src/src/pdkim/pdkim.h

   1 /*
   2  *  PDKIM - a RFC4871 (DKIM) implementation
   3  *
   4  *  Copyright (C) 2009 - 2012  Tom Kistner <tom@duncanthrax.net>
   5  *
   6  *  http://duncanthrax.net/pdkim/
   7  *
   8  *  This program is free software; you can redistribute it and/or modify
   9  *  it under the terms of the GNU General Public License as published by
  10  *  the Free Software Foundation; either version 2 of the License, or
  11  *  (at your option) any later version.
  12  *
  13  *  This program is distributed in the hope that it will be useful,
  14  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  *  GNU General Public License for more details.
  17  *
  18  *  You should have received a copy of the GNU General Public License along
  19  *  with this program; if not, write to the Free Software Foundation, Inc.,
  20  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  21  */
  22
  23 /* -------------------------------------------------------------------------- */
  24 /* Debugging. This can also be enabled/disabled at run-time. I recommend to
  25    leave it defined. */
  26 #define PDKIM_DEBUG
  27
  28 /* -------------------------------------------------------------------------- */
  29 /* Length of the preallocated buffer for the "answer" from the dns/txt
  30    callback function. This should match the maximum RDLENGTH from DNS. */
  31 #define PDKIM_DNS_TXT_MAX_RECLEN    (1 << 16)
  32
  33 /* -------------------------------------------------------------------------- */
  34 /* Function success / error codes */
  35 #define PDKIM_OK                      0
  36 #define PDKIM_FAIL                   -1
  37 #define PDKIM_ERR_OOM              -100
  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
  42
  43 /* -------------------------------------------------------------------------- */
  44 /* Main/Extended verification status */
  45 #define PDKIM_VERIFY_NONE      0
  46 #define PDKIM_VERIFY_INVALID   1
  47 #define PDKIM_VERIFY_FAIL      2
  48 #define PDKIM_VERIFY_PASS      3
  49
  50 #define PDKIM_VERIFY_FAIL_BODY                  1
  51 #define PDKIM_VERIFY_FAIL_MESSAGE               2
  52 #define PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE 3
  53 #define PDKIM_VERIFY_INVALID_BUFFER_SIZE        4
  54 #define PDKIM_VERIFY_INVALID_PUBKEY_PARSING     5
  55
  56 /* -------------------------------------------------------------------------- */
  57 /* Some parameter values */
  58 #define PDKIM_QUERYMETHOD_DNS_TXT 0
  59
  60 #define PDKIM_ALGO_RSA_SHA256     0
  61 #define PDKIM_ALGO_RSA_SHA1       1
  62
  63 #define PDKIM_CANON_SIMPLE        0
  64 #define PDKIM_CANON_RELAXED       1
  65
  66 #define PDKIM_HASH_SHA256         0
  67 #define PDKIM_HASH_SHA1           1
  68
  69 #define PDKIM_KEYTYPE_RSA         0
  70
  71 /* -------------------------------------------------------------------------- */
  72 /* Some required forward declarations, please ignore */
  73 typedef struct pdkim_stringlist pdkim_stringlist;
  74 typedef struct pdkim_str pdkim_str;
  75 typedef struct sha1_context sha1_context;
  76 typedef struct sha2_context sha2_context;
  77 #define HAVE_SHA1_CONTEXT
  78 #define HAVE_SHA2_CONTEXT
  79
  80 /* -------------------------------------------------------------------------- */
  81 /* Some concessions towards Redmond */
  82 #ifdef WINDOWS
  83 #define snprintf _snprintf
  84 #define strcasecmp _stricmp
  85 #define strncasecmp _strnicmp
  86 #define DLLEXPORT __declspec(dllexport)
  87 #else
  88 #define DLLEXPORT
  89 #endif
  90
  91
  92 /* -------------------------------------------------------------------------- */
  93 /* Public key as (usually) fetched from DNS */
  94 typedef struct pdkim_pubkey {
  95   char *version;                  /* v=  */
  96   char *granularity;              /* g=  */
  97
  98   char *hashes;                   /* h=  */
  99   char *keytype;                  /* k=  */
 100   char *srvtype;                  /* s=  */
 101   char *notes;                    /* n=  */
 102
 103   char *key;                      /* p=  */
 104   int   key_len;
 105
 106   int   testing;                  /* t=y */
 107   int   no_subdomaining;          /* t=s */
 108 } pdkim_pubkey;
 109
 110 /* -------------------------------------------------------------------------- */
 111 /* Signature as it appears in a DKIM-Signature header */
 112 typedef struct pdkim_signature {
 113
 114   /* Bits stored in a DKIM signature header --------------------------- */
 115
 116   /* (v=) The version, as an integer. Currently, always "1" */
 117   int version;
 118
 119   /* (a=) The signature algorithm. Either PDKIM_ALGO_RSA_SHA256
