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) Jeremy Harris 2016
   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 /* -------------------------------------------------------------------------- */
  30 /* Length of the preallocated buffer for the "answer" from the dns/txt
  31    callback function. This should match the maximum RDLENGTH from DNS. */
  32 #define PDKIM_DNS_TXT_MAX_RECLEN    (1 << 16)
  33
  34 /* -------------------------------------------------------------------------- */
  35 /* Function success / error codes */
  36 #define PDKIM_OK                      0
  37 #define PDKIM_FAIL                   -1
  38 #define PDKIM_ERR_OOM              -100
  39 #define PDKIM_ERR_RSA_PRIVKEY      -101
  40 #define PDKIM_ERR_RSA_SIGNING      -102
  41 #define PDKIM_ERR_LONG_LINE        -103
  42 #define PDKIM_ERR_BUFFER_TOO_SMALL -104
  43 #define PDKIM_SIGN_PRIVKEY_WRAP    -105
  44 #define PDKIM_SIGN_PRIVKEY_B64D    -106
  45
  46 /* -------------------------------------------------------------------------- */
  47 /* Main/Extended verification status */
  48 #define PDKIM_VERIFY_NONE      0
  49 #define PDKIM_VERIFY_INVALID   1
  50 #define PDKIM_VERIFY_FAIL      2
  51 #define PDKIM_VERIFY_PASS      3
  52
  53 #define PDKIM_VERIFY_FAIL_BODY                  1
  54 #define PDKIM_VERIFY_FAIL_MESSAGE               2
  55 #define PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE 3
  56 #define PDKIM_VERIFY_INVALID_BUFFER_SIZE        4
  57 #define PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD   5
  58 #define PDKIM_VERIFY_INVALID_PUBKEY_IMPORT      6
  59
  60 /* -------------------------------------------------------------------------- */
  61 /* Some parameter values */
  62 #define PDKIM_QUERYMETHOD_DNS_TXT 0
  63
  64 #define PDKIM_ALGO_RSA_SHA256     0
  65 #define PDKIM_ALGO_RSA_SHA1       1
  66
  67 #define PDKIM_CANON_SIMPLE        0
  68 #define PDKIM_CANON_RELAXED       1
  69
  70 #define PDKIM_HASH_SHA256         0
  71 #define PDKIM_HASH_SHA1           1
  72
  73 #define PDKIM_KEYTYPE_RSA         0
  74
  75 /* -------------------------------------------------------------------------- */
  76 /* Some required forward declarations, please ignore */
  77 typedef struct pdkim_stringlist pdkim_stringlist;
  78 typedef struct pdkim_str pdkim_str;
  79 typedef struct sha1_context sha1_context;
  80 typedef struct sha2_context sha2_context;
  81 #define HAVE_SHA1_CONTEXT
  82 #define HAVE_SHA2_CONTEXT
  83
  84 /* -------------------------------------------------------------------------- */
  85 /* Some concessions towards Redmond */
  86 #ifdef WINDOWS
  87 #define snprintf _snprintf
  88 #define strcasecmp _stricmp
  89 #define strncasecmp _strnicmp
  90 #define DLLEXPORT __declspec(dllexport)
  91 #else
  92 #define DLLEXPORT
  93 #endif
  94
  95
  96 /* -------------------------------------------------------------------------- */
  97 /* Public key as (usually) fetched from DNS */
  98 typedef struct pdkim_pubkey {
  99   char *version;                  /* v=  */
 100   char *granularity;              /* g=  */
 101
 102   char *hashes;                   /* h=  */
 103   char *keytype;                  /* k=  */
 104   char *srvtype;                  /* s=  */
 105   char *notes;                    /* n=  */
 106
 107   blob  key;                      /* p=  */
 108
 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 */
 115 typedef 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
 122   /* (a=) The signature algorithm. Either PDKIM_ALGO_RSA_SHA256
 123      or PDKIM_ALGO_RSA_SHA1 */
 124   int algo;
 125
 126   /* (c=x/) Header canonicalization method. Either PDKIM_CANON_SIMPLE
 127      or PDKIM_CANON_RELAXED */
 128   int canon_headers;
 129
 130   /* (c=/x) Body canonicalization method. Either PDKIM_CANON_SIMPLE
 131      or PDKIM_CANON_RELAXED */
 132   int canon_body;
 133
 134   /* (q=) Query Method. Currently, only PDKIM_QUERYMETHOD_DNS_TXT
 135      is specified */
 136   int querymethod;
 137
 138   /* (s=) The selector string as given in the signature */
 139   char *selector;
 140
 141   /* (d=) The domain as given in the signature */
 142   char *domain;
 143
 144   /* (i=) The identity as given in the signature */
 145   char *identity;
 146
 147   /* (t=) Timestamp of signature creation */
 148   unsigned long created;
 149
 150   /* (x=) Timestamp of expiry of signature */
 151   unsigned long expires;
 152
 153   /* (l=) Amount of hashed body bytes (after canonicalization). Default
 154      is -1. Note: a value of 0 means that the body is unsigned! */
 155   long bodylength;
 156
 157   /* (h=) Colon-separated list of header names that are included in the
 158      signature */
 159   uschar *headernames;
 160
 161   /* (z=) */
 162   char *copiedheaders;
 163
 164   /* (b=) Raw signature data, along with its length in bytes */
 165   blob sigdata;
 166
 167   /* (bh=) Raw body hash data, along with its length in bytes */
 168   blob bodyhash;
 169
 170   /* Folded DKIM-Signature: header. Singing only, NULL for verifying.
