mirror of git://anongit.mindrot.org/openssh.git
280 lines
6.9 KiB
C
280 lines
6.9 KiB
C
/*
|
|
|
|
hostfile.c
|
|
|
|
Author: Tatu Ylonen <ylo@cs.hut.fi>
|
|
|
|
Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
|
|
All rights reserved
|
|
|
|
Created: Thu Jun 29 07:10:56 1995 ylo
|
|
|
|
Functions for manipulating the known hosts files.
|
|
|
|
*/
|
|
|
|
#include "includes.h"
|
|
RCSID("$Id: hostfile.c,v 1.1 1999/10/27 03:42:44 damien Exp $");
|
|
|
|
#include "packet.h"
|
|
#include "ssh.h"
|
|
|
|
/* Reads a multiple-precision integer in hex from the buffer, and advances the
|
|
pointer. The integer must already be initialized. This function is
|
|
permitted to modify the buffer. This leaves *cpp to point just beyond
|
|
the last processed (and maybe modified) character. Note that this may
|
|
modify the buffer containing the number. */
|
|
|
|
int
|
|
auth_rsa_read_bignum(char **cpp, BIGNUM *value)
|
|
{
|
|
char *cp = *cpp;
|
|
int len, old;
|
|
|
|
/* Skip any leading whitespace. */
|
|
for (; *cp == ' ' || *cp == '\t'; cp++)
|
|
;
|
|
|
|
/* Check that it begins with a hex digit. */
|
|
if (*cp < '0' || *cp > '9')
|
|
return 0;
|
|
|
|
/* Save starting position. */
|
|
*cpp = cp;
|
|
|
|
/* Move forward until all hex digits skipped. */
|
|
for (; *cp >= '0' && *cp <= '9'; cp++)
|
|
;
|
|
|
|
/* Compute the length of the hex number. */
|
|
len = cp - *cpp;
|
|
|
|
/* Save the old terminating character, and replace it by \0. */
|
|
old = *cp;
|
|
*cp = 0;
|
|
|
|
|
|
/* Parse the number. */
|
|
if (BN_dec2bn(&value, *cpp) == 0)
|
|
return 0;
|
|
|
|
/* Restore old terminating character. */
|
|
*cp = old;
|
|
|
|
/* Move beyond the number and return success. */
|
|
*cpp = cp;
|
|
return 1;
|
|
}
|
|
|
|
/* Parses an RSA key (number of bits, e, n) from a string. Moves the pointer
|
|
over the key. Skips any whitespace at the beginning and at end. */
|
|
|
|
int
|
|
auth_rsa_read_key(char **cpp, unsigned int *bitsp, BIGNUM *e, BIGNUM *n)
|
|
{
|
|
unsigned int bits;
|
|
char *cp;
|
|
|
|
/* Skip leading whitespace. */
|
|
for (cp = *cpp; *cp == ' ' || *cp == '\t'; cp++)
|
|
;
|
|
|
|
/* Get number of bits. */
|
|
if (*cp < '0' || *cp > '9')
|
|
return 0; /* Bad bit count... */
|
|
for (bits = 0; *cp >= '0' && *cp <= '9'; cp++)
|
|
bits = 10 * bits + *cp - '0';
|
|
|
|
/* Get public exponent. */
|
|
if (!auth_rsa_read_bignum(&cp, e))
|
|
return 0;
|
|
|
|
/* Get public modulus. */
|
|
if (!auth_rsa_read_bignum(&cp, n))
|
|
return 0;
|
|
|
|
/* Skip trailing whitespace. */
|
|
for (; *cp == ' ' || *cp == '\t'; cp++)
|
|
;
|
|
|
|
/* Return results. */
|
|
*cpp = cp;
|
|
*bitsp = bits;
|
|
return 1;
|
|
}
|
|
|
|
/* Tries to match the host name (which must be in all lowercase) against the
|
|
comma-separated sequence of subpatterns (each possibly preceded by ! to
|
|
indicate negation). Returns true if there is a positive match; zero
|
|
otherwise. */
|
|
|
|
int
|
|
match_hostname(const char *host, const char *pattern, unsigned int len)
|
|
{
|
|
char sub[1024];
|
|
int negated;
|
|
int got_positive;
|
|
unsigned int i, subi;
|
|
|
|
got_positive = 0;
|
|
for (i = 0; i < len;)
|
|
{
|
|
/* Check if the subpattern is negated. */
|
|
if (pattern[i] == '!')
