#include <sys/types.h>
#include <sys/file.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>

static int fd;

static u_char verquery[13] = {0x02, 0x14, 0x41, 0x20, 0x20, 0x00, 0x00,
			      0x04, 0x00, 0x00, 0x00, 0x45, 0x02};

static u_char verquery_resp[10] = {0x41, 0x00, 0x04, 0x00, 0x00, 0x00,
				   '8', '.', '8', '.'};

static u_char download_hdr[3] = {0x02, 0x14, 0x40};
static u_char download_resp[2] = {0x40, 0x00};

send_stx()
{
	static u_char stx = 0x02;

	write(fd, &stx, 1);
}

send_rvtmux_byte(b)
{
	u_char buf[2];
	int l, o;

	buf[0] = 0x10;
	buf[1] = b;
	if (b == 0x02 || b == 0x10) {
		o = 0;
		l = 2;
	} else {
		o = 1;
		l = 1;
	}
	write(fd, buf + o, l);
}

send_etm_resp(data, datalen)
	u_char *data;
{
	u_char csum;
	int i;

	printf("Responding with:");
	send_stx();
	send_rvtmux_byte(0x14);
	csum = 0;
	for (i = 0; i < datalen; i++) {
		printf(" %02X", data[i]);
		send_rvtmux_byte(data[i]);
		csum ^= data[i];
	}
	send_rvtmux_byte(csum);
	send_stx();
	putchar('\n');
}

main(argc, argv)
	char **argv;
{
	u_char buf[1024];
	int cc, i;

	if (argc != 2) {
		fprintf(stderr, "usage: %s pty\n", argv[0]);
		exit(1);
	}
	fd = open(argv[1], O_RDWR);
	if (fd < 0) {
		perror(argv[1]);
		exit(1);
	}
	for (;;) {
		cc = read(fd, buf, sizeof buf);
		if (cc < 0) {
			perror("read error");
			exit(1);
		}
		if (cc == 0) {
			fprintf(stderr, "read EOF\n");
			exit(1);
		}
		printf("read %d bytes:", cc);
		for (i = 0; i < cc; i++)
			printf(" %02X", buf[i]);
		putchar('\n');
		if (cc == sizeof(verquery) && !bcmp(buf, verquery, cc))
			send_etm_resp(verquery_resp, sizeof verquery_resp);
		if (cc > 3 && !bcmp(buf, download_hdr, 3))
			send_etm_resp(download_resp, sizeof download_resp);
	}
}