e79d71e6e6d95fe78d2a76c27e81c0369ab954c3
[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_PUBKEY_KEYSIZE 8
80 #define PDKIM_VERIFY_INVALID_SIGNATURE_ERROR 9
81 #define PDKIM_VERIFY_INVALID_DKIM_VERSION 10
82
83 /* -------------------------------------------------------------------------- */
84 /* Some parameter values */
85 #define PDKIM_QUERYMETHOD_DNS_TXT 0
86
87 #define PDKIM_CANON_SIMPLE 0
88 #define PDKIM_CANON_RELAXED 1
89
90 /* -------------------------------------------------------------------------- */
91 /* Some required forward declarations, please ignore */
92 typedef struct pdkim_stringlist pdkim_stringlist;
93 typedef struct pdkim_str pdkim_str;
94 typedef struct sha1_context sha1_context;
95 typedef struct sha2_context sha2_context;
96 #define HAVE_SHA1_CONTEXT
97 #define HAVE_SHA2_CONTEXT
98
99 /* -------------------------------------------------------------------------- */
100 /* Some concessions towards Redmond */
101 #ifdef WINDOWS
102 #define snprintf _snprintf
103 #define strcasecmp _stricmp
104 #define strncasecmp _strnicmp
105 #define DLLEXPORT __declspec(dllexport)
106 #else
107 #define DLLEXPORT
108 #endif
109
110
111 /* -------------------------------------------------------------------------- */
112 /* Public key as (usually) fetched from DNS */
113 typedef struct pdkim_pubkey {
114 const uschar * version; /* v= */
115 const uschar *granularity; /* g= */
116
117 const uschar * hashes; /* h= */
118 const uschar * keytype; /* k= */
119 const uschar * srvtype; /* s= */
120 uschar *notes; /* n= */
121
122 blob key; /* p= */
123 int testing; /* t=y */
124 int no_subdomaining; /* t=s */
125 } pdkim_pubkey;
126
127 /* -------------------------------------------------------------------------- */
128 /* Body-hash to be calculated */
129 typedef struct pdkim_bodyhash {
130 struct pdkim_bodyhash * next;
131 int hashtype;
132 int canon_method;
133 long bodylength;
134
135 hctx body_hash_ctx;
136 unsigned long signed_body_bytes; /* done so far */
137 int num_buffered_blanklines;
138
139 blob bh; /* completed hash */
140 } pdkim_bodyhash;
141
142 /* -------------------------------------------------------------------------- */
143 /* Signature as it appears in a DKIM-Signature header */
144 typedef struct pdkim_signature {
145 struct pdkim_signature * next;
146
147 /* Bits stored in a DKIM signature header --------------------------- */
148
149 /* (v=) The version, as an integer. Currently, always "1" */
150 int version;
151
152 /* (a=) The signature algorithm. */
153 int keytype; /* pdkim_keytypes index */
154 unsigned keybits; /* size of the key */
155 int hashtype; /* pdkim_hashes index */
156
157 /* (c=x/) Header canonicalization method. Either PDKIM_CANON_SIMPLE
158 or PDKIM_CANON_RELAXED */
159 int canon_headers;
160
161 /* (c=/x) Body canonicalization method. Either PDKIM_CANON_SIMPLE
162 or PDKIM_CANON_RELAXED */
163 int canon_body;
164
165 /* (q=) Query Method. Currently, only PDKIM_QUERYMETHOD_DNS_TXT
166 is specified */
167 int querymethod;
168
169 /* (s=) The selector string as given in the signature */
170 uschar *selector;
171
172 /* (d=) The domain as given in the signature */
173 uschar *domain;
174
175 /* (i=) The identity as given in the signature */
176 uschar *identity;
177
178 /* (t=) Timestamp of signature creation */
179 unsigned long created;
180
181 /* (x=) Timestamp of expiry of signature */
182 unsigned long expires;
183
184 /* (l=) Amount of hashed body bytes (after canonicalization). Default
185 is -1. Note: a value of 0 means that the body is unsigned! */
186 long bodylength;
187
188 /* (h=) Colon-separated list of header names that are included in the
189 signature */
190 uschar *headernames;
191
192 /* (z=) */
193 uschar *copiedheaders;
194
195 /* (b=) Raw signature data, along with its length in bytes */
196 blob sighash;
197
198 /* (bh=) Raw body hash data, along with its length in bytes */
199 blob bodyhash;
200
201 /* Folded DKIM-Signature: header. Signing only, NULL for verifying.
202 Ready for insertion into the message. Note: Folded using CRLFTB,
203 but final line terminator is NOT included. Note2: This buffer is
204 free()d when you call pdkim_free_ctx(). */
205 uschar *signature_header;
206
207 /* The main verification status. Verification only. One of:
208
209 PDKIM_VERIFY_NONE Verification was not attempted. This status
210 should not appear.
211
212 PDKIM_VERIFY_INVALID There was an error while trying to verify
213 the signature. A more precise description
214 is available in verify_ext_status.
215
216 PDKIM_VERIFY_FAIL Verification failed because either the body
217 hash did not match, or the signature verification
218 failed. This means the message was modified.
219 Check verify_ext_status for the exact reason.
220
221 PDKIM_VERIFY_PASS Verification succeeded.
222 */
223 int verify_status;
224
225 /* Extended verification status. Verification only. Depending on the value
226 of verify_status, it can contain:
227
228 For verify_status == PDKIM_VERIFY_INVALID:
229
230 PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE
231 Unable to retrieve a public key container.
232
233 PDKIM_VERIFY_INVALID_BUFFER_SIZE
234 Either the DNS name constructed to retrieve the public key record
235 does not fit into PDKIM_DNS_TXT_MAX_NAMELEN bytes, or the retrieved
236 record is longer than PDKIM_DNS_TXT_MAX_RECLEN bytes.
