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.
30 /// A handle for an instance of MeshLink.
31 typedef struct meshlink_handle meshlink_handle_t;
33 /// A handle for a MeshLink node.
34 typedef struct meshlink_node meshlink_node_t;
36 /// Code of most recent error encountered.
38 MESHLINK_OK, // Everything is fine
39 MESHLINK_ENOMEM, // Out of memory
40 MESHLINK_ENOENT, // Node is not known
43 #ifndef MESHLINK_INTERNAL_H
45 struct meshlink_handle {
46 meshlink_errno_t meshlink_errno; /// Code of the last encountered error.
47 const char *errstr; /// Textual representation of most recent error encountered.
50 struct meshlink_node {
51 const char *name; // Textual name of this node.
52 void *priv; // Private pointer which the application can set at will.
55 #endif // MESHLINK_INTERNAL_H
57 /// Get the text for the given MeshLink error code.
58 /** This function returns a pointer to the string containing the description of the given error code.
60 * @param errno An error code returned by MeshLink.
62 * @return A pointer to a string containing the description of the error code.
64 extern const char *meshlink_strerror(meshlink_errno_t errno);
66 /// Initialize MeshLink's configuration directory.
67 /** This function causes MeshLink to initialize its configuration directory,
68 * if it hasn't already been initialized.
69 * It only has to be run the first time the application starts,
70 * but it is not a problem if it is run more than once, as long as
71 * the arguments given are the same.
73 * This function does not start any network I/O yet. The application should
74 * first set callbacks, and then call meshlink_start().
76 * @param confbase The directory in which MeshLink will store its configuration files.
77 * @param name The name which this instance of the application will use in the mesh.
79 * @return This function will return true if MeshLink has succesfully set up its configuration files, false otherwise.
81 extern meshlink_handle_t *meshlink_open(const char *confbase, const char *name);
84 /** This function causes MeshLink to open network sockets, make outgoing connections, and
85 * create a new thread, which will handle all network I/O.
87 * @param confbase The directory in which MeshLink will store its configuration files.
89 * @return This function will return true if MeshLink has succesfully started its thread, false otherwise.
91 extern bool meshlink_start(meshlink_handle_t *mesh);
94 /** This function causes MeshLink to disconnect from all other nodes,
95 * close all sockets, and shut down its own thread.
97 * @param handle A handle which represents an instance of MeshLink.
99 extern void meshlink_stop(meshlink_handle_t *mesh);
101 /// Close the MeshLink handle.
102 /** This function calls meshlink_stop() if necessary,
103 * and frees all memory allocated by MeshLink.
104 * Afterwards, the handle and any pointers to a struct meshlink_node are invalid.
106 * @param handle A handle which represents an instance of MeshLink.
108 extern void meshlink_close(meshlink_handle_t *mesh);
110 /// A callback for receiving data from the mesh.
111 /** @param handle A handle which represents an instance of MeshLink.
112 * @param source A pointer to a meshlink_node_t describing the source of the data.
113 * @param data A pointer to a buffer containing the data sent by the source.
114 * @param len The length of the received data.
116 typedef void (*meshlink_receive_cb_t)(meshlink_handle_t *mesh, meshlink_node_t *source, const void *data, size_t len);
118 /// Set the receive callback.
119 /** This functions sets the callback that is called whenever another node sends data to the local node.
120 * The callback is run in MeshLink's own thread.
121 * It is therefore important that the callback uses apprioriate methods (queues, pipes, locking, etc.)
122 * to hand the data over to the application's thread.
123 * The callback should also not block itself and return as quickly as possible.
125 * @param handle A handle which represents an instance of MeshLink.
126 * @param cb A pointer to the function which will be called when another node sends data to the local node.
128 extern void meshlink_set_receive_cb(meshlink_handle_t *mesh, meshlink_receive_cb_t cb);
130 /// A callback reporting node status changes.
131 /** @param handle A handle which represents an instance of MeshLink.
132 * @param node A pointer to a meshlink_node_t describing the node whose status changed.
