Question

我正在尝试在我的Linux笔记本电脑和Android手机之间创建一个简单的自定义蓝牙连接。在Linux方面，我使用BlueZ libbluetooth库来设置服务器。它的代码与我在github上看到的其他代码非常相似：

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <unistd.h>
#include <sys/socket.h>

#include <bluetooth/bluetooth.h>
#include <bluetooth/hci.h>
#include <bluetooth/hci_lib.h>

#include <bluetooth/sdp.h>
#include <bluetooth/sdp_lib.h>
#include <bluetooth/rfcomm.h>

sdp_session_t *register_service();

int main(int argc, char **argv)
{
    struct sockaddr_rc loc_addr = { 0 }, rem_addr = { 0 };
    char buf[1024] = { 0 };
    char str[1024] = { 0 };
    int s, client, bytes_read;
    sdp_session_t *session;
    socklen_t opt = sizeof(rem_addr);

    session = register_service();
    s = socket(AF_BLUETOOTH, SOCK_STREAM, BTPROTO_RFCOMM);
    loc_addr.rc_family = AF_BLUETOOTH;
    loc_addr.rc_bdaddr = *BDADDR_ANY;
    loc_addr.rc_channel = (uint8_t) 11;

    printf("Trying to bind...");
    fflush(stdout);
    bind(s, (struct sockaddr *)&loc_addr, sizeof(loc_addr));
    printf("bound\n");
    fflush(stdout);
    printf("Waiting for connection...");
    fflush(stdout);
    listen(s, 1);
    client = accept(s, (struct sockaddr *)&rem_addr, &opt);
    ba2str( &rem_addr.rc_bdaddr, buf );
    fprintf(stderr, "accepted connection from %s\n", buf);
    memset(buf, 0, sizeof(buf));
    bytes_read = read(client, buf, sizeof(buf));
    if( bytes_read > 0 ) {
     printf("received [%s]\n", buf);
    }
    sprintf(str,"to Android.");
    printf("sent [%s]\n",str);
    write(client, str, sizeof(str));
    close(client);
    close(s);
    sdp_close( session );

    return 0;
}

sdp_session_t *register_service()
{
  uint32_t svc_uuid_int[] = { 0x00000000,0x00000000,0x00000000,0x3233 };
  uint8_t rfcomm_channel = 11;
  const char *service_name = "Remote Host";
  const char *service_dsc = "What the remote should be connecting to.";
  const char *service_prov = "Your mother";

  uuid_t root_uuid, l2cap_uuid, rfcomm_uuid, svc_uuid;
  sdp_list_t *l2cap_list = 0,
       *rfcomm_list = 0,
       *root_list = 0,
       *proto_list = 0,
       *access_proto_list = 0;
  sdp_data_t *channel = 0, *psm = 0;

  sdp_record_t *record = sdp_record_alloc();

  // set the general service ID
  sdp_uuid128_create( &svc_uuid, &svc_uuid_int );
  sdp_set_service_id( record, svc_uuid );
  sdp_list_t service_class = {NULL, &svc_uuid};
  sdp_set_service_classes( record, &service_class);

  // make the service record publicly browsable
  sdp_uuid16_create(&root_uuid, PUBLIC_BROWSE_GROUP);
  root_list = sdp_list_append(0, &root_uuid);
  sdp_set_browse_groups( record, root_list );

  // set l2cap information
  sdp_uuid16_create(&l2cap_uuid, L2CAP_UUID);
  l2cap_list = sdp_list_append( 0, &l2cap_uuid );
  proto_list = sdp_list_append( 0, l2cap_list );

  // set rfcomm information
  sdp_uuid16_create(&rfcomm_uuid, RFCOMM_UUID);
  channel = sdp_data_alloc(SDP_UINT8, &rfcomm_channel);
  rfcomm_list = sdp_list_append( 0, &rfcomm_uuid );
  sdp_list_append( rfcomm_list, channel );
  sdp_list_append( proto_list, rfcomm_list );

  // attach protocol information to service record
  access_proto_list = sdp_list_append( 0, proto_list );
  sdp_set_access_protos( record, access_proto_list );

  // set the name, provider, and description
  sdp_set_info_attr(record, service_name, service_prov, service_dsc);

  int err = 0;
  sdp_session_t *session = 0;

  // connect to the local SDP server, register the service record, and
  // disconnect
  session = sdp_connect( BDADDR_ANY, BDADDR_LOCAL, SDP_RETRY_IF_BUSY );
  err = sdp_record_register(session, record, 0);

  // cleanup
  //sdp_data_free( channel );
  sdp_list_free( l2cap_list, 0 );
  sdp_list_free( rfcomm_list, 0 );
  sdp_list_free( root_list, 0 );
  sdp_list_free( access_proto_list, 0 );

  return session;
}

我可以在Linux中运行服务器端代码而不会出错：

$ ./bluetooth-server
Trying to bind...bound
Waiting for connection...

然后，我可以使用sdptool查看我的RFCOMM套接字和服务（说明，频道编号和所有其他信息看起来正确）：

Service Name: Remote Host
Service Description: What the remote should be connecting to.
Service Provider: Your mother
Service RecHandle: 0x10009
Service Class ID List:
  UUID 128: 00000000-0000-0000-0000-000033320000
Protocol Descriptor List:
  "L2CAP" (0x0100)
  "RFCOMM" (0x0003)
    Channel: 11

现在，在Android方面，我首先通过标准设置屏幕将手机与Linux服务器配对。配对后，我会在Android端使用代码来扫描蓝牙设备，如果是我的Linux设备，那么我会尝试连接它。我尝试了两种不同的方法，人们已经建议堆栈溢出来建立连接：

if (BluetoothDevice.ACTION_FOUND.equals(action)) {
    BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
    if(device.getName().equals("ubuntu-0")) {
        try {
            mBluetoothAdapter.cancelDiscovery();

            // This returns the value 00001103-0000-1000-8000-00805f9b34fb
            UUID uuid = device.getUuids()[0].getUuid();

            // This does not work
            //BluetoothSocket tmp = device.createRfcommSocketToServiceRecord(uuid);

            // And neither does this
            Method m = device.getClass().getMethod("createRfcommSocket", new Class[] {int.class});
            BluetoothSocket tmp = (BluetoothSocket) m.invoke(device, 11);  // Match channel 11

            tmp.connect();   // Exception is thrown here
        }
        catch(Exception e) {
            Log.e("BT", "Could not create RFCOMM socket " + e.toString());
        }
    }
}

当我实际尝试tmp.connect()调用时，我一直收到以下异常：

03-20 14:20:13.089: E/BT(16915): Could not create RFCOMM socket 
   java.io.IOException: read failed, socket might closed or timeout, read ret: -1

有没有人在尝试创建连接时看到我在做错了什么？请注意，当我致电UUID uuid = device.getUuids()[0].getUuid();时，我执行会返回一个UUID ...这让我相信配对是正常的，它会返回值00001103-0000-1000-8000-00805f9b34fb。

Answer 1

如果你在运行之前配对你的设备./bluetooth-server然后没有添加rfcomm服务记录，而远程设备不会提供有关此信息的信息，如果远程设备没有进行服务发现那么它可能不是能够连接到您的设备。

无法连接到Bluetooth / BlueZ服务器：无法创建RFCOMM插槽

1 个答案: