summaryrefslogtreecommitdiff
path: root/manual/html_node/Callback-functions.html
blob: 38e54814ea1ef1059ec5f17e9cef5190a40e333d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<!-- This manual is last updated 25 May 2013 for version
3.2.1 of GnuTLS.

Copyright (C) 2001-2013 Free Software Foundation, Inc.\\
Copyright (C) 2001-2013 Nikos Mavrogiannopoulos

Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation; with no
Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.  A
copy of the license is included in the section entitled "GNU Free
Documentation License". -->
<!-- Created by GNU Texinfo 4.13.90, http://www.gnu.org/software/texinfo/ -->
<head>
<title>GnuTLS 3.2.1: Callback functions</title>

<meta name="description" content="GnuTLS 3.2.1: Callback functions">
<meta name="keywords" content="GnuTLS 3.2.1: Callback functions">
<meta name="resource-type" content="document">
<meta name="distribution" content="global">
<meta name="Generator" content="makeinfo">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<link href="index.html#Top" rel="start" title="Top">
<link href="Function-and-Data-Index.html#Function-and-Data-Index" rel="index" title="Function and Data Index">
<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
<link href="Introduction-to-the-library.html#Introduction-to-the-library" rel="up" title="Introduction to the library">
<link href="Preparation.html#Preparation" rel="next" title="Preparation">
<link href="Thread-safety.html#Thread-safety" rel="previous" title="Thread safety">
<style type="text/css">
<!--
a.summary-letter {text-decoration: none}
blockquote.smallquotation {font-size: smaller}
div.display {margin-left: 3.2em}
div.example {margin-left: 3.2em}
div.indentedblock {margin-left: 3.2em}
div.lisp {margin-left: 3.2em}
div.smalldisplay {margin-left: 3.2em}
div.smallexample {margin-left: 3.2em}
div.smallindentedblock {margin-left: 3.2em; font-size: smaller}
div.smalllisp {margin-left: 3.2em}
kbd {font-style:oblique}
pre.display {font-family: inherit}
pre.format {font-family: inherit}
pre.menu-comment {font-family: serif}
pre.menu-preformatted {font-family: serif}
pre.smalldisplay {font-family: inherit; font-size: smaller}
pre.smallexample {font-size: smaller}
pre.smallformat {font-family: inherit; font-size: smaller}
pre.smalllisp {font-size: smaller}
span.nocodebreak {white-space:nowrap}
span.nolinebreak {white-space:nowrap}
span.roman {font-family:serif; font-weight:normal}
span.sansserif {font-family:sans-serif; font-weight:normal}
ul.no-bullet {list-style: none}
body { 
	margin: 2%;
	padding: 0 5%;
	background: #ffffff;
}
h1,h2,h3,h4,h5 {
    font-weight: bold;
    padding: 5px 5px 5px 5px;
    background-color: #c2e0ff;
    color: #336699;
}
h1 {
    padding: 2em 2em 2em 5%;
    color: white;
    background: #336699;
    text-align: center;
    letter-spacing: 3px;
}
h2 { text-decoration: underline; }
pre {
  margin: 0 5%;
  padding: 0.5em;
}
pre.example,pre.verbatim {
  padding-bottom: 1em;

  border: solid #c2e0ff;
  background: #f0faff;
  border-width: 1px 1px 1px 5px;
  margin: 1em auto;
  width: 90%;
}

div.node {
  margin: 0 -5% 0 -2%;
  padding: 0.5em 0.5em;
  margin-top: 0.5em;
  margin-bottom: 0.5em;
  font-weight: bold;
}
dd, li {
  padding-top: 0.1em;
  padding-bottom: 0.1em;
}
div.float {

  margin-bottom: 0.5em;
  text-align: center;
}

table {
  text-align: left;
  margin-left:auto;
  margin-right:auto;
  width: 50%;
}

th {
  padding: 0;
  color: #336699;
  background-color: #c2e0ff;
  border: solid #000000;
  border-width: 0px;
  margin: 1em auto;
  text-align: center;
  margin-left:auto;
  margin-right:auto;
}

td {
  padding: 0;
  border: solid #000000;
  background-color: #f0faff;
  border-width: 0px;
  margin: 1em auto;
  text-align: left;
  margin-left:auto;
  margin-right:auto;
  padding-left: 1em;
}

dl {
  text-align: left;
  margin-left:auto;
  margin-right:auto;
  width: 50%;

  padding-left: 1em;
  border: solid #c2e0ff;
  background: #f0faff;
  border-width: 5px 1px 1px 1px;
  margin: 1em auto;
}

-->
</style>


</head>

<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
<a name="Callback-functions"></a>
<div class="header">
<p>
Previous: <a href="Thread-safety.html#Thread-safety" accesskey="p" rel="previous">Thread safety</a>, Up: <a href="Introduction-to-the-library.html#Introduction-to-the-library" accesskey="u" rel="up">Introduction to the library</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Function-and-Data-Index.html#Function-and-Data-Index" title="Index" rel="index">Index</a>]</p>
</div>
<hr>
<a name="Callback-functions-1"></a>
<h4 class="subsection">6.1.6 Callback functions</h4>
<a name="index-callback-functions"></a>

<p>There are several cases where <acronym>GnuTLS</acronym> may need out of
band input from your program. This is now implemented using some
callback functions, which your program is expected to register.
</p>
<p>An example of this type of functions are the push and pull callbacks
which are used to specify the functions that will retrieve and send
data to the transport layer.
</p>
<dl compact="compact">
<dt><code><var>void</var> <a href="Core-TLS-API.html#gnutls_005ftransport_005fset_005fpush_005ffunction">gnutls_transport_set_push_function</a> (gnutls_session_t <var>session</var>, gnutls_push_func <var>push_func</var>)</code></dt>
<dt><code><var>void</var> <a href="Core-TLS-API.html#gnutls_005ftransport_005fset_005fpull_005ffunction">gnutls_transport_set_pull_function</a> (gnutls_session_t <var>session</var>, gnutls_pull_func <var>pull_func</var>)</code></dt>
</dl>

<p>Other callback functions may require more complicated input and data
to be allocated. Such an example is 
<a href="Core-TLS-API.html#gnutls_005fsrp_005fset_005fserver_005fcredentials_005ffunction">gnutls_srp_set_server_credentials_function</a>.
All callbacks should allocate and free memory using 
<code>gnutls_malloc</code> and <code>gnutls_free</code>.
</p>




</body>
</html>