DKIM: support multiple hash methods
[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>
d4e5e70b 5 * Copyright (c) 2016 - 2017 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
80a47a2c 29/* -------------------------------------------------------------------------- */
80a47a2c 30/* Length of the preallocated buffer for the "answer" from the dns/txt
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31 callback function. This should match the maximum RDLENGTH from DNS. */
32#define PDKIM_DNS_TXT_MAX_RECLEN (1 << 16)
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33
34/* -------------------------------------------------------------------------- */
35/* Function success / error codes */
36#define PDKIM_OK 0
37#define PDKIM_FAIL -1
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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
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42#define PDKIM_SIGN_PRIVKEY_WRAP -105
43#define PDKIM_SIGN_PRIVKEY_B64D -106
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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
07eeb4df 52#define PDKIM_VERIFY_FAIL_BODY 1
53#define PDKIM_VERIFY_FAIL_MESSAGE 2
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54#define PDKIM_VERIFY_FAIL_SIG_ALGO_MISMATCH 3
55#define PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE 4
56#define PDKIM_VERIFY_INVALID_BUFFER_SIZE 5
57#define PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD 6
58#define PDKIM_VERIFY_INVALID_PUBKEY_IMPORT 7
59#define PDKIM_VERIFY_INVALID_SIGNATURE_ERROR 8
60#define PDKIM_VERIFY_INVALID_DKIM_VERSION 9
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61
62/* -------------------------------------------------------------------------- */
63/* Some parameter values */
64#define PDKIM_QUERYMETHOD_DNS_TXT 0
65
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66#define PDKIM_CANON_SIMPLE 0
67#define PDKIM_CANON_RELAXED 1
68
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69/*XXX change to enums */
70#define PDKIM_HASH_SHA256 1
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71
72#define PDKIM_KEYTYPE_RSA 0
73
74/* -------------------------------------------------------------------------- */
75/* Some required forward declarations, please ignore */
76typedef struct pdkim_stringlist pdkim_stringlist;
77typedef struct pdkim_str pdkim_str;
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78typedef struct sha1_context sha1_context;
79typedef struct sha2_context sha2_context;
80#define HAVE_SHA1_CONTEXT
81#define HAVE_SHA2_CONTEXT
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82
83/* -------------------------------------------------------------------------- */
84/* Some concessions towards Redmond */
85#ifdef WINDOWS
86#define snprintf _snprintf
87#define strcasecmp _stricmp
88#define strncasecmp _strnicmp
89#define DLLEXPORT __declspec(dllexport)
90#else
91#define DLLEXPORT
92#endif
93
94
95/* -------------------------------------------------------------------------- */
96/* Public key as (usually) fetched from DNS */
97typedef struct pdkim_pubkey {
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98 const uschar * version; /* v= */
99 const uschar *granularity; /* g= */
80a47a2c 100
35cf75e9 101 const uschar * hashes; /* h= */
135e9496 102#ifdef notdef
e2e3255a 103 uschar *keytype; /* k= */
e21a4d00 104#endif
35cf75e9 105 const uschar *srvtype; /* s= */
e2e3255a 106 uschar *notes; /* n= */
80a47a2c 107
2592e6c0 108 blob key; /* p= */
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109 int testing; /* t=y */
110 int no_subdomaining; /* t=s */
111} pdkim_pubkey;
112
113/* -------------------------------------------------------------------------- */
114/* Signature as it appears in a DKIM-Signature header */
115typedef struct pdkim_signature {
116
117 /* Bits stored in a DKIM signature header --------------------------- */
118
119 /* (v=) The version, as an integer. Currently, always "1" */
120 int version;
121
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122 int keytype; /* PDKIM_KEYTYPE_RSA */
123 int hashtype; /* pdkim_hashes index */
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124
125 /* (c=x/) Header canonicalization method. Either PDKIM_CANON_SIMPLE
126 or PDKIM_CANON_RELAXED */
127 int canon_headers;
128
129 /* (c=/x) Body canonicalization method. Either PDKIM_CANON_SIMPLE
130 or PDKIM_CANON_RELAXED */
131 int canon_body;
132
133 /* (q=) Query Method. Currently, only PDKIM_QUERYMETHOD_DNS_TXT
134 is specified */
135 int querymethod;
136
137 /* (s=) The selector string as given in the signature */
e2e3255a 138 uschar *selector;
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139
140 /* (d=) The domain as given in the signature */
e2e3255a 141 uschar *domain;
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142
143 /* (i=) The identity as given in the signature */
e2e3255a 144 uschar *identity;
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145
146 /* (t=) Timestamp of signature creation */
147 unsigned long created;
148
149 /* (x=) Timestamp of expiry of signature */
150 unsigned long expires;
151
152 /* (l=) Amount of hashed body bytes (after canonicalization). Default
153 is -1. Note: a value of 0 means that the body is unsigned! */
154 long bodylength;
155
156 /* (h=) Colon-separated list of header names that are included in the
157 signature */
2592e6c0 158 uschar *headernames;
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159
160 /* (z=) */
e2e3255a 161 uschar *copiedheaders;
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162
163 /* (b=) Raw signature data, along with its length in bytes */
dcd03763 164 blob sighash;
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165
166 /* (bh=) Raw body hash data, along with its length in bytes */
2592e6c0 167 blob bodyhash;
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168
169 /* Folded DKIM-Signature: header. Singing only, NULL for verifying.
