Annotation of src/usr.bin/ssh/hostfile.c, Revision 1.26.2.2
1.1 deraadt 1: /*
1.8 deraadt 2: * Author: Tatu Ylonen <ylo@cs.hut.fi>
3: * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
4: * All rights reserved
5: * Functions for manipulating the known hosts files.
1.16 markus 6: *
1.20 deraadt 7: * As far as I am concerned, the code I have written for this software
8: * can be used freely for any purpose. Any derived versions of this
9: * software must be clearly marked as such, and if the derived work is
10: * incompatible with the protocol description in the RFC file, it must be
11: * called by a name other than "ssh" or "Secure Shell".
12: *
13: *
1.26.2.1 jason 14: * Copyright (c) 1999, 2000 Markus Friedl. All rights reserved.
1.20 deraadt 15: * Copyright (c) 1999 Niels Provos. All rights reserved.
16: *
17: * Redistribution and use in source and binary forms, with or without
18: * modification, are permitted provided that the following conditions
19: * are met:
20: * 1. Redistributions of source code must retain the above copyright
21: * notice, this list of conditions and the following disclaimer.
22: * 2. Redistributions in binary form must reproduce the above copyright
23: * notice, this list of conditions and the following disclaimer in the
24: * documentation and/or other materials provided with the distribution.
25: *
26: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
27: * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
28: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
29: * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
30: * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
31: * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
32: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
33: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
34: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
35: * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
1.8 deraadt 36: */
1.1 deraadt 37:
38: #include "includes.h"
1.26.2.2! miod 39: RCSID("$OpenBSD: hostfile.c,v 1.29 2001/12/18 10:04:21 jakob Exp $");
1.1 deraadt 40:
41: #include "packet.h"
1.14 markus 42: #include "match.h"
43: #include "key.h"
44: #include "hostfile.h"
1.24 markus 45: #include "log.h"
1.1 deraadt 46:
1.9 markus 47: /*
1.14 markus 48: * Parses an RSA (number of bits, e, n) or DSA key from a string. Moves the
49: * pointer over the key. Skips any whitespace at the beginning and at end.
1.9 markus 50: */
1.1 deraadt 51:
1.26.2.2! miod 52: int
1.22 markus 53: hostfile_read_key(char **cpp, u_int *bitsp, Key *ret)
1.1 deraadt 54: {
1.7 markus 55: char *cp;
56:
57: /* Skip leading whitespace. */
1.9 markus 58: for (cp = *cpp; *cp == ' ' || *cp == '\t'; cp++)
59: ;
1.1 deraadt 60:
1.21 markus 61: if (key_read(ret, &cp) != 1)
1.7 markus 62: return 0;
63:
64: /* Skip trailing whitespace. */
1.9 markus 65: for (; *cp == ' ' || *cp == '\t'; cp++)
66: ;
1.7 markus 67:
68: /* Return results. */
69: *cpp = cp;
1.21 markus 70: *bitsp = key_size(ret);
1.7 markus 71: return 1;
1.14 markus 72: }
1.1 deraadt 73:
1.26.2.1 jason 74: static int
1.14 markus 75: hostfile_check_key(int bits, Key *key, const char *host, const char *filename, int linenum)
1.1 deraadt 76: {
1.21 markus 77: if (key == NULL || key->type != KEY_RSA1 || key->rsa == NULL)
1.14 markus 78: return 1;
79: if (bits != BN_num_bits(key->rsa->n)) {
1.18 markus 80: log("Warning: %s, line %d: keysize mismatch for host %s: "
1.14 markus 81: "actual %d vs. announced %d.",
82: filename, linenum, host, BN_num_bits(key->rsa->n), bits);
1.18 markus 83: log("Warning: replace %d with %d in %s, line %d.",
1.14 markus 84: bits, BN_num_bits(key->rsa->n), filename, linenum);
1.1 deraadt 85: }
1.14 markus 86: return 1;
1.1 deraadt 87: }
88:
1.9 markus 89: /*
90: * Checks whether the given host (which must be in all lowercase) is already
91: * in the list of our known hosts. Returns HOST_OK if the host is known and
92: * has the specified key, HOST_NEW if the host is not known, and HOST_CHANGED
93: * if the host is known but used to have a different host key.
