Annotation of src/usr.bin/ssh/canohost.c, Revision 1.54
1.54 ! stevesk 1: /* $OpenBSD: canohost.c,v 1.53 2006/03/25 13:17:01 djm Exp $ */
1.1 deraadt 2: /*
1.7 deraadt 3: * Author: Tatu Ylonen <ylo@cs.hut.fi>
4: * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5: * All rights reserved
6: * Functions for returning the canonical host name of the remote site.
1.12 markus 7: *
1.14 deraadt 8: * As far as I am concerned, the code I have written for this software
9: * can be used freely for any purpose. Any derived versions of this
10: * software must be clearly marked as such, and if the derived work is
11: * incompatible with the protocol description in the RFC file, it must be
12: * called by a name other than "ssh" or "Secure Shell".
1.7 deraadt 13: */
1.1 deraadt 14:
15: #include "includes.h"
1.54 ! stevesk 16:
! 17: #include <sys/socket.h>
! 18:
! 19: #include <netinet/in.h>
1.49 stevesk 20:
21: #include <ctype.h>
1.1 deraadt 22:
23: #include "packet.h"
24: #include "xmalloc.h"
1.18 markus 25: #include "log.h"
1.21 itojun 26: #include "canohost.h"
1.1 deraadt 27:
1.27 itojun 28: static void check_ip_options(int, char *);
1.20 markus 29:
1.8 markus 30: /*
31: * Return the canonical name of the host at the other end of the socket. The
32: * caller should free the returned string with xfree.
33: */
1.1 deraadt 34:
1.27 itojun 35: static char *
1.40 avsm 36: get_remote_hostname(int sock, int use_dns)
1.1 deraadt 37: {
1.10 markus 38: struct sockaddr_storage from;
39: int i;
40: socklen_t fromlen;
41: struct addrinfo hints, *ai, *aitop;
1.20 markus 42: char name[NI_MAXHOST], ntop[NI_MAXHOST], ntop2[NI_MAXHOST];
1.6 markus 43:
44: /* Get IP address of client. */
45: fromlen = sizeof(from);
46: memset(&from, 0, sizeof(from));
1.40 avsm 47: if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) {
1.6 markus 48: debug("getpeername failed: %.100s", strerror(errno));
1.38 markus 49: cleanup_exit(255);
1.6 markus 50: }
1.20 markus 51:
1.10 markus 52: if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop),
1.29 deraadt 53: NULL, 0, NI_NUMERICHOST) != 0)
1.10 markus 54: fatal("get_remote_hostname: getnameinfo NI_NUMERICHOST failed");
1.45 dtucker 55:
56: if (from.ss_family == AF_INET)
57: check_ip_options(sock, ntop);
1.32 itojun 58:
1.37 markus 59: if (!use_dns)
60: return xstrdup(ntop);
1.10 markus 61:
1.26 markus 62: debug3("Trying to reverse map address %.100s.", ntop);
1.6 markus 63: /* Map the IP address to a host name. */
1.10 markus 64: if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name),
1.29 deraadt 65: NULL, 0, NI_NAMEREQD) != 0) {
1.20 markus 66: /* Host name not found. Use ip address. */
67: return xstrdup(ntop);
1.6 markus 68: }
69:
1.37 markus 70: /*
71: * if reverse lookup result looks like a numeric hostname,
72: * someone is trying to trick us by PTR record like following:
73: * 1.1.1.10.in-addr.arpa. IN PTR 2.3.4.5
74: */
75: memset(&hints, 0, sizeof(hints));
76: hints.ai_socktype = SOCK_DGRAM; /*dummy*/
77: hints.ai_flags = AI_NUMERICHOST;
78: if (getaddrinfo(name, "0", &hints, &ai) == 0) {
79: logit("Nasty PTR record \"%s\" is set up for %s, ignoring",
80: name, ntop);
81: freeaddrinfo(ai);
82: return xstrdup(ntop);
83: }
84:
1.20 markus 85: /*
86: * Convert it to all lowercase (which is expected by the rest
87: * of this software).
