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author | markm <markm@FreeBSD.org> | 2000-02-24 14:29:47 +0000 |
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committer | markm <markm@FreeBSD.org> | 2000-02-24 14:29:47 +0000 |
commit | fc557ff7d97438559e69347575f5aa8ef03a5f50 (patch) | |
tree | c90ea5392aa03e7619696143bde781f2bf5c0dff /crypto/openssh/hostfile.c | |
download | FreeBSD-src-fc557ff7d97438559e69347575f5aa8ef03a5f50.zip FreeBSD-src-fc557ff7d97438559e69347575f5aa8ef03a5f50.tar.gz |
Vendor import of OpenSSH.
Diffstat (limited to 'crypto/openssh/hostfile.c')
-rw-r--r-- | crypto/openssh/hostfile.c | 300 |
1 files changed, 300 insertions, 0 deletions
diff --git a/crypto/openssh/hostfile.c b/crypto/openssh/hostfile.c new file mode 100644 index 0000000..ea92fa0 --- /dev/null +++ b/crypto/openssh/hostfile.c @@ -0,0 +1,300 @@ +/* + * + * 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("$OpenBSD: hostfile.c,v 1.13 2000/02/18 10:20:20 markus Exp $"); + +#include "packet.h" +#include "ssh.h" + +/* + * Reads a multiple-precision integer in decimal 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 old; + + /* Skip any leading whitespace. */ + for (; *cp == ' ' || *cp == '\t'; cp++) + ; + + /* Check that it begins with a decimal digit. */ + if (*cp < '0' || *cp > '9') + return 0; + + /* Save starting position. */ + *cpp = cp; + + /* Move forward until all decimal digits skipped. */ + for (; *cp >= '0' && *cp <= '9'; cp++) + ; + + /* 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 */ + 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, + BIGNUM * e, BIGNUM * n, BIGNUM * ke, BIGNUM * kn) +{ + FILE *f; + char line[8192]; + int linenum = 0; + unsigned int kbits, hostlen; + char *cp, *cp2; + HostStatus end_return; + + /* Open the file containing the list of known hosts. */ + f = fopen(filename, "r"); + if (!f) + 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; + linenum++; + + /* Skip any leading whitespace, comments and empty lines. */ + for (; *cp == ' ' || *cp == '\t'; cp++) + ; + 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; + + if (kbits != BN_num_bits(kn)) { + error("Warning: %s, line %d: keysize mismatch for host %s: " + "actual %d vs. announced %d.", + filename, linenum, host, BN_num_bits(kn), kbits); + error("Warning: replace %d with %d in %s, line %d.", + kbits, BN_num_bits(kn), filename, linenum); + } + /* Check if the current key is the same as the given key. */ + if (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, + BIGNUM * e, BIGNUM * n) +{ + FILE *f; + char *buf; + unsigned int bits; + + /* Open the file for appending. */ + f = fopen(filename, "a"); + if (!f) + return 0; + + /* size of modulus 'n' */ + bits = BN_num_bits(n); + + /* Print the host name and key to the file. */ + fprintf(f, "%s %u ", host, bits); + buf = BN_bn2dec(e); + if (buf == NULL) { + error("add_host_to_hostfile: BN_bn2dec(e) failed"); + fclose(f); + return 0; + } + fprintf(f, "%s ", buf); + free(buf); + buf = BN_bn2dec(n); + if (buf == NULL) { + error("add_host_to_hostfile: BN_bn2dec(n) failed"); + fclose(f); + return 0; + } + fprintf(f, "%s\n", buf); + free(buf); + + /* Close the file. */ + fclose(f); + return 1; +} |