Annotation of src/usr.bin/ssh/canohost.c, Revision 1.10
1.1 deraadt 1: /*
1.7 deraadt 2: *
3: * canohost.c
4: *
5: * Author: Tatu Ylonen <ylo@cs.hut.fi>
6: *
7: * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
8: * All rights reserved
9: *
10: * Created: Sun Jul 2 17:52:22 1995 ylo
11: *
12: * Functions for returning the canonical host name of the remote site.
13: *
14: */
1.1 deraadt 15:
16: #include "includes.h"
1.10 ! markus 17: RCSID("$Id: canohost.c,v 1.9 1999/12/09 00:00:52 markus Exp $");
1.1 deraadt 18:
19: #include "packet.h"
20: #include "xmalloc.h"
21: #include "ssh.h"
22:
1.8 markus 23: /*
24: * Return the canonical name of the host at the other end of the socket. The
25: * caller should free the returned string with xfree.
26: */
1.1 deraadt 27:
1.6 markus 28: char *
29: get_remote_hostname(int socket)
1.1 deraadt 30: {
1.10 ! markus 31: struct sockaddr_storage from;
! 32: int i;
! 33: socklen_t fromlen;
! 34: struct addrinfo hints, *ai, *aitop;
1.6 markus 35: char name[MAXHOSTNAMELEN];
1.10 ! markus 36: char ntop[NI_MAXHOST], ntop2[NI_MAXHOST];
1.6 markus 37:
38: /* Get IP address of client. */
39: fromlen = sizeof(from);
40: memset(&from, 0, sizeof(from));
41: if (getpeername(socket, (struct sockaddr *) & from, &fromlen) < 0) {
42: debug("getpeername failed: %.100s", strerror(errno));
43: fatal_cleanup();
44: }
1.10 ! markus 45: if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop),
! 46: NULL, 0, NI_NUMERICHOST) != 0)
! 47: fatal("get_remote_hostname: getnameinfo NI_NUMERICHOST failed");
! 48:
1.6 markus 49: /* Map the IP address to a host name. */
1.10 ! markus 50: if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name),
! 51: NULL, 0, NI_NAMEREQD) == 0) {
! 52: /* Got host name. */
! 53: name[sizeof(name) - 1] = '\0';
1.8 markus 54: /*
55: * Convert it to all lowercase (which is expected by the rest
56: * of this software).
57: */
1.6 markus 58: for (i = 0; name[i]; i++)
59: if (isupper(name[i]))
60: name[i] = tolower(name[i]);
61:
1.8 markus 62: /*
63: * Map it back to an IP address and check that the given
64: * address actually is an address of this host. This is
65: * necessary because anyone with access to a name server can
66: * define arbitrary names for an IP address. Mapping from
67: * name to IP address can be trusted better (but can still be
68: * fooled if the intruder has access to the name server of
69: * the domain).
