block_http_client.c

/* For sockaddr_in */
#include <netinet/in.h>
/* For socket functions */
#include <sys/socket.h>
/* For gethostbyname */
#include <netdb.h>

#include <unistd.h>
#include <string.h>
#include <stdio.h>

int main(int argc, char **argv)
{
	const char query[] = 
		"GET / HTTP/1.0\r\n"
		"Host: www.baidu.com\r\n"
		"\r\n";
	const char hostname[] = "www.baidu.com";
	struct sockaddr_in sin;
	struct hostent *h;
	const char *cp;
	int fd;
	ssize_t n_written, remaining;
	char buf[1024];

	h = gethostbyname(hostname);
	if (!h)
	{
		fprintf(stderr, "Couldn't lookup %s:%s", hostname, hstrerror(h_errno));
		return 1;
	}

	if (h->h_addrtype != AF_INET)
	{
		fprintf(stderr, "No ipv6 support, sorry.");
		return 1;
	}

	fd = socket(AF_INET, SOCK_STREAM, 0);
	if (fd < 0)
	{
		perror("socket");
		return 1;
	}

	sin.sin_family = AF_INET;
	sin.sin_port = htons(80);
	sin.sin_addr = *(struct in_addr*)h->h_addr;
	if (connect(fd, (struct sockaddr*)&sin, sizeof(sin)))
	{
		perror("connect");
		close(fd);
		return 1;
	}

	cp = query;
	remaining = strlen(query);
	while(remaining)
	{
		n_written = send(fd, cp, remaining, 0);
		if (n_written <= 0)
		{
			perror("send");
			return 1;
		}
		remaining -= n_written;
		cp += n_written;
	}

	while(1)
	{
		ssize_t result = recv(fd, buf, sizeof(buf), 0);
		if (result == 0)
		{
			break;
		}
		else if (result < 0)
		{
			perror("recv");
			close(fd);
			return 1;
		}
		fwrite(buf, 1, result, stdout);
	}
	
	close(fd);
	return 0;
}