/ncat/http_digest.c
C | 428 lines | 222 code | 53 blank | 153 comment | 69 complexity | 6206cede8e2615225cad5a11dcf6c87c MD5 | raw file
Possible License(s): BSD-3-Clause, GPL-2.0, LGPL-2.0, LGPL-2.1
- /***************************************************************************
- * ncat_digest.c -- HTTP Digest authentication handling. *
- ***********************IMPORTANT NMAP LICENSE TERMS************************
- * *
- * The Nmap Security Scanner is (C) 1996-2013 Insecure.Com LLC. Nmap is *
- * also a registered trademark of Insecure.Com LLC. This program is free *
- * software; you may redistribute and/or modify it under the terms of the *
- * GNU General Public License as published by the Free Software *
- * Foundation; Version 2 ("GPL"), BUT ONLY WITH ALL OF THE CLARIFICATIONS *
- * AND EXCEPTIONS DESCRIBED HEREIN. This guarantees your right to use, *
- * modify, and redistribute this software under certain conditions. If *
- * you wish to embed Nmap technology into proprietary software, we sell *
- * alternative licenses (contact sales@nmap.com). Dozens of software *
- * vendors already license Nmap technology such as host discovery, port *
- * scanning, OS detection, version detection, and the Nmap Scripting *
- * Engine. *
- * *
- * Note that the GPL places important restrictions on "derivative works", *
- * yet it does not provide a detailed definition of that term. To avoid *
- * misunderstandings, we interpret that term as broadly as copyright law *
- * allows. For example, we consider an application to constitute a *
- * derivative work for the purpose of this license if it does any of the *
- * following with any software or content covered by this license *
- * ("Covered Software"): *
- * *
- * o Integrates source code from Covered Software. *
- * *
- * o Reads or includes copyrighted data files, such as Nmap's nmap-os-db *
- * or nmap-service-probes. *
- * *
- * o Is designed specifically to execute Covered Software and parse the *
- * results (as opposed to typical shell or execution-menu apps, which will *
- * execute anything you tell them to). *
- * *
- * o Includes Covered Software in a proprietary executable installer. The *
- * installers produced by InstallShield are an example of this. Including *
- * Nmap with other software in compressed or archival form does not *
- * trigger this provision, provided appropriate open source decompression *
- * or de-archiving software is widely available for no charge. For the *
- * purposes of this license, an installer is considered to include Covered *
- * Software even if it actually retrieves a copy of Covered Software from *
- * another source during runtime (such as by downloading it from the *
- * Internet). *
- * *
- * o Links (statically or dynamically) to a library which does any of the *
- * above. *
- * *
- * o Executes a helper program, module, or script to do any of the above. *
- * *
- * This list is not exclusive, but is meant to clarify our interpretation *
- * of derived works with some common examples. Other people may interpret *
- * the plain GPL differently, so we consider this a special exception to *
- * the GPL that we apply to Covered Software. Works which meet any of *
- * these conditions must conform to all of the terms of this license, *
- * particularly including the GPL Section 3 requirements of providing *
- * source code and allowing free redistribution of the work as a whole. *
- * *
- * As another special exception to the GPL terms, Insecure.Com LLC grants *
- * permission to link the code of this program with any version of the *
- * OpenSSL library which is distributed under a license identical to that *
- * listed in the included docs/licenses/OpenSSL.txt file, and distribute *
- * linked combinations including the two. *
- * *
- * Any redistribution of Covered Software, including any derived works, *
- * must obey and carry forward all of the terms of this license, including *
- * obeying all GPL rules and restrictions. For example, source code of *
- * the whole work must be provided and free redistribution must be *
- * allowed. All GPL references to "this License", are to be treated as *
- * including the terms and conditions of this license text as well. *
