Revert "DKIM: reduce memory usage"
[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>
80fea873 5 * Copyright (c) Jeremy Harris 2016
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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
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
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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 */
78typedef struct pdkim_stringlist pdkim_stringlist;
79typedef struct pdkim_str pdkim_str;
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80typedef struct sha1_context sha1_context;
81typedef struct sha2_context sha2_context;
82#define HAVE_SHA1_CONTEXT
83#define HAVE_SHA2_CONTEXT
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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 */
99typedef struct pdkim_pubkey {
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100 uschar *version; /* v= */
101 uschar *granularity; /* g= */
80a47a2c 102
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103 uschar *hashes; /* h= */
104 uschar *keytype; /* k= */
105 uschar *srvtype; /* s= */
106 uschar *notes; /* n= */
80a47a2c 107
2592e6c0 108 blob key; /* p= */
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109
110 int testing; /* t=y */
111 int no_subdomaining; /* t=s */
112} pdkim_pubkey;
113
114/* -------------------------------------------------------------------------- */
115/* Signature as it appears in a DKIM-Signature header */
116typedef struct pdkim_signature {
117
118 /* Bits stored in a DKIM signature header --------------------------- */
119
120 /* (v=) The version, as an integer. Currently, always "1" */
121 int version;
122
123 /* (a=) The signature algorithm. Either PDKIM_ALGO_RSA_SHA256
124 or PDKIM_ALGO_RSA_SHA1 */
125 int algo;
126
127 /* (c=x/) Header canonicalization method. Either PDKIM_CANON_SIMPLE
128 or PDKIM_CANON_RELAXED */
129 int canon_headers;
130
131 /* (c=/x) Body canonicalization method. Either PDKIM_CANON_SIMPLE
132 or PDKIM_CANON_RELAXED */
133 int canon_body;
134
135 /* (q=) Query Method. Currently, only PDKIM_QUERYMETHOD_DNS_TXT
136 is specified */
137 int querymethod;
138
139 /* (s=) The selector string as given in the signature */
e2e3255a 140 uschar *selector;
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141
142 /* (d=) The domain as given in the signature */
e2e3255a 143 uschar *domain;
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144
145 /* (i=) The identity as given in the signature */
e2e3255a 146 uschar *identity;
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147
148 /* (t=) Timestamp of signature creation */
149 unsigned long created;
150
151 /* (x=) Timestamp of expiry of signature */
152 unsigned long expires;
153
154 /* (l=) Amount of hashed body bytes (after canonicalization). Default
155 is -1. Note: a value of 0 means that the body is unsigned! */
156 long bodylength;
157
158 /* (h=) Colon-separated list of header names that are included in the
159 signature */
2592e6c0 160 uschar *headernames;
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161
162 /* (z=) */
e2e3255a 163 uschar *copiedheaders;
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164
165 /* (b=) Raw signature data, along with its length in bytes */
2592e6c0 166 blob sigdata;
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167
168 /* (bh=) Raw body hash data, along with its length in bytes */
2592e6c0 169 blob bodyhash;
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170
171 /* Folded DKIM-Signature: header. Singing only, NULL for verifying.
172 Ready for insertion into the message. Note: Folded using CRLFTB,
173 but final line terminator is NOT included. Note2: This buffer is
174 free()d when you call pdkim_free_ctx(). */
e2e3255a 175 uschar *signature_header;
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176
177 /* The main verification status. Verification only. One of:
178
179 PDKIM_VERIFY_NONE Verification was not attempted. This status
180 should not appear.
181
182 PDKIM_VERIFY_INVALID There was an error while trying to verify
183 the signature. A more precise description
184 is available in verify_ext_status.
185
186 PDKIM_VERIFY_FAIL Verification failed because either the body
187 hash did not match, or the signature verification
188 failed. This means the message was modified.
