Linux: receive data from Bluetooth LE - c

Question

I want send/receive data to microcontroller using Bluetooth LE.
I have been trying to use socket using BTPROTO_HCI protocol
sock = socket(AF_BLUETOOTH, SOCK_RAW, BTPROTO_HCI)
addr.hci_family = AF_BLUETOOTH;
hci_dev = hci_devid( "XX:XX:XX:XX:XX:XX" ); // Replace with actual MAC of device
bind(sock, (struct sockaddr *)&addr, sizeof(addr)
and for receiving data I am doing
recvmsg(sock, &msg, 0))
but I can't received msg.
In Android there is Serial Bluetooth Terminal which can connect to Bluetooth LE device and send/receive data over Bluetooth LE. In this application I am receiving data from microcontroller.
Code
#include <sys/types.h>
#include <asm/types.h>
#include <sys/socket.h>
#include <stdlib.h>
#include <bluetooth/bluetooth.h>
#include <bluetooth/hci.h>
#include <bluetooth/hci_lib.h>
struct dump_hdr
{
__u16 len;
__u8 in;
__u8 pad;
__u32 ts_sec;
__u32 ts_usec;
} __attribute__ ((packed));
#define DUMP_HDR_SIZE (sizeof(struct dump_hdr))
struct frame
{
void *data;
int data_len;
void *ptr;
int len;
int in;
int handle;
long flags;
struct timeval ts;
};
int main(void)
{
printf("Starting...");
struct sockaddr_hci addr;
struct hci_filter filter;
int sock, one = 1;
char packet[HCI_MAX_FRAME_SIZE];
struct cmsghdr *cmsg;
struct msghdr msg;
struct iovec iv;
struct dump_hdr *dh;
struct frame frm;
char *buf, *ctrl;
if((sock = socket(AF_BLUETOOTH, SOCK_RAW, BTPROTO_HCI)) < 0)
{
perror("socket");
exit(1);
}
if(setsockopt(sock, SOL_HCI, HCI_DATA_DIR, &one, sizeof(one)) < 0)
{
perror("Can't enable data direction info");
exit(1);
}
if(setsockopt(sock, SOL_HCI, HCI_TIME_STAMP, &one, sizeof(one)) < 0)
{
perror("Can't enable time stamp");
exit(1);
}
hci_filter_clear(&filter);
hci_filter_all_ptypes(&filter);
hci_filter_all_events(&filter);
if(setsockopt(sock, SOL_HCI, HCI_FILTER, &filter, sizeof(filter)) < 0)
{
perror("Can't set HCI filter");
exit(1);
}
addr.hci_family = AF_BLUETOOTH;
addr.hci_dev = hci_devid( "XX:XX:XX:XX:XX:XX" );//eplace with actual MAC of device
if(bind(sock, (struct sockaddr *)&addr, sizeof(addr)) < 0)
{
perror("bind");
exit(1);
}
if (!(buf = malloc(DUMP_HDR_SIZE)))
{
perror("Can't allocate data buffer");
exit(1);
}
dh = (void *) buf;
frm.data = buf + DUMP_HDR_SIZE;
if (!(ctrl = malloc(100)))
{
perror("Can't allocate control buffer");
exit(1);
}
memset(&msg, 0, sizeof(msg));
while (1)
{
printf(".");
iv.iov_base = frm.data;
iv.iov_len = sizeof(frm.data);//snap_len;
msg.msg_iov = &iv;
msg.msg_iovlen = 1;
msg.msg_control = ctrl;
msg.msg_controllen = 100;
if ((frm.data_len = recvmsg(sock, &msg, 0)) < 0)
{
perror("Receive failed");
exit(1);
}
/* Process control message */
frm.in = 0;
cmsg = CMSG_FIRSTHDR(&msg);
while (cmsg)
{
printf("%s\r\n", cmsg);
switch (cmsg->cmsg_type)
{
case HCI_CMSG_DIR:
frm.in = *((int *)CMSG_DATA(cmsg));
break;
case HCI_CMSG_TSTAMP:
frm.ts = *((struct timeval *)CMSG_DATA(cmsg));
break;
}
cmsg = CMSG_NXTHDR(&msg, cmsg);
}
frm.ptr = frm.data;
frm.len = frm.data_len;
/* Parse and print */
hci_dump(&frm);
}
close(sock);
return 0;
}
void hci_dump(struct frame *frm)
{
__u8 type = *(__u8 *)frm->ptr;
frm->ptr++; frm->len--;
if(type == HCI_ACLDATA_PKT)
{
hci_acl_hdr *hdr = (void *) frm->ptr;
__u16 handle = btohs(hdr->handle);
__u16 dlen = btohs(hdr->dlen);
__u8 flags = acl_flags(handle);
printf("ACL data: handle 0x%4.4x flags 0x%2.2x dlen %d\n",
acl_handle(handle), flags, dlen);
}
}

Answer 1

You need to use the result of hci_devid.
hci_dev = hci_devid( "XX:XX:XX:XX:XX:XX" );
should become
addr.hci_dev = hci_devid( "XX:XX:XX:XX:XX:XX" );
Although I wouldn't expect hci_dev to be defined in the current scope as a separate variable.