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 #ifndef MESHLINK_INTERNAL_H
53 struct meshlink_handle {
54 meshlink_errno_t meshlink_errno; ///< Code of the last encountered error.
55 const char *errstr; ///< Textual representation of most recent error encountered.
58 struct meshlink_node {
59 const char *name; ///< Textual name of this node.
60 void *priv; ///< Private pointer which the application can set at will.
63 struct meshlink_channel {
66 #endif // MESHLINK_INTERNAL_H
68 /// Get the text for the given MeshLink error code.
69 /** This function returns a pointer to the string containing the description of the given error code.
71 * @param errno An error code returned by MeshLink.
73 * @return A pointer to a string containing the description of the error code.
75 extern const char *meshlink_strerror(meshlink_errno_t errno);
77 /// Initialize MeshLink's configuration directory.
78 /** This function causes MeshLink to initialize its configuration directory,
79 * if it hasn't already been initialized.
80 * It only has to be run the first time the application starts,
81 * but it is not a problem if it is run more than once, as long as
82 * the arguments given are the same.
84 * This function does not start any network I/O yet. The application should
85 * first set callbacks, and then call meshlink_start().
87 * @param confbase The directory in which MeshLink will store its configuration files.
88 * @param name The name which this instance of the application will use in the mesh.
90 * @return This function will return true if MeshLink has succesfully set up its configuration files, false otherwise.
92 extern meshlink_handle_t *meshlink_open(const char *confbase, const char *name);
95 /** This function causes MeshLink to open network sockets, make outgoing connections, and
96 * create a new thread, which will handle all network I/O.
98 * @param mesh A handle which represents an instance of MeshLink.
100 * @return This function will return true if MeshLink has succesfully started its thread, false otherwise.
102 extern bool meshlink_start(meshlink_handle_t *mesh);
105 /** This function causes MeshLink to disconnect from all other nodes,
106 * close all sockets, and shut down its own thread.
108 * @param mesh A handle which represents an instance of MeshLink.
110 extern void meshlink_stop(meshlink_handle_t *mesh);
112 /// Close the MeshLink handle.
113 /** This function calls meshlink_stop() if necessary,
114 * and frees all memory allocated by MeshLink.
115 * Afterwards, the handle and any pointers to a struct meshlink_node are invalid.
117 * @param mesh A handle which represents an instance of MeshLink.
119 extern void meshlink_close(meshlink_handle_t *mesh);
121 /// A callback for receiving data from the mesh.
122 /** @param mesh A handle which represents an instance of MeshLink.
123 * @param source A pointer to a meshlink_node_t describing the source of the data.
124 * @param data A pointer to a buffer containing the data sent by the source.
125 * @param len The length of the received data.
127 typedef void (*meshlink_receive_cb_t)(meshlink_handle_t *mesh, meshlink_node_t *source, const void *data, size_t len);
129 /// Set the receive callback.
130 /** This functions sets the callback that is called whenever another node sends data to the local node.
131 * The callback is run in MeshLink's own thread.
132 * It is therefore important that the callback uses apprioriate methods (queues, pipes, locking, etc.)
133 * to hand the data over to the application's thread.
134 * The callback should also not block itself and return as quickly as possible.
136 * @param mesh A handle which represents an instance of MeshLink.
137 * @param cb A pointer to the function which will be called when another node sends data to the local node.
139 extern void meshlink_set_receive_cb(meshlink_handle_t *mesh, meshlink_receive_cb_t cb);
141 /// A callback reporting node status changes.
142 /** @param mesh A handle which represents an instance of MeshLink.
143 * @param node A pointer to a meshlink_node_t describing the node whose status changed.
144 * @param reachable True if the node is reachable, false otherwise.
146 typedef void (*meshlink_node_status_cb_t)(meshlink_handle_t *mesh, meshlink_node_t *node, bool reachable);
148 /// Set the node status callback.
149 /** This functions sets the callback that is called whenever another node's status changed.
150 * The callback is run in MeshLink's own thread.
151 * It is therefore important that the callback uses apprioriate methods (queues, pipes, locking, etc.)
152 * to hand the data over to the application's thread.
153 * The callback should also not block itself and return as quickly as possible.
155 * @param mesh A handle which represents an instance of MeshLink.