 120      or PDKIM_ALGO_RSA_SHA1 */
 121   int algo;
 122
 123   /* (c=x/) Header canonicalization method. Either PDKIM_CANON_SIMPLE
 124      or PDKIM_CANON_RELAXED */
 125   int canon_headers;
 126
 127   /* (c=/x) Body canonicalization method. Either PDKIM_CANON_SIMPLE
 128      or PDKIM_CANON_RELAXED */
 129   int canon_body;
 130
 131   /* (q=) Query Method. Currently, only PDKIM_QUERYMETHOD_DNS_TXT
 132      is specified */
 133   int querymethod;
 134
 135   /* (s=) The selector string as given in the signature */
 136   char *selector;
 137
 138   /* (d=) The domain as given in the signature */
 139   char *domain;
 140
 141   /* (i=) The identity as given in the signature */
 142   char *identity;
 143
 144   /* (t=) Timestamp of signature creation */
 145   unsigned long created;
 146
 147   /* (x=) Timestamp of expiry of signature */
 148   unsigned long expires;
 149
 150   /* (l=) Amount of hashed body bytes (after canonicalization). Default
 151      is -1. Note: a value of 0 means that the body is unsigned! */
 152   long bodylength;
 153
 154   /* (h=) Colon-separated list of header names that are included in the
 155      signature */
 156   char *headernames;
 157
 158   /* (z=) */
 159   char *copiedheaders;
 160
 161   /* (b=) Raw signature data, along with its length in bytes */
 162   char *sigdata;
 163   int   sigdata_len;
 164
 165   /* (bh=) Raw body hash data, along with its length in bytes */
 166   char *bodyhash;
 167   int   bodyhash_len;
 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(). */
 173   char *signature_header;
 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 ----------------------------------- */
 233   sha1_context *sha1_body; /* SHA1 block                                */
 234   sha2_context *sha2_body; /* SHA256 block                              */
 235   unsigned long signed_body_bytes; /* How many body bytes we hashed     */
 236   pdkim_stringlist *headers; /* Raw headers included in the sig         */
 237   /* Signing specific ------------------------------------------------- */
 238   char *rsa_privkey;     /* Private RSA key                             */
 239   char *sign_headers;    /* To-be-signed header names                   */
 240   char *rawsig_no_b_val; /* Original signature header w/o b= tag value. */
 241 } pdkim_signature;
 242
 243
 244 /* -------------------------------------------------------------------------- */
 245 /* Context to keep state between all operations. */
 246 #define PDKIM_MODE_SIGN     0
 247 #define PDKIM_MODE_VERIFY   1
 248 #define PDKIM_INPUT_NORMAL  0
 249 #define PDKIM_INPUT_SMTP    1
 250 typedef struct pdkim_ctx {
 251
 252   /* PDKIM_MODE_VERIFY or PDKIM_MODE_SIGN */
 253   int mode;
 254
 255   /* PDKIM_INPUT_SMTP or PDKIM_INPUT_NORMAL */
 256   int input_mode;
 257
 258   /* One (signing) or several chained (verification) signatures */
 259   pdkim_signature *sig;
 260
 261   /* Callback for dns/txt query method (verification only) */
 262   int(*dns_txt_callback)(char *, char *);
 263
 264   /* Coder's little helpers */
 265   pdkim_str *cur_header;
 266   char      *linebuf;
 267   int        linebuf_offset;
 268   int        seen_lf;
 269   int        seen_eod;
 270   int        past_headers;
 271   int        num_buffered_crlf;
 272   int        num_headers;
 273   pdkim_stringlist *headers; /* Raw headers for verification         */
 274
 275 #ifdef PDKIM_DEBUG
 276   /* A FILE pointer. When not NULL, debug output will be generated
 277     and sent to this stream */
 278   FILE *debug_stream;
 279 #endif
 280
 281 } pdkim_ctx;
 282
 283
 284 /* -------------------------------------------------------------------------- */
 285 /* API functions. Please see the sample code in sample/test_sign.c and
 286    sample/test_verify.c for documentation.
 287 */
 288
 289 #ifdef __cplusplus
 290 extern "C" {
 291 #endif
 292
 293 DLLEXPORT
 294 pdkim_ctx *pdkim_init_sign    (int, char *, char *, char *);
 295
 296 DLLEXPORT
 297 pdkim_ctx *pdkim_init_verify  (int, int(*)(char *, char *));
 298
 299 DLLEXPORT
 300 int        pdkim_set_optional (pdkim_ctx *, char *, char *,int, int,
 301                                long, int,
 302                                unsigned long,
 303                                unsigned long);
 304
 305 DLLEXPORT
 306 int        pdkim_feed         (pdkim_ctx *, char *, int);
 307 DLLEXPORT
 308 int        pdkim_feed_finish  (pdkim_ctx *, pdkim_signature **);
 309
 310 DLLEXPORT
 311 void       pdkim_free_ctx     (pdkim_ctx *);
 312
 313 #ifdef PDKIM_DEBUG
 314 DLLEXPORT
 315 void       pdkim_set_debug_stream(pdkim_ctx *, FILE *);
 316 #endif
 317
 318 #ifdef __cplusplus
 319 }
 320 #endif