/* * PDKIM - a RFC4871 (DKIM) implementation * * Copyright (C) 2009 - 2012 Tom Kistner * Copyright (c) 2016 - 2020 Jeremy Harris * * http://duncanthrax.net/pdkim/ * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License along * with this program; if not, write to the Free Software Foundation, Inc., * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. */ #ifndef PDKIM_H #define PDKIM_H #include "../blob.h" #include "../hash.h" #define PDKIM_DEFAULT_SIGN_HEADERS "From:Sender:Reply-To:Subject:Date:"\ "Message-ID:To:Cc:MIME-Version:Content-Type:"\ "Content-Transfer-Encoding:Content-ID:"\ "Content-Description:Resent-Date:Resent-From:"\ "Resent-Sender:Resent-To:Resent-Cc:"\ "Resent-Message-ID:In-Reply-To:References:"\ "List-Id:List-Help:List-Unsubscribe:"\ "List-Subscribe:List-Post:List-Owner:List-Archive" #define PDKIM_OVERSIGN_HEADERS "+From:+Sender:+Reply-To:+Subject:+Date:"\ "+Message-ID:+To:+Cc:+MIME-Version:+Content-Type:"\ "+Content-Transfer-Encoding:+Content-ID:"\ "+Content-Description:+Resent-Date:+Resent-From:"\ "+Resent-Sender:+Resent-To:+Resent-Cc:"\ "+Resent-Message-ID:+In-Reply-To:+References:"\ "+List-Id:+List-Help:+List-Unsubscribe:"\ "+List-Subscribe:+List-Post:+List-Owner:+List-Archive" /* -------------------------------------------------------------------------- */ /* Length of the preallocated buffer for the "answer" from the dns/txt callback function. This should match the maximum RDLENGTH from DNS. */ #define PDKIM_DNS_TXT_MAX_RECLEN (1 << 16) /* -------------------------------------------------------------------------- */ /* Function success / error codes */ #define PDKIM_OK 0 #define PDKIM_FAIL -1 #define PDKIM_ERR_RSA_PRIVKEY -101 #define PDKIM_ERR_RSA_SIGNING -102 #define PDKIM_ERR_LONG_LINE -103 #define PDKIM_ERR_BUFFER_TOO_SMALL -104 #define PDKIM_ERR_EXCESS_SIGS -105 #define PDKIM_SIGN_PRIVKEY_WRAP -106 #define PDKIM_SIGN_PRIVKEY_B64D -107 /* -------------------------------------------------------------------------- */ /* Main/Extended verification status */ #define PDKIM_VERIFY_NONE 0 #define PDKIM_VERIFY_INVALID 1 #define PDKIM_VERIFY_FAIL 2 #define PDKIM_VERIFY_PASS 3 #define PDKIM_VERIFY_POLICY BIT(31) #define PDKIM_VERIFY_FAIL_BODY 1 #define PDKIM_VERIFY_FAIL_MESSAGE 2 #define PDKIM_VERIFY_FAIL_SIG_ALGO_MISMATCH 3 #define PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE 4 #define PDKIM_VERIFY_INVALID_BUFFER_SIZE 5 #define PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD 6 #define PDKIM_VERIFY_INVALID_PUBKEY_IMPORT 7 #define PDKIM_VERIFY_INVALID_PUBKEY_KEYSIZE 8 #define PDKIM_VERIFY_INVALID_SIGNATURE_ERROR 9 #define PDKIM_VERIFY_INVALID_DKIM_VERSION 10 /* -------------------------------------------------------------------------- */ /* Some parameter values */ #define PDKIM_QUERYMETHOD_DNS_TXT 0 #define PDKIM_CANON_SIMPLE 0 #define PDKIM_CANON_RELAXED 1 /* -------------------------------------------------------------------------- */ /* Some required forward declarations, please ignore */ typedef struct pdkim_stringlist pdkim_stringlist; typedef struct pdkim_str pdkim_str; typedef struct sha1_context sha1_context; typedef struct sha2_context sha2_context; #define HAVE_SHA1_CONTEXT #define HAVE_SHA2_CONTEXT /* -------------------------------------------------------------------------- */ /* Some concessions towards Redmond */ #ifdef WINDOWS #define snprintf _snprintf #define strcasecmp _stricmp #define strncasecmp _strnicmp #define DLLEXPORT __declspec(dllexport) #else #define DLLEXPORT #endif /* -------------------------------------------------------------------------- */ /* Public key as (usually) fetched from DNS */ typedef struct pdkim_pubkey { const uschar * version; /* v= */ const uschar *granularity; /* g= */ const uschar * hashes; /* h= */ const uschar * keytype; /* k= */ const uschar * srvtype; /* s= */ uschar *notes; /* n= */ blob key; /* p= */ int testing; /* t=y */ int no_subdomaining; /* t=s */ } pdkim_pubkey; /* -------------------------------------------------------------------------- */ /* Body-hash to be calculated */ typedef struct pdkim_bodyhash { struct pdkim_bodyhash * next; int hashtype; int canon_method; long bodylength; hctx body_hash_ctx; unsigned long signed_body_bytes; /* done so far */ int num_buffered_blanklines; blob bh; /* completed hash */ } pdkim_bodyhash; /* -------------------------------------------------------------------------- */ /* Signature as it appears in a DKIM-Signature header */ typedef struct pdkim_signature { struct pdkim_signature * next; /* Bits stored in a DKIM signature header --------------------------- */ /* (v=) The version, as an integer. Currently, always "1" */ int version; /* (a=) The signature algorithm. */ int keytype; /* pdkim_keytypes index */ unsigned keybits; /* size of the key */ int hashtype; /* pdkim_hashes index */ /* (c=x/) Header canonicalization method. Either PDKIM_CANON_SIMPLE or PDKIM_CANON_RELAXED */ int canon_headers; /* (c=/x) Body canonicalization method. Either PDKIM_CANON_SIMPLE or PDKIM_CANON_RELAXED */ int canon_body; /* (q=) Query Method. Currently, only PDKIM_QUERYMETHOD_DNS_TXT is specified */ int querymethod; /* (s=) The selector string as given in the signature */ uschar *selector; /* (d=) The domain as given in the signature */ uschar *domain; /* (i=) The identity as given in the signature */ uschar *identity; /* (t=) Timestamp of signature creation */ unsigned long created; /* (x=) Timestamp of expiry of signature */ unsigned long expires; /* (l=) Amount of hashed body bytes (after canonicalization). Default is -1. Note: a value of 0 means that the body is unsigned! */ long bodylength; /* (h=) Colon-separated list of header names that are included in the signature */ uschar *headernames; /* (z=) */ uschar *copiedheaders; /* (b=) Raw signature data, along with its length in bytes */ blob sighash; /* (bh=) Raw body hash data, along with its length in bytes */ blob bodyhash; /* Folded DKIM-Signature: header. Signing only, NULL for verifying. Ready for insertion into the message. Note: Folded using CRLFTB, but final line terminator is NOT included. Note2: This buffer is free()d when you call pdkim_free_ctx(). */ uschar *signature_header; /* The main verification status. Verification only. One of: PDKIM_VERIFY_NONE Verification was not attempted. This status should not appear. PDKIM_VERIFY_INVALID There was an error while trying to verify the signature. A more precise description is available in verify_ext_status. PDKIM_VERIFY_FAIL Verification failed because either the body hash did not match, or the signature verification failed. This means the message was modified. Check verify_ext_status for the exact reason. PDKIM_VERIFY_PASS Verification succeeded. */ int verify_status; /* Extended verification status. Verification only. Depending on the value of verify_status, it can contain: For verify_status == PDKIM_VERIFY_INVALID: PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE Unable to retrieve a public key container. PDKIM_VERIFY_INVALID_BUFFER_SIZE Either the DNS name constructed to retrieve the public key record does not fit into PDKIM_DNS_TXT_MAX_NAMELEN bytes, or the retrieved record is longer than PDKIM_DNS_TXT_MAX_RECLEN bytes. PDKIM_VERIFY_INVALID_PUBKEY_PARSING (Syntax) error while parsing the retrieved public key record. For verify_status == PDKIM_VERIFY_FAIL: PDKIM_VERIFY_FAIL_BODY The calculated body hash does not match the