156 * @param cb A pointer to the function which will be called when another node's status changes.
158 extern void meshlink_set_node_status_cb(meshlink_handle_t *mesh, meshlink_node_status_cb_t cb);
160 /// Severity of log messages generated by MeshLink.
162 MESHLINK_DEBUG, ///< Internal debugging messages. Only useful during application development.
163 MESHLINK_INFO, ///< Informational messages.
164 MESHLINK_WARNING, ///< Warnings which might indicate problems, but which are not real errors.
165 MESHLINK_ERROR, ///< Errors which hamper correct functioning of MeshLink, without causing it to fail completely.
166 MESHLINK_CRITICAL, ///< Critical errors which cause MeshLink to fail completely.
167 } meshlink_log_level_t;
169 /// A callback for receiving log messages generated by MeshLink.
170 /** @param mesh A handle which represents an instance of MeshLink.
171 * @param level An enum describing the severity level of the message.
172 * @param text A pointer to a string containing the textual log message.
174 typedef void (*meshlink_log_cb_t)(meshlink_handle_t *mesh, meshlink_log_level_t level, const char *text);
176 /// Set the log callback.
177 /** This functions sets the callback that is called whenever MeshLink has some information to log.
178 * The callback is run in MeshLink's own thread.
179 * It is important that the callback uses apprioriate methods (queues, pipes, locking, etc.)
180 * to hand the data over to the application's thread.
181 * The callback should also not block itself and return as quickly as possible.
183 * @param mesh A handle which represents an instance of MeshLink.
184 * @param level An enum describing the minimum severity level. Debugging information with a lower level will not trigger the callback.
185 * @param cb A pointer to the function which will be called when another node sends data to the local node.
187 extern void meshlink_set_log_cb(meshlink_handle_t *mesh, meshlink_log_level_t level, meshlink_log_cb_t cb);
189 /// Send data to another node.
190 /** This functions sends one packet of data to another node in the mesh.
191 * The packet is sent using UDP semantics, which means that
192 * the packet is sent as one unit and is received as one unit,
193 * and that there is no guarantee that the packet will arrive at the destination.
194 * The application should take care of getting an acknowledgement and retransmission if necessary.
196 * @param mesh A handle which represents an instance of MeshLink.
197 * @param destination A pointer to a meshlink_node_t describing the destination for the data.
198 * @param data A pointer to a buffer containing the data to be sent to the source.
199 * @param len The length of the data.
200 * @return This function will return true if MeshLink has queued the message for transmission, and false otherwise.
201 * A return value of true does not guarantee that the message will actually arrive at the destination.
203 extern bool meshlink_send(meshlink_handle_t *mesh, meshlink_node_t *destination, const void *data, unsigned int len);
205 /// Get a handle for a specific node.
206 /** This function returns a handle for the node with the given name.
208 * @param mesh A handle which represents an instance of MeshLink.
209 * @param name The name of the node for which a handle is requested.
211 * @return A pointer to a meshlink_node_t which represents the requested node,
212 * or NULL if the requested node does not exist.
214 extern meshlink_node_t *meshlink_get_node(meshlink_handle_t *mesh, const char *name);
216 /// Get a list of all nodes.
217 /** This function returns a list with handles for all known nodes.
219 * @param mesh A handle which represents an instance of MeshLink.
220 * @param nodes A pointer to an array of pointers to meshlink_node_t, which should be allocated by the application.
221 * @param nmemb The maximum number of pointers that can be stored in the nodes array.
223 * @return The number of known nodes. This can be larger than nmemb, in which case not all nodes were stored in the nodes array.
225 extern size_t meshlink_get_all_nodes(meshlink_handle_t *mesh, meshlink_node_t **nodes, size_t nmemb);
227 /// Sign data using the local node's MeshLink key.
228 /** This function signs data using the local node's MeshLink key.
229 * The generated signature can be securely verified by other nodes.
231 * @param mesh A handle which represents an instance of MeshLink.
232 * @param data A pointer to a buffer containing the data to be signed.
233 * @param len The length of the data to be signed.
234 * @param signature A pointer to a buffer where the signature will be stored.
235 * @param siglen The size of the signature buffer. Will be changed after the call to match the size of the signature itself.
237 * @return This function returns true if the signature was correctly generated, false otherwise.