- * *
- * Because this license imposes special exceptions to the GPL, Covered *
- * Work may not be combined (even as part of a larger work) with plain GPL *
- * software. The terms, conditions, and exceptions of this license must *
- * be included as well. This license is incompatible with some other open *
- * source licenses as well. In some cases we can relicense portions of *
- * Nmap or grant special permissions to use it in other open source *
- * software. Please contact fyodor@nmap.org with any such requests. *
- * Similarly, we don't incorporate incompatible open source software into *
- * Covered Software without special permission from the copyright holders. *
- * *
- * If you have any questions about the licensing restrictions on using *
- * Nmap in other works, are happy to help. As mentioned above, we also *
- * offer alternative license to integrate Nmap into proprietary *
- * applications and appliances. These contracts have been sold to dozens *
- * of software vendors, and generally include a perpetual license as well *
- * as providing for priority support and updates. They also fund the *
- * continued development of Nmap. Please email sales@nmap.com for further *
- * information. *
- * *
- * If you have received a written license agreement or contract for *
- * Covered Software stating terms other than these, you may choose to use *
- * and redistribute Covered Software under those terms instead of these. *
- * *
- * Source is provided to this software because we believe users have a *
- * right to know exactly what a program is going to do before they run it. *
- * This also allows you to audit the software for security holes (none *
- * have been found so far). *
- * *
- * Source code also allows you to port Nmap to new platforms, fix bugs, *
- * and add new features. You are highly encouraged to send your changes *
- * to the dev@nmap.org mailing list for possible incorporation into the *
- * main distribution. By sending these changes to Fyodor or one of the *
- * Insecure.Org development mailing lists, or checking them into the Nmap *
- * source code repository, it is understood (unless you specify otherwise) *
- * that you are offering the Nmap Project (Insecure.Com LLC) the *
- * unlimited, non-exclusive right to reuse, modify, and relicense the *
- * code. Nmap will always be available Open Source, but this is important *
- * because the inability to relicense code has caused devastating problems *
- * for other Free Software projects (such as KDE and NASM). We also *
- * occasionally relicense the code to third parties as discussed above. *
- * If you wish to specify special license conditions of your *
- * contributions, just say so when you send them. *
- * *
- * This program is distributed in the hope that it will be useful, but *
- * WITHOUT ANY WARRANTY; without even the implied warranty of *
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the Nmap *
- * license file for more details (it's in a COPYING file included with *
- * Nmap, and also available from https://svn.nmap.org/nmap/COPYING *
- * *
- ***************************************************************************/
- /* $Id$ */
- /* Nonces returned by make_nonce have the form
- timestamp-MD5(secret:timestamp)
- using representative values, this may look like
- 1263929285.015273-a8e75fae174fc0e6a5df47bf9900beb6
- Sending a timestamp in the clear allows us to compute how long ago the nonce
- was issued without local state. Including microseconds reduces the chance
- that the same nonce will be issued for two different requests. When a nonce
- is received from a client, the time is extracted and then the nonce is
- recalculated locally to make sure they match. This is similar to the strategy
- recommended in section 3.2.1 of RFC 2617.
- When Ncat does Digest authentication as a client, it only does so to make a
- single CONNECT request to a proxy server. Therefore we don't use a differing
- nc (nonce count) but always the constant 00000001. */
- #include "ncat.h"
- #include "http.h"
- #include <openssl/md5.h>
- #include <openssl/rand.h>
- /* What's a good length for this? I think it exists only to prevent us from
- hashing known plaintext from the server. */
