DKIM: Predefined macro for standard headers, oversigned
[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) 2016 - 2018 Jeremy Harris
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 #define PDKIM_DEFAULT_SIGN_HEADERS "From:Sender:Reply-To:Subject:Date:"\
30 "Message-ID:To:Cc:MIME-Version:Content-Type:"\
31 "Content-Transfer-Encoding:Content-ID:"\
32 "Content-Description:Resent-Date:Resent-From:"\
33 "Resent-Sender:Resent-To:Resent-Cc:"\
34 "Resent-Message-ID:In-Reply-To:References:"\
35 "List-Id:List-Help:List-Unsubscribe:"\
36 "List-Subscribe:List-Post:List-Owner:List-Archive"
37
38 #define PDKIM_OVERSIGN_HEADERS "+From:+Sender:+Reply-To:+Subject:+Date:"\
39 "+Message-ID:+To:+Cc:+MIME-Version:+Content-Type:"\
40 "+Content-Transfer-Encoding:+Content-ID:"\
41 "+Content-Description:+Resent-Date:+Resent-From:"\
42 "+Resent-Sender:+Resent-To:+Resent-Cc:"\
43 "+Resent-Message-ID:+In-Reply-To:+References:"\
44 "+List-Id:+List-Help:+List-Unsubscribe:"\
45 "+List-Subscribe:+List-Post:+List-Owner:+List-Archive"
46
47 /* -------------------------------------------------------------------------- */
48 /* Length of the preallocated buffer for the "answer" from the dns/txt
49 callback function. This should match the maximum RDLENGTH from DNS. */
50 #define PDKIM_DNS_TXT_MAX_RECLEN (1 << 16)
51
52 /* -------------------------------------------------------------------------- */
53 /* Function success / error codes */
54 #define PDKIM_OK 0
55 #define PDKIM_FAIL -1
56 #define PDKIM_ERR_RSA_PRIVKEY -101
57 #define PDKIM_ERR_RSA_SIGNING -102
58 #define PDKIM_ERR_LONG_LINE -103
59 #define PDKIM_ERR_BUFFER_TOO_SMALL -104
60 #define PDKIM_ERR_EXCESS_SIGS -105
61 #define PDKIM_SIGN_PRIVKEY_WRAP -106
62 #define PDKIM_SIGN_PRIVKEY_B64D -107
63
64 /* -------------------------------------------------------------------------- */
65 /* Main/Extended verification status */
66 #define PDKIM_VERIFY_NONE 0
67 #define PDKIM_VERIFY_INVALID 1
68 #define PDKIM_VERIFY_FAIL 2
69 #define PDKIM_VERIFY_PASS 3
70 #define PDKIM_VERIFY_POLICY BIT(31)
71
72 #define PDKIM_VERIFY_FAIL_BODY 1
73 #define PDKIM_VERIFY_FAIL_MESSAGE 2
74 #define PDKIM_VERIFY_FAIL_SIG_ALGO_MISMATCH 3
75 #define PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE 4
76 #define PDKIM_VERIFY_INVALID_BUFFER_SIZE 5
77 #define PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD 6
78 #define PDKIM_VERIFY_INVALID_PUBKEY_IMPORT 7
79 #define PDKIM_VERIFY_INVALID_SIGNATURE_ERROR 8
80 #define PDKIM_VERIFY_INVALID_DKIM_VERSION 9
81
82 /* -------------------------------------------------------------------------- */
83 /* Some parameter values */
84 #define PDKIM_QUERYMETHOD_DNS_TXT 0
85
86 #define PDKIM_CANON_SIMPLE 0
87 #define PDKIM_CANON_RELAXED 1
88
89 /* -------------------------------------------------------------------------- */
90 /* Some required forward declarations, please ignore */
91 typedef struct pdkim_stringlist pdkim_stringlist;
92 typedef struct pdkim_str pdkim_str;
93 typedef struct sha1_context sha1_context;
94 typedef struct sha2_context sha2_context;
95 #define HAVE_SHA1_CONTEXT
96 #define HAVE_SHA2_CONTEXT
97
98 /* -------------------------------------------------------------------------- */
99 /* Some concessions towards Redmond */
100 #ifdef WINDOWS
101 #define snprintf _snprintf
102 #define strcasecmp _stricmp
103 #define strncasecmp _strnicmp
104 #define DLLEXPORT __declspec(dllexport)
105 #else
106 #define DLLEXPORT
107 #endif
108
109
110 /* -------------------------------------------------------------------------- */
111 /* Public key as (usually) fetched from DNS */
112 typedef struct pdkim_pubkey {
113 const uschar * version; /* v= */
114 const uschar *granularity; /* g= */
115
116 const uschar * hashes; /* h= */
117 const uschar * keytype; /* k= */
118 const uschar * srvtype; /* s= */
119 uschar *notes; /* n= */
120
121 blob key; /* p= */
122 int testing; /* t=y */
123 int no_subdomaining; /* t=s */
124 } pdkim_pubkey;
125
126 /* -------------------------------------------------------------------------- */
