#include <err.h>
#include <openssl/bio.h>
#include <openssl/ssl.h>
#include <stdio.h>
#include <string.h>

/*
 * If when a chunk is read into tmpbuf and the portion of the
 * response we are looking for, the answer, is truncated, parseres()
 * will either output the truncated answer or none at all.
 */ 
void
parseres(BIO *sbio)
{
	char tmpbuf[2048];
	int len;
	char *ans;

	while ((len = BIO_read(sbio, tmpbuf, 2048)) > 0) {
		if ((ans = strstr(tmpbuf, "Your IP address is ")) == NULL)
			continue;
		printf("%s\n", strsep(&ans, "\""));
		break;
	}
}

/*
 * Create connection to duckduckgo and make GET request query for
 * "what is my ip" with a json formatted response.
 * HTTP/1.0 in GET causes server to close connection automatically.
 */
BIO *
makereq(SSL_CTX *ctx)
{
	BIO *sbio;
        char *request = "GET /?q=what+is+my+ip&format=json&no_html=1"
                        " HTTP/1.0\r\nHost: duckduckgo.com\r\n\r\n";

	sbio = BIO_new_ssl_connect(ctx);
	if (sbio == NULL)
		err(1, "BIO_new_ssl_connect");
	BIO_set_conn_hostname(sbio, "duckduckgo.com:https");
        /*
	 * BIO_do_connection and BIO_do_handshake are called
         * automatically from any I/O request (in this case BIO_puts)
         * and are here only for clarity
	 */
	if (BIO_do_connect(sbio) <= 0)
		err(1, "BIO_do_connect");
	if (BIO_do_handshake(sbio) <= 0)
		err(1, "BIO_do_handshake");
	BIO_puts(sbio, request);
	return sbio;
}

/*
 * make an https request to duckduckgo
 * query "what is my ip"
 * parse json response
 * write to stdout
 * TODO: verbose err strings
 */
int
main()
{
	SSL_CTX *ctx;
	BIO *sbio;

	SSL_library_init();
	if ((ctx = SSL_CTX_new(TLS_client_method())) == NULL)
		err(1, "SSL_CTX_new");
	sbio = makereq(ctx);
	parseres(sbio);
	BIO_free_all(sbio);
	SSL_CTX_free(ctx);
	return 0;
}