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      1 /*
      2  * chap-new.c - New CHAP implementation.
      3  *
      4  * Copyright (c) 2003 Paul Mackerras. All rights reserved.
      5  *
      6  * Redistribution and use in source and binary forms, with or without
      7  * modification, are permitted provided that the following conditions
      8  * are met:
      9  *
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  *
     13  * 2. The name(s) of the authors of this software must not be used to
     14  *    endorse or promote products derived from this software without
     15  *    prior written permission.
     16  *
     17  * 3. Redistributions of any form whatsoever must retain the following
     18  *    acknowledgment:
     19  *    "This product includes software developed by Paul Mackerras
     20  *     <paulus (at) samba.org>".
     21  *
     22  * THE AUTHORS OF THIS SOFTWARE DISCLAIM ALL WARRANTIES WITH REGARD TO
     23  * THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
     24  * AND FITNESS, IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
     25  * SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
     26  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
     27  * AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
     28  * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
     29  */
     30 
     31 /*
     32  * CHAP packets begin with a standard header with code, id, len (2 bytes).
     33  */
     34 #define CHAP_HDRLEN	4
     35 
     36 /*
     37  * Values for the code field.
     38  */
     39 #define CHAP_CHALLENGE	1
     40 #define CHAP_RESPONSE	2
     41 #define CHAP_SUCCESS	3
     42 #define CHAP_FAILURE	4
     43 
     44 /*
     45  * CHAP digest codes.
     46  */
     47 #define CHAP_MD5		5
     48 #define CHAP_MICROSOFT		0x80
     49 #define CHAP_MICROSOFT_V2	0x81
     50 
     51 /*
     52  * Semi-arbitrary limits on challenge and response fields.
     53  */
     54 #define MAX_CHALLENGE_LEN	64
     55 #define MAX_RESPONSE_LEN	64
     56 
     57 /* bitmask of supported algorithms */
     58 #define MDTYPE_MICROSOFT_V2	0x1
     59 #define MDTYPE_MICROSOFT	0x2
     60 #define MDTYPE_MD5		0x4
     61 #define MDTYPE_NONE		0
     62 
     63 /* hashes supported by this instance of pppd */
     64 extern int chap_mdtype_all;
     65 
     66 /* Return the digest alg. ID for the most preferred digest type. */
     67 #define CHAP_DIGEST(mdtype) \
     68     ((mdtype) & MDTYPE_MD5)? CHAP_MD5: \
     69     ((mdtype) & MDTYPE_MICROSOFT_V2)? CHAP_MICROSOFT_V2: \
     70     ((mdtype) & MDTYPE_MICROSOFT)? CHAP_MICROSOFT: \
     71     0
     72 
     73 /* Return the bit flag (lsb set) for our most preferred digest type. */
     74 #define CHAP_MDTYPE(mdtype) ((mdtype) ^ ((mdtype) - 1)) & (mdtype)
     75 
     76 /* Return the bit flag for a given digest algorithm ID. */
     77 #define CHAP_MDTYPE_D(digest) \
     78     ((digest) == CHAP_MICROSOFT_V2)? MDTYPE_MICROSOFT_V2: \
     79     ((digest) == CHAP_MICROSOFT)? MDTYPE_MICROSOFT: \
     80     ((digest) == CHAP_MD5)? MDTYPE_MD5: \
     81     0
     82 
     83 /* Can we do the requested digest? */
     84 #define CHAP_CANDIGEST(mdtype, digest) \
     85     ((digest) == CHAP_MICROSOFT_V2)? (mdtype) & MDTYPE_MICROSOFT_V2: \
     86     ((digest) == CHAP_MICROSOFT)? (mdtype) & MDTYPE_MICROSOFT: \
     87     ((digest) == CHAP_MD5)? (mdtype) & MDTYPE_MD5: \
     88     0
     89 
     90 /*
     91  * The code for each digest type has to supply one of these.
     92  */
     93 struct chap_digest_type {
     94 	int code;
     95 
     96 	/*
     97 	 * Note: challenge and response arguments below are formatted as
     98 	 * a length byte followed by the actual challenge/response data.
     99 	 */
    100 	void (*generate_challenge)(unsigned char *challenge);
    101 	int (*verify_response)(int id, char *name,
    102 		unsigned char *secret, int secret_len,
    103 		unsigned char *challenge, unsigned char *response,
    104 		char *message, int message_space);
    105 	void (*make_response)(unsigned char *response, int id, char *our_name,
    106 		unsigned char *challenge, char *secret, int secret_len,
    107 		unsigned char *priv);
    108 	int (*check_success)(unsigned char *pkt, int len, unsigned char *priv);
    109 	void (*handle_failure)(unsigned char *pkt, int len);
    110 
    111 	struct chap_digest_type *next;
    112 };
    113 
    114 /* Hook for a plugin to validate CHAP challenge */
    115 extern int (*chap_verify_hook)(char *name, char *ourname, int id,
    116 			struct chap_digest_type *digest,
    117 			unsigned char *challenge, unsigned char *response,
    118 			char *message, int message_space);
    119 
    120 /* Called by digest code to register a digest type */
    121 extern void chap_register_digest(struct chap_digest_type *);
    122 
    123 /* Called by authentication code to start authenticating the peer. */
    124 extern void chap_auth_peer(int unit, char *our_name, int digest_code);
    125 
    126 /* Called by auth. code to start authenticating us to the peer. */
    127 extern void chap_auth_with_peer(int unit, char *our_name, int digest_code);
    128 
    129 /* Represents the CHAP protocol to the main pppd code */
    130 extern struct protent chap_protent;
    131