239 extern bool meshlink_sign(meshlink_handle_t *mesh, const void *data, size_t len, void *signature, size_t *siglen);
241 /// Verify the signature generated by another node of a piece of data.
242 /** This function verifies the signature that another node generated for a piece of data.
244 * @param mesh A handle which represents an instance of MeshLink.
245 * @param source A pointer to a meshlink_node_t describing the source of the signature.
246 * @param data A pointer to a buffer containing the data to be verified.
247 * @param len The length of the data to be verified.
248 * @param signature A pointer to a string containing the signature.
249 * @param siglen The size of the signature.
251 * @return This function returns true if the signature is valid, false otherwise.
253 extern bool meshlink_verify(meshlink_handle_t *mesh, meshlink_node_t *source, const void *data, size_t len, const void *signature, size_t siglen);
255 /// Add an Address for the local node.
256 /** This function adds an Address for the local node, which will be used for invitation URLs.
258 * @param mesh A handle which represents an instance of MeshLink.
259 * @param address A string containing the address, which can be either in numeric format or a hostname.
261 * @return This function returns true if the address was added, false otherwise.
263 extern bool meshlink_add_address(meshlink_handle_t *mesh, const char *address);
265 /// Invite another node into the mesh.
266 /** This function generates an invitation that can be used by another node to join the same mesh as the local node.
267 * The generated invitation is a string containing a URL.
268 * This URL should be passed by the application to the invitee in a way that no eavesdroppers can see the URL.
269 * The URL can only be used once, after the user has joined the mesh the URL is no longer valid.
271 * @param mesh A handle which represents an instance of MeshLink.
272 * @param name The name that the invitee will use in the mesh.
274 * @return This function returns a string that contains the invitation URL.
275 * The application should call free() after it has finished using the URL.
277 extern char *meshlink_invite(meshlink_handle_t *mesh, const char *name);
279 /// Use an invitation to join a mesh.
280 /** This function allows the local node to join an existing mesh using an invitation URL generated by another node.
281 * An invitation can only be used if the local node has never connected to other nodes before.
282 * After a succesfully accepted invitation, the name of the local node may have changed.
284 * @param mesh A handle which represents an instance of MeshLink.
285 * @param invitation A string containing the invitation URL.
287 * @return This function returns true if the local node joined the mesh it was invited to, false otherwise.
289 extern bool meshlink_join(meshlink_handle_t *mesh, const char *invitation);
291 /// Export the local node's key and addresses.
292 /** This function generates a string that contains the local node's public key and one or more IP addresses.
293 * The application can pass it in some way to another node, which can then import it,
294 * granting the local node access to the other node's mesh.
296 * @param mesh A handle which represents an instance of MeshLink.
298 * @return This function returns a string that contains the exported key and addresses.
299 * The application should call free() after it has finished using this string.
301 extern char *meshlink_export(meshlink_handle_t *mesh);
303 /// Import another node's key and addresses.
304 /** This function accepts a string containing the exported public key and addresses of another node.
305 * By importing this data, the local node grants the other node access to its mesh.
307 * @param mesh A handle which represents an instance of MeshLink.
308 * @param data A string containing the other node's exported key and addresses.
310 * @return This function returns true if the data was valid and the other node has been granted access to the mesh, false otherwise.
312 extern bool meshlink_import(meshlink_handle_t *mesh, const char *data);
314 /// Blacklist a node from the mesh.
315 /** This function causes the local node to blacklist another node.
316 * The local node will drop any existing connections to that node,
317 * and will not send data to it nor accept any data received from it any more.
319 * @param mesh A handle which represents an instance of MeshLink.
320 * @param node A pointer to a meshlink_node_t describing the node to be blacklisted.
322 extern void meshlink_blacklist(meshlink_handle_t *mesh, meshlink_node_t *node);
324 /// A callback for accepting incoming channels.
325 /** This function is called whenever a remote node wants to open a channel to the local node.
326 * The application then has to decide whether to accept or reject this channel.
328 * @param mesh A handle which represents an instance of MeshLink.
329 * @param channel A handle for the incoming channel.
330 * @param node The node from which this channel is being initiated.
331 * @param port The port number the peer wishes to connect to.