170 Ready for insertion into the message. Note: Folded using CRLFTB,
171 but final line terminator is NOT included. Note2: This buffer is
172 free()d when you call pdkim_free_ctx(). */
e2e3255a 173 uschar *signature_header;
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174
175 /* The main verification status. Verification only. One of:
176
177 PDKIM_VERIFY_NONE Verification was not attempted. This status
178 should not appear.
179
180 PDKIM_VERIFY_INVALID There was an error while trying to verify
181 the signature. A more precise description
182 is available in verify_ext_status.
183
184 PDKIM_VERIFY_FAIL Verification failed because either the body
185 hash did not match, or the signature verification
186 failed. This means the message was modified.
187 Check verify_ext_status for the exact reason.
188
189 PDKIM_VERIFY_PASS Verification succeeded.
190 */
191 int verify_status;
192
193 /* Extended verification status. Verification only. Depending on the value
194 of verify_status, it can contain:
195
196 For verify_status == PDKIM_VERIFY_INVALID:
197
198 PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE
199 Unable to retrieve a public key container.
200
201 PDKIM_VERIFY_INVALID_BUFFER_SIZE
202 Either the DNS name constructed to retrieve the public key record
203 does not fit into PDKIM_DNS_TXT_MAX_NAMELEN bytes, or the retrieved
204 record is longer than PDKIM_DNS_TXT_MAX_RECLEN bytes.
205
206 PDKIM_VERIFY_INVALID_PUBKEY_PARSING
207 (Syntax) error while parsing the retrieved public key record.
208
209
210 For verify_status == PDKIM_VERIFY_FAIL:
211
212 PDKIM_VERIFY_FAIL_BODY
213 The calculated body hash does not match the advertised body hash
214 from the bh= tag of the signature.
215
216 PDKIM_VERIFY_FAIL_MESSAGE
217 RSA verification of the signature (b= tag) failed.
218 */
219 int verify_ext_status;
220
221 /* Pointer to a public key record that was used to verify the signature.
222 See pdkim_pubkey declaration above for more information.
223 Caution: is NULL if signing or if no record was retrieved. */
224 pdkim_pubkey *pubkey;
225
226 /* Pointer to the next pdkim_signature signature. NULL if signing or if
227 this is the last signature. */
228 void *next;
229
230 /* Properties below this point are used internally only ------------- */
231
232 /* Per-signature helper variables ----------------------------------- */
dcd03763 233 hctx body_hash_ctx;
2592e6c0 234
80a47a2c 235 unsigned long signed_body_bytes; /* How many body bytes we hashed */
cb224393 236 pdkim_stringlist *headers; /* Raw headers included in the sig */
80a47a2c 237 /* Signing specific ------------------------------------------------- */
d73e45df 238 uschar * privkey; /* Private key */
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239 uschar * sign_headers; /* To-be-signed header names */
240 uschar * rawsig_no_b_val; /* Original signature header w/o b= tag value. */
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241} pdkim_signature;
242
243
244/* -------------------------------------------------------------------------- */
245/* Context to keep state between all operations. */
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246typedef struct pdkim_ctx {
247
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248#define PDKIM_MODE_SIGN BIT(0) /* if unset, mode==verify */
249#define PDKIM_DOT_TERM BIT(1) /* dot termination and unstuffing */
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250#define PDKIM_SEEN_CR BIT(2)
251#define PDKIM_SEEN_LF BIT(3)
e983e85a 252#define PDKIM_PAST_HDRS BIT(4)
b895f4b2 253#define PDKIM_SEEN_EOD BIT(5)
e983e85a 254 unsigned flags;
80a47a2c 255
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256 /* One (signing) or several chained (verification) signatures */
257 pdkim_signature *sig;
258
259 /* Callback for dns/txt query method (verification only) */
260 int(*dns_txt_callback)(char *, char *);
261
262 /* Coder's little helpers */
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263 uschar *cur_header;
264 int cur_header_size;
265 int cur_header_len;
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266 char *linebuf;
267 int linebuf_offset;
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268 int num_buffered_crlf;
269 int num_headers;
37f8b554 270 pdkim_stringlist *headers; /* Raw headers for verification */
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271} pdkim_ctx;
272
273
274/* -------------------------------------------------------------------------- */
275/* API functions. Please see the sample code in sample/test_sign.c and
276 sample/test_verify.c for documentation.
277*/
278
279#ifdef __cplusplus
280extern "C" {
281#endif
282
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283void pdkim_init (void);
284
80a47a2c 285DLLEXPORT
d73e45df 286pdkim_ctx *pdkim_init_sign (uschar *, uschar *, uschar *, uschar *,
b9df1829 287 BOOL, int(*)(char *, char *), const uschar **);
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288
289DLLEXPORT
e983e85a 290pdkim_ctx *pdkim_init_verify (int(*)(char *, char *), BOOL);
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291
292DLLEXPORT
293int pdkim_set_optional (pdkim_ctx *, char *, char *,int, int,
f444c2c7 294 long,
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295 unsigned long,
296 unsigned long);
297
298DLLEXPORT
ef698bf6 299int pdkim_feed (pdkim_ctx *, uschar *, int);
80a47a2c 300DLLEXPORT
b9df1829 301int pdkim_feed_finish (pdkim_ctx *, pdkim_signature **, const uschar **);
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302
303DLLEXPORT
304void pdkim_free_ctx (pdkim_ctx *);
305
f7302073 306
b9df1829 307const uschar * pdkim_errstr(int);
f7302073 308
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309uschar * dkim_sig_to_a_tag(pdkim_signature * sig);
310
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311#ifdef __cplusplus
312}
313#endif
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314
315#endif