A http Client that Works Similar to wget

http-client.c

// Because we are using POSIX features that aren't part of the C standard, we
// need to #define this macro before #including standard library headers to be
// granted access to POSIX-specific definitions such as struct addrinfo.
#define _GNU_SOURCE

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

#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netdb.h>

/*
 * Convenient error handler for printing errno-associated message and exit(1).
 */
static void die(char *msg) {
    perror(msg);
    exit(1);
}

int main(int argc, char **argv){
	if(argc != 4){
		fprintf(stderr, "Usage: %s <host-name> <port-number> <URI>\n   ex) ./http-client www.example.com 80/index.html\n",argv[0]);
		exit(1);
	}

    	char *server_ip = argv[1];
    	char *server_port = argv[2];
	char *URI = argv[3];	

	//Obtain server address info using getaddrinfo()
	struct addrinfo hints;//the struct we receving the actual answer
	memset(&hints, 0, sizeof(hints));
	
	// Specify what kind of connection we intend to make; these values tell
    	// getaddrinfo() that we don't care about other kinds of addresses.
    	hints.ai_family = AF_INET;        // Only accept IPv4 addresses
    	hints.ai_socktype = SOCK_STREAM;  // stream socket for TCP connections
    	hints.ai_protocol = IPPROTO_TCP;  // TCP protocol

    	// Define where getaddrinfo() will return the information it found.
    	struct addrinfo *info;

    	// Call getaddrinfo(), specifying the server IP address and port as strings.
    	// getaddrinfo() will parse those for us and point info to the result.
    	int addr_err;
    	if ((addr_err = getaddrinfo(server_ip, server_port, &hints, &info)) != 0) {
        	fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(addr_err));
        	exit(1);
    	}

       /*
     	* Create socket() and connect() it to server.
     	*/

    	// Create socket() according to the address family, socket type, and
    	// protocol of the address info.
    	int serv_fd = socket(info->ai_family, info->ai_socktype, info->ai_protocol);
    	if (serv_fd < 0)
        	die("socket");
	
	// Connect socket with server address; the IP address and port in
    	// info->ai_addr should be the same address and port that getaddrinfo()
    	// parsed from server_address and server_port.
    	if (connect(serv_fd, info->ai_addr, info->ai_addrlen) < 0)
        	die("connect");

	freeaddrinfo(info);

	//Specific to this lab
	FILE *fpw = fdopen(serv_fd,"wb");
	if (fpw == NULL)
		die("1: fdopen (for writing)");
	setlinebuf(fpw);
	/*FILE *fpr = fdopen(dup(serv_fd),"rb");
	if (fpr == NULL)
                die("2: fdopen (for reading)");
	setlinebuf(fpr);
*/

	//Send Http request
	//char* request;
	char buff[8192] = "";
	char* request = strcat(buff,"GET ");
	request = strcat(buff,URI);
	request = strcat(buff," HTTP/1.0\r\nHost: ");
	request = strcat(buff,server_ip);
	request = strcat(buff,":");
	request = strcat(buff,server_port);
	request = strcat(buff,"\r\n\r\n");
	printf("%s",request);
	fwrite(request,1,8192,fpw);
//	send(serv_fd, request, 8192, 0);	

	/*
	FILE *fpw = fdopen(serv_fd,"wb");
        if (fpw == NULL)
                die("fdopen (for writing)")
        FILE *fpr = fdopen(dup(serv_fd),"rb");
        if (fpr == NULL)
                die("fdopen (for reading)")
*/
	FILE *fpr = fdopen(dup(serv_fd),"rb");
        if (fpr == NULL)
                die("2: fdopen (for reading)");
        setlinebuf(fpr);
	
	char buf[8192] = "";	
	char* first_line = fgets(buf,sizeof(buf),fpr);
	printf("%s",first_line);
	if(first_line == NULL){
		printf("%s",buf);
		die("1: fget(the fist line)");
	}

	
	//skip the http/1.0 and see whether the 9th char is 200
	if(strncmp("200",buf+9,3) != 0){
		printf("%s",buf);
		die("400 bad request");
	}

	//get rid of header
	while(1){
		if(fgets(buf,8192,fpr) == NULL){
			die("No \r\n");
		}
		if(strcmp(buf,"\r\n")==0){
			break;
		}
	
	}

	
	//Output file
	FILE *fpo = fopen(strrchr(URI,'/')+1,"wb");
	if (fpo == NULL)
                die("fopen (for writing)");
	
	// FILE pointers are block-buffered by default;
    	// configure fpw to be line-buffered.
	setlinebuf(fpo);
	//char buf[8192];
	//Write the files from the response to the output file
	size_t line_size;
	while((line_size = fread(buf,1,8192,fpr))>0){
		size_t write_size = fwrite(buf,1,line_size,fpo);
		if(write_size != line_size){
			die("writing something not expected");
		}
	}	
	
	fclose(fpr);
	fclose(fpw);
	fclose(fpo);




	return 0;
}