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Diffstat (limited to 'src/pdkim/pdkim.h')
| -rw-r--r-- | src/pdkim/pdkim.h | 369 |
1 files changed, 369 insertions, 0 deletions
diff --git a/src/pdkim/pdkim.h b/src/pdkim/pdkim.h new file mode 100644 index 0000000..f6ff782 --- /dev/null +++ b/src/pdkim/pdkim.h @@ -0,0 +1,369 @@ +/* + * PDKIM - a RFC4871 (DKIM) implementation + * + * Copyright (C) 2009 - 2012 Tom Kistner <tom@duncanthrax.net> + * 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 |