2 meshlink.h -- MeshLink API
3 Copyright (C) 2014 Guus Sliepen <guus@meshlink.io>
5 This program is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; either version 2 of the License, or
8 (at your option) any later version.
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
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16 with this program; if not, write to the Free Software Foundation, Inc.,
17 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
26 /// A handle for an instance of MeshLink.
27 typedef struct meshlink_handle meshlink_handle_t;
29 /// A handle for a MeshLink node.
30 typedef struct meshlink_node meshlink_node_t;
32 /// Code of most recent error encountered.
34 MESHLINK_OK, // Everything is fine
35 MESHLINK_ENOMEM, // Out of memory
36 MESHLINK_ENOENT, // Node is not known
39 #ifndef MESHLINK_INTERNAL_H
41 struct meshlink_handle {
42 meshlink_errno_t meshlink_errno; /// Code of the last encountered error.
43 const char *errstr; /// Textual representation of most recent error encountered.
46 struct meshlink_node {
47 const char *name; // Textual name of this node.
48 void *priv; // Private pointer which the application can set at will.
51 #endif // MESHLINK_INTERNAL_H
53 /// Get the text for the given MeshLink error code.
54 /** This function returns a pointer to the string containing the description of the given error code.
56 * @param errno An error code returned by MeshLink.
58 * @return A pointer to a string containing the description of the error code.
60 extern const char *meshlink_strerror(meshlink_errno_t errno);
62 /// Initialize MeshLink's configuration directory.
63 /** This function causes MeshLink to initialize its configuration directory,
64 * if it hasn't already been initialized.
65 * It only has to be run the first time the application starts,
66 * but it is not a problem if it is run more than once, as long as
67 * the arguments given are the same.
69 * This function does not start any network I/O yet. The application should
70 * first set callbacks, and then call meshlink_start().
72 * @param confbase The directory in which MeshLink will store its configuration files.
73 * @param name The name which this instance of the application will use in the mesh.
75 * @return This function will return true if MeshLink has succesfully set up its configuration files, false otherwise.
77 extern meshlink_handle_t *meshlink_open(const char *confbase, const char *name);
80 /** This function causes MeshLink to open network sockets, make outgoing connections, and
81 * create a new thread, which will handle all network I/O.
83 * @param confbase The directory in which MeshLink will store its configuration files.
85 * @return This function will return true if MeshLink has succesfully started its thread, false otherwise.
87 extern bool meshlink_start(meshlink_handle_t *mesh);
90 /** This function causes MeshLink to disconnect from all other nodes,
91 * close all sockets, and shut down its own thread.
93 * @param handle A handle which represents an instance of MeshLink.
95 extern void meshlink_stop(meshlink_handle_t *mesh);
97 /// Close the MeshLink handle.
98 /** This function calls meshlink_stop() if necessary,
99 * and frees all memory allocated by MeshLink.
100 * Afterwards, the handle and any pointers to a struct meshlink_node are invalid.
102 * @param handle A handle which represents an instance of MeshLink.
104 extern void meshlink_close(meshlink_handle_t *mesh);
106 /// A callback for receiving data from the mesh.
107 /** @param handle A handle which represents an instance of MeshLink.
108 * @param source A pointer to a meshlink_node_t describing the source of the data.
109 * @param data A pointer to a buffer containing the data sent by the source.
110 * @param len The length of the received data.
112 typedef void (*meshlink_receive_cb_t)(meshlink_handle_t *mesh, meshlink_node_t *source, const void *data, size_t len);
114 /// Set the receive callback.
115 /** This functions sets the callback that is called whenever another node sends data to the local node.
116 * The callback is run in MeshLink's own thread.
117 * It is therefore important that the callback uses apprioriate methods (queues, pipes, locking, etc.)
118 * to hand the data over to the application's thread.
119 * The callback should also not block itself and return as quickly as possible.
121 * @param handle A handle which represents an instance of MeshLink.
122 * @param cb A pointer to the function which will be called when another node sends data to the local node.
124 extern void meshlink_set_receive_cb(meshlink_handle_t *mesh, meshlink_receive_cb_t cb);
126 /// A callback reporting node status changes.
