tidying
[exim.git] / src / src / pdkim / pdkim.h
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1/*
2 * PDKIM - a RFC4871 (DKIM) implementation
3 *
c4ceed07 4 * Copyright (C) 2009 - 2012 Tom Kistner <tom@duncanthrax.net>
f9ba5e22 5 * Copyright (c) 2016 - 2018 Jeremy Harris
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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 */
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23#ifndef PDKIM_H
24#define PDKIM_H
25
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26#include "../blob.h"
27#include "../hash.h"
80a47a2c 28
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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
80a47a2c 38/* -------------------------------------------------------------------------- */
80a47a2c 39/* Length of the preallocated buffer for the "answer" from the dns/txt
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40 callback function. This should match the maximum RDLENGTH from DNS. */
41#define PDKIM_DNS_TXT_MAX_RECLEN (1 << 16)
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42
43/* -------------------------------------------------------------------------- */
44/* Function success / error codes */
45#define PDKIM_OK 0
46#define PDKIM_FAIL -1
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47#define PDKIM_ERR_RSA_PRIVKEY -101
48#define PDKIM_ERR_RSA_SIGNING -102
49#define PDKIM_ERR_LONG_LINE -103
50#define PDKIM_ERR_BUFFER_TOO_SMALL -104
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51#define PDKIM_ERR_EXCESS_SIGS -105
52#define PDKIM_SIGN_PRIVKEY_WRAP -106
53#define PDKIM_SIGN_PRIVKEY_B64D -107
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54
55/* -------------------------------------------------------------------------- */
56/* Main/Extended verification status */
57#define PDKIM_VERIFY_NONE 0
58#define PDKIM_VERIFY_INVALID 1
59#define PDKIM_VERIFY_FAIL 2
60#define PDKIM_VERIFY_PASS 3
dfbcb5ac 61#define PDKIM_VERIFY_POLICY BIT(31)
80a47a2c 62
07eeb4df 63#define PDKIM_VERIFY_FAIL_BODY 1
64#define PDKIM_VERIFY_FAIL_MESSAGE 2
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65#define PDKIM_VERIFY_FAIL_SIG_ALGO_MISMATCH 3
66#define PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE 4
67#define PDKIM_VERIFY_INVALID_BUFFER_SIZE 5
68#define PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD 6
69#define PDKIM_VERIFY_INVALID_PUBKEY_IMPORT 7
70#define PDKIM_VERIFY_INVALID_SIGNATURE_ERROR 8
71#define PDKIM_VERIFY_INVALID_DKIM_VERSION 9
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72
73/* -------------------------------------------------------------------------- */
74/* Some parameter values */
75#define PDKIM_QUERYMETHOD_DNS_TXT 0
76
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77#define PDKIM_CANON_SIMPLE 0
78#define PDKIM_CANON_RELAXED 1
79
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80/* -------------------------------------------------------------------------- */
81/* Some required forward declarations, please ignore */
82typedef struct pdkim_stringlist pdkim_stringlist;
83typedef struct pdkim_str pdkim_str;
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84typedef struct sha1_context sha1_context;
85typedef struct sha2_context sha2_context;
86#define HAVE_SHA1_CONTEXT
87#define HAVE_SHA2_CONTEXT
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88
89/* -------------------------------------------------------------------------- */
90/* Some concessions towards Redmond */
91#ifdef WINDOWS
92#define snprintf _snprintf
93#define strcasecmp _stricmp
94#define strncasecmp _strnicmp
95#define DLLEXPORT __declspec(dllexport)
96#else
97#define DLLEXPORT
98#endif
99
100
101/* -------------------------------------------------------------------------- */
102/* Public key as (usually) fetched from DNS */
103typedef struct pdkim_pubkey {
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104 const uschar * version; /* v= */
105 const uschar *granularity; /* g= */
80a47a2c 106
35cf75e9 107 const uschar * hashes; /* h= */
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108 const uschar * keytype; /* k= */
109 const uschar * srvtype; /* s= */
e2e3255a 110 uschar *notes; /* n= */
80a47a2c 111
2592e6c0 112 blob key; /* p= */
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113 int testing; /* t=y */
114 int no_subdomaining; /* t=s */
115} pdkim_pubkey;
116
117/* -------------------------------------------------------------------------- */
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118/* Body-hash to be calculated */
119typedef struct pdkim_bodyhash {
120 struct pdkim_bodyhash * next;
121 int hashtype;
