l2cap_signaling.c

00001 /*
00002  * Copyright (C) 2009-2012 by Matthias Ringwald
00003  *
00004  * Redistribution and use in source and binary forms, with or without
00005  * modification, are permitted provided that the following conditions
00006  * are met:
00007  *
00008  * 1. Redistributions of source code must retain the above copyright
00009  *    notice, this list of conditions and the following disclaimer.
00010  * 2. Redistributions in binary form must reproduce the above copyright
00011  *    notice, this list of conditions and the following disclaimer in the
00012  *    documentation and/or other materials provided with the distribution.
00013  * 3. Neither the name of the copyright holders nor the names of
00014  *    contributors may be used to endorse or promote products derived
00015  *    from this software without specific prior written permission.
00016  * 4. Any redistribution, use, or modification is done solely for
00017  *    personal benefit and not for any commercial purpose or for
00018  *    monetary gain.
00019  *
00020  * THIS SOFTWARE IS PROVIDED BY MATTHIAS RINGWALD AND CONTRIBUTORS
00021  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
00022  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
00023  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL MATTHIAS
00024  * RINGWALD OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
00025  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
00026  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
00027  * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
00028  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
00029  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
00030  * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
00031  * SUCH DAMAGE.
00032  *
00033  * Please inquire about commercial licensing options at btstack@ringwald.ch
00034  *
00035  */
00036 
00037 /*
00038  *  l2cap_signaling.h
00039  *
00040  *  Created by Matthias Ringwald on 7/23/09.
00041  */
00042 
00043 #include "l2cap_signaling.h"
00044 
00045 #include <string.h>
00046 
00047 static char *l2cap_signaling_commands_format[] = {
00048 "D",    // 0x01 command reject: reason {cmd not understood (0), sig MTU exceeded (2:max sig MTU), invalid CID (4:req CID)}, data len, data
00049 "22",   // 0x02 connection request: PSM, Source CID
00050 "2222", // 0x03 connection response: Dest CID, Source CID, Result, Status
00051 "22D",  // 0x04 config request: Dest CID, Flags, Configuration options
00052 "222D", // 0x05 config response: Source CID, Flags, Result, Configuration options
00053 "22",   // 0x06 disconection request: Dest CID, Source CID
00054 "22",   // 0x07 disconection response: Dest CID, Source CID
00055 "D",    // 0x08 echo request: Data
00056 "D",    // 0x09 echo response: Data
00057 "2",    // 0x0a information request: InfoType {1=Connectionless MTU, 2=Extended features supported}
00058 "22D",  // 0x0b information response: InfoType, Result, Data
00059 };
00060 
00061 uint8_t   sig_seq_nr  = 0xff;
00062 uint16_t  source_cid  = 0x40;
00063 
00064 uint8_t l2cap_next_sig_id(void){
00065     if (sig_seq_nr == 0xff) {
00066         sig_seq_nr = 1;
00067     } else {
00068         sig_seq_nr++;
00069     }
00070     return sig_seq_nr;
00071 }
00072 
00073 uint16_t l2cap_next_local_cid(void){
00074     return source_cid++;
00075 }
00076 
00077 uint16_t l2cap_create_signaling_internal(uint8_t * acl_buffer, hci_con_handle_t handle, L2CAP_SIGNALING_COMMANDS cmd, uint8_t identifier, va_list argptr){
00078     
00079     // 0 - Connection handle : PB=10 : BC=00 
00080     bt_store_16(acl_buffer, 0, handle | (2 << 12) | (0 << 14));
00081     // 6 - L2CAP channel = 1
00082     bt_store_16(acl_buffer, 6, 1);
00083     // 8 - Code
00084     acl_buffer[8] = cmd;
00085     // 9 - id (!= 0 sequentially)
00086     acl_buffer[9] = identifier;
00087     
00088     // 12 - L2CAP signaling parameters
00089     uint16_t pos = 12;
00090     const char *format = l2cap_signaling_commands_format[cmd-1];
00091     uint16_t word;
00092     uint8_t * ptr;
00093     while (*format) {
00094         switch(*format) {
00095             case '1': //  8 bit value
00096             case '2': // 16 bit value
00097                 word = va_arg(argptr, int);
00098                 // minimal va_arg is int: 2 bytes on 8+16 bit CPUs
00099                 acl_buffer[pos++] = word & 0xff;
00100                 if (*format == '2') {
00101                     acl_buffer[pos++] = word >> 8;
00102                 }
00103                 break;
00104             case 'D': // variable data. passed: len, ptr
00105                 word = va_arg(argptr, int);
00106                 ptr  = va_arg(argptr, uint8_t *);
00107                 memcpy(&acl_buffer[pos], ptr, word);
00108                 pos += word;
00109                 break;
00110             default:
00111                 break;
00112         }
00113         format++;
00114     };
00115     va_end(argptr);
00116     
00117     // Fill in various length fields: it's the number of bytes following for ACL lenght and l2cap parameter length
00118     // - the l2cap payload length is counted after the following channel id (only payload) 
00119     
00120     // 2 - ACL length
00121     bt_store_16(acl_buffer, 2,  pos - 4);
00122     // 4 - L2CAP packet length
00123     bt_store_16(acl_buffer, 4,  pos - 6 - 2);
00124     // 10 - L2CAP signaling parameter length
00125     bt_store_16(acl_buffer, 10, pos - 12);
00126     
00127     return pos;
00128 }