88: */
89: for (i = 0; name[i]; i++)
90: if (isupper(name[i]))
1.52 deraadt 91: name[i] = (char)tolower(name[i]);
1.8 markus 92: /*
1.20 markus 93: * Map it back to an IP address and check that the given
94: * address actually is an address of this host. This is
95: * necessary because anyone with access to a name server can
96: * define arbitrary names for an IP address. Mapping from
97: * name to IP address can be trusted better (but can still be
98: * fooled if the intruder has access to the name server of
99: * the domain).
1.8 markus 100: */
1.20 markus 101: memset(&hints, 0, sizeof(hints));
102: hints.ai_family = from.ss_family;
103: hints.ai_socktype = SOCK_STREAM;
104: if (getaddrinfo(name, NULL, &hints, &aitop) != 0) {
1.36 itojun 105: logit("reverse mapping checking getaddrinfo for %.700s "
1.50 djm 106: "[%s] failed - POSSIBLE BREAK-IN ATTEMPT!", name, ntop);
1.20 markus 107: return xstrdup(ntop);
108: }
109: /* Look for the address from the list of addresses. */
110: for (ai = aitop; ai; ai = ai->ai_next) {
111: if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2,
112: sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 &&
113: (strcmp(ntop, ntop2) == 0))
114: break;
115: }
116: freeaddrinfo(aitop);
117: /* If we reached the end of the list, the address was not there. */
118: if (!ai) {
119: /* Address not found for the host name. */
1.36 itojun 120: logit("Address %.100s maps to %.600s, but this does not "
1.48 stevesk 121: "map back to the address - POSSIBLE BREAK-IN ATTEMPT!",
1.20 markus 122: ntop, name);
123: return xstrdup(ntop);
124: }
125: return xstrdup(name);
126: }
1.6 markus 127:
1.20 markus 128: /*
129: * If IP options are supported, make sure there are none (log and
130: * disconnect them if any are found). Basically we are worried about
131: * source routing; it can be used to pretend you are somebody
132: * (ip-address) you are not. That itself may be "almost acceptable"
133: * under certain circumstances, but rhosts autentication is useless
134: * if source routing is accepted. Notice also that if we just dropped
135: * source routing here, the other side could use IP spoofing to do
136: * rest of the interaction and could still bypass security. So we
137: * exit here if we detect any IP options.
138: */
139: /* IPv4 only */
1.27 itojun 140: static void
1.40 avsm 141: check_ip_options(int sock, char *ipaddr)
1.20 markus 142: {
1.22 markus 143: u_char options[200];
144: char text[sizeof(options) * 3 + 1];
1.20 markus 145: socklen_t option_size;
1.44 djm 146: u_int i;
147: int ipproto;
1.20 markus 148: struct protoent *ip;
149:
150: if ((ip = getprotobyname("ip")) != NULL)
151: ipproto = ip->p_proto;
152: else
153: ipproto = IPPROTO_IP;
154: option_size = sizeof(options);
1.40 avsm 155: if (getsockopt(sock, ipproto, IP_OPTIONS, options,
1.20 markus 156: &option_size) >= 0 && option_size != 0) {
1.22 markus 157: text[0] = '\0';
158: for (i = 0; i < option_size; i++)
159: snprintf(text + i*3, sizeof(text) - i*3,
160: " %2.2x", options[i]);
1.46 dtucker 161: fatal("Connection from %.100s with IP options:%.800s",
1.20 markus 162: ipaddr, text);
1.6 markus 163: }
1.1 deraadt 164: }
165:
1.8 markus 166: /*
167: * Return the canonical name of the host in the other side of the current
168: * connection. The host name is cached, so it is efficient to call this
169: * several times.