127 /* Body-hash to be calculated */
128 typedef struct pdkim_bodyhash {
129 struct pdkim_bodyhash * next;
130 int hashtype;
131 int canon_method;
132 long bodylength;
133
134 hctx body_hash_ctx;
135 unsigned long signed_body_bytes; /* done so far */
136 int num_buffered_blanklines;
137
138 blob bh; /* completed hash */
139 } pdkim_bodyhash;
140
141 /* -------------------------------------------------------------------------- */
142 /* Signature as it appears in a DKIM-Signature header */
143 typedef struct pdkim_signature {
144 struct pdkim_signature * next;
145
146 /* Bits stored in a DKIM signature header --------------------------- */
147
148 /* (v=) The version, as an integer. Currently, always "1" */
149 int version;
150
151 /* (a=) The signature algorithm. */
152 int keytype; /* pdkim_keytypes index */
153 int hashtype; /* pdkim_hashes index */
154
155 /* (c=x/) Header canonicalization method. Either PDKIM_CANON_SIMPLE
156 or PDKIM_CANON_RELAXED */
157 int canon_headers;
158
159 /* (c=/x) Body canonicalization method. Either PDKIM_CANON_SIMPLE
160 or PDKIM_CANON_RELAXED */
161 int canon_body;
162
163 /* (q=) Query Method. Currently, only PDKIM_QUERYMETHOD_DNS_TXT
164 is specified */
165 int querymethod;
166
167 /* (s=) The selector string as given in the signature */
168 uschar *selector;
169
170 /* (d=) The domain as given in the signature */
171 uschar *domain;
172
173 /* (i=) The identity as given in the signature */
174 uschar *identity;
175
176 /* (t=) Timestamp of signature creation */
177 unsigned long created;
178
179 /* (x=) Timestamp of expiry of signature */
180 unsigned long expires;
181
182 /* (l=) Amount of hashed body bytes (after canonicalization). Default
183 is -1. Note: a value of 0 means that the body is unsigned! */
184 long bodylength;
185
186 /* (h=) Colon-separated list of header names that are included in the
187 signature */
188 uschar *headernames;
189
190 /* (z=) */
191 uschar *copiedheaders;
192
193 /* (b=) Raw signature data, along with its length in bytes */
194 blob sighash;
195
196 /* (bh=) Raw body hash data, along with its length in bytes */
197 blob bodyhash;
198
199 /* Folded DKIM-Signature: header. Signing only, NULL for verifying.
200 Ready for insertion into the message. Note: Folded using CRLFTB,
201 but final line terminator is NOT included. Note2: This buffer is
202 free()d when you call pdkim_free_ctx(). */
203 uschar *signature_header;
204
205 /* The main verification status. Verification only. One of:
206
207 PDKIM_VERIFY_NONE Verification was not attempted. This status
208 should not appear.
209
210 PDKIM_VERIFY_INVALID There was an error while trying to verify
211 the signature. A more precise description
212 is available in verify_ext_status.
213
214 PDKIM_VERIFY_FAIL Verification failed because either the body
215 hash did not match, or the signature verification
216 failed. This means the message was modified.
217 Check verify_ext_status for the exact reason.
218
219 PDKIM_VERIFY_PASS Verification succeeded.
220 */
221 int verify_status;
222
223 /* Extended verification status. Verification only. Depending on the value
224 of verify_status, it can contain:
225
226 For verify_status == PDKIM_VERIFY_INVALID:
227
228 PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE
229 Unable to retrieve a public key container.
230
231 PDKIM_VERIFY_INVALID_BUFFER_SIZE
232 Either the DNS name constructed to retrieve the public key record
233 does not fit into PDKIM_DNS_TXT_MAX_NAMELEN bytes, or the retrieved
234 record is longer than PDKIM_DNS_TXT_MAX_RECLEN bytes.
235
236 PDKIM_VERIFY_INVALID_PUBKEY_PARSING
237 (Syntax) error while parsing the retrieved public key record.
238
239
240 For verify_status == PDKIM_VERIFY_FAIL:
241
242 PDKIM_VERIFY_FAIL_BODY
243 The calculated body hash does not match the advertised body hash
244 from the bh= tag of the signature.
245
246 PDKIM_VERIFY_FAIL_MESSAGE
247 RSA verification of the signature (b= tag) failed.
248 */
249 int verify_ext_status;
250
251 /* Pointer to a public key record that was used to verify the signature.