- #define CNONCE_LENGTH 8
- #define SECRET_LENGTH 16
- static unsigned char secret[SECRET_LENGTH];
- static int secret_initialized = 0;
- static int append_quoted_string(char **buf, size_t *size, size_t *offset, const char *s)
- {
- const char *t;
- strbuf_append_str(buf, size, offset, "\"");
- for (;;) {
- t = s;
- while (!((*t >= 0 && *t <= 31) || *t == 127 || *t == '\\'))
- t++;
- strbuf_append(buf, size, offset, s, t - s);
- if (*t == '\0')
- break;
- strbuf_sprintf(buf, size, offset, "\\%c", *t);
- s = t + 1;
- }
- strbuf_append_str(buf, size, offset, "\"");
- return *size;
- }
- /* n is the size of src. dest must have at least n * 2 + 1 allocated bytes. */
- static char *enhex(char *dest, const unsigned char *src, size_t n)
- {
- unsigned int i;
- for (i = 0; i < n; i++)
- Snprintf(dest + i * 2, 3, "%02x", src[i]);
- return dest;
- }
- /* Initialize the server secret used in generating nonces. Return -1 on
- failure. */
- int http_digest_init_secret(void)
- {
- if (!RAND_status())
- return -1;
- if (RAND_bytes(secret, sizeof(secret)) != 1)
- return -1;
- secret_initialized = 1;
- return 0;
- }
- static char *make_nonce(const struct timeval *tv)
- {
- char *buf = NULL;
- size_t size = 0, offset = 0;
- MD5_CTX md5;
- unsigned char hashbuf[MD5_DIGEST_LENGTH];
- char hash_hex[MD5_DIGEST_LENGTH * 2 + 1];
- char time_buf[32];
- /* Crash if someone forgot to call http_digest_init_secret. */
- if (!secret_initialized)
- bye("Server secret not initialized for Digest authentication. Call http_digest_init_secret.");
- Snprintf(time_buf, sizeof(time_buf), "%lu.%06lu",
- (long unsigned) tv->tv_sec, (long unsigned) tv->tv_usec);
- MD5_Init(&md5);
- MD5_Update(&md5, secret, sizeof(secret));
- MD5_Update(&md5, ":", 1);
- MD5_Update(&md5, time_buf, strlen(time_buf));
- MD5_Final(hashbuf, &md5);
- enhex(hash_hex, hashbuf, sizeof(hashbuf));
- strbuf_sprintf(&buf, &size, &offset, "%s-%s", time_buf, hash_hex);
- return buf;
- }
- /* Arguments are assumed to be non-NULL, with the exception of nc and cnonce,
- which may be garbage only if qop == QOP_NONE. */
- static void make_response(char buf[MD5_DIGEST_LENGTH * 2 + 1],
- const char *username, const char *realm, const char *password,
- const char *method, const char *uri, const char *nonce,
- enum http_digest_qop qop, const char *nc, const char *cnonce)
- {
- char HA1_hex[MD5_DIGEST_LENGTH * 2 + 1], HA2_hex[MD5_DIGEST_LENGTH * 2 + 1];
- unsigned char hashbuf[MD5_DIGEST_LENGTH];
- MD5_CTX md5;
- /* Calculate H(A1). */
- MD5_Init(&md5);
- MD5_Update(&md5, username, strlen(username));
- MD5_Update(&md5, ":", 1);
- MD5_Update(&md5, realm, strlen(realm));
- MD5_Update(&md5, ":", 1);
- MD5_Update(&md5, password, strlen(password));
- MD5_Final(hashbuf, &md5);
- enhex(HA1_hex, hashbuf, sizeof(hashbuf));
- /* Calculate H(A2). */
- MD5_Init(&md5);
- MD5_Update(&md5, method, strlen(method));
- MD5_Update(&md5, ":", 1);
- MD5_Update(&md5, uri, strlen(uri));
- MD5_Final(hashbuf, &md5);
- enhex(HA2_hex, hashbuf, sizeof(hashbuf));
- /* Calculate response. */
- MD5_Init(&md5);
- MD5_Update(&md5, HA1_hex, strlen(HA1_hex));
- MD5_Update(&md5, ":", 1);
- MD5_Update(&md5, nonce, strlen(nonce));
- if (qop == QOP_AUTH) {
- MD5_Update(&md5, ":", 1);
- MD5_Update(&md5, nc, strlen(nc));
- MD5_Update(&md5, ":", 1);
- MD5_Update(&md5, cnonce, strlen(cnonce));
- MD5_Update(&md5, ":", 1);
- MD5_Update(&md5, "auth", strlen("auth"));
- }
- MD5_Update(&md5, ":", 1);
- MD5_Update(&md5, HA2_hex, strlen(HA2_hex));
- MD5_Final(hashbuf, &md5);
- enhex(buf, hashbuf, sizeof(hashbuf));
- }
- /* Extract the issuance time from a nonce (without checking other aspects of
- validity. If the time can't be extracted, returns -1, 0 otherwise. */
- int http_digest_nonce_time(const char *nonce, struct timeval *tv)
- {
- unsigned long sec, usec;
- if (sscanf(nonce, "%lu.%lu", &sec, &usec) != 2)
- return -1;
- tv->tv_sec = sec;
- tv->tv_usec = usec;
- return 0;
- }
- char *http_digest_proxy_authenticate(const char *realm, int stale)
- {
- char *buf = NULL;
- size_t size = 0, offset = 0;
- struct timeval tv;
- char *nonce;
- if (gettimeofday(&tv, NULL) == -1)
- return NULL;
- strbuf_append_str(&buf, &size, &offset, "Digest realm=");
