[exim.git] / src / src / tls.c

/*************************************************
*     Exim - an Internet mail transport agent    *
*************************************************/

/* Copyright (c) University of Cambridge 1995 - 2009 */
/* See the file NOTICE for conditions of use and distribution. */

/* This module provides TLS (aka SSL) support for Exim. The code for OpenSSL is
based on a patch that was originally contributed by Steve Haslam. It was
adapted from stunnel, a GPL program by Michal Trojnara. The code for GNU TLS is
based on a patch contributed by Nikos Mavroyanopoulos. Because these packages
are so very different, the functions for each are kept in separate files. The
relevant file is #included as required, after any any common functions.

No cryptographic code is included in Exim. All this module does is to call
functions from the OpenSSL or GNU TLS libraries. */


#include "exim.h"

/* This module is compiled only when it is specifically requested in the
build-time configuration. However, some compilers don't like compiling empty
modules, so keep them happy with a dummy when skipping the rest. Make it
reference itself to stop picky compilers complaining that it is unused, and put
in a dummy argument to stop even pickier compilers complaining about infinite
loops. */

#ifndef SUPPORT_TLS
static void dummy(int x) { dummy(x-1); }
#else

/* Static variables that are used for buffering data by both sets of
functions and the common functions below. */


static uschar *ssl_xfer_buffer = NULL;
static const int ssl_xfer_buffer_size = 4096;
static int ssl_xfer_buffer_lwm = 0;
static int ssl_xfer_buffer_hwm = 0;
static int ssl_xfer_eof = 0;
static int ssl_xfer_error = 0;

uschar *tls_channelbinding_b64 = NULL;


/*************************************************
*       Expand string; give error on failure     *
*************************************************/

/* If expansion is forced to fail, set the result NULL and return TRUE.
Other failures return FALSE. For a server, an SMTP response is given.

Arguments:
  s         the string to expand; if NULL just return TRUE
  name      name of string being expanded (for error)
  result    where to put the result

Returns:    TRUE if OK; result may still be NULL after forced failure
*/

static BOOL
expand_check(const uschar *s, const uschar *name, uschar **result)
{
if (s == NULL) *result = NULL; else
  {
  *result = expand_string(US s); /* need to clean up const some more */
  if (*result == NULL && !expand_string_forcedfail)
    {
    log_write(0, LOG_MAIN|LOG_PANIC, "expansion of %s failed: %s", name,
      expand_string_message);
    return FALSE;
    }
  }
return TRUE;
}


/*************************************************
*        Many functions are package-specific     *
*************************************************/

#ifdef USE_GNUTLS
#include "tls-gnu.c"
#else
#include "tls-openssl.c"
#endif


/*************************************************
*           TLS version of ungetc                *
*************************************************/

/* Puts a character back in the input buffer. Only ever
called once.

Arguments:
  ch           the character

Returns:       the character
*/

int
tls_ungetc(int ch)
{
ssl_xfer_buffer[--ssl_xfer_buffer_lwm] = ch;
return ch;
}


/*************************************************
*           TLS version of feof                  *
*************************************************/

/* Tests for a previous EOF

Arguments:     none
Returns:       non-zero if the eof flag is set
*/

int
tls_feof(void)
{
return ssl_xfer_eof;
}


/*************************************************
*              TLS version of ferror             *
*************************************************/

/* Tests for a previous read error, and returns with errno
restored to what it was when the error was detected.

>>>>> Hmm. Errno not handled yet. Where do we get it from?  >>>>>

Arguments:     none
Returns:       non-zero if the error flag is set
*/

int
tls_ferror(void)
{
return ssl_xfer_error;
}


/*************************************************
*           TLS version of smtp_buffered         *
*************************************************/

/* Tests for unused chars in the TLS input buffer.

Arguments:     none
Returns:       TRUE/FALSE
*/

BOOL
tls_smtp_buffered(void)
{
return ssl_xfer_buffer_lwm < ssl_xfer_buffer_hwm;
}


