2 SILC Client Library Manual
8 SILC Client library is a full featured SILC Client protocolimplementation.
9 The library has been designed to be complete SILC client without actual
10 user interface. The library provides the API for the appliation which
11 it can use to implement generally whatever user interface it wants. The
12 SILC Client Library recides in the lib/silcclient/ directory. It uses
13 common and core compomnent of SILC protocol from the lib/silccore, SKE
14 from lib/silcske and general utility routines from lib/silcutil.
16 The `silcapi.h' file defines the function prototypes that application
17 must implement in order to be able to create the user interface with the
18 library. The idea is that the application can implement whatever user
19 interface routines in the functions and display the data whatever way
20 it wants. The library is entirely transparent to the user interface and
21 it does not include any user interface specific issues such as window
22 handling or item handling on the screen etc. These does not interest
23 the library. The `silcapi.h' also defines the client libary interface
24 the application can call. The interface includes for example functions
25 for sending channel and private messages, client and channel retrieval
26 and other utility functions.
31 The client is context or entity based, so several client entitites can
32 be created in the application if needed. However, it should be noted
33 that they are completely independent from each other and can be seen
34 as different applications. Usually only one client entity is needed
37 The client object is SilcClient which is usually allocated in following
40 SilcClient client = silc_client_alloc(&ops, context, version);
42 `ops' is the static structure of client operations that library will call.
43 `context' can be some application specific context that will be saved into
44 the SilcClient object. It is up to the caller to free this context.
45 SilcClient is always passed to the application thus the application
46 specific context can be retrieved from the SilcClient object. See
47 `client.h' file for detailed definition of SilcClient object.
49 `ops' can be defined for example as follows:
51 SilcClientOperations ops = {
61 silc_verify_public_key,
67 Please see the `client_ops_example.h' header file in lib/silcclient/
68 directory for predefined structure and stub functions for your
69 convenince. It is provided for programmers so that they can copy
70 it and use it directly in their application.
73 1.2 Initializing the Client
75 The client must be initialized before running. However, there are also
76 some other tasks that must be done before initializing the client.
77 The following pointers must be set by the application before calling
78 the initializing function:
87 You may also set client->nickname if you want. If it is set then the
88 library will change the nickname to that one after the client is connected
89 to the server. If not set, then server will initially give the nickname
90 which is same as the username.
92 After setting the pointers one must call:
94 silc_client_init(client);
96 which then initializes the client library for the `client'. If the
97 pointers mentioned above are not initialized the silc_client_init will
98 fail. The application should check the return value of the silc_client_init
102 1.3 Running the Client
104 The client is run by calling silc_client_run. The function will call
105 the scheduler from utility library that will be run until the program is
106 ended. When silc_client_run returns the application is ended. Thus,
107 to run the client, call:
109 silc_client_run(client);
111 Usually application may do some other initializations before calling
112 this function. For example before calling this function application
113 should initialize the user interface.
116 1.4 Creating Connection to Server
118 Connection to remote SILC server is done by calling:
120 silc_client_connect_to_server(client, port, hostname, context);
122 The function will create the connection asynchronously to the server, ie.
123 the function will return before the actual connection is created. After
124 the connection is created the client->ops->connect operation is called.
126 Generally speaking the connections are associated with windows' on the
127 screen. IRC is usually implemented this way, however it is not the
128 necessary way to associate the client's connections. SilcClientConnection
129 object is provided by the library (and is always passed to the application)
130 that can be used in the application to associate the connection from the
131 library. Application specific context can be saved to the
132 SilcClientConnection object which then can be retrieved in the application,
133 thus perhaps associate the connection with what ever object in
134 application (window or something else).
137 1.4.1 Using Own Connecting
139 Application might not want to use silc_client_connect_to_server function
140 if it wants to perform its own connecting for some reason. In this case
141 application must call function silc_client_start_key_exchange after it
142 has created the connection by itself. This function starts the key
143 exhange protocol between the client and server and the library takes care
144 of everything after that.
146 After connection has been created application must call:
148 SilcClientConnection conn;
150 /* Add new connection to client */
151 conn = silc_client_add_connection(client, hostname, port, context);
153 /* Start key exchange and let the library handle everything
154 after this point on. */
155 silc_client_start_key_exchange(client, conn, sock);
157 NOTE: These calls are performed only and only if application did not call
158 silc_client_connect_to_server function, but performed the connecting
164 This section includes an example SILC client implementation in pseudo-like
165 C code. It creates and initializes the client and sets up an imaginary
166 user interface. The user will use the user interface then to create
167 the connections. The SilcClientOperations are expected to be implemented.
169 #include "silcincludes.h"
174 SilcClientOperations ops = {
176 silc_channel_message,
177 silc_private_message,
183 silc_get_auth_method,
184 silc_verify_public_key,
192 /* Allocate SILC client. The `silc_version_string' is defined
193 in includes/version.h file. */
194 client = silc_client_alloc(&ops, NULL, silc_version_string);
196 /* Register default ciphers, pkcs, hash funtions and hmacs. */
197 silc_cipher_register_default();
198 silc_pkcs_register_default();
199 silc_hash_register_default();
200 silc_hmac_register_default();
202 /* Set the mandatory pointers, read public and private key from
203 files (or somewhere) and return pointers and PKCS context. */
204 client->username = silc_get_username();
205 client->hostname = silc_net_localhost();
206 client->realname = silc_get_real_name();
207 client->pkcs = get_public_and_private_key(&client->public_key,
208 &client->private_key);
210 /* If the keys does not exist, create a key pair since we must
211 provide key pair to the library. */
213 generate_key_new_key_pair(client);
215 /* Iinitialize client */
216 if (!silc_client_init(client))
217 fatal_error("Could not initialize client");
219 /* Initialize user interface. The user interface can be generally
220 initialized at any phase, including before actually allocating
221 and initializing the client, if wished. */
225 /* Start the client. This will start the scheduler. At this phase
226 the user might have the user interface in front of him already.
227 He will use the user interface to create the connection to the
228 server for example. When this function returns the program is
230 silc_client_run(client);
232 /* Client is ended */