Easily make HTTP requests over internet, on Windows.

easy-http-client.c

#include <winsock2.h>
#include <assert.h>
#include <stdio.h>
#include <string.h>
#include <stdarg.h>

/*///////////////////////////////////
	
		easy-strings
		
///////////////////////////////////*/

int indexOf(char* source, char* key, int pos) {		
	int i, j, dest;
	
	assert(pos > -1);
		
	for (i=0, j=0, dest=0; i<strlen(source); i++) {
		
		(source[i] == key[j]) ? (j++) : (j=0);
		
		if (j == strlen(key)) {
			j = 0;
			dest = i;
			if (pos == 0) return dest - strlen(key) +1;
			pos--;			
		}
	}
	
	return -1;	
}

char* substring(char* source, int start, int end) {
	int i;
	char *dest, *back;
	
	assert(start > -1);
	assert(end > -1);
	assert(start <= end);
	
	dest = malloc(sizeof(char) * strlen(source) +1);
	assert(dest != NULL);
	strcpy(dest, source);
	back = dest;
	
	dest = dest + start;	
	*(dest + end - start + 1) = 0;	
	
	strcpy(back, dest);
	return back;
}

/*///////////////////////////////////
	
		implementation
		
///////////////////////////////////*/

typedef struct routes {		
	char *version;
	char *statusline;	
	char *headers;
	char *body;			
} *Response;

Response go(char* url, char* data, char* custom_headers, char* force_method, char* alternative_port, ...) {}
#define go(...) _go(__VA_ARGS__, "", "", "", "")
Response _go(char* url, char* data, char* custom_headers, char* force_method, char* alternative_port, ...) {
	//variables
	WSADATA wsa;
	SOCKET s;
	struct routes *r;
	struct sockaddr_in serverToConnect;
	struct hostent* he;
	struct in_addr **addr_list;
	char *domain, *resource, *msg, method[20], *response;
	int size, port, content_length;
	
	//init
	if (WSAStartup(MAKEWORD(2,2), &wsa) != 0) {
		fprintf(stderr, "Couldn't start winsock with error %i\n", WSAGetLastError());
		return 0;
	}
		
	if ((s = socket(AF_INET, SOCK_STREAM, 0)) == INVALID_SOCKET) {
		fprintf(stderr, "Couldn't create a socket with error %i\n", WSAGetLastError());
		return 0;
	}			
	
	//setting domain
	if (indexOf(url, "//", 0) != -1) {
		if (indexOf(url, "/", 2) != -1)
			domain = substring(url, indexOf(url, "//", 0)+2, indexOf(url, "/", 2)-1);		
		else 
			domain = substring(url, indexOf(url, "//", 0)+2, strlen(url));
	} 
	else {
		if (indexOf(url, "/", 0) != -1)				
			domain = substring(url, 0, indexOf(url, "/", 0)-1);
		else
			domain = substring(url, 0, strlen(url));			
	}		
	
	if ((he = gethostbyname(domain)) == NULL) {
		fprintf(stderr, "Couldn't get information from host with error %i\n", WSAGetLastError());
		return 0;		
	}
		
	//setting connection
	addr_list = (struct in_addr **) he->h_addr_list;
	
	if (atoi(alternative_port) == 0) port = 80;
	else port = atoi(alternative_port);	
		
	serverToConnect.sin_addr.s_addr = inet_addr(inet_ntoa(*addr_list[0]));
	serverToConnect.sin_port = htons(port);
	serverToConnect.sin_family = AF_INET;	
		
	//setting resource
	if (indexOf(url, "//", 0) != -1) {
		if (indexOf(url, "/", 2) != -1)
			resource = substring(url, indexOf(url, "/", 2), strlen(url));
		else
			resource = "/";
	}
	else {
		if (indexOf(url, "/", 0) != -1)
			resource = substring(url, indexOf(url, "/", 0), strlen(url));
		else
		resource = "/";
	}			
	
	//setting method		
	if (strlen(force_method) == 0) {
		if (strlen(data) == 0) strcpy(method, "GET");
		else strcpy(method, "POST");
	} else {		
		strcpy(method, force_method);
	}		
	
	//setting content-length
	if (strlen(data) > 0) content_length = strlen(data)+3;
	else content_length = 0;	
	
	//preparing request		
	msg = (char*)malloc( (sizeof(char) * strlen(method))		
					  +  (sizeof(char) * strlen(resource))
					  +  (sizeof(char) * strlen(domain))
					  +  (sizeof(int)) //content_length
					  +  (sizeof(char) * strlen(custom_headers))
					  +  (sizeof(char) * strlen(data))
					  +  50);
					 
	sprintf(msg, "%s %s HTTP/1.1\n"
				"Host: %s\n"
				"Content-Length: %lu\n"
				"%s"
				"\n\n"
				"%s", method, resource, domain, content_length, custom_headers, data);
	
	//connecting
	if (connect(s, (struct sockaddr*)&serverToConnect, sizeof(serverToConnect)) == SOCKET_ERROR) {
		fprintf(stderr, "Couldn't connect to socket with error %i\n", WSAGetLastError());
		return 0;
	}	
	
	//sending request					
	if (send(s, msg, strlen(msg), 0) == SOCKET_ERROR) {
		fprintf(stderr, "Couldn't send request with error %i\n", WSAGetLastError());
		return 0;		
	}	
	
	//getting response	
	size = sizeof(char) * 10240;
	response = (char*)malloc(size);
	if (recv(s, response, size, 0) == SOCKET_ERROR) {
		fprintf(stderr, "Couldn't get response with error %i\n", WSAGetLastError());
		return 0;
	}
								
	//parsing response			
	r = (struct routes*)malloc(sizeof(struct routes));
	r->statusline = substring(response, indexOf(response, " ", 0)+1, indexOf(response, "\n", 0));
	r->version = substring(response, 0, indexOf(response, " ", 0));
	r->headers = substring(response, indexOf(response, "\n", 0)+1, indexOf(response, "\n\r", 0)-2);
	r->body = substring(response, indexOf(response, "\n\r", 0)+1, strlen(response));	

	//free varialbes
	free(msg);
	free(domain);
	free(response);
	free(resource);

	//cleanup	
	closesocket(s);
	WSACleanup();	
	return r;
}

void response_free(Response r) {
	free(r->version);
	free(r->statusline);
	free(r->headers);
	free(r->body);
	free(r);
}

/*///////////////////////////////////
	
		Testing:
		
///////////////////////////////////*/

int main() {			
	Response r = go("http://help.websiteos.com/websiteos/example_of_a_simple_html_page.htm");	
	//data, headers, method and port are optional arguments

	printf("%s %s\n%s\n\n%s", r->version, r->statusline, r->headers, r->body);
	response_free(r);
}