133 * @param reachable True if the node is reachable, false otherwise.
135 typedef void (*meshlink_node_status_cb_t)(meshlink_handle_t *mesh, meshlink_node_t *node, bool reachable);
137 /// Set the node status callback.
138 /** This functions sets the callback that is called whenever another node's status changed.
139 * The callback is run in MeshLink's own thread.
140 * It is therefore important that the callback uses apprioriate methods (queues, pipes, locking, etc.)
141 * to hand the data over to the application's thread.
142 * The callback should also not block itself and return as quickly as possible.
144 * @param handle A handle which represents an instance of MeshLink.
145 * @param cb A pointer to the function which will be called when another node's status changes.
147 extern void meshlink_set_node_status_cb(meshlink_handle_t *mesh, meshlink_node_status_cb_t cb);
149 /// Severity of log messages generated by MeshLink.
151 MESHLINK_DEBUG, // Internal debugging messages. Only useful during application development.
152 MESHLINK_INFO, // Informational messages.
153 MESHLINK_WARNING, // Warnings which might indicate problems, but which are not real errors.
154 MESHLINK_ERROR, // Errors which hamper correct functioning of MeshLink, without causing it to fail completely.
155 MESHLINK_CRITICAL, // Critical errors which cause MeshLink to fail completely.
156 } meshlink_log_level_t;
158 /// A callback for receiving log messages generated by MeshLink.
159 /** @param handle A handle which represents an instance of MeshLink.
160 * @param level An enum describing the severity level of the message.
161 * @param text A pointer to a string containing the textual log message.
163 typedef void (*meshlink_log_cb_t)(meshlink_handle_t *mesh, meshlink_log_level_t level, const char *text);
165 /// Set the log callback.
166 /** This functions sets the callback that is called whenever MeshLink has some information to log.
167 * The callback is run in MeshLink's own thread.
168 * It is important that the callback uses apprioriate methods (queues, pipes, locking, etc.)
169 * to hand the data over to the application's thread.
170 * The callback should also not block itself and return as quickly as possible.
172 * @param handle A handle which represents an instance of MeshLink.
173 * @param level An enum describing the minimum severity level. Debugging information with a lower level will not trigger the callback.
174 * @param cb A pointer to the function which will be called when another node sends data to the local node.
176 extern void meshlink_set_log_cb(meshlink_handle_t *mesh, meshlink_log_level_t level, meshlink_log_cb_t cb);
178 /// Send data to another node.
179 /** This functions sends one packet of data to another node in the mesh.
180 * The packet is sent using UDP semantics, which means that
181 * the packet is sent as one unit and is received as one unit,
182 * and that there is no guarantee that the packet will arrive at the destination.
183 * The application should take care of getting an acknowledgement and retransmission if necessary.
185 * @param handle A handle which represents an instance of MeshLink.
186 * @param destination A pointer to a meshlink_node_t describing the destination for the data.
187 * @param data A pointer to a buffer containing the data to be sent to the source.
188 * @param len The length of the data.
189 * @return This function will return true if MeshLink has queued the message for transmission, and false otherwise.
190 * A return value of true does not guarantee that the message will actually arrive at the destination.
192 extern bool meshlink_send(meshlink_handle_t *mesh, meshlink_node_t *destination, const void *data, unsigned int len);
194 /// Get a handle for a specific node.
195 /** This function returns a handle for the node with the given name.
197 * @param handle A handle which represents an instance of MeshLink.
198 * @param name The name of the node for which a handle is requested.
200 * @return A pointer to a meshlink_node_t which represents the requested node,
201 * or NULL if the requested node does not exist.
203 extern meshlink_node_t *meshlink_get_node(meshlink_handle_t *mesh, const char *name);
205 /// Get a list of all nodes.
206 /** This function returns a list with handles for all known nodes.
208 * @param handle A handle which represents an instance of MeshLink.
209 * @param nodes A pointer to an array of pointers to meshlink_node_t, which should be allocated by the application.