127 /** @param handle A handle which represents an instance of MeshLink.
128 * @param node A pointer to a meshlink_node_t describing the node whose status changed.
129 * @param reachable True if the node is reachable, false otherwise.
131 typedef void (*meshlink_node_status_cb_t)(meshlink_handle_t *mesh, meshlink_node_t *node, bool reachable);
133 /// Set the node status callback.
134 /** This functions sets the callback that is called whenever another node's status changed.
135 * The callback is run in MeshLink's own thread.
136 * It is therefore important that the callback uses apprioriate methods (queues, pipes, locking, etc.)
137 * to hand the data over to the application's thread.
138 * The callback should also not block itself and return as quickly as possible.
140 * @param handle A handle which represents an instance of MeshLink.
141 * @param cb A pointer to the function which will be called when another node's status changes.
143 extern void meshlink_set_node_status_cb(meshlink_handle_t *mesh, meshlink_node_status_cb_t cb);
145 /// Severity of log messages generated by MeshLink.
147 MESHLINK_DEBUG, // Internal debugging messages. Only useful during application development.
148 MESHLINK_INFO, // Informational messages.
149 MESHLINK_WARNING, // Warnings which might indicate problems, but which are not real errors.
150 MESHLINK_ERROR, // Errors which hamper correct functioning of MeshLink, without causing it to fail completely.
151 MESHLINK_CRITICAL, // Critical errors which cause MeshLink to fail completely.
152 } meshlink_log_level_t;
154 /// A callback for receiving log messages generated by MeshLink.
155 /** @param handle A handle which represents an instance of MeshLink.
156 * @param level An enum describing the severity level of the message.
157 * @param text A pointer to a string containing the textual log message.
159 typedef void (*meshlink_log_cb_t)(meshlink_handle_t *mesh, meshlink_log_level_t level, const char *text);
161 /// Set the log callback.
162 /** This functions sets the callback that is called whenever MeshLink has some information to log.
163 * The callback is run in MeshLink's own thread.
164 * It is important that the callback uses apprioriate methods (queues, pipes, locking, etc.)
165 * to hand the data over to the application's thread.
166 * The callback should also not block itself and return as quickly as possible.
168 * @param handle A handle which represents an instance of MeshLink.
169 * @param level An enum describing the minimum severity level. Debugging information with a lower level will not trigger the callback.
170 * @param cb A pointer to the function which will be called when another node sends data to the local node.
172 extern void meshlink_set_log_cb(meshlink_handle_t *mesh, meshlink_log_level_t level, meshlink_log_cb_t cb);
174 /// Send data to another node.
175 /** This functions sends one packet of data to another node in the mesh.
176 * The packet is sent using UDP semantics, which means that
177 * the packet is sent as one unit and is received as one unit,
178 * and that there is no guarantee that the packet will arrive at the destination.
179 * The application should take care of getting an acknowledgement and retransmission if necessary.
181 * @param handle A handle which represents an instance of MeshLink.
182 * @param destination A pointer to a meshlink_node_t describing the destination for the data.
183 * @param data A pointer to a buffer containing the data to be sent to the source.
184 * @param len The length of the data.
185 * @return This function will return true if MeshLink has queued the message for transmission, and false otherwise.
186 * A return value of true does not guarantee that the message will actually arrive at the destination.
188 extern bool meshlink_send(meshlink_handle_t *mesh, meshlink_node_t *destination, const void *data, unsigned int len);
190 /// Get a handle for a specific node.
191 /** This function returns a handle for the node with the given name.
193 * @param handle A handle which represents an instance of MeshLink.
194 * @param name The name of the node for which a handle is requested.
196 * @return A pointer to a meshlink_node_t which represents the requested node,
197 * or NULL if the requested node does not exist.
199 extern meshlink_node_t *meshlink_get_node(meshlink_handle_t *mesh, const char *name);
201 /// Get a list of all nodes.
202 /** This function returns a list with handles for all known nodes.
204 * @param handle A handle which represents an instance of MeshLink.
205 * @param nodes A pointer to an array of pointers to meshlink_node_t, which should be allocated by the application.