- append_quoted_string(&buf, &size, &offset, realm);
- nonce = make_nonce(&tv);
- strbuf_append_str(&buf, &size, &offset, ", nonce=");
- append_quoted_string(&buf, &size, &offset, nonce);
- free(nonce);
- strbuf_append_str(&buf, &size, &offset, ", qop=\"auth\"");
- if (stale)
- strbuf_append_str(&buf, &size, &offset, ", stale=true");
- return buf;
- }
- char *http_digest_proxy_authorization(const struct http_challenge *challenge,
- const char *username, const char *password,
- const char *method, const char *uri)
- {
- /* For now we authenticate successfully at most once, so we don't need a
- varying client nonce count. */
- static const u32 nc = 0x00000001;
- char response_hex[MD5_DIGEST_LENGTH * 2 + 1];
- unsigned char cnonce[CNONCE_LENGTH];
- char cnonce_buf[CNONCE_LENGTH * 2 + 1];
- char nc_buf[8 + 1];
- char *buf = NULL;
- size_t size = 0, offset = 0;
- enum http_digest_qop qop;
- if (challenge->scheme != AUTH_DIGEST || challenge->realm == NULL
- || challenge->digest.nonce == NULL
- || challenge->digest.algorithm != ALGORITHM_MD5)
- return NULL;
- if (challenge->digest.qop & QOP_AUTH) {
- Snprintf(nc_buf, sizeof(nc_buf), "%08x", nc);
- if (!RAND_status())
- return NULL;
- if (RAND_bytes(cnonce, sizeof(cnonce)) != 1)
- return NULL;
- enhex(cnonce_buf, cnonce, sizeof(cnonce));
- qop = QOP_AUTH;
- } else {
- qop = QOP_NONE;
- }
- strbuf_append_str(&buf, &size, &offset, " Digest");
- strbuf_append_str(&buf, &size, &offset, " username=");
- append_quoted_string(&buf, &size, &offset, username);
- strbuf_append_str(&buf, &size, &offset, ", realm=");
- append_quoted_string(&buf, &size, &offset, challenge->realm);
- strbuf_append_str(&buf, &size, &offset, ", nonce=");
- append_quoted_string(&buf, &size, &offset, challenge->digest.nonce);
- strbuf_append_str(&buf, &size, &offset, ", uri=");
- append_quoted_string(&buf, &size, &offset, uri);
- if (qop == QOP_AUTH) {
- strbuf_append_str(&buf, &size, &offset, ", qop=auth");
- strbuf_append_str(&buf, &size, &offset, ", cnonce=");
- append_quoted_string(&buf, &size, &offset, cnonce_buf);
- strbuf_sprintf(&buf, &size, &offset, ", nc=%s", nc_buf);
- }
- make_response(response_hex, username, challenge->realm, password,
- method, uri, challenge->digest.nonce, qop, nc_buf, cnonce_buf);
- strbuf_append_str(&buf, &size, &offset, ", response=");
- append_quoted_string(&buf, &size, &offset, response_hex);
- if (challenge->digest.opaque != NULL) {
- strbuf_append_str(&buf, &size, &offset, ", opaque=");
- append_quoted_string(&buf, &size, &offset, challenge->digest.opaque);
- }
- strbuf_append_str(&buf, &size, &offset, "\r\n");
- return buf;
- }
- /* Check that a nonce is one that we issued, and that the response is what is
- expected. This doesn't do any checking aginst the lifetime of the nonce. */
- int http_digest_check_credentials(const char *username, const char *realm,
- const char *password, const char *method,
- const struct http_credentials *credentials)
- {
- char response_hex[MD5_DIGEST_LENGTH * 2 + 1];
- struct timeval tv;
- char *nonce;
- if (credentials->scheme != AUTH_DIGEST
- || credentials->u.digest.username == NULL
- || credentials->u.digest.realm == NULL
- || credentials->u.digest.nonce == NULL
- || credentials->u.digest.uri == NULL
- || credentials->u.digest.response == NULL) {
- return 0;
- }
- if (credentials->u.digest.qop != QOP_NONE && credentials->u.digest.qop != QOP_AUTH)
- return 0;
- if (credentials->u.digest.qop == QOP_AUTH
- && (credentials->u.digest.nc == NULL
- || credentials->u.digest.cnonce == NULL)) {
- return 0;
- }
- if (strcmp(username, credentials->u.digest.username) != 0)
- return 0;
- if (strcmp(realm, credentials->u.digest.realm) != 0)
- return 0;
- if (http_digest_nonce_time(credentials->u.digest.nonce, &tv) == -1)
- return 0;
- nonce = make_nonce(&tv);
- if (strcmp(nonce, credentials->u.digest.nonce) != 0) {
- /* We could not have handed out this nonce. */
- free(nonce);
- return 0;
- }
- free(nonce);
- make_response(response_hex, credentials->u.digest.username, realm,
- password, method, credentials->u.digest.uri,
- credentials->u.digest.nonce, credentials->u.digest.qop,
- credentials->u.digest.nc, credentials->u.digest.cnonce);
- return strcmp(response_hex, credentials->u.digest.response) == 0;
- }