #else if (getaddrinfo(host->name, "0", &hints, &res0) == 0) #endif { tcpd_warn("Nasty PTR record is configured"); freeaddrinfo(res0); /* name is bad, clobber it */ (void)strlcpy(host->name, paranoid, sizeof(host->name)); return; } /* * 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 */ (void)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); }