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/* $Cambridge: exim/src/src/tls.c,v 1.6 2009/11/16 19:50:37 nm4 Exp $ */
/*************************************************
* 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 */
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