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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17 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
32 /// The length in bytes of a signature made with meshlink_sign()
33 #define MESHLINK_SIGLEN 64
35 /// A handle for an instance of MeshLink.
36 typedef struct meshlink_handle meshlink_handle_t;
38 /// A handle for a MeshLink node.
39 typedef struct meshlink_node meshlink_node_t;
41 /// A handle for a MeshLink channel.
42 typedef struct meshlink_channel meshlink_channel_t;
44 /// Code of most recent error encountered.
46 MESHLINK_OK, ///< Everything is fine
47 MESHLINK_ENOMEM, ///< Out of memory
48 MESHLINK_ENOENT, ///< Node is not known
51 /// A variable holding the last encountered error from MeshLink.
52 extern __thread meshlink_errno_t meshlink_errno;
54 #ifndef MESHLINK_INTERNAL_H
56 struct meshlink_handle {
59 struct meshlink_node {
60 const char *name; ///< Textual name of this node.
61 void *priv; ///< Private pointer which the application can set at will.
64 struct meshlink_channel {
67 #endif // MESHLINK_INTERNAL_H
69 /// Get the text for the given MeshLink error code.
70 /** This function returns a pointer to the string containing the description of the given error code.
72 * @param errno An error code returned by MeshLink.
74 * @return A pointer to a string containing the description of the error code.
76 extern const char *meshlink_strerror(meshlink_errno_t errno);
78 /// Initialize MeshLink's configuration directory.
79 /** This function causes MeshLink to initialize its configuration directory,
80 * if it hasn't already been initialized.
81 * It only has to be run the first time the application starts,
82 * but it is not a problem if it is run more than once, as long as
83 * the arguments given are the same.
85 * This function does not start any network I/O yet. The application should
86 * first set callbacks, and then call meshlink_start().
88 * @param confbase The directory in which MeshLink will store its configuration files.
89 * @param name The name which this instance of the application will use in the mesh.
91 * @return This function will return true if MeshLink has succesfully set up its configuration files, false otherwise.
93 extern meshlink_handle_t *meshlink_open(const char *confbase, const char *name);
96 /** This function causes MeshLink to open network sockets, make outgoing connections, and
97 * create a new thread, which will handle all network I/O.
99 * @param mesh A handle which represents an instance of MeshLink.
101 * @return This function will return true if MeshLink has succesfully started its thread, false otherwise.
103 extern bool meshlink_start(meshlink_handle_t *mesh);
106 /** This function causes MeshLink to disconnect from all other nodes,
107 * close all sockets, and shut down its own thread.
109 * @param mesh A handle which represents an instance of MeshLink.
111 extern void meshlink_stop(meshlink_handle_t *mesh);
113 /// Close the MeshLink handle.
114 /** This function calls meshlink_stop() if necessary,
115 * and frees all memory allocated by MeshLink.
116 * Afterwards, the handle and any pointers to a struct meshlink_node are invalid.
118 * @param mesh A handle which represents an instance of MeshLink.
120 extern void meshlink_close(meshlink_handle_t *mesh);
122 /// A callback for receiving data from the mesh.
123 /** @param mesh A handle which represents an instance of MeshLink.
124 * @param source A pointer to a meshlink_node_t describing the source of the data.
125 * @param data A pointer to a buffer containing the data sent by the source.
126 * @param len The length of the received data.
128 typedef void (*meshlink_receive_cb_t)(meshlink_handle_t *mesh, meshlink_node_t *source, const void *data, size_t len);
130 /// Set the receive callback.
131 /** This functions sets the callback that is called whenever another node sends data to the local node.
132 * The callback is run in MeshLink's own thread.
133 * It is therefore important that the callback uses apprioriate methods (queues, pipes, locking, etc.)
134 * to hand the data over to the application's thread.
135 * The callback should also not block itself and return as quickly as possible.
137 * @param mesh A handle which represents an instance of MeshLink.
138 * @param cb A pointer to the function which will be called when another node sends data to the local node.
140 extern void meshlink_set_receive_cb(meshlink_handle_t *mesh, meshlink_receive_cb_t cb);
142 /// A callback reporting node status changes.
143 /** @param mesh A handle which represents an instance of MeshLink.
144 * @param node A pointer to a meshlink_node_t describing the node whose status changed.
145 * @param reachable True if the node is reachable, false otherwise.
147 typedef void (*meshlink_node_status_cb_t)(meshlink_handle_t *mesh, meshlink_node_t *node, bool reachable);
149 /// Set the node status callback.
