1 /* $NetBSD: socket.c,v 1.16 2003/03/30 00:32:52 thorpej Exp $ */ 2 3 /* 4 * This module determines the type of socket (datagram, stream), the client 5 * socket address and port, the server socket address and port. In addition, 6 * it provides methods to map a transport address to a printable host name 7 * or address. Socket address information results are in static memory. 8 * 9 * The result from the hostname lookup method is STRING_PARANOID when a host 10 * pretends to have someone elses name, or when a host name is available but 11 * could not be verified. 12 * 13 * When lookup or conversion fails the result is set to STRING_UNKNOWN. 14 * 15 * Diagnostics are reported through syslog(3). 16 * 17 * Author: Wietse Venema, Eindhoven University of Technology, The Netherlands. 18 */ 19 20 #include <sys/cdefs.h> 21 #ifndef lint 22 #if 0 23 static char sccsid[] = "@(#) socket.c 1.15 97/03/21 19:27:24"; 24 #else 25 __RCSID("$NetBSD: socket.c,v 1.16 2003/03/30 00:32:52 thorpej Exp $"); 26 #endif 27 #endif 28 29 /* System libraries. */ 30 31 #include <sys/types.h> 32 #include <sys/param.h> 33 #include <sys/socket.h> 34 #include <netinet/in.h> 35 #include <netdb.h> 36 #include <stdio.h> 37 #include <syslog.h> 38 #include <string.h> 39 #include <arpa/inet.h> 40 41 /* Local stuff. */ 42 43 #include "tcpd.h" 44 45 /* Forward declarations. */ 46 47 #ifdef APPEND_DOT 48 static const char *append_dot __P((const char *)); 49 #endif 50 static void sock_sink __P((int)); 51 52 #ifdef APPEND_DOT 53 /* 54 * Speed up DNS lookups by terminating the host name with a dot. Should be 55 * done with care. The speedup can give problems with lookups from sources 56 * that lack DNS-style trailing dot magic, such as local files or NIS maps. 57 */ 58 59 static const char * 60 append_dot(name) 61 const char *name; 62 { 63 static char hbuf[MAXHOSTNAMELEN + 1]; 64 65 /* 66 * Don't append dots to unqualified names. Such names are likely to come 67 * from local hosts files or from NIS. 68 */ 69 70 if (strchr(name, '.') == 0 || strlen(name) + 2 > sizeof(hbuf)) 71 strlcpy(hbuf, name, sizeof(hbuf)); 72 else 73 (void)snprintf(hbuf, sizeof(hbuf), "%s.", name); 74 return hbuf; 75 } 76 #endif 77 78 /* sock_host - look up endpoint addresses and install conversion methods */ 79 80 void sock_host(request) 81 struct request_info *request; 82 { 83 static struct sockaddr_storage client; 84 static struct sockaddr_storage server; 85 int len; 86 char buf[BUFSIZ]; 87 int fd = request->fd; 88 89 sock_methods(request); 90 91 /* 92 * Look up the client host address. Hal R. Brand <BRAND@addvax.llnl.gov> 93 * suggested how to get the client host info in case of UDP connections: 94 * peek at the first message without actually looking at its contents. We 95 * really should verify that client.sin_family gets the value AF_INET, 96 * but this program has already caused too much grief on systems with 97 * broken library code. 98 * 99 * XXX the last sentence is untrue as we support AF_INET6 as well :-) 100 */ 101 102 if (request->client->sin == NULL) { 103 len = sizeof(client); 104 if (getpeername(fd, (struct sockaddr *) & client, &len) < 0) { 105 request->sink = sock_sink; 106 len = sizeof(client); 107 if (recvfrom(fd, buf, sizeof(buf), MSG_PEEK, 108 (struct sockaddr *) & client, &len) < 0) { 109 tcpd_warn("can't get client address: %m"); 110 return; /* give up */ 111 } 112 #ifdef really_paranoid 113 memset(buf, 0, sizeof(buf)); 114 #endif 115 } 116 request->client->sin = (struct sockaddr *)&client; 117 } 118 119 /* 120 * Determine the server binding. This is used for client username 121 * lookups, and for access control rules that trigger on the server 122 * address or name. 123 */ 124 125 if (request->server->sin == NULL) { 126 len = sizeof(server); 127 if (getsockname(fd, (struct sockaddr *) & server, &len) < 0) { 128 tcpd_warn("getsockname: %m"); 129 return; 130 } 131 request->server->sin = (struct sockaddr *)&server; 132 } 133 } 134 135 /* sock_hostaddr - map endpoint address to printable form */ 