unix socket

libus.c

/* nice unix socket exaple from: http://beej.us/guide/bgipc/output/html/multipage/unixsock.html */#include "libus.h"

#include <errno.h>

#define SOCK_PATH "unixsocket"
#define die(msg) ({perror(msg);exit(EXIT_FAILURE);})

int main(int argc, char **argv)
{
	char *slash = strchr(argv[0], '/');

	argv[0] = (slash ? slash + 1 : argv[0]);
	if (!strncmp(argv[0], "usserver", strlen("usserver"))) {
		argv[0] = (slash ? slash + 1 : argv[0]);
		int sock;
		struct sockaddr_un local, remote;
		int len;
		int error;

		sock = socket(AF_UNIX, SOCK_STREAM, 0);
		local.sun_family = AF_UNIX;
		strncpy(local.sun_path, SOCK_PATH, strlen(SOCK_PATH));
		unlink(local.sun_path);
		len = strlen(local.sun_path) + sizeof(local.sun_family);
		error = bind(sock, (struct sockaddr *)&local, len);
		if (error) die("bind");

		error = listen(sock, 5);
		if (error) die ("listem");

		for(;;) {
			char str[100];
			int s2;
			int done, n;
			unsigned int t = sizeof(remote);
			printf("Waiting for a connection...\n");
			s2 = accept(sock, (struct sockaddr *)&remote, &t);
			if (s2 == -1)
				die("accept");
			printf("Connected.\n");

			done = 0;
			do {
				n = recv(s2, str, 100, 0);
				if (n <= 0) {
					if (n < 0) perror("recv");
					done = 1;
				}

				if (!done)
					if (send(s2, str, n, 0) < 0) {
						perror("send");
						done = 1;
					}
			} while (!done);

			close(s2);
		}

	} else if (!strncmp(argv[0], "usclient", strlen("usclient"))) {
		int s, len;
		struct sockaddr_un remote;
		char str[100];

		s = socket(AF_UNIX, SOCK_STREAM, 0);
		if (s == -1) die("socket");

		puts("Trying to connect.");
		remote.sun_family = AF_UNIX;
		strncpy(remote.sun_path, SOCK_PATH, strlen(SOCK_PATH));
		len = strlen(SOCK_PATH) + sizeof(remote.sun_family);
		int error = connect(s, (struct sockaddr *)&remote, len);
		if (error) die("connect");
		puts("Connected.");
		while (printf("> "), fgets(str, 100, stdin), !feof(stdin)) {
			int n = send(s, str, strlen(str), 0);
			if (n == -1) die("send");
			int t = recv(s, str, 100, 0);
			if (t > 0)
				printf("echo > %s", str);
			else
				die("Server closed the connection.");
		}
	}
	return 0;
}

Makefile

libus: libus.c libus.h
	$(CC) $(CFLAGS) $(LDFLAGS) -o $@ $<
clean:
	rm libus