2 * PDKIM - a RFC4871 (DKIM) implementation
4 * Copyright (C) 2009 - 2012 Tom Kistner <tom@duncanthrax.net>
5 * Copyright (c) Jeremy Harris 2016
7 * http://duncanthrax.net/pdkim/
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation; either version 2 of the License, or
12 * (at your option) any later version.
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Public License for more details.
19 * You should have received a copy of the GNU General Public License along
20 * with this program; if not, write to the Free Software Foundation, Inc.,
21 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
29 /* -------------------------------------------------------------------------- */
30 /* Length of the preallocated buffer for the "answer" from the dns/txt
31 callback function. This should match the maximum RDLENGTH from DNS. */
32 #define PDKIM_DNS_TXT_MAX_RECLEN (1 << 16)
34 /* -------------------------------------------------------------------------- */
35 /* Function success / error codes */
38 #define PDKIM_ERR_OOM -100
39 #define PDKIM_ERR_RSA_PRIVKEY -101
40 #define PDKIM_ERR_RSA_SIGNING -102
41 #define PDKIM_ERR_LONG_LINE -103
42 #define PDKIM_ERR_BUFFER_TOO_SMALL -104
43 #define PDKIM_SIGN_PRIVKEY_WRAP -105
44 #define PDKIM_SIGN_PRIVKEY_B64D -106
46 /* -------------------------------------------------------------------------- */
47 /* Main/Extended verification status */
48 #define PDKIM_VERIFY_NONE 0
49 #define PDKIM_VERIFY_INVALID 1
50 #define PDKIM_VERIFY_FAIL 2
51 #define PDKIM_VERIFY_PASS 3
53 #define PDKIM_VERIFY_FAIL_BODY 1
54 #define PDKIM_VERIFY_FAIL_MESSAGE 2
55 #define PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE 3
56 #define PDKIM_VERIFY_INVALID_BUFFER_SIZE 4
57 #define PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD 5
58 #define PDKIM_VERIFY_INVALID_PUBKEY_IMPORT 6
60 /* -------------------------------------------------------------------------- */
61 /* Some parameter values */
62 #define PDKIM_QUERYMETHOD_DNS_TXT 0
64 #define PDKIM_ALGO_RSA_SHA256 0
65 #define PDKIM_ALGO_RSA_SHA1 1
67 #define PDKIM_CANON_SIMPLE 0
68 #define PDKIM_CANON_RELAXED 1
70 #define PDKIM_HASH_SHA256 0
71 #define PDKIM_HASH_SHA1 1
73 #define PDKIM_KEYTYPE_RSA 0
75 /* -------------------------------------------------------------------------- */
76 /* Some required forward declarations, please ignore */
77 typedef struct pdkim_stringlist pdkim_stringlist;
78 typedef struct pdkim_str pdkim_str;
79 typedef struct sha1_context sha1_context;
80 typedef struct sha2_context sha2_context;
81 #define HAVE_SHA1_CONTEXT
82 #define HAVE_SHA2_CONTEXT
84 /* -------------------------------------------------------------------------- */
85 /* Some concessions towards Redmond */
87 #define snprintf _snprintf
88 #define strcasecmp _stricmp
89 #define strncasecmp _strnicmp
90 #define DLLEXPORT __declspec(dllexport)
96 /* -------------------------------------------------------------------------- */
97 /* Public key as (usually) fetched from DNS */
98 typedef struct pdkim_pubkey {
99 char *version; /* v= */
100 char *granularity; /* g= */
102 char *hashes; /* h= */
103 char *keytype; /* k= */
104 char *srvtype; /* s= */
105 char *notes; /* n= */
109 int testing; /* t=y */
110 int no_subdomaining; /* t=s */
113 /* -------------------------------------------------------------------------- */
114 /* Signature as it appears in a DKIM-Signature header */
115 typedef struct pdkim_signature {
117 /* Bits stored in a DKIM signature header --------------------------- */
119 /* (v=) The version, as an integer. Currently, always "1" */
122 /* (a=) The signature algorithm. Either PDKIM_ALGO_RSA_SHA256
123 or PDKIM_ALGO_RSA_SHA1 */
126 /* (c=x/) Header canonicalization method. Either PDKIM_CANON_SIMPLE
127 or PDKIM_CANON_RELAXED */
130 /* (c=/x) Body canonicalization method. Either PDKIM_CANON_SIMPLE
131 or PDKIM_CANON_RELAXED */
134 /* (q=) Query Method. Currently, only PDKIM_QUERYMETHOD_DNS_TXT
138 /* (s=) The selector string as given in the signature */
141 /* (d=) The domain as given in the signature */
144 /* (i=) The identity as given in the signature */
147 /* (t=) Timestamp of signature creation */
148 unsigned long created;
150 /* (x=) Timestamp of expiry of signature */
151 unsigned long expires;
153 /* (l=) Amount of hashed body bytes (after canonicalization). Default
154 is -1. Note: a value of 0 means that the body is unsigned! */
157 /* (h=) Colon-separated list of header names that are included in the
164 /* (b=) Raw signature data, along with its length in bytes */
167 /* (bh=) Raw body hash data, along with its length in bytes */
170 /* Folded DKIM-Signature: header. Singing only, NULL for verifying.