210 * @param nmemb The maximum number of pointers that can be stored in the nodes array.
212 * @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.
214 extern size_t meshlink_get_all_nodes(meshlink_handle_t *mesh, meshlink_node_t **nodes, size_t nmemb);
216 /// Sign data using the local node's MeshLink key.
217 /** This function signs data using the local node's MeshLink key.
218 * The generated signature can be securely verified by other nodes.
220 * @param handle A handle which represents an instance of MeshLink.
221 * @param data A pointer to a buffer containing the data to be signed.
222 * @param len The length of the data to be signed.
224 * @return This function returns a pointer to a string containing the signature, or NULL in case of an error.
225 * The application should call free() after it has finished using the signature.
227 extern char *meshlink_sign(meshlink_handle_t *mesh, const char *data, size_t len);
229 /// Verify the signature generated by another node of a piece of data.
230 /** This function verifies the signature that another node generated for a piece of data.
232 * @param handle A handle which represents an instance of MeshLink.
233 * @param source A pointer to a meshlink_node_t describing the source of the signature.
234 * @param data A pointer to a buffer containing the data to be verified.
235 * @param len The length of the data to be verified.
236 * @param signature A pointer to a string containing the signature.
238 * @return This function returns true if the signature is valid, false otherwise.
240 extern bool meshlink_verify(meshlink_handle_t *mesh, meshlink_node_t *source, const char *data, size_t len, const char *signature);
242 /// Invite another node into the mesh.
243 /** This function generates an invitation that can be used by another node to join the same mesh as the local node.
244 * The generated invitation is a string containing a URL.
245 * This URL should be passed by the application to the invitee in a way that no eavesdroppers can see the URL.
246 * The URL can only be used once, after the user has joined the mesh the URL is no longer valid.
248 * @param handle A handle which represents an instance of MeshLink.
249 * @param name The name that the invitee will use in the mesh.
251 * @return This function returns a string that contains the invitation URL.
252 * The application should call free() after it has finished using the URL.
254 extern char *meshlink_invite(meshlink_handle_t *mesh, const char *name);
256 /// Use an invitation to join a mesh.
257 /** This function allows the local node to join an existing mesh using an invitation URL generated by another node.
258 * An invitation can only be used if the local node has never connected to other nodes before.
259 * After a succesfully accepted invitation, the name of the local node may have changed.
261 * @param handle A handle which represents an instance of MeshLink.
262 * @param invitation A string containing the invitation URL.
264 * @return This function returns true if the local node joined the mesh it was invited to, false otherwise.
266 extern bool meshlink_join(meshlink_handle_t *mesh, const char *invitation);
268 /// Export the local node's key and addresses.
269 /** This function generates a string that contains the local node's public key and one or more IP addresses.
270 * The application can pass it in some way to another node, which can then import it,
271 * granting the local node access to the other node's mesh.
273 * @param handle A handle which represents an instance of MeshLink.
275 * @return This function returns a string that contains the exported key and addresses.
276 * The application should call free() after it has finished using this string.
278 extern char *meshlink_export(meshlink_handle_t *mesh);
280 /// Import another node's key and addresses.
281 /** This function accepts a string containing the exported public key and addresses of another node.
282 * By importing this data, the local node grants the other node access to its mesh.
284 * @param handle A handle which represents an instance of MeshLink.
285 * @param data A string containing the other node's exported key and addresses.
287 * @return This function returns true if the data was valid and the other node has been granted access to the mesh, false otherwise.
289 extern bool meshlink_import(meshlink_handle_t *mesh, const char *data);
291 /// Blacklist a node from the mesh.
292 /** This function causes the local node to blacklist another node.
293 * The local node will drop any existing connections to that node,
294 * and will not send data to it nor accept any data received from it any more.
296 * @param handle A handle which represents an instance of MeshLink.
297 * @param node A pointer to a meshlink_node_t describing the node to be blacklisted.
299 extern void meshlink_blacklist(meshlink_handle_t *mesh, meshlink_node_t *node);