170: */
1.1 deraadt 171:
1.6 markus 172: const char *
1.37 markus 173: get_canonical_hostname(int use_dns)
1.1 deraadt 174: {
1.47 dtucker 175: char *host;
1.10 markus 176: static char *canonical_host_name = NULL;
1.47 dtucker 177: static char *remote_ip = NULL;
1.10 markus 178:
1.20 markus 179: /* Check if we have previously retrieved name with same option. */
1.47 dtucker 180: if (use_dns && canonical_host_name != NULL)
181: return canonical_host_name;
182: if (!use_dns && remote_ip != NULL)
183: return remote_ip;
1.6 markus 184:
185: /* Get the real hostname if socket; otherwise return UNKNOWN. */
1.10 markus 186: if (packet_connection_is_on_socket())
1.47 dtucker 187: host = get_remote_hostname(packet_get_connection_in(), use_dns);
1.6 markus 188: else
1.47 dtucker 189: host = "UNKNOWN";
1.1 deraadt 190:
1.47 dtucker 191: if (use_dns)
192: canonical_host_name = host;
193: else
194: remote_ip = host;
195: return host;
1.1 deraadt 196: }
197:
1.8 markus 198: /*
1.35 stevesk 199: * Returns the local/remote IP-address/hostname of socket as a string.
200: * The returned string must be freed.
1.8 markus 201: */
1.27 itojun 202: static char *
1.40 avsm 203: get_socket_address(int sock, int remote, int flags)
1.1 deraadt 204: {
1.25 markus 205: struct sockaddr_storage addr;
206: socklen_t addrlen;
1.10 markus 207: char ntop[NI_MAXHOST];
1.42 djm 208: int r;
1.1 deraadt 209:
1.6 markus 210: /* Get IP address of client. */
1.25 markus 211: addrlen = sizeof(addr);
212: memset(&addr, 0, sizeof(addr));
213:
214: if (remote) {
1.40 avsm 215: if (getpeername(sock, (struct sockaddr *)&addr, &addrlen)
1.34 stevesk 216: < 0)
1.25 markus 217: return NULL;
218: } else {
1.40 avsm 219: if (getsockname(sock, (struct sockaddr *)&addr, &addrlen)
1.34 stevesk 220: < 0)
1.25 markus 221: return NULL;
222: }
223: /* Get the address in ascii. */
1.42 djm 224: if ((r = getnameinfo((struct sockaddr *)&addr, addrlen, ntop,
225: sizeof(ntop), NULL, 0, flags)) != 0) {
226: error("get_socket_address: getnameinfo %d failed: %s", flags,
227: r == EAI_SYSTEM ? strerror(errno) : gai_strerror(r));
1.19 markus 228: return NULL;
229: }
230: return xstrdup(ntop);
1.25 markus 231: }
232:
233: char *
1.40 avsm 234: get_peer_ipaddr(int sock)
1.25 markus 235: {
1.34 stevesk 236: char *p;
237:
1.40 avsm 238: if ((p = get_socket_address(sock, 1, NI_NUMERICHOST)) != NULL)
1.34 stevesk 239: return p;
240: return xstrdup("UNKNOWN");
1.25 markus 241: }
242:
243: char *
1.40 avsm 244: get_local_ipaddr(int sock)
1.25 markus 245: {
1.34 stevesk 246: char *p;
247:
1.40 avsm 248: if ((p = get_socket_address(sock, 0, NI_NUMERICHOST)) != NULL)
1.34 stevesk 249: return p;
250: return xstrdup("UNKNOWN");
1.25 markus 251: }
252:
253: char *
1.40 avsm 254: get_local_name(int sock)
1.25 markus 255: {
1.40 avsm 256: return get_socket_address(sock, 0, NI_NAMEREQD);
1.19 markus 257: }
258:
259: /*
260: * Returns the IP-address of the remote host as a string. The returned
261: * string must not be freed.
