[LUAU] Help needed with a c program

[Antonio Querubin]

On Mon, 19 Dec 2005, Tim Newsham wrote:

> Date: Mon, 19 Dec 2005 08:57:36 -1000 (HST)
> From: Tim Newsham <newsham at lava.net>
> Reply-To: LUAU <luau at lists.hosef.org>
> To: LUAU <luau at lists.hosef.org>
> Subject: Re: [LUAU] Help needed with a c program
> 
>> I am looking for sample c code that connects to a URL.  I tried to cobble
>> something together but it isn't working out too well.
>> 
>> All it needs to do is connect to a url like "
>> https://www.example.com/sample?option1=matt%option2=darnell%option3=please_help
>> "
>
> Does it have to be C code?  If not, you can use a utility like curl
> or wget to do the work for you, or you can even use a general utility
> like netcat:
>
>   (echo GET /url/here HTTP/1.0; echo) | nc hosthere 80
>
> Anyway, below is some C code.  It's written for a unix system, but
> since it looks like you're coding this for windows, I tried to include
> hints for converting the code to windows (they use a socket API for
> networking access which is similar but not identical to the one used
> in unix).

Below is a slightly modified variation of Tim's code that is independent 
of IP version (as long as you're compiling on an OS from this century :)).

Antonio Querubin
tony at lava.net

----------------

/* in windows you would include <windows.h> and <winsock.h> */
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>

/*
  * Things are slightly different in windows.  They use different types
  * for sockets than are used in Unix.  To make it clearer I added the
  * following defines for Unix.  You wouldn't need these in windows.
  **/
#define SOCKET int			/* a socket handle */
#define INVALID_SOCKET -1		/* A bogus handle indicating error
*/
#define SOCKET_ERROR -1			/* error return value */


/* resolve a host.  Return 0 for success */
int
resolvHost(char *host, char *port, struct sockaddr *ad)
{
 	struct addrinfo hints, *res0;
 	int error;

 	memset(&hints, 0, sizeof hints);
 	hints.ai_family = PF_UNSPEC;
 	hints.ai_socktype = SOCK_STREAM;

 	/* go to dns */
 	error = getaddrinfo(host, port, &hints, &res0);
 	if (error) {
 		perror(host);
 		return -1;
 	}
 	memcpy(ad, res0->ai_addr, res0->ai_addrlen);
 	return 0;
}

int
conUrl(char *host, char *port, char *path)
{

 	char buf[1024];
 	struct sockaddr_storage ad;
 	SOCKET s;
 	int len;

 	if(strlen(host) + strlen(path) > 900) {
 		fprintf(stderr, "url too long (%s: %s)\n", host, path);
 		return -1;
 	}

 	/* resolve the host then connect to it */
 	if (resolvHost(host, port, (struct sockaddr *)&ad) == -1) {
 		fprintf(stderr, "bad address %s\n", host);
 		return -1;
 	}
 	s = socket(ad.ss_family, SOCK_STREAM, 0);
 	if(s == INVALID_SOCKET) {
 		perror("socket");	/* use WSAGetLastError in windows */
 		return -1;
 	}
 	if(connect(s, (struct sockaddr*)&ad, ad.ss_len) == SOCKET_ERROR) {
 		perror(host);		/* use WSAGetLastError in windows */
 		close(s);
 		return -1;
 	}

 	/* send our request */
 	sprintf(buf, "GET %s HTTP/1.0\n\n", path);
 	send(s, buf, strlen(buf), 0);

 	/*
 	 * read back the result -- this is for testing since you
 	 * indicated you don't need the resulting text.
 	 */
 	while((len = recv(s, buf, sizeof buf, 0)) > 0)
 		write(1, buf, len);
 	close(s);			/* use closesocket in windows */
 	return 0;
}

int
main(int argc, char **argv)
{
 	/* initialize with WSAStartup in windows */

 	if(conUrl("www.lava.net", "80", "/~newsham/") == -1)
 		return 1;
 	return 0;
}