[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 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;


/*************************************************
*       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(uschar *s, uschar *name, uschar **result)
{
if (s == NULL) *result = NULL; else
  {
  *result = expand_string(s);
  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;
	37	static int ssl_xfer_buffer_size = 4096;
	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
	43
	44
	45	/*************************************************
	46	* Expand string; give error on failure *
	47	*************************************************/
	48
	49	/* If expansion is forced to fail, set the result NULL and return TRUE.
	50	Other failures return FALSE. For a server, an SMTP response is given.
	51
	52	Arguments:
	53	s the string to expand; if NULL just return TRUE
	54	name name of string being expanded (for error)
	55	result where to put the result
	56
	57	Returns: TRUE if OK; result may still be NULL after forced failure
	58	*/
	59
	60	static BOOL
	61	expand_check(uschar s, uschar name, uschar **result)
	62	{
	63	if (s == NULL) *result = NULL; else
	64	{
	65	*result = expand_string(s);
	66	if (*result == NULL && !expand_string_forcedfail)
	67	{
	68	log_write(0, LOG_MAIN\|LOG_PANIC, "expansion of %s failed: %s", name,
	69	expand_string_message);
70	return FALSE;
71	}
72	}
73	return TRUE;
74	}
75
76
77	/*************************************************
78	* Many functions are package-specific *
79	*************************************************/
80
81	#ifdef USE_GNUTLS
82	#include "tls-gnu.c"
83	#else
84	#include "tls-openssl.c"
85	#endif
86
87
88
89	/*************************************************
90	* TLS version of ungetc *
91	*************************************************/
92
93	/* Puts a character back in the input buffer. Only ever
94	called once.
95
96	Arguments:
97	ch the character
98
99	Returns: the character
100	*/
101
102	int
103	tls_ungetc(int ch)
104	{
105	ssl_xfer_buffer[--ssl_xfer_buffer_lwm] = ch;
106	return ch;
107	}
108
109
110
111	/*************************************************
112	* TLS version of feof *
113	*************************************************/
114
115	/* Tests for a previous EOF
116
117	Arguments: none
118	Returns: non-zero if the eof flag is set
119	*/
120
121	int
122	tls_feof(void)
123	{
124	return ssl_xfer_eof;
125	}
126
127
128
129	/*************************************************
130	* TLS version of ferror *
131	*************************************************/
132
133	/* Tests for a previous read error, and returns with errno
134	restored to what it was when the error was detected.
135
136	>>>>> Hmm. Errno not handled yet. Where do we get it from? >>>>>
137
138	Arguments: none
139	Returns: non-zero if the error flag is set
140	*/
141
142	int
143	tls_ferror(void)
144	{
145	return ssl_xfer_error;
146	}
147
58eb016e PH	148
	149	/*************************************************
	150	* TLS version of smtp_buffered *
	151	*************************************************/
	152
	153	/* Tests for unused chars in the TLS input buffer.
	154
	155	Arguments: none
	156	Returns: TRUE/FALSE
	157	*/
	158
	159	BOOL
	160	tls_smtp_buffered(void)
	161	{
	162	return ssl_xfer_buffer_lwm < ssl_xfer_buffer_hwm;
	163	}
	164
	165
059ec3d9 PH	166	#endif /* SUPPORT_TLS */
	167
	168	/* End of tls.c */