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/*
* Copyright © 2017 Keith Packard <keithp@keithp.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU 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
* General Public License for more details.
*/
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <termios.h>
#include <errno.h>
#include <unistd.h>
#include <ctype.h>
#include <dirent.h>
#include <bluetooth/bluetooth.h>
#include <bluetooth/hci.h>
#include <bluetooth/hci_lib.h>
#include <bluetooth/rfcomm.h>
#include <bluetooth/sdp.h>
#include <bluetooth/sdp_lib.h>
#include <bluetooth/l2cap.h>
#include <poll.h>
#define ATT_OP_MTU_REQ 0x02
#define ATT_OP_MTU_RESP 0x03
#define ATT_OP_WRITE_CMD 0x52
#define ATT_OP_HANDLE_NOTIFY 0x1b
#define CID_ATT 0x0004
#define TX_ENDPOINT 0x003a
#define RX_ENDPOINT 0x0037
#define RX_NOTIFY 0x0038
int
main(int argc, char **argv)
{
int sk;
int psm;
struct sockaddr_l2 src_addr = { 0 };
struct sockaddr_l2 dst_addr = { 0 };
char buf[1024];
struct pollfd fd[2];
int n, i;
char *btaddr;
int mtu;
btaddr = argc > 1 ? argv[1] : "D8:80:39:F3:4E:A5";
sk = socket(PF_BLUETOOTH, SOCK_SEQPACKET, BTPROTO_L2CAP);
if (sk < 0) {
perror("socket");
exit(1);
}
src_addr.l2_family = AF_BLUETOOTH;
/* Leave src_addr.l2_bdaddr all zeros */
src_addr.l2_cid = htobs(CID_ATT);
src_addr.l2_bdaddr_type = BDADDR_LE_PUBLIC;
if (bind(sk, (struct sockaddr *) &src_addr, sizeof (src_addr)) < 0) {
perror("bind");
exit(1);
}
dst_addr.l2_family = AF_BLUETOOTH;
str2ba(btaddr, &dst_addr.l2_bdaddr);
dst_addr.l2_cid = htobs(CID_ATT);
dst_addr.l2_bdaddr_type = BDADDR_LE_PUBLIC;
if (connect(sk, (struct sockaddr *) &dst_addr, sizeof(dst_addr)) < 0) {
perror("connect");
exit(1);
}
buf[0] = ATT_OP_MTU_REQ;
buf[1] = sizeof(buf) & 0xff;
buf[2] = sizeof(buf) >> 8;
n = write(sk, buf, 3);
if (n != 3) {
perror("write mtu\n");
exit(1);
}
fd[0].fd = sk;
fd[0].events = POLLIN;
for (;;) {
n = poll(fd, 1, 3000);
if (n <= 0) {
printf("timeout waiting for MTU response\n");
exit(1);
}
if (fd[0].revents & POLLIN) {
n = read(sk, buf, sizeof(buf));
printf("read %d\n", n);
for (i = 0; i < n; i++)
printf("%02x\n", buf[i]);
if (buf[0] == ATT_OP_MTU_RESP) {
mtu = (buf[1] & 0xff) | ((buf[2] & 0xff) << 8);
break;
}
}
}
printf("mtu %d\n", mtu);
buf[0] = ATT_OP_WRITE_CMD;
buf[1] = RX_NOTIFY & 0xff;
buf[2] = RX_NOTIFY >> 8;
buf[3] = 1;
n = write(sk, buf, 4);
if (n != 4) {
perror("write notify");
exit(1);
}
fd[0].fd = 0;
fd[0].events = POLLIN;
fd[1].fd = sk;
fd[1].events = POLLIN;
for (;;) {
n = poll(fd, 2, -1);
if (n == 0)
continue;
if (fd[0].revents & POLLIN) {
char *b;
n = read(0, buf+3, sizeof(buf)-3);
if (n < 0) {
perror("read stdin");
exit(1);
}
if (n == 0)
break;
b = buf;
while (n > 0) {
int this = n;
if (this > mtu - 3)
this = mtu - 3;
b[0] = ATT_OP_WRITE_CMD;
b[1] = TX_ENDPOINT;
b[2] = TX_ENDPOINT >> 8;
if (write(sk, b, this + 3) != this + 3) {
perror("write sk");
exit(1);
}
b += this;
n -= this;
}
}
if (fd[1].revents & POLLIN) {
uint16_t ch;
n = read(sk, buf, sizeof(buf));
if (n < 0) {
perror("read sk");
exit(1);
}
if (n == 0)
continue;
ch = buf[1] | (buf[2] << 8);
switch (buf[0]) {
case ATT_OP_HANDLE_NOTIFY:
if (ch == RX_ENDPOINT)
write(1, buf+3, n-3);
break;
}
}
if (fd[1].revents & (POLLERR|POLLHUP))
break;
}
close(sk);
return 0;
}
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