237
238 PDKIM_VERIFY_INVALID_PUBKEY_PARSING
239 (Syntax) error while parsing the retrieved public key record.
240
241
242 For verify_status == PDKIM_VERIFY_FAIL:
243
244 PDKIM_VERIFY_FAIL_BODY
245 The calculated body hash does not match the advertised body hash
246 from the bh= tag of the signature.
247
248 PDKIM_VERIFY_FAIL_MESSAGE
249 RSA verification of the signature (b= tag) failed.
250 */
251 int verify_ext_status;
252
253 /* Pointer to a public key record that was used to verify the signature.
254 See pdkim_pubkey declaration above for more information.
255 Caution: is NULL if signing or if no record was retrieved. */
256 pdkim_pubkey *pubkey;
257
258 /* Properties below this point are used internally only ------------- */
259
260 /* Per-signature helper variables ----------------------------------- */
261 pdkim_bodyhash *calc_body_hash; /* hash to be / being calculated */
262
263 pdkim_stringlist *headers; /* Raw headers included in the sig */
264
265 /* Signing specific ------------------------------------------------- */
266 uschar * privkey; /* Private key */
267 uschar * sign_headers; /* To-be-signed header names */
268 uschar * rawsig_no_b_val; /* Original signature header w/o b= tag value. */
269 } pdkim_signature;
270
271
272 /* -------------------------------------------------------------------------- */
273 /* Context to keep state between all operations. */
274 typedef struct pdkim_ctx {
275
276 #define PDKIM_MODE_SIGN BIT(0) /* if unset, mode==verify */
277 #define PDKIM_DOT_TERM BIT(1) /* dot termination and unstuffing */
278 #define PDKIM_SEEN_CR BIT(2)
279 #define PDKIM_SEEN_LF BIT(3)
280 #define PDKIM_PAST_HDRS BIT(4)
281 #define PDKIM_SEEN_EOD BIT(5)
282 unsigned flags;
283
284 /* One (signing) or several chained (verification) signatures */
285 pdkim_signature *sig;
286
287 /* One (signing) or several chained (verification) bodyhashes */
288 pdkim_bodyhash *bodyhash;
289
290 /* Callback for dns/txt query method (verification only) */
291 uschar * (*dns_txt_callback)(const uschar *);
292
293 /* Coder's little helpers */
294 gstring *cur_header;
295 uschar *linebuf;
296 int linebuf_offset;
297 int num_headers;
298 pdkim_stringlist *headers; /* Raw headers for verification */
299 } pdkim_ctx;
300
301
302 /******************************************************************************/
303
304 typedef struct {
305 const uschar * dkim_hashname;
306 hashmethod exim_hashmethod;
307 } pdkim_hashtype;
308 extern const pdkim_hashtype pdkim_hashes[];
309
310 /******************************************************************************/
311
312
313 /* -------------------------------------------------------------------------- */
314 /* API functions. Please see the sample code in sample/test_sign.c and
315 sample/test_verify.c for documentation.
316 */
317
318 #ifdef __cplusplus
319 extern "C" {
320 #endif
321
322 void pdkim_init (void);
323
324 void pdkim_init_context (pdkim_ctx *, BOOL, uschar * (*)(const uschar *));
325
326 DLLEXPORT
327 pdkim_signature *pdkim_init_sign (pdkim_ctx *,
328 uschar *, uschar *, uschar *, uschar *,
329 const uschar **);
330
331 DLLEXPORT
332 pdkim_ctx *pdkim_init_verify (uschar * (*)(const uschar *), BOOL);
333
334 DLLEXPORT
335 void pdkim_set_optional (pdkim_signature *, char *, char *,int, int,
336 long,
337 unsigned long,
338 unsigned long);
339
340 int pdkim_hashname_to_hashtype(const uschar *, unsigned);
341 void pdkim_cstring_to_canons(const uschar *, unsigned, int *, int *);
342 pdkim_bodyhash *pdkim_set_bodyhash(pdkim_ctx *, int, int, long);
343 pdkim_bodyhash *pdkim_set_sig_bodyhash(pdkim_ctx *, pdkim_signature *);
344
345 DLLEXPORT
346 int pdkim_feed (pdkim_ctx *, uschar *, int);
347 DLLEXPORT
348 int pdkim_feed_finish (pdkim_ctx *, pdkim_signature **, const uschar **);
349
350 DLLEXPORT
351 void pdkim_free_ctx (pdkim_ctx *);
352
353
354 const uschar * pdkim_errstr(int);
355
356 extern uschar * pdkim_encode_base64(blob *);
357 extern void pdkim_decode_base64(const uschar *, blob *);
358 extern void pdkim_hexprint(const uschar *, int);
359 extern void pdkim_quoteprint(const uschar *, int);
360 extern pdkim_pubkey * pdkim_parse_pubkey_record(const uschar *);
361 extern uschar * pdkim_relax_header_n(const uschar *, int, BOOL);
362 extern uschar * pdkim_relax_header(const uschar *, BOOL);
363 extern uschar * dkim_sig_to_a_tag(const pdkim_signature *);
364
365 #ifdef __cplusplus
366 }
367 #endif
368
369 #endif