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Commit	Line	Data
	1	/*
	2	*
	3	* hostfile.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: Thu Jun 29 07:10:56 1995 ylo
	11	*
	12	* Functions for manipulating the known hosts files.
	13	*
	14	*/
	15
	16	#include "includes.h"
	17	RCSID("$OpenBSD: hostfile.c,v 1.19 2000/06/06 19:32:13 markus Exp $");
	18
	19	#include "packet.h"
	20	#include "match.h"
	21	#include "ssh.h"
	22	#include <openssl/rsa.h>
	23	#include <openssl/dsa.h>
	24	#include "key.h"
	25	#include "hostfile.h"
	26
	27	/*
	28	* Parses an RSA (number of bits, e, n) or DSA key from a string. Moves the
	29	* pointer over the key. Skips any whitespace at the beginning and at end.
	30	*/
	31
	32	int
	33	hostfile_read_key(char *cpp, unsigned int bitsp, Key *ret)
	34	{
	35	unsigned int bits;
	36	char *cp;
	37
	38	/* Skip leading whitespace. */
	39	for (cp = cpp; cp == ' ' \|\| *cp == '\t'; cp++)
	40	;
	41
	42	bits = key_read(ret, &cp);
	43	if (bits == 0)
	44	return 0;
	45
	46	/* Skip trailing whitespace. */
	47	for (; cp == ' ' \|\| cp == '\t'; cp++)
	48	;
	49
	50	/* Return results. */
	51	*cpp = cp;
	52	*bitsp = bits;
	53	return 1;
	54	}
	55
	56	int
	57	auth_rsa_read_key(char *cpp, unsigned int bitsp, BIGNUM * e, BIGNUM * n)
	58	{
	59	Key *k = key_new(KEY_RSA);
	60	int ret = hostfile_read_key(cpp, bitsp, k);
	61	BN_copy(e, k->rsa->e);
	62	BN_copy(n, k->rsa->n);
	63	key_free(k);
	64	return ret;
	65	}
	66
	67	int
	68	hostfile_check_key(int bits, Key key, const char host, const char *filename, int linenum)
	69	{
	70	if (key == NULL \|\| key->type != KEY_RSA \|\| key->rsa == NULL)
	71	return 1;
	72	if (bits != BN_num_bits(key->rsa->n)) {
	73	log("Warning: %s, line %d: keysize mismatch for host %s: "
	74	"actual %d vs. announced %d.",
	75	filename, linenum, host, BN_num_bits(key->rsa->n), bits);
	76	log("Warning: replace %d with %d in %s, line %d.",
	77	bits, BN_num_bits(key->rsa->n), filename, linenum);
	78	}
	79	return 1;
	80	}
	81
	82	/*
	83	* Checks whether the given host (which must be in all lowercase) is already
	84	* in the list of our known hosts. Returns HOST_OK if the host is known and
	85	* has the specified key, HOST_NEW if the host is not known, and HOST_CHANGED
	86	* if the host is known but used to have a different host key.
	87	*/
	88
	89	HostStatus
	90	check_host_in_hostfile(const char filename, const char host, Key key, Key found)
	91	{
	92	FILE *f;
	93	char line[8192];
	94	int linenum = 0;
	95	unsigned int kbits, hostlen;
	96	char cp, cp2;
	97	HostStatus end_return;
	98
	99	if (key == NULL)
	100	fatal("no key to look up");
	101	/* Open the file containing the list of known hosts. */
	102	f = fopen(filename, "r");
	103	if (!f)
	104	return HOST_NEW;
	105
	106	/* Cache the length of the host name. */
	107	hostlen = strlen(host);
	108
	109	/*
	110	* Return value when the loop terminates. This is set to
	111	* HOST_CHANGED if we have seen a different key for the host and have
	112	* not found the proper one.
	113	*/
	114	end_return = HOST_NEW;
	115
	116	/* Go trough the file. */
	117	while (fgets(line, sizeof(line), f)) {
	118	cp = line;
	119	linenum++;
	120
	121	/* Skip any leading whitespace, comments and empty lines. */
	122	for (; cp == ' ' \|\| cp == '\t'; cp++)
	123	;
	124	if (!cp \|\| cp == '#' \|\| *cp == '\n')
	125	continue;
	126
	127	/* Find the end of the host name portion. */
	128	for (cp2 = cp; cp2 && cp2 != ' ' && *cp2 != '\t'; cp2++)
	129	;
	130
	131	/* Check if the host name matches. */
	132	if (match_hostname(host, cp, (unsigned int) (cp2 - cp)) != 1)
	133	continue;
	134
	135	/* Got a match. Skip host name. */
	136	cp = cp2;
	137
	138	/*
	139	* Extract the key from the line. This will skip any leading
	140	* whitespace. Ignore badly formatted lines.
	141	*/
	142	if (!hostfile_read_key(&cp, &kbits, found))
	143	continue;
	144	if (!hostfile_check_key(kbits, found, host, filename, linenum))
	145	continue;
	146
	147	/* Check if the current key is the same as the given key. */
	148	if (key_equal(key, found)) {
	149	/* Ok, they match. */
	150	fclose(f);
	151	return HOST_OK;
	152	}
	153	/*
	154	* They do not match. We will continue to go through the
	155	* file; however, we note that we will not return that it is
	156	* new.
	157	*/
	158	end_return = HOST_CHANGED;
	159	}
	160	/* Clear variables and close the file. */
	161	fclose(f);
	162
	163	/*
	164	* Return either HOST_NEW or HOST_CHANGED, depending on whether we
	165	* saw a different key for the host.
	166	*/
	167	return end_return;
	168	}
	169
	170	/*
	171	* Appends an entry to the host file. Returns false if the entry could not
	172	* be appended.
	173	*/
	174
	175	int
	176	add_host_to_hostfile(const char filename, const char host, Key *key)
	177	{
	178	FILE *f;
	179	int success = 0;
	180	if (key == NULL)
	181	return 1; /* XXX ? */
	182	f = fopen(filename, "a");
	183	if (!f)
	184	return 0;
	185	fprintf(f, "%s ", host);
	186	if (key_write(key, f)) {
	187	success = 1;
	188	} else {
	189	error("add_host_to_hostfile: saving key in %s failed", filename);
	190	}
	191	fprintf(f, "\n");
	192	fclose(f);
	193	return success;
	194	}