150 /** This functions sets the callback that is called whenever another node's status changed.
151 * The callback is run in MeshLink's own thread.
152 * It is therefore important that the callback uses apprioriate methods (queues, pipes, locking, etc.)
153 * to hand the data over to the application's thread.
154 * The callback should also not block itself and return as quickly as possible.
156 * @param mesh A handle which represents an instance of MeshLink.
157 * @param cb A pointer to the function which will be called when another node's status changes.
159 extern void meshlink_set_node_status_cb(meshlink_handle_t *mesh, meshlink_node_status_cb_t cb);
161 /// Severity of log messages generated by MeshLink.
163 MESHLINK_DEBUG, ///< Internal debugging messages. Only useful during application development.
164 MESHLINK_INFO, ///< Informational messages.
165 MESHLINK_WARNING, ///< Warnings which might indicate problems, but which are not real errors.
166 MESHLINK_ERROR, ///< Errors which hamper correct functioning of MeshLink, without causing it to fail completely.
167 MESHLINK_CRITICAL, ///< Critical errors which cause MeshLink to fail completely.
168 } meshlink_log_level_t;
170 /// A callback for receiving log messages generated by MeshLink.
171 /** @param mesh A handle which represents an instance of MeshLink.
172 * @param level An enum describing the severity level of the message.
173 * @param text A pointer to a string containing the textual log message.
175 typedef void (*meshlink_log_cb_t)(meshlink_handle_t *mesh, meshlink_log_level_t level, const char *text);
177 /// Set the log callback.
178 /** This functions sets the callback that is called whenever MeshLink has some information to log.
179 * The callback is run in MeshLink's own thread.
180 * It is important that the callback uses apprioriate methods (queues, pipes, locking, etc.)
181 * to hand the data over to the application's thread.
182 * The callback should also not block itself and return as quickly as possible.
184 * @param mesh A handle which represents an instance of MeshLink.
185 * @param level An enum describing the minimum severity level. Debugging information with a lower level will not trigger the callback.
186 * @param cb A pointer to the function which will be called when another node sends data to the local node.
188 extern void meshlink_set_log_cb(meshlink_handle_t *mesh, meshlink_log_level_t level, meshlink_log_cb_t cb);
190 /// Send data to another node.
191 /** This functions sends one packet of data to another node in the mesh.
192 * The packet is sent using UDP semantics, which means that
193 * the packet is sent as one unit and is received as one unit,
194 * and that there is no guarantee that the packet will arrive at the destination.
195 * The application should take care of getting an acknowledgement and retransmission if necessary.
197 * @param mesh A handle which represents an instance of MeshLink.
198 * @param destination A pointer to a meshlink_node_t describing the destination for the data.
199 * @param data A pointer to a buffer containing the data to be sent to the source.
200 * @param len The length of the data.
201 * @return This function will return true if MeshLink has queued the message for transmission, and false otherwise.
202 * A return value of true does not guarantee that the message will actually arrive at the destination.
204 extern bool meshlink_send(meshlink_handle_t *mesh, meshlink_node_t *destination, const void *data, unsigned int len);
206 /// Get a handle for a specific node.
207 /** This function returns a handle for the node with the given name.
209 * @param mesh A handle which represents an instance of MeshLink.
210 * @param name The name of the node for which a handle is requested.
212 * @return A pointer to a meshlink_node_t which represents the requested node,
213 * or NULL if the requested node does not exist.
215 extern meshlink_node_t *meshlink_get_node(meshlink_handle_t *mesh, const char *name);
217 /// Get a list of all nodes.
218 /** This function returns a list with handles for all known nodes.
220 * @param mesh A handle which represents an instance of MeshLink.
221 * @param nodes A pointer to an array of pointers to meshlink_node_t, which should be allocated by the application.
222 * @param nmemb The maximum number of pointers that can be stored in the nodes array.
224 * @return The number of known nodes. This can be larger than nmemb, in which case not all nodes were stored in the nodes array.
226 extern size_t meshlink_get_all_nodes(meshlink_handle_t *mesh, meshlink_node_t **nodes, size_t nmemb);
228 /// Sign data using the local node's MeshLink key.
229 /** This function signs data using the local node's MeshLink key.
230 * The generated signature can be securely verified by other nodes.
232 * @param mesh A handle which represents an instance of MeshLink.
233 * @param data A pointer to a buffer containing the data to be signed.
234 * @param len The length of the data to be signed.
235 * @param signature A pointer to a buffer where the signature will be stored.