136 137 void sock_hostaddr(host) 138 struct host_info *host; 139 { 140 struct sockaddr *sa = host->sin; 141 142 if (!sa) 143 return; 144 host->addr[0] = '\0'; 145 getnameinfo(sa, sa->sa_len, host->addr, sizeof(host->addr), 146 NULL, 0, NI_NUMERICHOST); 147 } 148 149 /* sock_hostname - map endpoint address to host name */ 150 151 void sock_hostname(host) 152 struct host_info *host; 153 { 154 struct sockaddr *sa = host->sin; 155 char h1[NI_MAXHOST], h2[NI_MAXHOST]; 156 struct addrinfo hints, *res, *res0; 157 #ifdef INET6 158 struct sockaddr_in tmp; 159 #endif 160 161 if (!sa) 162 return; 163 #ifdef INET6 164 /* special case on reverse lookup: mapped addr. I hate it */ 165 if (sa->sa_family == AF_INET6 && 166 IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)sa)->sin6_addr)) { 167 memset(&tmp, 0, sizeof(tmp)); 168 tmp.sin_family = AF_INET; 169 tmp.sin_len = sizeof(struct sockaddr_in); 170 memcpy(&tmp.sin_addr, 171 &((struct sockaddr_in6 *)sa)->sin6_addr.s6_addr[12], 4); 172 sa = (struct sockaddr *)&tmp; 173 } 174 #endif 175 if (getnameinfo(sa, sa->sa_len, h1, sizeof(h1), NULL, 0, 176 NI_NUMERICHOST) != 0) { 177 return; 178 } 179 if (getnameinfo(sa, sa->sa_len, host->name, sizeof(host->name), NULL, 0, 180 NI_NAMEREQD) == 0) { 181 /* 182 * Verify that the address is a member of the address list returned 183 * by getaddrinfo(hostname). 184 * 185 * Verify also that getnameinfo() and getaddrinfo() return the same 186 * hostname, or rshd and rlogind may still end up being spoofed. 187 * 188 * On some sites, getaddrinfo("localhost") returns "localhost.domain". 189 * This is a DNS artefact. We treat it as a special case. When we 190 * can't believe the address list from getaddrinfo("localhost") 191 * we're in big trouble anyway. 192 */ 193 memset(&hints, 0, sizeof(hints)); 194 hints.ai_family = sa->sa_family; 195 hints.ai_socktype = SOCK_DGRAM; /*dummy*/ 196 hints.ai_flags = AI_CANONNAME; 197 #ifdef APPEND_DOT 198 if (getaddrinfo(append_dot(host->name), "0", &hints, &res0) != 0) 199 #else 200 if (getaddrinfo(host->name, "0", &hints, &res0) != 0) 201 #endif 202 { 203 /* 204 * Unable to verify that the host name matches the address. This 205 * may be a transient problem or a botched name server setup. 206 */ 207 208 tcpd_warn("can't verify hostname: getaddrinfo(%s, %d) failed", 209 host->name, hints.ai_family); 210 } else if (res0->ai_canonname && 211 STR_NE(host->name, res0->ai_canonname) && 212 STR_NE(host->name, "localhost")) { 213 /* 214 * The getnameinfo() and getaddrinfo() calls did not return 215 * the same hostname. This could be a nameserver configuration 216 * problem. It could also be that someone is trying to spoof us. 217 */ 218 219 tcpd_warn("host name/name mismatch: %s != %s", 220 host->name, res0->ai_canonname); 221 freeaddrinfo(res0); 222 } else { 223 /* 224 * The address should be a member of the address list returned by 225 * getaddrinfo(). 226 */ 227 228 for (res = res0; res; res = res->ai_next) { 229 if (getnameinfo(res->ai_addr, res->ai_addrlen, h2, sizeof(h2), 230 NULL, 0, NI_NUMERICHOST) != 0) { 231 continue; 232 } 233 if (STR_EQ(h1, h2)) { 234 freeaddrinfo(res0); 235 return; 236 } 237 } 238 239 /* 240 * The host name does not map to the initial address. Perhaps 241 * someone has messed up. Perhaps someone compromised a name 242 * server. 243 */ 244 245 tcpd_warn("host name/address mismatch: %s != %s", h1, 246 res0->ai_canonname ? res0->ai_canonname : "?"); 247 248 freeaddrinfo(res0); 249 } 250 /* name is bad, clobber it */ 251 (void)strlcpy(host->name, paranoid, sizeof(host->name)); 252 } 253 } 254 255 /* sock_sink - absorb unreceived IP datagram */ 256 257 static void sock_sink(fd) 258 int fd; 259 { 260 char buf[BUFSIZ]; 261 struct sockaddr_storage ss; 262 int size = sizeof(ss); 263 264 /* 265 * Eat up the not-yet received datagram. Some systems insist on a 266 * non-zero source address argument in the recvfrom() call below. 267 */ 268 269 (void) recvfrom(fd, buf, sizeof(buf), 0, (struct sockaddr *) & ss, &size); 270 } 271