[代碼片段] 創建TCP套接字

#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <poll.h>
#include <pthread.h>
#include <pwd.h>
#include <netdb.h>
#include <fcntl.h>
#include <arpa/inet.h>

int transport_connect_socket(const char* host/*127.0.0.1*/, const char* port/*2228*/) {
	int i, flags, sock = -1;
	struct addrinfo hints, *res_list, *res;

	/* Connect to a server */
	memset(&hints, 0, sizeof hints);
	hints.ai_family = AF_UNSPEC;
	hints.ai_socktype = SOCK_STREAM;
	hints.ai_protocol = IPPROTO_TCP;
	i = getaddrinfo(host, port, &hints, &res_list);
	if (i != 0) {
		fprintf(stderr, "Unable to translate the host address (%s).", gai_strerror(i));
		return (-1);
	}

	for (i = 0, res = res_list; res != NULL; res = res->ai_next) {
		sock = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
		if (sock == -1) {
			/* socket was not created, try another resource */
			i = errno;
			goto errloop;
		}

		if (connect(sock, res->ai_addr, res->ai_addrlen) == -1) {
			/* network connection failed, try another resource */
			i = errno;
			close(sock);
			sock = -1;
			goto errloop;
		}

		/* make the socket non-blocking */
		if (((flags = fcntl(sock, F_GETFL)) == -1) || (fcntl(sock, F_SETFL, flags | O_NONBLOCK) == -1)) {
			fprintf(stderr, "Fcntl failed (%s).", strerror(errno));
			close(sock);
			return -1;
		}

		/* we're done, network connection established */
		break;
errloop:
		fprintf(stdout, "Unable to connect to %s:%s over %s (%s).", host, port,
				(res->ai_family == AF_INET6) ? "IPv6" : "IPv4", strerror(i));
		continue;
	}
	freeaddrinfo(res_list);

	if (sock == -1) {
		fprintf(stderr, "Unable to connect to %s:%s.", host, port);
	}

	return (sock);
}