252 See pdkim_pubkey declaration above for more information.
253 Caution: is NULL if signing or if no record was retrieved. */
254 pdkim_pubkey *pubkey;
255
256 /* Properties below this point are used internally only ------------- */
257
258 /* Per-signature helper variables ----------------------------------- */
259 pdkim_bodyhash *calc_body_hash; /* hash to be / being calculated */
260
261 pdkim_stringlist *headers; /* Raw headers included in the sig */
262
263 /* Signing specific ------------------------------------------------- */
264 uschar * privkey; /* Private key */
265 uschar * sign_headers; /* To-be-signed header names */
266 uschar * rawsig_no_b_val; /* Original signature header w/o b= tag value. */
267 } pdkim_signature;
268
269
270 /* -------------------------------------------------------------------------- */
271 /* Context to keep state between all operations. */
272 typedef struct pdkim_ctx {
273
274 #define PDKIM_MODE_SIGN BIT(0) /* if unset, mode==verify */
275 #define PDKIM_DOT_TERM BIT(1) /* dot termination and unstuffing */
276 #define PDKIM_SEEN_CR BIT(2)
277 #define PDKIM_SEEN_LF BIT(3)
278 #define PDKIM_PAST_HDRS BIT(4)
279 #define PDKIM_SEEN_EOD BIT(5)
280 unsigned flags;
281
282 /* One (signing) or several chained (verification) signatures */
283 pdkim_signature *sig;
284
285 /* One (signing) or several chained (verification) bodyhashes */
286 pdkim_bodyhash *bodyhash;
287
288 /* Callback for dns/txt query method (verification only) */
289 uschar * (*dns_txt_callback)(const uschar *);
290
291 /* Coder's little helpers */
292 gstring *cur_header;
293 uschar *linebuf;
294 int linebuf_offset;
295 int num_headers;
296 pdkim_stringlist *headers; /* Raw headers for verification */
297 } pdkim_ctx;
298
299
300 /******************************************************************************/
301
302 typedef struct {
303 const uschar * dkim_hashname;
304 hashmethod exim_hashmethod;
305 } pdkim_hashtype;
306 extern const pdkim_hashtype pdkim_hashes[];
307
308 /******************************************************************************/
309
310
311 /* -------------------------------------------------------------------------- */
312 /* API functions. Please see the sample code in sample/test_sign.c and
313 sample/test_verify.c for documentation.
314 */
315
316 #ifdef __cplusplus
317 extern "C" {
318 #endif
319
320 void pdkim_init (void);
321
322 void pdkim_init_context (pdkim_ctx *, BOOL, uschar * (*)(const uschar *));
323
324 DLLEXPORT
325 pdkim_signature *pdkim_init_sign (pdkim_ctx *,
326 uschar *, uschar *, uschar *, uschar *,
327 const uschar **);
328
329 DLLEXPORT
330 pdkim_ctx *pdkim_init_verify (uschar * (*)(const uschar *), BOOL);
331
332 DLLEXPORT
333 void pdkim_set_optional (pdkim_signature *, char *, char *,int, int,
334 long,
335 unsigned long,
336 unsigned long);
337
338 int pdkim_hashname_to_hashtype(const uschar *, unsigned);
339 void pdkim_cstring_to_canons(const uschar *, unsigned, int *, int *);
340 pdkim_bodyhash *pdkim_set_bodyhash(pdkim_ctx *, int, int, long);
341 pdkim_bodyhash *pdkim_set_sig_bodyhash(pdkim_ctx *, pdkim_signature *);
342
343 DLLEXPORT
344 int pdkim_feed (pdkim_ctx *, uschar *, int);
345 DLLEXPORT
346 int pdkim_feed_finish (pdkim_ctx *, pdkim_signature **, const uschar **);
347
348 DLLEXPORT
349 void pdkim_free_ctx (pdkim_ctx *);
350
351
352 const uschar * pdkim_errstr(int);
353
354 extern uschar * pdkim_encode_base64(blob *);
355 extern void pdkim_decode_base64(const uschar *, blob *);
356 extern void pdkim_hexprint(const uschar *, int);
357 extern void pdkim_quoteprint(const uschar *, int);
358 extern pdkim_pubkey * pdkim_parse_pubkey_record(const uschar *);
359 extern uschar * pdkim_relax_header_n(const uschar *, int, BOOL);
360 extern uschar * pdkim_relax_header(const uschar *, BOOL);
361 extern uschar * dkim_sig_to_a_tag(const pdkim_signature *);
362
363 #ifdef __cplusplus
364 }
365 #endif
366
367 #endif