171 Ready for insertion into the message. Note: Folded using CRLFTB,
172 but final line terminator is NOT included. Note2: This buffer is
173 free()d when you call pdkim_free_ctx(). */
174 char *signature_header;
176 /* The main verification status. Verification only. One of:
178 PDKIM_VERIFY_NONE Verification was not attempted. This status
181 PDKIM_VERIFY_INVALID There was an error while trying to verify
182 the signature. A more precise description
183 is available in verify_ext_status.
185 PDKIM_VERIFY_FAIL Verification failed because either the body
186 hash did not match, or the signature verification
187 failed. This means the message was modified.
188 Check verify_ext_status for the exact reason.
190 PDKIM_VERIFY_PASS Verification succeeded.
194 /* Extended verification status. Verification only. Depending on the value
195 of verify_status, it can contain:
197 For verify_status == PDKIM_VERIFY_INVALID:
199 PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE
200 Unable to retrieve a public key container.
202 PDKIM_VERIFY_INVALID_BUFFER_SIZE
203 Either the DNS name constructed to retrieve the public key record
204 does not fit into PDKIM_DNS_TXT_MAX_NAMELEN bytes, or the retrieved
205 record is longer than PDKIM_DNS_TXT_MAX_RECLEN bytes.
207 PDKIM_VERIFY_INVALID_PUBKEY_PARSING
208 (Syntax) error while parsing the retrieved public key record.
211 For verify_status == PDKIM_VERIFY_FAIL:
213 PDKIM_VERIFY_FAIL_BODY
214 The calculated body hash does not match the advertised body hash
215 from the bh= tag of the signature.
217 PDKIM_VERIFY_FAIL_MESSAGE
218 RSA verification of the signature (b= tag) failed.
220 int verify_ext_status;
222 /* Pointer to a public key record that was used to verify the signature.
223 See pdkim_pubkey declaration above for more information.
224 Caution: is NULL if signing or if no record was retrieved. */
225 pdkim_pubkey *pubkey;
227 /* Pointer to the next pdkim_signature signature. NULL if signing or if
228 this is the last signature. */
231 /* Properties below this point are used internally only ------------- */
233 /* Per-signature helper variables ----------------------------------- */
236 unsigned long signed_body_bytes; /* How many body bytes we hashed */
237 pdkim_stringlist *headers; /* Raw headers included in the sig */
238 /* Signing specific ------------------------------------------------- */
239 char *rsa_privkey; /* Private RSA key */
240 char *sign_headers; /* To-be-signed header names */
241 char *rawsig_no_b_val; /* Original signature header w/o b= tag value. */
245 /* -------------------------------------------------------------------------- */
246 /* Context to keep state between all operations. */
247 #define PDKIM_MODE_SIGN 0
248 #define PDKIM_MODE_VERIFY 1
249 typedef struct pdkim_ctx {
251 /* PDKIM_MODE_VERIFY or PDKIM_MODE_SIGN */
254 /* One (signing) or several chained (verification) signatures */
255 pdkim_signature *sig;
257 /* Callback for dns/txt query method (verification only) */
258 int(*dns_txt_callback)(char *, char *);
260 /* Coder's little helpers */
261 pdkim_str *cur_header;
267 int num_buffered_crlf;
269 pdkim_stringlist *headers; /* Raw headers for verification */
273 /* -------------------------------------------------------------------------- */
274 /* API functions. Please see the sample code in sample/test_sign.c and
275 sample/test_verify.c for documentation.
282 void pdkim_init (void);
285 pdkim_ctx *pdkim_init_sign (char *, char *, char *, int);
288 pdkim_ctx *pdkim_init_verify (int(*)(char *, char *));
291 int pdkim_set_optional (pdkim_ctx *, char *, char *,int, int,
297 int pdkim_feed (pdkim_ctx *, char *, int);
299 int pdkim_feed_finish (pdkim_ctx *, pdkim_signature **);
302 void pdkim_free_ctx (pdkim_ctx *);