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) 2016 - 2017  Jeremy Harris
   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 #define PDKIM_DEFAULT_SIGN_HEADERS "From:Sender:Reply-To:Subject:Date:"\
  30                              "Message-ID:To:Cc:MIME-Version:Content-Type:"\
  31                              "Content-Transfer-Encoding:Content-ID:"\
  32                              "Content-Description:Resent-Date:Resent-From:"\
  33                              "Resent-Sender:Resent-To:Resent-Cc:"\
  34                              "Resent-Message-ID:In-Reply-To:References:"\
  35                              "List-Id:List-Help:List-Unsubscribe:"\
  36                              "List-Subscribe:List-Post:List-Owner:List-Archive"
  37
  38 /* -------------------------------------------------------------------------- */
  39 /* Length of the preallocated buffer for the "answer" from the dns/txt
  40    callback function. This should match the maximum RDLENGTH from DNS. */
  41 #define PDKIM_DNS_TXT_MAX_RECLEN    (1 << 16)
  42
  43 /* -------------------------------------------------------------------------- */
  44 /* Function success / error codes */
  45 #define PDKIM_OK                      0
  46 #define PDKIM_FAIL                   -1
  47 #define PDKIM_ERR_RSA_PRIVKEY      -101
  48 #define PDKIM_ERR_RSA_SIGNING      -102
  49 #define PDKIM_ERR_LONG_LINE        -103
  50 #define PDKIM_ERR_BUFFER_TOO_SMALL -104
  51 #define PDKIM_SIGN_PRIVKEY_WRAP    -105
  52 #define PDKIM_SIGN_PRIVKEY_B64D    -106
  53
  54 /* -------------------------------------------------------------------------- */
  55 /* Main/Extended verification status */
  56 #define PDKIM_VERIFY_NONE      0
  57 #define PDKIM_VERIFY_INVALID   1
  58 #define PDKIM_VERIFY_FAIL      2
  59 #define PDKIM_VERIFY_PASS      3
  60
  61 #define PDKIM_VERIFY_FAIL_BODY                    1
  62 #define PDKIM_VERIFY_FAIL_MESSAGE                 2
  63 #define PDKIM_VERIFY_FAIL_SIG_ALGO_MISMATCH       3
  64 #define PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE   4
  65 #define PDKIM_VERIFY_INVALID_BUFFER_SIZE          5
  66 #define PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD     6
  67 #define PDKIM_VERIFY_INVALID_PUBKEY_IMPORT        7
  68 #define PDKIM_VERIFY_INVALID_SIGNATURE_ERROR      8
  69 #define PDKIM_VERIFY_INVALID_DKIM_VERSION         9
  70
  71 /* -------------------------------------------------------------------------- */
  72 /* Some parameter values */
  73 #define PDKIM_QUERYMETHOD_DNS_TXT 0
  74
  75 #define PDKIM_CANON_SIMPLE        0
  76 #define PDKIM_CANON_RELAXED       1
  77
  78 /*XXX change to enums */
  79 #define PDKIM_HASH_SHA256         1
  80
  81 #define PDKIM_KEYTYPE_RSA         0
  82
  83 /* -------------------------------------------------------------------------- */
  84 /* Some required forward declarations, please ignore */
  85 typedef struct pdkim_stringlist pdkim_stringlist;
  86 typedef struct pdkim_str pdkim_str;
  87 typedef struct sha1_context sha1_context;
  88 typedef struct sha2_context sha2_context;
  89 #define HAVE_SHA1_CONTEXT
  90 #define HAVE_SHA2_CONTEXT
  91
  92 /* -------------------------------------------------------------------------- */
  93 /* Some concessions towards Redmond */
  94 #ifdef WINDOWS
  95 #define snprintf _snprintf
  96 #define strcasecmp _stricmp
  97 #define strncasecmp _strnicmp
  98 #define DLLEXPORT __declspec(dllexport)
  99 #else
 100 #define DLLEXPORT
 101 #endif
 102
 103
 104 /* -------------------------------------------------------------------------- */
 105 /* Public key as (usually) fetched from DNS */
 106 typedef struct pdkim_pubkey {
 107   const uschar * version;         /* v=  */
 108   const uschar *granularity;      /* g=  */
 109
 110   const uschar * hashes;          /* h=  */
 111 #ifdef notdef
 112   uschar *keytype;                /* k=  */
 113 #endif
 114   const uschar *srvtype;          /* s=  */