236 * @param siglen The size of the signature buffer. Will be changed after the call to match the size of the signature itself.
238 * @return This function returns true if the signature was correctly generated, false otherwise.
240 extern bool meshlink_sign(meshlink_handle_t *mesh, const void *data, size_t len, void *signature, size_t *siglen);
242 /// Verify the signature generated by another node of a piece of data.
243 /** This function verifies the signature that another node generated for a piece of data.
245 * @param mesh A handle which represents an instance of MeshLink.
246 * @param source A pointer to a meshlink_node_t describing the source of the signature.
247 * @param data A pointer to a buffer containing the data to be verified.
248 * @param len The length of the data to be verified.
249 * @param signature A pointer to a string containing the signature.
250 * @param siglen The size of the signature.
252 * @return This function returns true if the signature is valid, false otherwise.
254 extern bool meshlink_verify(meshlink_handle_t *mesh, meshlink_node_t *source, const void *data, size_t len, const void *signature, size_t siglen);
256 /// Add an Address for the local node.
257 /** This function adds an Address for the local node, which will be used for invitation URLs.
259 * @param mesh A handle which represents an instance of MeshLink.
260 * @param address A string containing the address, which can be either in numeric format or a hostname.
262 * @return This function returns true if the address was added, false otherwise.
264 extern bool meshlink_add_address(meshlink_handle_t *mesh, const char *address);
266 /// Invite another node into the mesh.
267 /** This function generates an invitation that can be used by another node to join the same mesh as the local node.
268 * The generated invitation is a string containing a URL.
269 * This URL should be passed by the application to the invitee in a way that no eavesdroppers can see the URL.
270 * The URL can only be used once, after the user has joined the mesh the URL is no longer valid.
272 * @param mesh A handle which represents an instance of MeshLink.
273 * @param name The name that the invitee will use in the mesh.
275 * @return This function returns a string that contains the invitation URL.
276 * The application should call free() after it has finished using the URL.
278 extern char *meshlink_invite(meshlink_handle_t *mesh, const char *name);
280 /// Use an invitation to join a mesh.
281 /** This function allows the local node to join an existing mesh using an invitation URL generated by another node.
282 * An invitation can only be used if the local node has never connected to other nodes before.
283 * After a succesfully accepted invitation, the name of the local node may have changed.
285 * @param mesh A handle which represents an instance of MeshLink.
286 * @param invitation A string containing the invitation URL.
288 * @return This function returns true if the local node joined the mesh it was invited to, false otherwise.
290 extern bool meshlink_join(meshlink_handle_t *mesh, const char *invitation);
292 /// Export the local node's key and addresses.
293 /** This function generates a string that contains the local node's public key and one or more IP addresses.
294 * The application can pass it in some way to another node, which can then import it,
295 * granting the local node access to the other node's mesh.
297 * @param mesh A handle which represents an instance of MeshLink.
299 * @return This function returns a string that contains the exported key and addresses.
300 * The application should call free() after it has finished using this string.
302 extern char *meshlink_export(meshlink_handle_t *mesh);
304 /// Import another node's key and addresses.
305 /** This function accepts a string containing the exported public key and addresses of another node.
306 * By importing this data, the local node grants the other node access to its mesh.
308 * @param mesh A handle which represents an instance of MeshLink.
309 * @param data A string containing the other node's exported key and addresses.
311 * @return This function returns true if the data was valid and the other node has been granted access to the mesh, false otherwise.
313 extern bool meshlink_import(meshlink_handle_t *mesh, const char *data);
315 /// Blacklist a node from the mesh.
316 /** This function causes the local node to blacklist another node.
317 * The local node will drop any existing connections to that node,
318 * and will not send data to it nor accept any data received from it any more.
320 * @param mesh A handle which represents an instance of MeshLink.
321 * @param node A pointer to a meshlink_node_t describing the node to be blacklisted.
323 extern void meshlink_blacklist(meshlink_handle_t *mesh, meshlink_node_t *node);
325 /// A callback for accepting incoming channels.
326 /** This function is called whenever a remote node wants to open a channel to the local node.
327 * The application then has to decide whether to accept or reject this channel.
329 * @param mesh A handle which represents an instance of MeshLink.
330 * @param channel A handle for the incoming channel.
331 * @param node The node from which this channel is being initiated.
332 * @param port The port number the peer wishes to connect to.
333 * @param data A pointer to a buffer containing data already received. (Not yet used.)
334 * @param len The length of the data. (Not yet used.)
336 * @return This function should return true if the application accepts the incoming channel, false otherwise.