advertised body hash from the bh= tag of the signature. PDKIM_VERIFY_FAIL_MESSAGE RSA verification of the signature (b= tag) failed. */ int verify_ext_status; /* Pointer to a public key record that was used to verify the signature. See pdkim_pubkey declaration above for more information. Caution: is NULL if signing or if no record was retrieved. */ pdkim_pubkey *pubkey; /* Properties below this point are used internally only ------------- */ /* Per-signature helper variables ----------------------------------- */ pdkim_bodyhash *calc_body_hash; /* hash to be / being calculated */ pdkim_stringlist *headers; /* Raw headers included in the sig */ /* Signing specific ------------------------------------------------- */ uschar * privkey; /* Private key */ uschar * sign_headers; /* To-be-signed header names */ uschar * rawsig_no_b_val; /* Original signature header w/o b= tag value. */ } pdkim_signature; /* -------------------------------------------------------------------------- */ /* Context to keep state between all operations. */ typedef struct pdkim_ctx { #define PDKIM_MODE_SIGN BIT(0) /* if unset, mode==verify */ #define PDKIM_DOT_TERM BIT(1) /* dot termination and unstuffing */ #define PDKIM_SEEN_CR BIT(2) #define PDKIM_SEEN_LF BIT(3) #define PDKIM_PAST_HDRS BIT(4) #define PDKIM_SEEN_EOD BIT(5) unsigned flags; /* One (signing) or several chained (verification) signatures */ pdkim_signature *sig; /* One (signing) or several chained (verification) bodyhashes */ pdkim_bodyhash *bodyhash; /* Callback for dns/txt query method (verification only) */ uschar * (*dns_txt_callback)(const uschar *); /* Coder's little helpers */ gstring *cur_header; uschar *linebuf; int linebuf_offset; int num_headers; pdkim_stringlist *headers; /* Raw headers for verification */ } pdkim_ctx; /******************************************************************************/ typedef struct { const uschar * dkim_hashname; hashmethod exim_hashmethod; } pdkim_hashtype; extern const pdkim_hashtype pdkim_hashes[]; /******************************************************************************/ /* -------------------------------------------------------------------------- */ /* API functions. Please see the sample code in sample/test_sign.c and sample/test_verify.c for documentation. */ #ifdef __cplusplus extern "C" { #endif void pdkim_init (void); void pdkim_init_context (pdkim_ctx *, BOOL, uschar * (*)(const uschar *)); DLLEXPORT pdkim_signature *pdkim_init_sign (pdkim_ctx *, uschar *, uschar *, uschar *, uschar *, const uschar **); DLLEXPORT pdkim_ctx *pdkim_init_verify (uschar * (*)(const uschar *), BOOL); DLLEXPORT void pdkim_set_optional (pdkim_signature *, char *, char *,int, int, long, unsigned long, unsigned long); int pdkim_hashname_to_hashtype(const uschar *, unsigned); void pdkim_cstring_to_canons(const uschar *, unsigned, int *, int *); pdkim_bodyhash *pdkim_set_bodyhash(pdkim_ctx *, int, int, long); pdkim_bodyhash *pdkim_set_sig_bodyhash(pdkim_ctx *, pdkim_signature *); DLLEXPORT int pdkim_feed (pdkim_ctx *, uschar *, int); DLLEXPORT int pdkim_feed_finish (pdkim_ctx *, pdkim_signature **, const uschar **); DLLEXPORT void pdkim_free_ctx (pdkim_ctx *); const uschar * pdkim_errstr(int); extern uschar * pdkim_encode_base64(blob *); extern void pdkim_decode_base64(const uschar *, blob *); extern void pdkim_hexprint(const uschar *, int); extern void pdkim_quoteprint(const uschar *, int); extern pdkim_pubkey * pdkim_parse_pubkey_record(const uschar *); extern uschar * pdkim_relax_header_n(const uschar *, int, BOOL); extern uschar * pdkim_relax_header(const uschar *, BOOL); extern uschar * dkim_sig_to_a_tag(const pdkim_signature *); #ifdef __cplusplus } #endif #endif