OpenOBEX Documentation


Legal notice

OpenOBEX is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with OpenOBEX. If not, see <>.


This library tries to implement a generic OBEX Session Protocol. It does not implement the OBEX Application FrameWork.

When you read this it's very useful to have a copy of the OBEX specification. It is available for download on IrDA's website Make sure you have obex.h and obex_const.h too. You might also find the OpenOBEX test-apps useful.

Programming the library


To be able to use the OpenOBEX API you must include the file openobex/obex.h.

First of all you must create an OBEX instance by calling OBEX_Init. In this call you specify what transport you want to use, an event callback, and optional flags. OBEX_Init will return a handle which shall be passed to almost all other functions.

To let the parser do some work you must call OBEX_HandleInput. It will block for the specified timeout if there is no data to read. You can call OBEX_GetFD if you want to do select() yourself.

The event callback

The event callback shall be a function with the obex_event_t prototype:
void *obex_event_t(obex_t *handle, obex_object_t *obj, int mode, int event, int obex_cmd, int obex_rsp)


To this function events from the library will be passed to you, for example when an operation finishes. OBEX_SetUserData and OBEX_GetUserData are useful if you need to access your own private data from inside the event callback.

Client Operations

First of all you must connect the transport using OBEX_TransportConnect or one of

When the transport is connected you shall most likely also send an OBEX Connect, to let the library negotiate MTU etc. OBEX Connect is sent as any other OBEX command.

When you are done sending your requests you shall end by sending an OBEX Disconnect request and then call OBEX_TransportDisconnect.

To send a request to you must first create an OBEX Object by calling OBEX_ObjectNew with the command opcode as argument. Next you add headers to it using OBEX_ObjectAddHeader. Finally you send away the request using OBEX_Request.

When the request has finished you'll get an OBEX_EV_REQDONE event. You can get any headers sent in response (like in a OBEX Get) by calling OBEX_ObjectGetNextHeader.

A Put would look something like this:

OBEX Put example

obex_object_t *object;
obex_headerdata_t hd;

object = OBEX_ObjectNew(handle, OBEX_CMD_PUT);
if(object == NULL) {
        /* Error */

/* Add length header */
hd.bq4 = body_size;
OBEX_ObjectAddHeader(handle, object,
            OBEX_HDR_LENGTH, hd, 4, 0);

/* Add unicode name header*/ = unicodename;
OBEX_ObjectAddHeader(handle, object,
            OBEX_HDR_NAME, hd, name_size, 0);

/* Add body header*/ = body;
OBEX_ObjectAddHeader(handle, object,
            OBEX_HDR_BODY, hd, body_size, 0);

if(OBEX_Request(handle, object) &lt; 0) {
        /* Error */

Server Operations

To act as a server you must first tell the transport to receive incoming connections via the function OBEX_ServerRegister. When an incoming connection is coming you'll get an OBEX_EV_ACCEPTHINT event. If you ignore this event no more incoming connections will be accepted, but if you call OBEX_ServerAccept you'll get back a new OBEX handle and the old handle will still be listening to connections.

When an incoming request comes you'll first get an OBEX_EV_REQHINT event. The supplied OBEX Object is allocated by the library so you do not need to create it yourself.

The OBEX_EV_REQHINT event comes before the parser start receiving the request, so you can cancel requests that your application does not support early.

Set the response to the request using OBEX_ObjectSetRsp.

You can tell the parser to deliver the body-header as a stream when this event comes using OBEX_ObjectReadStream.

When the request is received you'll get an OBEX_EV_REQ event. Get the headers from the object by calling OBEX_ObjectGetNextHeader. You can now change the response if you decide to reject the request. Add any headers you want in the response here too.

When your response is successfully sent you'll get an OBEX_EV_REQDONE event.

After you have received and answered an OBEX Disconnect request you shall call OBEX_TransportDisconnect.

Event callback of a typical server

switch (event)  {
    /* An incoming request */
    switch(obex_cmd) {
    /* Dont need to do anything here.
       Response is already set to
       success by OBEX_EV_REQHINT event */
    case OBEX_CMD_PUT:


    /* A new request is coming in */
    switch(obex_cmd) {
    /* Accept xome commands! */
    case OBEX_CMD_PUT:

        /* Reject any other commands */                 
        OBEX_ObjectSetRsp(object, OBEX_RSP_NOT_IMPLEMENTED,


    if(obex_cmd == OBEX_CMD_DISCONNECT) {
        /* Disconnect transport here */

    /* Not good */


API Reference

See: lib/obex.c, include/openobex/obex.h, include/openobex/obex_const.h.

Authors and Contact

Authors and major contributors:


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