337 * If returning false, the channel is invalid and may not be used anymore.
339 typedef bool (*meshlink_channel_accept_cb_t)(meshlink_handle_t *mesh, meshlink_channel_t *channel, meshlink_node_t *node, uint16_t port, const void *data, size_t len);
341 /// A callback for receiving data from a channel.
342 /** This function is called whenever a remote node wants to open a channel to the local node.
343 * The application then has to decide whether to accept or reject this channel.
345 * @param mesh A handle which represents an instance of MeshLink.
346 * @param channel A handle for the channel.
347 * @param data A pointer to a buffer containing data sent by the source.
348 * @param len The length of the data.
350 typedef void (*meshlink_channel_receive_cb_t)(meshlink_handle_t *mesh, meshlink_channel_t *channel, const void *data, size_t len);
352 /// Set the accept callback.
353 /** This functions sets the callback that is called whenever another node sends data to the local node.
354 * The callback is run in MeshLink's own thread.
355 * It is therefore important that the callback uses apprioriate methods (queues, pipes, locking, etc.)
356 * to hand the data over to the application's thread.
357 * The callback should also not block itself and return as quickly as possible.
359 * @param mesh A handle which represents an instance of MeshLink.
360 * @param cb A pointer to the function which will be called when another node sends data to the local node.
362 extern void meshlink_set_channel_accept_cb(meshlink_handle_t *mesh, meshlink_channel_accept_cb_t cb);
364 /// Set the receive callback.
365 /** This functions sets the callback that is called whenever another node sends data to the local node.
366 * The callback is run in MeshLink's own thread.
367 * It is therefore important that the callback uses apprioriate methods (queues, pipes, locking, etc.)
368 * to hand the data over to the application's thread.
369 * The callback should also not block itself and return as quickly as possible.
371 * @param mesh A handle which represents an instance of MeshLink.
372 * @param channel A handle for the channel.
373 * @param cb A pointer to the function which will be called when another node sends data to the local node.
375 extern void meshlink_set_channel_receive_cb(meshlink_handle_t *mesh, meshlink_channel_t *channel, meshlink_channel_receive_cb_t cb);
377 /// Open a reliable stream channel to another node.
378 /** This function is called whenever a remote node wants to open a channel to the local node.
379 * The application then has to decide whether to accept or reject this channel.
381 * @param mesh A handle which represents an instance of MeshLink.
382 * @param node The node to which this channel is being initiated.
383 * @param port The port number the peer wishes to connect to.
384 * @param cb A pointer to the function which will be called when the remote node sends data to the local node.
385 * @param data A pointer to a buffer containing data to already queue for sending.
386 * @param len The length of the data.
388 * @return A handle for the channel, or NULL in case of an error.
390 extern meshlink_channel_t *meshlink_channel_open(meshlink_handle_t *mesh, meshlink_node_t *node, uint16_t port, meshlink_channel_receive_cb_t cb, const void *data, size_t len);
392 /// Partially close a reliable stream channel.
393 /** This shuts down the read or write side of a channel, or both, without closing the handle.
394 * It can be used to inform the remote node that the local node has finished sending all data on the channel,
395 * but still allows waiting for incoming data from the remote node.
397 * @param mesh A handle which represents an instance of MeshLink.
398 * @param channel A handle for the channel.
399 * @param direction Must be one of SHUT_RD, SHUT_WR or SHUT_RDWR.
401 extern void meshlink_channel_shutdown(meshlink_handle_t *mesh, meshlink_channel_t *channel, int direction);
403 /// Close a reliable stream channel.
404 /** This informs the remote node that the local node has finished sending all data on the channel.
405 * It also causes the local node to stop accepting incoming data from the remote node.
406 * Afterwards, the channel handle is invalid and must not be used any more.
408 * @param mesh A handle which represents an instance of MeshLink.
409 * @param channel A handle for the channel.
411 extern void meshlink_channel_close(meshlink_handle_t *mesh, meshlink_channel_t *channel);
413 /// Transmit data on a channel
414 /** This queues data to send to the remote node.
416 * @param mesh A handle which represents an instance of MeshLink.
417 * @param channel A handle for the channel.
418 * @param data A pointer to a buffer containing data sent by the source.
419 * @param len The length of the data.
421 * @return The amount of data that was queued, which can be less than len, or a negative value in case of an error.
423 extern ssize_t meshlink_channel_send(meshlink_handle_t *mesh, meshlink_channel_t *channel, const void *data, size_t len);