07ba5b5c4801b3888311e0d2d0c352717de9e809
[exim.git] / src / src / pdkim / pdkim.h
1 /*
2 * PDKIM - a RFC4871 (DKIM) implementation
3 *
4 * Copyright (C) 2009 - 2012 Tom Kistner <tom@duncanthrax.net>
5 * Copyright (c) Jeremy Harris 2016
6 *
7 * http://duncanthrax.net/pdkim/
8 *
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.
13 *
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.
18 *
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.
22 */
23 #ifndef PDKIM_H
24 #define PDKIM_H
25
26 #include "../blob.h"
27 #include "../hash.h"
28
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)
33
34 /* -------------------------------------------------------------------------- */
35 /* Function success / error codes */
36 #define PDKIM_OK 0
37 #define PDKIM_FAIL -1
38 #define PDKIM_ERR_RSA_PRIVKEY -101
39 #define PDKIM_ERR_RSA_SIGNING -102
40 #define PDKIM_ERR_LONG_LINE -103
41 #define PDKIM_ERR_BUFFER_TOO_SMALL -104
42 #define PDKIM_SIGN_PRIVKEY_WRAP -105
43 #define PDKIM_SIGN_PRIVKEY_B64D -106
44
45 /* -------------------------------------------------------------------------- */
46 /* Main/Extended verification status */
47 #define PDKIM_VERIFY_NONE 0
48 #define PDKIM_VERIFY_INVALID 1
49 #define PDKIM_VERIFY_FAIL 2
50 #define PDKIM_VERIFY_PASS 3
51
52 #define PDKIM_VERIFY_FAIL_BODY 1
53 #define PDKIM_VERIFY_FAIL_MESSAGE 2
54 #define PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE 3
55 #define PDKIM_VERIFY_INVALID_BUFFER_SIZE 4
56 #define PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD 5
57 #define PDKIM_VERIFY_INVALID_PUBKEY_IMPORT 6
58 #define PDKIM_VERIFY_INVALID_SIGNATURE_ERROR 7
59 #define PDKIM_VERIFY_INVALID_DKIM_VERSION 8
60
61 /* -------------------------------------------------------------------------- */
62 /* Some parameter values */
63 #define PDKIM_QUERYMETHOD_DNS_TXT 0
64
65 #define PDKIM_ALGO_RSA_SHA256 0
66 #define PDKIM_ALGO_RSA_SHA1 1
67
68 #define PDKIM_CANON_SIMPLE 0
69 #define PDKIM_CANON_RELAXED 1
70
71 #define PDKIM_HASH_SHA256 0
72 #define PDKIM_HASH_SHA1 1
73
74 #define PDKIM_KEYTYPE_RSA 0
75
76 /* -------------------------------------------------------------------------- */
77 /* Some required forward declarations, please ignore */
78 typedef struct pdkim_stringlist pdkim_stringlist;
79 typedef struct pdkim_str pdkim_str;
80 typedef struct sha1_context sha1_context;
81 typedef struct sha2_context sha2_context;
82 #define HAVE_SHA1_CONTEXT
83 #define HAVE_SHA2_CONTEXT
84
85 /* -------------------------------------------------------------------------- */
86 /* Some concessions towards Redmond */
87 #ifdef WINDOWS
88 #define snprintf _snprintf
89 #define strcasecmp _stricmp
90 #define strncasecmp _strnicmp
91 #define DLLEXPORT __declspec(dllexport)
92 #else
93 #define DLLEXPORT
94 #endif
95
96
97 /* -------------------------------------------------------------------------- */
98 /* Public key as (usually) fetched from DNS */
99 typedef struct pdkim_pubkey {
100 uschar *version; /* v= */
101 uschar *granularity; /* g= */
102
103 #ifdef notdef
104 uschar *hashes; /* h= */
105 uschar *keytype; /* k= */
106 #endif
107 uschar *srvtype; /* s= */
108 uschar *notes; /* n= */
109
110 blob key; /* p= */
111 int testing; /* t=y */
112 int no_subdomaining; /* t=s */
113 } pdkim_pubkey;
114
115 /* -------------------------------------------------------------------------- */
116 /* Signature as it appears in a DKIM-Signature header */
117 typedef struct pdkim_signature {
118
119 /* Bits stored in a DKIM signature header --------------------------- */
120
121 /* (v=) The version, as an integer. Currently, always "1" */
122 int version;
123
124 /* (a=) The signature algorithm. Either PDKIM_ALGO_RSA_SHA256
125 or PDKIM_ALGO_RSA_SHA1 */
126 int algo;
127
128 /* (c=x/) Header canonicalization method. Either PDKIM_CANON_SIMPLE
129 or PDKIM_CANON_RELAXED */
130 int canon_headers;
131
132 /* (c=/x) Body canonicalization method. Either PDKIM_CANON_SIMPLE
133 or PDKIM_CANON_RELAXED */
134 int canon_body;
135
136 /* (q=) Query Method. Currently, only PDKIM_QUERYMETHOD_DNS_TXT
137 is specified */
138 int querymethod;
139
140 /* (s=) The selector string as given in the signature */
141 uschar *selector;
142
143 /* (d=) The domain as given in the signature */
144 uschar *domain;
145
146 /* (i=) The identity as given in the signature */
147 uschar *identity;
148
149 /* (t=) Timestamp of signature creation */
150 unsigned long created;
151
152 /* (x=) Timestamp of expiry of signature */
153 unsigned long expires;
154
155 /* (l=) Amount of hashed body bytes (after canonicalization). Default
156 is -1. Note: a value of 0 means that the body is unsigned! */
157 long bodylength;
158
159 /* (h=) Colon-separated list of header names that are included in the
160 signature */
161 uschar *headernames;
162
163 /* (z=) */
164 uschar *copiedheaders;
165
166 /* (b=) Raw signature data, along with its length in bytes */
167 blob sigdata;
168
169 /* (bh=) Raw body hash data, along with its length in bytes */
170 blob bodyhash;
171
172 /* Folded DKIM-Signature: header. Singing only, NULL for verifying.
