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_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 #define PDKIM_SIGN_PRIVKEY_WRAP    -105
  43 #define PDKIM_SIGN_PRIVKEY_B64D    -106
  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
  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
  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 */
  78 typedef struct pdkim_stringlist pdkim_stringlist;
  79 typedef struct pdkim_str pdkim_str;
  80 typedef struct sha1_context sha1_context;
  81 typedef struct sha2_context sha2_context;
  82 #define HAVE_SHA1_CONTEXT
  83 #define HAVE_SHA2_CONTEXT
  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 */
  99 typedef struct pdkim_pubkey {
 100   uschar *version;                /* v=  */
 101   uschar *granularity;            /* g=  */
 102
 103   uschar *hashes;                 /* h=  */
 104   uschar *keytype;                /* k=  */
 105   uschar *srvtype;                /* s=  */
 106   uschar *notes;                  /* n=  */
 107
 108   blob  key;                      /* p=  */
 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 */
 116 typedef 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 */
 140   uschar *selector;
 141
 142   /* (d=) The domain as given in the signature */
 143   uschar *domain;
 144
 145   /* (i=) The identity as given in the signature */
 146   uschar *identity;
 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 */
 160   uschar *headernames;
 161
 162   /* (z=) */
 163   uschar *copiedheaders;
 164
 165   /* (b=) Raw signature data, along with its length in bytes */
 166   blob sigdata;
 167
 168   /* (bh=) Raw body hash data, along with its length in bytes */
 169   blob bodyhash;
 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(). */
 175   uschar *signature_header;
 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 ----------------------------------- */
 235   hctx         body_hash;
 236
 237   unsigned long signed_body_bytes; /* How many body bytes we hashed     */
 238   pdkim_stringlist *headers; /* Raw headers included in the sig         */
 239   /* Signing specific ------------------------------------------------- */
 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. */
 243 } pdkim_signature;
 244
 245
 246 /* -------------------------------------------------------------------------- */
 247 /* Context to keep state between all operations. */
 248 typedef struct pdkim_ctx {
 249
 250 #define PDKIM_MODE_SIGN   BIT(0)        /* if unset, mode==verify */
 251 #define PDKIM_DOT_TERM    BIT(1)        /* dot termination and unstuffing */
 252 #define PDKIM_SEEN_LF     BIT(2)
 253 #define PDKIM_SEEN_EOD    BIT(3)
 254 #define PDKIM_PAST_HDRS   BIT(4)
 255   unsigned   flags;
 256
 257   /* One (signing) or several chained (verification) signatures */
 258   pdkim_signature *sig;
 259
 260   /* Callback for dns/txt query method (verification only) */
 261   int(*dns_txt_callback)(char *, char *);
 262
 263   /* Coder's little helpers */
 264   uschar    *cur_header;
 265   int        cur_header_size;
 266   int        cur_header_len;
 267   char      *linebuf;
 268   int        linebuf_offset;
 269   int        num_buffered_crlf;
 270   int        num_headers;
 271   pdkim_stringlist *headers; /* Raw headers for verification         */
 272 } pdkim_ctx;
 273
 274
 275 /* -------------------------------------------------------------------------- */
 276 /* API functions. Please see the sample code in sample/test_sign.c and
 277    sample/test_verify.c for documentation.
 278 */
 279
 280 #ifdef __cplusplus
 281 extern "C" {
 282 #endif
 283
 284 void       pdkim_init         (void);
 285
 286 DLLEXPORT
 287 pdkim_ctx *pdkim_init_sign    (char *, char *, char *, int, BOOL);
 288
 289 DLLEXPORT
 290 pdkim_ctx *pdkim_init_verify  (int(*)(char *, char *), BOOL);
 291
 292 DLLEXPORT
 293 int        pdkim_set_optional (pdkim_ctx *, char *, char *,int, int,
 294                                long,
 295                                unsigned long,
 296                                unsigned long);
 297
 298 DLLEXPORT
 299 int        pdkim_feed         (pdkim_ctx *, char *, int);
 300 DLLEXPORT
 301 int        pdkim_feed_finish  (pdkim_ctx *, pdkim_signature **);
 302
 303 DLLEXPORT
 304 void       pdkim_free_ctx     (pdkim_ctx *);
 305
 306
 307 const char *    pdkim_errstr(int);
 308
 309 #ifdef __cplusplus
 310 }
 311 #endif
 312
 313 #endif