332 * @param data A pointer to a buffer containing data already received. (Not yet used.)
333 * @param len The length of the data. (Not yet used.)
335 * @return This function should return true if the application accepts the incoming channel, false otherwise.
336 * If returning false, the channel is invalid and may not be used anymore.
338 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);
340 /// A callback for receiving data from a channel.
341 /** This function is called whenever a remote node wants to open a channel to the local node.
342 * The application then has to decide whether to accept or reject this channel.
344 * @param mesh A handle which represents an instance of MeshLink.
345 * @param channel A handle for the channel.
346 * @param data A pointer to a buffer containing data sent by the source.
347 * @param len The length of the data.
349 typedef void (*meshlink_channel_receive_cb_t)(meshlink_handle_t *mesh, meshlink_channel_t *channel, const void *data, size_t len);
351 /// Set the accept callback.
352 /** This functions sets the callback that is called whenever another node sends data to the local node.
353 * The callback is run in MeshLink's own thread.
354 * It is therefore important that the callback uses apprioriate methods (queues, pipes, locking, etc.)
355 * to hand the data over to the application's thread.
356 * The callback should also not block itself and return as quickly as possible.
358 * @param mesh A handle which represents an instance of MeshLink.
359 * @param cb A pointer to the function which will be called when another node sends data to the local node.
361 extern void meshlink_set_channel_accept_cb(meshlink_handle_t *mesh, meshlink_channel_accept_cb_t cb);
363 /// Set the receive callback.
364 /** This functions sets the callback that is called whenever another node sends data to the local node.
365 * The callback is run in MeshLink's own thread.
366 * It is therefore important that the callback uses apprioriate methods (queues, pipes, locking, etc.)
367 * to hand the data over to the application's thread.
368 * The callback should also not block itself and return as quickly as possible.
370 * @param mesh A handle which represents an instance of MeshLink.
371 * @param channel A handle for the channel.
372 * @param cb A pointer to the function which will be called when another node sends data to the local node.
374 extern void meshlink_set_channel_receive_cb(meshlink_handle_t *mesh, meshlink_channel_t *channel, meshlink_channel_receive_cb_t cb);
376 /// Open a reliable stream channel to another node.
377 /** This function is called whenever a remote node wants to open a channel to the local node.
378 * The application then has to decide whether to accept or reject this channel.
380 * @param mesh A handle which represents an instance of MeshLink.
381 * @param node The node to which this channel is being initiated.
382 * @param port The port number the peer wishes to connect to.
383 * @param cb A pointer to the function which will be called when the remote node sends data to the local node.
384 * @param data A pointer to a buffer containing data to already queue for sending.
385 * @param len The length of the data.
387 * @return A handle for the channel, or NULL in case of an error.
389 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);
391 /// Partially close a reliable stream channel.
392 /** This shuts down the read or write side of a channel, or both, without closing the handle.
393 * It can be used to inform the remote node that the local node has finished sending all data on the channel,
394 * but still allows waiting for incoming data from the remote node.
396 * @param mesh A handle which represents an instance of MeshLink.
397 * @param channel A handle for the channel.
398 * @param direction Must be one of SHUT_RD, SHUT_WR or SHUT_RDWR.
400 extern void meshlink_channel_shutdown(meshlink_handle_t *mesh, meshlink_channel_t *channel, int direction);
402 /// Close a reliable stream channel.
403 /** This informs the remote node that the local node has finished sending all data on the channel.
404 * It also causes the local node to stop accepting incoming data from the remote node.
405 * Afterwards, the channel handle is invalid and must not be used any more.
407 * @param mesh A handle which represents an instance of MeshLink.
408 * @param channel A handle for the channel.
410 extern void meshlink_channel_close(meshlink_handle_t *mesh, meshlink_channel_t *channel);
412 /// Transmit data on a channel
413 /** This queues data to send to the remote node.
415 * @param mesh A handle which represents an instance of MeshLink.
416 * @param channel A handle for the channel.
417 * @param data A pointer to a buffer containing data sent by the source.
418 * @param len The length of the data.
420 * @return The amount of data that was queued, which can be less than len, or a negative value in case of an error.
422 extern ssize_t meshlink_channel_send(meshlink_handle_t *mesh, meshlink_channel_t *channel, const void *data, size_t len);