122 int canon_method;
123 long bodylength;
124
125 hctx body_hash_ctx;
126 unsigned long signed_body_bytes; /* done so far */
127 int num_buffered_blanklines;
128
129 blob bh; /* completed hash */
130} pdkim_bodyhash;
131
132/* -------------------------------------------------------------------------- */
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133/* Signature as it appears in a DKIM-Signature header */
134typedef struct pdkim_signature {
9e70917d 135 struct pdkim_signature * next;
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136
137 /* Bits stored in a DKIM signature header --------------------------- */
138
139 /* (v=) The version, as an integer. Currently, always "1" */
140 int version;
141
042e558f 142 /* (a=) The signature algorithm. */
cf1cce5e 143 int keytype; /* pdkim_keytypes index */
d73e45df 144 int hashtype; /* pdkim_hashes index */
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145
146 /* (c=x/) Header canonicalization method. Either PDKIM_CANON_SIMPLE
147 or PDKIM_CANON_RELAXED */
148 int canon_headers;
149
150 /* (c=/x) Body canonicalization method. Either PDKIM_CANON_SIMPLE
151 or PDKIM_CANON_RELAXED */
152 int canon_body;
153
154 /* (q=) Query Method. Currently, only PDKIM_QUERYMETHOD_DNS_TXT
155 is specified */
156 int querymethod;
157
158 /* (s=) The selector string as given in the signature */
e2e3255a 159 uschar *selector;
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160
161 /* (d=) The domain as given in the signature */
e2e3255a 162 uschar *domain;
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163
164 /* (i=) The identity as given in the signature */
e2e3255a 165 uschar *identity;
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166
167 /* (t=) Timestamp of signature creation */
168 unsigned long created;
169
170 /* (x=) Timestamp of expiry of signature */
171 unsigned long expires;
172
173 /* (l=) Amount of hashed body bytes (after canonicalization). Default
174 is -1. Note: a value of 0 means that the body is unsigned! */
175 long bodylength;
176
177 /* (h=) Colon-separated list of header names that are included in the
178 signature */
2592e6c0 179 uschar *headernames;
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180
181 /* (z=) */
e2e3255a 182 uschar *copiedheaders;
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183
184 /* (b=) Raw signature data, along with its length in bytes */
dcd03763 185 blob sighash;
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186
187 /* (bh=) Raw body hash data, along with its length in bytes */
2592e6c0 188 blob bodyhash;
80a47a2c 189
9e70917d 190 /* Folded DKIM-Signature: header. Signing only, NULL for verifying.
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191 Ready for insertion into the message. Note: Folded using CRLFTB,
192 but final line terminator is NOT included. Note2: This buffer is
193 free()d when you call pdkim_free_ctx(). */
e2e3255a 194 uschar *signature_header;
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195
196 /* The main verification status. Verification only. One of:
197
198 PDKIM_VERIFY_NONE Verification was not attempted. This status
199 should not appear.
200
201 PDKIM_VERIFY_INVALID There was an error while trying to verify
202 the signature. A more precise description
203 is available in verify_ext_status.
204
205 PDKIM_VERIFY_FAIL Verification failed because either the body
206 hash did not match, or the signature verification
207 failed. This means the message was modified.
208 Check verify_ext_status for the exact reason.
209
210 PDKIM_VERIFY_PASS Verification succeeded.
211 */
212 int verify_status;
213
214 /* Extended verification status. Verification only. Depending on the value
215 of verify_status, it can contain:
216
217 For verify_status == PDKIM_VERIFY_INVALID:
218
219 PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE
220 Unable to retrieve a public key container.
221
222 PDKIM_VERIFY_INVALID_BUFFER_SIZE
223 Either the DNS name constructed to retrieve the public key record
224 does not fit into PDKIM_DNS_TXT_MAX_NAMELEN bytes, or the retrieved
225 record is longer than PDKIM_DNS_TXT_MAX_RECLEN bytes.
226
227 PDKIM_VERIFY_INVALID_PUBKEY_PARSING
228 (Syntax) error while parsing the retrieved public key record.
229
230
231 For verify_status == PDKIM_VERIFY_FAIL:
232
233 PDKIM_VERIFY_FAIL_BODY
234 The calculated body hash does not match the advertised body hash
235 from the bh= tag of the signature.
236
237 PDKIM_VERIFY_FAIL_MESSAGE
238 RSA verification of the signature (b= tag) failed.
239 */
240 int verify_ext_status;
241
242 /* Pointer to a public key record that was used to verify the signature.