189 Check verify_ext_status for the exact reason.
190
191 PDKIM_VERIFY_PASS Verification succeeded.
192 */
193 int verify_status;
194
195 /* Extended verification status. Verification only. Depending on the value
196 of verify_status, it can contain:
197
198 For verify_status == PDKIM_VERIFY_INVALID:
199
200 PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE
201 Unable to retrieve a public key container.
202
203 PDKIM_VERIFY_INVALID_BUFFER_SIZE
204 Either the DNS name constructed to retrieve the public key record
205 does not fit into PDKIM_DNS_TXT_MAX_NAMELEN bytes, or the retrieved
206 record is longer than PDKIM_DNS_TXT_MAX_RECLEN bytes.
207
208 PDKIM_VERIFY_INVALID_PUBKEY_PARSING
209 (Syntax) error while parsing the retrieved public key record.
210
211
212 For verify_status == PDKIM_VERIFY_FAIL:
213
214 PDKIM_VERIFY_FAIL_BODY
215 The calculated body hash does not match the advertised body hash
216 from the bh= tag of the signature.
217
218 PDKIM_VERIFY_FAIL_MESSAGE
219 RSA verification of the signature (b= tag) failed.
220 */
221 int verify_ext_status;
222
223 /* Pointer to a public key record that was used to verify the signature.
224 See pdkim_pubkey declaration above for more information.
225 Caution: is NULL if signing or if no record was retrieved. */
226 pdkim_pubkey *pubkey;
227
228 /* Pointer to the next pdkim_signature signature. NULL if signing or if
229 this is the last signature. */
230 void *next;
231
232 /* Properties below this point are used internally only ------------- */
233
234 /* Per-signature helper variables ----------------------------------- */
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235 hctx body_hash;
236
80a47a2c 237 unsigned long signed_body_bytes; /* How many body bytes we hashed */
cb224393 238 pdkim_stringlist *headers; /* Raw headers included in the sig */
80a47a2c 239 /* Signing specific ------------------------------------------------- */
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240 uschar * rsa_privkey; /* Private RSA key */
241 uschar * sign_headers; /* To-be-signed header names */
242 uschar * rawsig_no_b_val; /* Original signature header w/o b= tag value. */
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243} pdkim_signature;
244
245
246/* -------------------------------------------------------------------------- */
247/* Context to keep state between all operations. */
248#define PDKIM_MODE_SIGN 0
249#define PDKIM_MODE_VERIFY 1
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250typedef struct pdkim_ctx {
251
252 /* PDKIM_MODE_VERIFY or PDKIM_MODE_SIGN */
253 int mode;
254
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255 /* One (signing) or several chained (verification) signatures */
256 pdkim_signature *sig;
257
258 /* Callback for dns/txt query method (verification only) */
259 int(*dns_txt_callback)(char *, char *);
260
261 /* Coder's little helpers */
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262 uschar *cur_header;
263 int cur_header_size;
264 int cur_header_len;
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265 char *linebuf;
266 int linebuf_offset;
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267 BOOL seen_lf;
268 BOOL seen_eod;
269 BOOL past_headers;
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270 int num_buffered_crlf;
271 int num_headers;
37f8b554 272 pdkim_stringlist *headers; /* Raw headers for verification */
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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
282extern "C" {
283#endif
284
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285void pdkim_init (void);
286
80a47a2c 287DLLEXPORT
f444c2c7 288pdkim_ctx *pdkim_init_sign (char *, char *, char *, int);
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289
290DLLEXPORT
0d04a285 291pdkim_ctx *pdkim_init_verify (int(*)(char *, char *));
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292
293DLLEXPORT
294int pdkim_set_optional (pdkim_ctx *, char *, char *,int, int,
f444c2c7 295 long,
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296 unsigned long,
297 unsigned long);
298
299DLLEXPORT
300int pdkim_feed (pdkim_ctx *, char *, int);
301DLLEXPORT
302int pdkim_feed_finish (pdkim_ctx *, pdkim_signature **);
303
304DLLEXPORT
305void pdkim_free_ctx (pdkim_ctx *);
306
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307
308const char * pdkim_errstr(int);
309
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310#ifdef __cplusplus
311}
312#endif
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313
314#endif