 115   uschar *notes;                  /* n=  */
 116
 117   blob  key;                      /* p=  */
 118   int   testing;                  /* t=y */
 119   int   no_subdomaining;          /* t=s */
 120 } pdkim_pubkey;
 121
 122 /* -------------------------------------------------------------------------- */
 123 /* Signature as it appears in a DKIM-Signature header */
 124 typedef struct pdkim_signature {
 125   struct pdkim_signature * next;
 126
 127   /* Bits stored in a DKIM signature header --------------------------- */
 128
 129   /* (v=) The version, as an integer. Currently, always "1" */
 130   int version;
 131
 132   int keytype;  /* PDKIM_KEYTYPE_RSA */
 133   int hashtype; /* pdkim_hashes index */
 134
 135   /* (c=x/) Header canonicalization method. Either PDKIM_CANON_SIMPLE
 136      or PDKIM_CANON_RELAXED */
 137   int canon_headers;
 138
 139   /* (c=/x) Body canonicalization method. Either PDKIM_CANON_SIMPLE
 140      or PDKIM_CANON_RELAXED */
 141   int canon_body;
 142
 143   /* (q=) Query Method. Currently, only PDKIM_QUERYMETHOD_DNS_TXT
 144      is specified */
 145   int querymethod;
 146
 147   /* (s=) The selector string as given in the signature */
 148   uschar *selector;
 149
 150   /* (d=) The domain as given in the signature */
 151   uschar *domain;
 152
 153   /* (i=) The identity as given in the signature */
 154   uschar *identity;
 155
 156   /* (t=) Timestamp of signature creation */
 157   unsigned long created;
 158
 159   /* (x=) Timestamp of expiry of signature */
 160   unsigned long expires;
 161
 162   /* (l=) Amount of hashed body bytes (after canonicalization). Default
 163      is -1. Note: a value of 0 means that the body is unsigned! */
 164   long bodylength;
 165
 166   /* (h=) Colon-separated list of header names that are included in the
 167      signature */
 168   uschar *headernames;
 169
 170   /* (z=) */
 171   uschar *copiedheaders;
 172
 173   /* (b=) Raw signature data, along with its length in bytes */
 174   blob sighash;
 175
 176   /* (bh=) Raw body hash data, along with its length in bytes */
 177   blob bodyhash;
 178
 179   /* Folded DKIM-Signature: header. Signing only, NULL for verifying.
 180      Ready for insertion into the message. Note: Folded using CRLFTB,
 181      but final line terminator is NOT included. Note2: This buffer is
 182      free()d when you call pdkim_free_ctx(). */
 183   uschar *signature_header;
 184
 185   /* The main verification status. Verification only. One of:
 186
 187      PDKIM_VERIFY_NONE      Verification was not attempted. This status
 188                             should not appear.
 189
 190      PDKIM_VERIFY_INVALID   There was an error while trying to verify
 191                             the signature. A more precise description
 192                             is available in verify_ext_status.
 193
 194      PDKIM_VERIFY_FAIL      Verification failed because either the body
 195                             hash did not match, or the signature verification
 196                             failed. This means the message was modified.
 197                             Check verify_ext_status for the exact reason.
 198
 199      PDKIM_VERIFY_PASS      Verification succeeded.
 200   */
 201   int verify_status;
 202
 203   /* Extended verification status. Verification only. Depending on the value
 204      of verify_status, it can contain:
 205
 206      For verify_status == PDKIM_VERIFY_INVALID:
 207
 208         PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE
 209           Unable to retrieve a public key container.
 210
 211         PDKIM_VERIFY_INVALID_BUFFER_SIZE
 212           Either the DNS name constructed to retrieve the public key record
 213           does not fit into PDKIM_DNS_TXT_MAX_NAMELEN bytes, or the retrieved
 214           record is longer than PDKIM_DNS_TXT_MAX_RECLEN bytes.
 215
 216         PDKIM_VERIFY_INVALID_PUBKEY_PARSING
 217           (Syntax) error while parsing the retrieved public key record.