206 * @param nmemb The maximum number of pointers that can be stored in the nodes array.
208 * @param return The number of known nodes. This can be larger than nmemb, in which case not all nodes were stored in the nodes array.
210 extern size_t meshlink_get_all_nodes(meshlink_handle_t *mesh, meshlink_node_t **nodes, size_t nmemb);
212 /// Sign data using the local node's MeshLink key.
213 /** This function signs data using the local node's MeshLink key.
214 * The generated signature can be securely verified by other nodes.
216 * @param handle A handle which represents an instance of MeshLink.
217 * @param data A pointer to a buffer containing the data to be signed.
218 * @param len The length of the data to be signed.
220 * @return This function returns a pointer to a string containing the signature, or NULL in case of an error.
221 * The application should call free() after it has finished using the signature.
223 extern char *meshlink_sign(meshlink_handle_t *mesh, const char *data, size_t len);
225 /// Verify the signature generated by another node of a piece of data.
226 /** This function verifies the signature that another node generated for a piece of data.
228 * @param handle A handle which represents an instance of MeshLink.
229 * @param source A pointer to a meshlink_node_t describing the source of the signature.
230 * @param data A pointer to a buffer containing the data to be verified.
231 * @param len The length of the data to be verified.
232 * @param signature A pointer to a string containing the signature.
234 * @return This function returns true if the signature is valid, false otherwise.
236 extern bool meshlink_verify(meshlink_handle_t *mesh, meshlink_node_t *source, const char *data, size_t len, const char *signature);
238 /// Invite another node into the mesh.
239 /** This function generates an invitation that can be used by another node to join the same mesh as the local node.
240 * The generated invitation is a string containing a URL.
241 * This URL should be passed by the application to the invitee in a way that no eavesdroppers can see the URL.
242 * The URL can only be used once, after the user has joined the mesh the URL is no longer valid.
244 * @param handle A handle which represents an instance of MeshLink.
245 * @param name The name that the invitee will use in the mesh.
247 * @return This function returns a string that contains the invitation URL.
248 * The application should call free() after it has finished using the URL.
250 extern char *meshlink_invite(meshlink_handle_t *mesh, const char *name);
252 /// Use an invitation to join a mesh.
253 /** This function allows the local node to join an existing mesh using an invitation URL generated by another node.
254 * An invitation can only be used if the local node has never connected to other nodes before.
255 * After a succesfully accepted invitation, the name of the local node may have changed.
257 * @param handle A handle which represents an instance of MeshLink.
258 * @param invitation A string containing the invitation URL.
260 * @return This function returns true if the local node joined the mesh it was invited to, false otherwise.
262 extern bool meshlink_join(meshlink_handle_t *mesh, const char *invitation);
264 /// Export the local node's key and addresses.
265 /** This function generates a string that contains the local node's public key and one or more IP addresses.
266 * The application can pass it in some way to another node, which can then import it,
267 * granting the local node access to the other node's mesh.
269 * @param handle A handle which represents an instance of MeshLink.
271 * @return This function returns a string that contains the exported key and addresses.
272 * The application should call free() after it has finished using this string.
274 extern char *meshlink_export(meshlink_handle_t *mesh);
276 /// Import another node's key and addresses.
277 /** This function accepts a string containing the exported public key and addresses of another node.
278 * By importing this data, the local node grants the other node access to its mesh.
280 * @param handle A handle which represents an instance of MeshLink.
281 * @param data A string containing the other node's exported key and addresses.
283 * @return This function returns true if the data was valid and the other node has been granted access to the mesh, false otherwise.
285 extern bool meshlink_import(meshlink_handle_t *mesh, const char *data);
287 /// Blacklist a node from the mesh.
288 /** This function causes the local node to blacklist another node.
289 * The local node will drop any existing connections to that node,
290 * and will not send data to it nor accept any data received from it any more.
292 * @param handle A handle which represents an instance of MeshLink.
293 * @param node A pointer to a meshlink_node_t describing the node to be blacklisted.
295 extern void meshlink_blacklist(meshlink_handle_t *mesh, meshlink_node_t *node);