262: */
1.10 markus 263:
1.19 markus 264: const char *
1.28 itojun 265: get_remote_ipaddr(void)
1.19 markus 266: {
267: static char *canonical_host_ip = NULL;
1.1 deraadt 268:
1.19 markus 269: /* Check whether we have cached the ipaddr. */
270: if (canonical_host_ip == NULL) {
271: if (packet_connection_is_on_socket()) {
272: canonical_host_ip =
273: get_peer_ipaddr(packet_get_connection_in());
274: if (canonical_host_ip == NULL)
1.38 markus 275: cleanup_exit(255);
1.19 markus 276: } else {
277: /* If not on socket, return UNKNOWN. */
278: canonical_host_ip = xstrdup("UNKNOWN");
279: }
280: }
1.6 markus 281: return canonical_host_ip;
1.24 stevesk 282: }
283:
284: const char *
1.37 markus 285: get_remote_name_or_ip(u_int utmp_len, int use_dns)
1.24 stevesk 286: {
287: static const char *remote = "";
288: if (utmp_len > 0)
1.37 markus 289: remote = get_canonical_hostname(use_dns);
1.24 stevesk 290: if (utmp_len == 0 || strlen(remote) > utmp_len)
291: remote = get_remote_ipaddr();
292: return remote;
1.1 deraadt 293: }
294:
1.10 markus 295: /* Returns the local/remote port for the socket. */
1.1 deraadt 296:
1.27 itojun 297: static int
1.10 markus 298: get_sock_port(int sock, int local)
1.1 deraadt 299: {
1.10 markus 300: struct sockaddr_storage from;
301: socklen_t fromlen;
302: char strport[NI_MAXSERV];
1.42 djm 303: int r;
1.1 deraadt 304:
1.6 markus 305: /* Get IP address of client. */
306: fromlen = sizeof(from);
307: memset(&from, 0, sizeof(from));
1.10 markus 308: if (local) {
309: if (getsockname(sock, (struct sockaddr *)&from, &fromlen) < 0) {
310: error("getsockname failed: %.100s", strerror(errno));
311: return 0;
312: }
313: } else {
1.35 stevesk 314: if (getpeername(sock, (struct sockaddr *)&from, &fromlen) < 0) {
1.10 markus 315: debug("getpeername failed: %.100s", strerror(errno));
1.43 markus 316: return -1;
1.10 markus 317: }
1.6 markus 318: }
319: /* Return port number. */
1.42 djm 320: if ((r = getnameinfo((struct sockaddr *)&from, fromlen, NULL, 0,
321: strport, sizeof(strport), NI_NUMERICSERV)) != 0)
322: fatal("get_sock_port: getnameinfo NI_NUMERICSERV failed: %s",
323: r == EAI_SYSTEM ? strerror(errno) : gai_strerror(r));
1.10 markus 324: return atoi(strport);
1.1 deraadt 325: }
326:
1.10 markus 327: /* Returns remote/local port number for the current connection. */
1.1 deraadt 328:
1.27 itojun 329: static int
1.10 markus 330: get_port(int local)
1.1 deraadt 331: {
1.8 markus 332: /*
333: * If the connection is not a socket, return 65535. This is
334: * intentionally chosen to be an unprivileged port number.
335: */
1.10 markus 336: if (!packet_connection_is_on_socket())
1.6 markus 337: return 65535;
1.1 deraadt 338:
1.10 markus 339: /* Get socket and return the port number. */
340: return get_sock_port(packet_get_connection_in(), local);
341: }
342:
1.12 markus 343: int
1.10 markus 344: get_peer_port(int sock)
345: {
346: return get_sock_port(sock, 0);
347: }
348:
1.12 markus 349: int
1.28 itojun 350: get_remote_port(void)
1.10 markus 351: {
1.41 djm 352: static int port = -1;
353:
354: /* Cache to avoid getpeername() on a dead connection */
355: if (port == -1)
356: port = get_port(0);
357:
358: return port;
1.10 markus 359: }
1.1 deraadt 360:
1.10 markus 361: int
1.28 itojun 362: get_local_port(void)
1.10 markus 363: {
364: return get_port(1);
1.1 deraadt 365: }
![[BACK]](/icons/back.gif){kind=icon}
Return to canohost.c CVS log ![[TXT]](/icons/text.gif){kind=icon}
![[DIR]](/icons/dir.gif){kind=icon}
Up to [local] / src / usr.bin / ssh