 171      Ready for insertion into the message. Note: Folded using CRLFTB,
 172      but final line terminator is NOT included. Note2: This buffer is
 173      free()d when you call pdkim_free_ctx(). */
 174   char *signature_header;
 175
 176   /* The main verification status. Verification only. One of:
 177
 178      PDKIM_VERIFY_NONE      Verification was not attempted. This status
 179                             should not appear.
 180
 181      PDKIM_VERIFY_INVALID   There was an error while trying to verify
 182                             the signature. A more precise description
 183                             is available in verify_ext_status.
 184
 185      PDKIM_VERIFY_FAIL      Verification failed because either the body
 186                             hash did not match, or the signature verification
 187                             failed. This means the message was modified.
 188                             Check verify_ext_status for the exact reason.
 189
 190      PDKIM_VERIFY_PASS      Verification succeeded.
 191   */
 192   int verify_status;
 193
 194   /* Extended verification status. Verification only. Depending on the value
 195      of verify_status, it can contain:
 196
 197      For verify_status == PDKIM_VERIFY_INVALID:
 198
 199         PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE
 200           Unable to retrieve a public key container.
 201
 202         PDKIM_VERIFY_INVALID_BUFFER_SIZE
 203           Either the DNS name constructed to retrieve the public key record
 204           does not fit into PDKIM_DNS_TXT_MAX_NAMELEN bytes, or the retrieved
 205           record is longer than PDKIM_DNS_TXT_MAX_RECLEN bytes.
 206
 207         PDKIM_VERIFY_INVALID_PUBKEY_PARSING
 208           (Syntax) error while parsing the retrieved public key record.
 209
 210
 211      For verify_status == PDKIM_VERIFY_FAIL:
 212
 213         PDKIM_VERIFY_FAIL_BODY
 214           The calculated body hash does not match the advertised body hash
 215           from the bh= tag of the signature.
 216
 217         PDKIM_VERIFY_FAIL_MESSAGE
 218           RSA verification of the signature (b= tag) failed.
 219   */
 220   int verify_ext_status;
 221
 222   /* Pointer to a public key record that was used to verify the signature.
 223      See pdkim_pubkey declaration above for more information.
 224      Caution: is NULL if signing or if no record was retrieved. */
 225   pdkim_pubkey *pubkey;
 226
 227   /* Pointer to the next pdkim_signature signature. NULL if signing or if
 228      this is the last signature. */
 229   void *next;
 230
 231   /* Properties below this point are used internally only ------------- */
 232
 233   /* Per-signature helper variables ----------------------------------- */
 234   hctx         body_hash;
 235
 236   unsigned long signed_body_bytes; /* How many body bytes we hashed     */
 237   pdkim_stringlist *headers; /* Raw headers included in the sig         */
 238   /* Signing specific ------------------------------------------------- */
 239   char *rsa_privkey;     /* Private RSA key                             */
 240   char *sign_headers;    /* To-be-signed header names                   */
 241   char *rawsig_no_b_val; /* Original signature header w/o b= tag value. */
 242 } pdkim_signature;
 243
 244
 245 /* -------------------------------------------------------------------------- */
 246 /* Context to keep state between all operations. */
 247 #define PDKIM_MODE_SIGN     0
 248 #define PDKIM_MODE_VERIFY   1
 249 typedef struct pdkim_ctx {
 250
 251   /* PDKIM_MODE_VERIFY or PDKIM_MODE_SIGN */
 252   int mode;
 253
 254   /* One (signing) or several chained (verification) signatures */
 255   pdkim_signature *sig;
 256
 257   /* Callback for dns/txt query method (verification only) */
 258   int(*dns_txt_callback)(char *, char *);
 259
 260   /* Coder's little helpers */
 261   pdkim_str *cur_header;
 262   char      *linebuf;
 263   int        linebuf_offset;
 264   BOOL       seen_lf;
 265   BOOL       seen_eod;
 266   BOOL       past_headers;
 267   int        num_buffered_crlf;
 268   int        num_headers;
 269   pdkim_stringlist *headers; /* Raw headers for verification         */
 270 } pdkim_ctx;
 271
 272
 273 /* -------------------------------------------------------------------------- */
 274 /* API functions. Please see the sample code in sample/test_sign.c and
 275    sample/test_verify.c for documentation.
 276 */
 277
 278 #ifdef __cplusplus
 279 extern "C" {
 280 #endif
 281
 282 void       pdkim_init         (void);
 283
 284 DLLEXPORT
 285 pdkim_ctx *pdkim_init_sign    (char *, char *, char *, int);
 286
 287 DLLEXPORT
 288 pdkim_ctx *pdkim_init_verify  (int(*)(char *, char *));
 289
 290 DLLEXPORT
 291 int        pdkim_set_optional (pdkim_ctx *, char *, char *,int, int,
 292                                long,
 293                                unsigned long,
 294                                unsigned long);
 295
 296 DLLEXPORT
 297 int        pdkim_feed         (pdkim_ctx *, char *, int);
 298 DLLEXPORT
 299 int        pdkim_feed_finish  (pdkim_ctx *, pdkim_signature **);
 300
 301 DLLEXPORT
 302 void       pdkim_free_ctx     (pdkim_ctx *);
 303
 304 #ifdef __cplusplus
 305 }
 306 #endif
 307
 308 #endif