|
|
{
|
|
negated = 1;
|
|
i++;
|
|
}
|
|
else
|
|
negated = 0;
|
|
|
|
/* Extract the subpattern up to a comma or end. Convert the subpattern
|
|
to lowercase. */
|
|
for (subi = 0;
|
|
i < len && subi < sizeof(sub) - 1 && pattern[i] != ',';
|
|
subi++, i++)
|
|
sub[subi] = isupper(pattern[i]) ? tolower(pattern[i]) : pattern[i];
|
|
/* If subpattern too long, return failure (no match). */
|
|
if (subi >= sizeof(sub) - 1)
|
|
return 0;
|
|
|
|
/* If the subpattern was terminated by a comma, skip the comma. */
|
|
if (i < len && pattern[i] == ',')
|
|
i++;
|
|
|
|
/* Null-terminate the subpattern. */
|
|
sub[subi] = '\0';
|
|
|
|
/* Try to match the subpattern against the host name. */
|
|
if (match_pattern(host, sub)) {
|
|
if (negated)
|
|
return 0; /* Fail if host matches any negated subpattern. */
|
|
else
|
|
got_positive = 1;
|
|
}
|
|
}
|
|
|
|
/* Return success if got a positive match. If there was a negative match,
|
|
we have already returned zero and never get here. */
|
|
return got_positive;
|
|
}
|
|
|
|
/* Checks whether the given host (which must be in all lowercase) is
|
|
already in the list of our known hosts.
|
|
Returns HOST_OK if the host is known and has the specified key,
|
|
HOST_NEW if the host is not known, and HOST_CHANGED if the host is known
|
|
but used to have a different host key. */
|
|
|
|
HostStatus
|
|
check_host_in_hostfile(const char *filename,
|
|
const char *host, unsigned int bits,
|
|
BIGNUM *e, BIGNUM *n,
|
|
BIGNUM *ke, BIGNUM *kn)
|
|
{
|
|
FILE *f;
|
|
char line[8192];
|
|
unsigned int kbits, hostlen;
|
|
char *cp, *cp2;
|
|
HostStatus end_return;
|
|
struct stat st;
|
|
|
|
/* Open the file containing the list of known hosts. */
|
|
f = fopen(filename, "r");
|
|
if (!f)
|
|
{
|
|
if (stat(filename, &st) >= 0)
|
|
{
|
|
packet_send_debug("Could not open %.900s for reading.", filename);
|
|
packet_send_debug("If your home directory is on an NFS volume, it may need to be world-readable.");
|
|
}
|
|
return HOST_NEW;
|
|
}
|
|
|
|
/* Cache the length of the host name. */
|
|
hostlen = strlen(host);
|
|
|
|
/* Return value when the loop terminates. This is set to HOST_CHANGED if
|
|
we have seen a different key for the host and have not found the proper
|
|
one. */
|
|
end_return = HOST_NEW;
|
|
|
|
/* Go trough the file. */
|
|
while (fgets(line, sizeof(line), f))
|
|
{
|
|
cp = line;
|
|
|
|
/* Skip any leading whitespace. */
|
|
for (; *cp == ' ' || *cp == '\t'; cp++)
|
|
;
|
|
|
|
/* Ignore comment lines and empty lines. */
|
|
if (!*cp || *cp == '#' || *cp == '\n')
|
|
continue;
|
|
|
|
/* Find the end of the host name portion. */
|
|
for (cp2 = cp; *cp2 && *cp2 != ' ' && *cp2 != '\t'; cp2++)
|
|
;
|
|
|
|
/* Check if the host name matches. */
|
|
if (!match_hostname(host, cp, (unsigned int)(cp2 - cp)))
|
|
continue;
|
|
|
|
/* Got a match. Skip host name. */
|
|
cp = cp2;
|
|
|
|
/* Extract the key from the line. This will skip any leading
|
|
whitespace. Ignore badly formatted lines. */
|
|
if (!auth_rsa_read_key(&cp, &kbits, ke, kn))
|
|
continue;
|
|
|
|
/* Check if the current key is the same as the previous one. */
|
|
if (kbits == bits && BN_cmp(ke, e) == 0 && BN_cmp(kn, n) == 0)
|
|
{
|
|
/* Ok, they match. */
|
|
fclose(f);
|
|
return HOST_OK;
|
|
}
|
|
|
|
/* They do not match. We will continue to go through the file; however,
|
|
we note that we will not return that it is new. */
|
|
end_return = HOST_CHANGED;
|
|
}
|
|
/* Clear variables and close the file. */
|
|
fclose(f);
|
|
|
|
/* Return either HOST_NEW or HOST_CHANGED, depending on whether we saw a
|
|
different key for the host. */
|
|
return end_return;
|
|
}
|
|
|
|
/* Appends an entry to the host file. Returns false if the entry
|
|
could not be appended. */
|
|
|
|
int
|
|
add_host_to_hostfile(const char *filename, const char *host,
|
|
unsigned int bits, BIGNUM *e, BIGNUM *n)
|
|
{
|
|
FILE *f;
|
|
char *buf;
|
|
|
|
/* Open the file for appending. */
|
|
f = fopen(filename, "a");
|
|
if (!f)
|
|
return 0;
|
|
|
|
/* Print the host name and key to the file. */
|
|
fprintf(f, "%s %u ", host, bits);
|
|
buf = BN_bn2dec(e);
|
|
assert(buf != NULL);
|
|
fprintf(f, "%s ", buf);
|
|
free (buf);
|
|
buf = BN_bn2dec(n);
|
|
assert(buf != NULL);
|
|
fprintf(f, "%s\n", buf);
|
|
free (buf);
|
|
|
|
/* Close the file. */
|
|
fclose(f);
|
|
return 1;
|
|
}
|