 218
 219
 220      For verify_status == PDKIM_VERIFY_FAIL:
 221
 222         PDKIM_VERIFY_FAIL_BODY
 223           The calculated body hash does not match the advertised body hash
 224           from the bh= tag of the signature.
 225
 226         PDKIM_VERIFY_FAIL_MESSAGE
 227           RSA verification of the signature (b= tag) failed.
 228   */
 229   int verify_ext_status;
 230
 231   /* Pointer to a public key record that was used to verify the signature.
 232      See pdkim_pubkey declaration above for more information.
 233      Caution: is NULL if signing or if no record was retrieved. */
 234   pdkim_pubkey *pubkey;
 235
 236   /* Properties below this point are used internally only ------------- */
 237
 238   /* Per-signature helper variables ----------------------------------- */
 239   hctx         body_hash_ctx;
 240
 241   unsigned long signed_body_bytes; /* How many body bytes we hashed     */
 242   int num_buffered_blanklines;
 243   pdkim_stringlist *headers; /* Raw headers included in the sig         */
 244
 245   /* Signing specific ------------------------------------------------- */
 246   uschar * privkey;          /* Private key                                 */
 247   uschar * sign_headers;    /* To-be-signed header names                   */
 248   uschar * rawsig_no_b_val; /* Original signature header w/o b= tag value. */
 249 } pdkim_signature;
 250
 251
 252 /* -------------------------------------------------------------------------- */
 253 /* Context to keep state between all operations. */
 254 typedef struct pdkim_ctx {
 255
 256 #define PDKIM_MODE_SIGN   BIT(0)        /* if unset, mode==verify */
 257 #define PDKIM_DOT_TERM    BIT(1)        /* dot termination and unstuffing */
 258 #define PDKIM_SEEN_CR     BIT(2)
 259 #define PDKIM_SEEN_LF     BIT(3)
 260 #define PDKIM_PAST_HDRS   BIT(4)
 261 #define PDKIM_SEEN_EOD    BIT(5)
 262   unsigned   flags;
 263
 264   /* One (signing) or several chained (verification) signatures */
 265   pdkim_signature *sig;
 266
 267   /* Callback for dns/txt query method (verification only) */
 268   int(*dns_txt_callback)(char *, char *);
 269
 270   /* Coder's little helpers */
 271   gstring   *cur_header;
 272   uschar    *linebuf;
 273   int        linebuf_offset;
 274   int        num_headers;
 275   pdkim_stringlist *headers; /* Raw headers for verification         */
 276 } pdkim_ctx;
 277
 278
 279 /* -------------------------------------------------------------------------- */
 280 /* API functions. Please see the sample code in sample/test_sign.c and
 281    sample/test_verify.c for documentation.
 282 */
 283
 284 #ifdef __cplusplus
 285 extern "C" {
 286 #endif
 287
 288 void       pdkim_init         (void);
 289
 290 void       pdkim_init_context (pdkim_ctx *, BOOL, int(*)(char *, char *));
 291
 292 DLLEXPORT
 293 pdkim_signature *pdkim_init_sign    (pdkim_ctx *,
 294                                uschar *, uschar *, uschar *, uschar *,
 295                                const uschar **);
 296
 297 DLLEXPORT
 298 pdkim_ctx *pdkim_init_verify  (int(*)(char *, char *), BOOL);
 299
 300 DLLEXPORT
 301 void       pdkim_set_optional (pdkim_signature *, char *, char *,int, int,
 302                                long,
 303                                unsigned long,
 304                                unsigned long);
 305
 306 DLLEXPORT
 307 int        pdkim_feed         (pdkim_ctx *, uschar *, int);
 308 DLLEXPORT
 309 int        pdkim_feed_finish  (pdkim_ctx *, pdkim_signature **, const uschar **);
 310
 311 DLLEXPORT
 312 void       pdkim_free_ctx     (pdkim_ctx *);
 313
 314
 315 const uschar *  pdkim_errstr(int);
 316
 317 uschar *        dkim_sig_to_a_tag(const pdkim_signature * sig);
 318
 319 #ifdef __cplusplus
 320 }
 321 #endif
 322
 323 #endif