#endif  /* SUPPORT_TLS */

/* End of tls.c */
Commit	Line	Data
059ec3d9 PH	1	/*************************************************
	2	* Exim - an Internet mail transport agent *
	3	*************************************************/
	4
0a49a7a4	5	/* Copyright (c) University of Cambridge 1995 - 2009 */
059ec3d9 PH	6	/* See the file NOTICE for conditions of use and distribution. */
	7
	8	/* This module provides TLS (aka SSL) support for Exim. The code for OpenSSL is
	9	based on a patch that was originally contributed by Steve Haslam. It was
	10	adapted from stunnel, a GPL program by Michal Trojnara. The code for GNU TLS is
	11	based on a patch contributed by Nikos Mavroyanopoulos. Because these packages
	12	are so very different, the functions for each are kept in separate files. The
	13	relevant file is #included as required, after any any common functions.
	14
	15	No cryptographic code is included in Exim. All this module does is to call
	16	functions from the OpenSSL or GNU TLS libraries. */
	17
	18
	19	#include "exim.h"
	20
	21	/* This module is compiled only when it is specifically requested in the
	22	build-time configuration. However, some compilers don't like compiling empty
	23	modules, so keep them happy with a dummy when skipping the rest. Make it
	24	reference itself to stop picky compilers complaining that it is unused, and put
	25	in a dummy argument to stop even pickier compilers complaining about infinite
	26	loops. */
	27
	28	#ifndef SUPPORT_TLS
	29	static void dummy(int x) { dummy(x-1); }
	30	#else
	31
	32	/* Static variables that are used for buffering data by both sets of
	33	functions and the common functions below. */
	34
	35
	36	static uschar *ssl_xfer_buffer = NULL;
17c76198	37	static const int ssl_xfer_buffer_size = 4096;
059ec3d9 PH	38	static int ssl_xfer_buffer_lwm = 0;
	39	static int ssl_xfer_buffer_hwm = 0;
	40	static int ssl_xfer_eof = 0;
	41	static int ssl_xfer_error = 0;
	42
44bbabb5	43	uschar *tls_channelbinding_b64 = NULL;
059ec3d9 PH	44
	45
	46	/*************************************************
	47	* Expand string; give error on failure *
	48	*************************************************/
	49
	50	/* If expansion is forced to fail, set the result NULL and return TRUE.
	51	Other failures return FALSE. For a server, an SMTP response is given.
	52
	53	Arguments:
	54	s the string to expand; if NULL just return TRUE
	55	name name of string being expanded (for error)
	56	result where to put the result
	57
	58	Returns: TRUE if OK; result may still be NULL after forced failure
	59	*/
	60
	61	static BOOL
17c76198	62	expand_check(const uschar s, const uschar name, uschar **result)
059ec3d9 PH	63	{
	64	if (s == NULL) *result = NULL; else
	65	{
17c76198	66	result = expand_string(US s); / need to clean up const some more */
059ec3d9 PH	67	if (*result == NULL && !expand_string_forcedfail)
	68	{
	69	log_write(0, LOG_MAIN\|LOG_PANIC, "expansion of %s failed: %s", name,
	70	expand_string_message);
	71	return FALSE;
	72	}
	73	}
	74	return TRUE;
	75	}
	76
	77
	78	/*************************************************
	79	* Many functions are package-specific *
	80	*************************************************/
	81
	82	#ifdef USE_GNUTLS
	83	#include "tls-gnu.c"
	84	#else
	85	#include "tls-openssl.c"
	86	#endif
	87
	88
	89
	90	/*************************************************
	91	* TLS version of ungetc *
	92	*************************************************/
	93
	94	/* Puts a character back in the input buffer. Only ever
	95	called once.
	96
	97	Arguments:
	98	ch the character
	99
	100	Returns: the character
	101	*/
	102
	103	int
	104	tls_ungetc(int ch)
	105	{
	106	ssl_xfer_buffer[--ssl_xfer_buffer_lwm] = ch;
	107	return ch;
	108	}
	109
	110
	111
	112	/*************************************************
	113	* TLS version of feof *
	114	*************************************************/
	115
	116	/* Tests for a previous EOF
	117
	118	Arguments: none
	119	Returns: non-zero if the eof flag is set
	120	*/
	121
	122	int
	123	tls_feof(void)
	124	{
	125	return ssl_xfer_eof;
	126	}
	127
	128
	129
	130	/*************************************************
131	* TLS version of ferror *
132	*************************************************/
133
134	/* Tests for a previous read error, and returns with errno
135	restored to what it was when the error was detected.
136
137	>>>>> Hmm. Errno not handled yet. Where do we get it from? >>>>>
138
139	Arguments: none
140	Returns: non-zero if the error flag is set
141	*/
142
143	int
144	tls_ferror(void)
145	{
146	return ssl_xfer_error;
147	}
148
58eb016e PH	149
	150	/*************************************************
	151	* TLS version of smtp_buffered *
	152	*************************************************/
	153
	154	/* Tests for unused chars in the TLS input buffer.
	155
	156	Arguments: none
	157	Returns: TRUE/FALSE
	158	*/
	159
	160	BOOL
	161	tls_smtp_buffered(void)
	162	{
	163	return ssl_xfer_buffer_lwm < ssl_xfer_buffer_hwm;
	164	}
	165
	166
059ec3d9 PH	167	#endif /* SUPPORT_TLS */
	168
	169	/* End of tls.c */