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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 | ||
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 | |
62 | expand_check(uschar *s, uschar *name, uschar **result) | |
63 | { | |
64 | if (s == NULL) *result = NULL; else | |
65 | { | |
66 | *result = expand_string(s); | |
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 | ||
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167 | #endif /* SUPPORT_TLS */ |
168 | ||
169 | /* End of tls.c */ |