70: */
1.10 ! markus 71: memset(&hints, 0, sizeof(hints));
! 72: hints.ai_family = from.ss_family;
! 73: if (getaddrinfo(name, NULL, &hints, &aitop) != 0) {
! 74: log("reverse mapping checking getaddrinfo for %.700s failed - POSSIBLE BREAKIN ATTEMPT!", name);
! 75: strlcpy(name, ntop, sizeof name);
1.6 markus 76: goto check_ip_options;
77: }
78: /* Look for the address from the list of addresses. */
1.10 ! markus 79: for (ai = aitop; ai; ai = ai->ai_next) {
! 80: if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2,
! 81: sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 &&
! 82: (strcmp(ntop, ntop2) == 0))
! 83: break;
! 84: }
! 85: freeaddrinfo(aitop);
! 86: /* If we reached the end of the list, the address was not there. */
! 87: if (!ai) {
1.6 markus 88: /* Address not found for the host name. */
89: log("Address %.100s maps to %.600s, but this does not map back to the address - POSSIBLE BREAKIN ATTEMPT!",
1.10 ! markus 90: ntop, name);
! 91: strlcpy(name, ntop, sizeof name);
1.6 markus 92: goto check_ip_options;
93: }
94: /* Address was found for the host name. We accept the host name. */
95: } else {
96: /* Host name not found. Use ascii representation of the address. */
1.10 ! markus 97: strlcpy(name, ntop, sizeof name);
1.6 markus 98: log("Could not reverse map address %.100s.", name);
99: }
100:
101: check_ip_options:
102:
1.8 markus 103: /*
104: * If IP options are supported, make sure there are none (log and
105: * disconnect them if any are found). Basically we are worried about
106: * source routing; it can be used to pretend you are somebody
107: * (ip-address) you are not. That itself may be "almost acceptable"
108: * under certain circumstances, but rhosts autentication is useless
109: * if source routing is accepted. Notice also that if we just dropped
110: * source routing here, the other side could use IP spoofing to do
111: * rest of the interaction and could still bypass security. So we
112: * exit here if we detect any IP options.
113: */
1.10 ! markus 114: /* IP options -- IPv4 only */
! 115: if (from.ss_family == AF_INET) {
1.6 markus 116: unsigned char options[200], *ucp;
117: char text[1024], *cp;
1.10 ! markus 118: socklen_t option_size;
! 119: int ipproto;
1.6 markus 120: struct protoent *ip;
121:
122: if ((ip = getprotobyname("ip")) != NULL)
123: ipproto = ip->p_proto;
124: else
125: ipproto = IPPROTO_IP;
126: option_size = sizeof(options);
127: if (getsockopt(0, ipproto, IP_OPTIONS, (char *) options,
1.10 ! markus 128: &option_size) >= 0 && option_size != 0) {
1.6 markus 129: cp = text;
130: /* Note: "text" buffer must be at least 3x as big as options. */
131: for (ucp = options; option_size > 0; ucp++, option_size--, cp += 3)
132: sprintf(cp, " %2.2x", *ucp);
133: log("Connection from %.100s with IP options:%.800s",
1.10 ! markus 134: ntop, text);
1.6 markus 135: packet_disconnect("Connection from %.100s with IP options:%.800s",
1.10 ! markus 136: ntop, text);
1.6 markus 137: }
138: }
1.1 deraadt 139:
1.6 markus 140: return xstrdup(name);
1.1 deraadt 141: }
142:
1.8 markus 143: /*
144: * Return the canonical name of the host in the other side of the current
145: * connection. The host name is cached, so it is efficient to call this
146: * several times.
147: */
1.1 deraadt 148:
1.6 markus 149: const char *
150: get_canonical_hostname()
1.1 deraadt 151: {
1.10 ! markus 152: static char *canonical_host_name = NULL;
! 153:
1.6 markus 154: /* Check if we have previously retrieved this same name. */
155: if (canonical_host_name != NULL)
156: return canonical_host_name;
157:
158: /* Get the real hostname if socket; otherwise return UNKNOWN. */
1.10 ! markus 159: if (packet_connection_is_on_socket())
1.6 markus 160: canonical_host_name = get_remote_hostname(packet_get_connection_in());
161: else
162: canonical_host_name = xstrdup("UNKNOWN");
1.1 deraadt 163:
1.6 markus 164: return canonical_host_name;
1.1 deraadt 165: }
166:
1.8 markus 167: /*
168: * Returns the IP-address of the remote host as a string. The returned
1.10 ! markus 169: * string must not be freed.
