flightgear/scripts/example/fgfsclient.c

/* $Id$ */
/* gcc -O2 -g -pedantic -Wall fgfsclient.c -o fgfsclient */
/* USAGE: ./fgfsclient [hostname [port]] */
/* Public Domain */

#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <netinet/in.h>
#include <stdarg.h>
#include <string.h>


#define DFLTHOST	"localhost"
#define DFLTPORT	5501
#define MAXMSG		256
#define fgfsclose	close


void init_sockaddr(struct sockaddr_in *name, const char *hostname, unsigned port);
int fgfswrite(int sock, char *msg, ...);
const char *fgfsread(int sock, int wait);
void fgfsflush(int sock);



int fgfswrite(int sock, char *msg, ...)
{
	va_list va;
	ssize_t len;
	char buf[MAXMSG];

	va_start(va, msg);
	vsnprintf(buf, MAXMSG - 2, msg, va);
	va_end(va);
	printf("SEND: \t<%s>\n", buf);
	strcat(buf, "\015\012");

	len = write(sock, buf, strlen(buf));
	if (len < 0) {
		perror("fgfswrite");
		exit(EXIT_FAILURE);
	}
	return len;
}



const char *fgfsread(int sock, int timeout)
{
	static char buf[MAXMSG];
	char *p;
	fd_set ready;
	struct timeval tv;
	ssize_t len;

	FD_ZERO(&ready);
	FD_SET(sock, &ready);
	tv.tv_sec = timeout;
	tv.tv_usec = 0;
	if (!select(32, &ready, 0, 0, &tv))
		return NULL;

	len = read(sock, buf, MAXMSG - 1);
	if (len < 0) {
		perror("fgfsread");
		exit(EXIT_FAILURE);
	} 
	if (len == 0)
		return NULL;

	for (p = &buf[len - 1]; p >= buf; p--)
		if (*p != '\015' && *p != '\012')
			break;
	*++p = '\0';
	return strlen(buf) ? buf : NULL;
}



void fgfsflush(int sock)
{
	const char *p;
	while ((p = fgfsread(sock, 0)) != NULL) {
		printf("IGNORE: \t<%s>\n", p);
	}
}



int fgfsconnect(const char *hostname, const int port)
{
	struct sockaddr_in serv_addr;
	struct hostent *hostinfo;
	int sock;

	sock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP);
	if (sock < 0) {
		perror("fgfsconnect/socket");
		return -1;
	}

	hostinfo = gethostbyname(hostname);
	if (hostinfo == NULL) {
		fprintf(stderr, "fgfsconnect: unknown host: \"%s\"\n", hostname);
		close(sock);
		return -2;
	}

	serv_addr.sin_family = AF_INET;
	serv_addr.sin_port = htons(port);
	serv_addr.sin_addr = *(struct in_addr *)hostinfo->h_addr;

	if (connect(sock, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0) {
		perror("fgfsconnect/connect");
		close(sock);
		return -3;
	}
	return sock;
}



int main(int argc, char **argv)
{
	int sock;
	unsigned port;
	const char *hostname, *p;

	hostname = argc > 1 ? argv[1] : DFLTHOST;
	port = argc > 2 ? atoi(argv[2]) : DFLTPORT;

	sock = fgfsconnect(hostname, port);
	if (sock < 0)
		return EXIT_FAILURE;

	fgfswrite(sock, "data");
	fgfswrite(sock, "set /controls/engines/engine[%d]/throttle %d", 0, 1);
	fgfswrite(sock, "get /sim/aircraft");
	p = fgfsread(sock, 3);
	if (p != NULL)
		printf("READ: \t<%s>\n", p);
	fgfswrite(sock, "quit");
	fgfsclose(sock);
	return EXIT_SUCCESS;
}