173 Ready for insertion into the message. Note: Folded using CRLFTB,
174 but final line terminator is NOT included. Note2: This buffer is
175 free()d when you call pdkim_free_ctx(). */
176 uschar *signature_header;
177
178 /* The main verification status. Verification only. One of:
179
180 PDKIM_VERIFY_NONE Verification was not attempted. This status
181 should not appear.
182
183 PDKIM_VERIFY_INVALID There was an error while trying to verify
184 the signature. A more precise description
185 is available in verify_ext_status.
186
187 PDKIM_VERIFY_FAIL Verification failed because either the body
188 hash did not match, or the signature verification
189 failed. This means the message was modified.
190 Check verify_ext_status for the exact reason.
191
192 PDKIM_VERIFY_PASS Verification succeeded.
193 */
194 int verify_status;
195
196 /* Extended verification status. Verification only. Depending on the value
197 of verify_status, it can contain:
198
199 For verify_status == PDKIM_VERIFY_INVALID:
200
201 PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE
202 Unable to retrieve a public key container.
203
204 PDKIM_VERIFY_INVALID_BUFFER_SIZE
205 Either the DNS name constructed to retrieve the public key record
206 does not fit into PDKIM_DNS_TXT_MAX_NAMELEN bytes, or the retrieved
207 record is longer than PDKIM_DNS_TXT_MAX_RECLEN bytes.
208
209 PDKIM_VERIFY_INVALID_PUBKEY_PARSING
210 (Syntax) error while parsing the retrieved public key record.
211
212
213 For verify_status == PDKIM_VERIFY_FAIL:
214
215 PDKIM_VERIFY_FAIL_BODY
216 The calculated body hash does not match the advertised body hash
217 from the bh= tag of the signature.
218
219 PDKIM_VERIFY_FAIL_MESSAGE
220 RSA verification of the signature (b= tag) failed.
221 */
222 int verify_ext_status;
223
224 /* Pointer to a public key record that was used to verify the signature.
225 See pdkim_pubkey declaration above for more information.
226 Caution: is NULL if signing or if no record was retrieved. */
227 pdkim_pubkey *pubkey;
228
229 /* Pointer to the next pdkim_signature signature. NULL if signing or if
230 this is the last signature. */
231 void *next;
232
233 /* Properties below this point are used internally only ------------- */
234
235 /* Per-signature helper variables ----------------------------------- */
236 hctx body_hash;
237
238 unsigned long signed_body_bytes; /* How many body bytes we hashed */
239 pdkim_stringlist *headers; /* Raw headers included in the sig */
240 /* Signing specific ------------------------------------------------- */
241 uschar * rsa_privkey; /* Private RSA key */
242 uschar * sign_headers; /* To-be-signed header names */
243 uschar * rawsig_no_b_val; /* Original signature header w/o b= tag value. */
244 } pdkim_signature;
245
246
247 /* -------------------------------------------------------------------------- */
248 /* Context to keep state between all operations. */
249 typedef struct pdkim_ctx {
250
251 #define PDKIM_MODE_SIGN BIT(0) /* if unset, mode==verify */
252 #define PDKIM_DOT_TERM BIT(1) /* dot termination and unstuffing */
253 #define PDKIM_SEEN_LF BIT(2)
254 #define PDKIM_SEEN_EOD BIT(3)
255 #define PDKIM_PAST_HDRS BIT(4)
256 unsigned flags;
257
258 /* One (signing) or several chained (verification) signatures */
259 pdkim_signature *sig;
260
261 /* Callback for dns/txt query method (verification only) */
262 int(*dns_txt_callback)(char *, char *);
263
264 /* Coder's little helpers */
265 uschar *cur_header;
266 int cur_header_size;
267 int cur_header_len;
268 char *linebuf;
269 int linebuf_offset;
270 int num_buffered_crlf;
271 int num_headers;
272 pdkim_stringlist *headers; /* Raw headers for verification */
273 } pdkim_ctx;
274
275
276 /* -------------------------------------------------------------------------- */
277 /* API functions. Please see the sample code in sample/test_sign.c and
278 sample/test_verify.c for documentation.
279 */
280
281 #ifdef __cplusplus
282 extern "C" {
283 #endif
284
285 void pdkim_init (void);
286
287 DLLEXPORT
288 pdkim_ctx *pdkim_init_sign (char *, char *, char *, int, BOOL);
289
290 DLLEXPORT
291 pdkim_ctx *pdkim_init_verify (int(*)(char *, char *), BOOL);
292
293 DLLEXPORT
294 int pdkim_set_optional (pdkim_ctx *, char *, char *,int, int,
295 long,
296 unsigned long,
297 unsigned long);
298
299 DLLEXPORT
300 int pdkim_feed (pdkim_ctx *, char *, int);
301 DLLEXPORT
302 int pdkim_feed_finish (pdkim_ctx *, pdkim_signature **);
303
304 DLLEXPORT
305 void pdkim_free_ctx (pdkim_ctx *);
306
307
308 const char * pdkim_errstr(int);
309
310 #ifdef __cplusplus
311 }
312 #endif
313
314 #endif