1.8 markus 170: */
1.1 deraadt 171:
1.6 markus 172: const char *
173: get_remote_ipaddr()
1.1 deraadt 174: {
1.10 ! markus 175: static char *canonical_host_ip = NULL;
! 176: struct sockaddr_storage from;
! 177: socklen_t fromlen;
! 178: int socket;
! 179: char ntop[NI_MAXHOST];
1.1 deraadt 180:
1.8 markus 181: /* Check whether we have chached the name. */
1.6 markus 182: if (canonical_host_ip != NULL)
183: return canonical_host_ip;
184:
185: /* If not a socket, return UNKNOWN. */
1.10 ! markus 186: if (!packet_connection_is_on_socket()) {
1.6 markus 187: canonical_host_ip = xstrdup("UNKNOWN");
188: return canonical_host_ip;
189: }
190: /* Get client socket. */
191: socket = packet_get_connection_in();
1.1 deraadt 192:
1.6 markus 193: /* Get IP address of client. */
194: fromlen = sizeof(from);
195: memset(&from, 0, sizeof(from));
196: if (getpeername(socket, (struct sockaddr *) & from, &fromlen) < 0) {
197: debug("getpeername failed: %.100s", strerror(errno));
198: fatal_cleanup();
199: }
200: /* Get the IP address in ascii. */
1.10 ! markus 201: if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop),
! 202: NULL, 0, NI_NUMERICHOST) != 0)
! 203: fatal("get_remote_hostname: getnameinfo NI_NUMERICHOST failed");
! 204:
! 205: canonical_host_ip = xstrdup(ntop);
1.1 deraadt 206:
1.6 markus 207: /* Return ip address string. */
208: return canonical_host_ip;
1.1 deraadt 209: }
210:
1.10 ! markus 211: /* Returns the local/remote port for the socket. */
1.1 deraadt 212:
1.10 ! markus 213: int
! 214: get_sock_port(int sock, int local)
1.1 deraadt 215: {
1.10 ! markus 216: struct sockaddr_storage from;
! 217: socklen_t fromlen;
! 218: char strport[NI_MAXSERV];
1.1 deraadt 219:
1.6 markus 220: /* Get IP address of client. */
221: fromlen = sizeof(from);
222: memset(&from, 0, sizeof(from));
1.10 ! markus 223: if (local) {
! 224: if (getsockname(sock, (struct sockaddr *)&from, &fromlen) < 0) {
! 225: error("getsockname failed: %.100s", strerror(errno));
! 226: return 0;
! 227: }
! 228: } else {
! 229: if (getpeername(sock, (struct sockaddr *) & from, &fromlen) < 0) {
! 230: debug("getpeername failed: %.100s", strerror(errno));
! 231: fatal_cleanup();
! 232: }
1.6 markus 233: }
234: /* Return port number. */
1.10 ! markus 235: if (getnameinfo((struct sockaddr *)&from, fromlen, NULL, 0,
! 236: strport, sizeof(strport), NI_NUMERICSERV) != 0)
! 237: fatal("get_sock_port: getnameinfo NI_NUMERICSERV failed");
! 238: return atoi(strport);
1.1 deraadt 239: }
240:
1.10 ! markus 241: /* Returns remote/local port number for the current connection. */
1.1 deraadt 242:
1.6 markus 243: int
1.10 ! markus 244: get_port(int local)
1.1 deraadt 245: {
1.8 markus 246: /*
247: * If the connection is not a socket, return 65535. This is
248: * intentionally chosen to be an unprivileged port number.
249: */
1.10 ! markus 250: if (!packet_connection_is_on_socket())
1.6 markus 251: return 65535;
1.1 deraadt 252:
1.10 ! markus 253: /* Get socket and return the port number. */
! 254: return get_sock_port(packet_get_connection_in(), local);
! 255: }
! 256:
! 257: int
! 258: get_peer_port(int sock)
! 259: {
! 260: return get_sock_port(sock, 0);
! 261: }
! 262:
! 263: int
! 264: get_remote_port()
! 265: {
! 266: return get_port(0);
! 267: }
1.1 deraadt 268:
1.10 ! markus 269: int
! 270: get_local_port()
! 271: {
! 272: return get_port(1);
1.1 deraadt 273: }
![[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