94: */
1.1 deraadt 95:
1.2 provos 96: HostStatus
1.23 markus 97: check_host_in_hostfile(const char *filename, const char *host, Key *key,
98: Key *found, int *numret)
1.1 deraadt 99: {
1.7 markus 100: FILE *f;
101: char line[8192];
102: int linenum = 0;
1.25 stevesk 103: u_int kbits;
1.7 markus 104: char *cp, *cp2;
105: HostStatus end_return;
106:
1.26 markus 107: debug3("check_host_in_hostfile: filename %s", filename);
1.14 markus 108: if (key == NULL)
109: fatal("no key to look up");
1.7 markus 110: /* Open the file containing the list of known hosts. */
111: f = fopen(filename, "r");
112: if (!f)
113: return HOST_NEW;
114:
1.9 markus 115: /*
116: * Return value when the loop terminates. This is set to
117: * HOST_CHANGED if we have seen a different key for the host and have
118: * not found the proper one.
119: */
1.7 markus 120: end_return = HOST_NEW;
121:
1.25 stevesk 122: /* Go through the file. */
1.7 markus 123: while (fgets(line, sizeof(line), f)) {
124: cp = line;
125: linenum++;
126:
1.9 markus 127: /* Skip any leading whitespace, comments and empty lines. */
128: for (; *cp == ' ' || *cp == '\t'; cp++)
129: ;
1.7 markus 130: if (!*cp || *cp == '#' || *cp == '\n')
131: continue;
132:
133: /* Find the end of the host name portion. */
1.9 markus 134: for (cp2 = cp; *cp2 && *cp2 != ' ' && *cp2 != '\t'; cp2++)
135: ;
1.7 markus 136:
137: /* Check if the host name matches. */
1.22 markus 138: if (match_hostname(host, cp, (u_int) (cp2 - cp)) != 1)
1.7 markus 139: continue;
140:
141: /* Got a match. Skip host name. */
142: cp = cp2;
143:
1.9 markus 144: /*
145: * Extract the key from the line. This will skip any leading
146: * whitespace. Ignore badly formatted lines.
147: */
1.14 markus 148: if (!hostfile_read_key(&cp, &kbits, found))
149: continue;
150: if (!hostfile_check_key(kbits, found, host, filename, linenum))
1.7 markus 151: continue;
1.23 markus 152:
153: if (numret != NULL)
154: *numret = linenum;
1.7 markus 155:
156: /* Check if the current key is the same as the given key. */
1.14 markus 157: if (key_equal(key, found)) {
1.7 markus 158: /* Ok, they match. */
1.26 markus 159: debug3("check_host_in_hostfile: match line %d", linenum);
1.7 markus 160: fclose(f);
161: return HOST_OK;
162: }
1.9 markus 163: /*
164: * They do not match. We will continue to go through the
165: * file; however, we note that we will not return that it is
166: * new.
167: */
1.7 markus 168: end_return = HOST_CHANGED;
1.1 deraadt 169: }
1.7 markus 170: /* Clear variables and close the file. */
171: fclose(f);
172:
1.9 markus 173: /*
174: * Return either HOST_NEW or HOST_CHANGED, depending on whether we
175: * saw a different key for the host.
176: */
1.7 markus 177: return end_return;
1.1 deraadt 178: }
179:
1.9 markus 180: /*
181: * Appends an entry to the host file. Returns false if the entry could not
182: * be appended.
183: */
1.1 deraadt 184:
1.2 provos 185: int
1.14 markus 186: add_host_to_hostfile(const char *filename, const char *host, Key *key)
1.1 deraadt 187: {
1.7 markus 188: FILE *f;
1.14 markus 189: int success = 0;
190: if (key == NULL)
1.17 markus 191: return 1; /* XXX ? */
1.7 markus 192: f = fopen(filename, "a");
193: if (!f)
194: return 0;
1.14 markus 195: fprintf(f, "%s ", host);
196: if (key_write(key, f)) {
197: success = 1;
198: } else {
1.17 markus 199: error("add_host_to_hostfile: saving key in %s failed", filename);
1.7 markus 200: }
1.17 markus 201: fprintf(f, "\n");
1.7 markus 202: fclose(f);
1.14 markus 203: return success;
1.1 deraadt 204: }
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