A simple HTTP/1.0 request client. This is a free software code, use fairly!

gistfile1.c

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

/*
 *	a simple http/1.0 client
 *		2013 nvurgaft
 *	
 *	usage: httpclient -h <URL>
 *		-h: sends HEAD request instead of GET
 *		<URL>: the requested url, should start with either 'http://' or 'www.'
 */

// main
int main(int argc, char* argv[])
{
	// sanity check
	if (argc>3 || argc<2) {
		printf("invalid argument count, format is: client [–h] <URL>\n");
		return 1;
	}
	// start assigning values for param processing 
	int responseHeaderFlag = 0;
	char* URL = "null"; // we'll use this later to check if our url is a good one
	int i;
	// lookup for -h flag
	for (i=1; i<argc; i++) {
		if ((strncmp(argv[i], "-h", 2))==0) {
			responseHeaderFlag = 1;
			break;
		}
	}

	// lookup for <URL> argument, format is: http://hostname[:port]/filepath.
	for (i=1; i<argc; i++) {
		// a URL can start with either or without the 'http://' prefix 
		if ((strncmp(argv[i], "www.", 4))==0 || (strncmp(argv[i], "http://", 7))==0) {
			URL = argv[i];
			printf("URL: %s\n", URL);
			break;
		}
	}
	if (URL=="null") {
		printf("invalid or malformed url was given\n");
		return 1;
	}
	
	struct sockaddr_in serv_addr; 	// server address
	struct hostent *server_host;	// host (will be the URL provided)
	int sockfd, nbytes, size = 0; 	// socket and IO byte count
	char buff[1024]; // message buffer

    server_host = gethostbyname(URL);
    if (server_host==NULL) {
    	herror("error, unable to resolve hostname\n");
    	exit(1);
    }
    
	sockfd = socket(AF_INET, SOCK_STREAM, 0); 
	if (sockfd<0) {
		perror("error, cannot create a socket\n");
		exit(1);
	}

    serv_addr.sin_family = AF_INET;
    serv_addr.sin_port = htons(80);
    serv_addr.sin_addr = *(struct in_addr*)server_host->h_addr;

	// connect to server
	if (connect(sockfd, (struct sockaddr*) &serv_addr, sizeof(serv_addr)) <0) {
		perror("error, cannot connect\n");
		exit(1);
	}
	
	// use the parameters to build the http message
	bzero(buff, sizeof(buff));
	// if -h send HEAD instead of default GET, when -t <time-since> enter with If-Modified_since header
	if (responseHeaderFlag) {
		printf("Sending HEAD query to %s for response!\n", URL);
		sprintf(buff, "HEAD %s HTTP/1.0\r\nConnection: Close\r\n\r\n", URL);
	} else { // send a GET if -h was not entered
		printf("Sending GET query to %s for response!\n", URL);
		sprintf(buff, "GET %s HTTP/1.0\r\nConnection: Close\r\n\r\n", URL);
	}
	printf("HTTP request =\n%s\nLEN = %d\n", buff, strlen(buff));

	// send the request to server	
	if ((nbytes = write(sockfd, buff, strlen(buff))) < 0) {
		perror("error on write\n");
		exit(1);
	}
	
	buff[sizeof(buff)-1] = '\0';
	// read the response from the server
	while ((nbytes = read(sockfd, buff, strlen(buff))) > 0) {
		if (nbytes<0) {
			perror("error on read\n");
			exit(1);
		}
		if (nbytes==0) {
			break;
		}
		size += nbytes;
		if (nbytes<sizeof(buff)) {
			buff[nbytes] = '\0';
		}
		printf("%s", buff); // print the response
	} 
	printf("\n\tTotal received response bytes: %d\n", size);
	
	// close socket and exit
	close(sockfd);
	exit(0);
}