243 See pdkim_pubkey declaration above for more information.
244 Caution: is NULL if signing or if no record was retrieved. */
245 pdkim_pubkey *pubkey;
246
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247 /* Properties below this point are used internally only ------------- */
248
249 /* Per-signature helper variables ----------------------------------- */
cf1cce5e 250 pdkim_bodyhash *calc_body_hash; /* hash to be / being calculated */
2592e6c0 251
cf1cce5e 252 pdkim_stringlist *headers; /* Raw headers included in the sig */
9e70917d 253
80a47a2c 254 /* Signing specific ------------------------------------------------- */
d73e45df 255 uschar * privkey; /* Private key */
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256 uschar * sign_headers; /* To-be-signed header names */
257 uschar * rawsig_no_b_val; /* Original signature header w/o b= tag value. */
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258} pdkim_signature;
259
260
261/* -------------------------------------------------------------------------- */
262/* Context to keep state between all operations. */
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263typedef struct pdkim_ctx {
264
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265#define PDKIM_MODE_SIGN BIT(0) /* if unset, mode==verify */
266#define PDKIM_DOT_TERM BIT(1) /* dot termination and unstuffing */
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267#define PDKIM_SEEN_CR BIT(2)
268#define PDKIM_SEEN_LF BIT(3)
e983e85a 269#define PDKIM_PAST_HDRS BIT(4)
b895f4b2 270#define PDKIM_SEEN_EOD BIT(5)
e983e85a 271 unsigned flags;
80a47a2c 272
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273 /* One (signing) or several chained (verification) signatures */
274 pdkim_signature *sig;
275
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276 /* One (signing) or several chained (verification) bodyhashes */
277 pdkim_bodyhash *bodyhash;
278
80a47a2c 279 /* Callback for dns/txt query method (verification only) */
fc2ba7b9 280 uschar * (*dns_txt_callback)(const uschar *);
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281
282 /* Coder's little helpers */
acec9514 283 gstring *cur_header;
7845dbb3 284 uschar *linebuf;
80a47a2c 285 int linebuf_offset;
80a47a2c 286 int num_headers;
37f8b554 287 pdkim_stringlist *headers; /* Raw headers for verification */
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288} pdkim_ctx;
289
290
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291/******************************************************************************/
292
293typedef struct {
294 const uschar * dkim_hashname;
295 hashmethod exim_hashmethod;
296} pdkim_hashtype;
297extern const pdkim_hashtype pdkim_hashes[];
298
299/******************************************************************************/
300
301
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302/* -------------------------------------------------------------------------- */
303/* API functions. Please see the sample code in sample/test_sign.c and
304 sample/test_verify.c for documentation.
305*/
306
307#ifdef __cplusplus
308extern "C" {
309#endif
310
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311void pdkim_init (void);
312
fc2ba7b9 313void pdkim_init_context (pdkim_ctx *, BOOL, uschar * (*)(const uschar *));
9e70917d 314
80a47a2c 315DLLEXPORT
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316pdkim_signature *pdkim_init_sign (pdkim_ctx *,
317 uschar *, uschar *, uschar *, uschar *,
318 const uschar **);
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319
320DLLEXPORT
fc2ba7b9 321pdkim_ctx *pdkim_init_verify (uschar * (*)(const uschar *), BOOL);
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322
323DLLEXPORT
9e70917d 324void pdkim_set_optional (pdkim_signature *, char *, char *,int, int,
f444c2c7 325 long,
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326 unsigned long,
327 unsigned long);
328
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329int pdkim_hashname_to_hashtype(const uschar *, unsigned);
330void pdkim_cstring_to_canons(const uschar *, unsigned, int *, int *);
331pdkim_bodyhash *pdkim_set_bodyhash(pdkim_ctx *, int, int, long);
332pdkim_bodyhash *pdkim_set_sig_bodyhash(pdkim_ctx *, pdkim_signature *);
cf1cce5e 333
80a47a2c 334DLLEXPORT
ef698bf6 335int pdkim_feed (pdkim_ctx *, uschar *, int);
80a47a2c 336DLLEXPORT
b9df1829 337int pdkim_feed_finish (pdkim_ctx *, pdkim_signature **, const uschar **);
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338
339DLLEXPORT
340void pdkim_free_ctx (pdkim_ctx *);
341
f7302073 342
b9df1829 343const uschar * pdkim_errstr(int);
f7302073 344
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345extern uschar * pdkim_encode_base64(blob *);
346extern void pdkim_decode_base64(const uschar *, blob *);
347extern void pdkim_hexprint(const uschar *, int);
348extern void pdkim_quoteprint(const uschar *, int);
349extern pdkim_pubkey * pdkim_parse_pubkey_record(const uschar *);
350extern uschar * pdkim_relax_header_n(const uschar *, int, BOOL);
351extern uschar * pdkim_relax_header(const uschar *, BOOL);
352extern uschar * dkim_sig_to_a_tag(const pdkim_signature *);
d73e45df 353
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354#ifdef __cplusplus
355}
356#endif
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357
358#endif