libwebsockets/minimal-examples/http-client/minimal-http-client/minimal-http-client.c

/*
 * lws-minimal-http-client
 *
 * Copyright (C) 2018 Andy Green <andy@warmcat.com>
 *
 * This file is made available under the Creative Commons CC0 1.0
 * Universal Public Domain Dedication.
 *
 * This demonstrates the a minimal http client using lws.
 *
 * It visits https://warmcat.com/ and receives the html page there.  You
 * can dump the page data by changing the #if 0 below.
 */

#include <libwebsockets.h>
#include <string.h>
#include <signal.h>

static int interrupted;
static struct lws *client_wsi;

static int
callback_http(struct lws *wsi, enum lws_callback_reasons reason,
	      void *user, void *in, size_t len)
{
	switch (reason) {

	/* because we are protocols[0] ... */
	case LWS_CALLBACK_CLIENT_CONNECTION_ERROR:
		lwsl_err("CLIENT_CONNECTION_ERROR: %s\n",
			 in ? (char *)in : "(null)");
		client_wsi = NULL;
		break;

	/* chunks of chunked content, with header removed */
	case LWS_CALLBACK_RECEIVE_CLIENT_HTTP_READ:
		lwsl_user("RECEIVE_CLIENT_HTTP_READ: read %d\n", (int)len);
#if 0  /* enable to dump the html */
		{
			const char *p = in;

			while (len--)
				if (*p < 0x7f)
					putchar(*p++);
				else
					putchar('.');
		}
#endif
		return 0; /* don't passthru */

	/* uninterpreted http content */
	case LWS_CALLBACK_RECEIVE_CLIENT_HTTP:
		{
			char buffer[1024 + LWS_PRE];
			char *px = buffer + LWS_PRE;
			int lenx = sizeof(buffer) - LWS_PRE;

			if (lws_http_client_read(wsi, &px, &lenx) < 0)
				return -1;
		}
		return 0; /* don't passthru */

	case LWS_CALLBACK_COMPLETED_CLIENT_HTTP:
		lwsl_user("LWS_CALLBACK_COMPLETED_CLIENT_HTTP\n");
		client_wsi = NULL;
		break;

	default:
		break;
	}

	return lws_callback_http_dummy(wsi, reason, user, in, len);
}

static const struct lws_protocols protocols[] = {
	{
		"http",
		callback_http,
		0,
		0,
	},
	{ NULL, NULL, 0, 0 }
};

static void
sigint_handler(int sig)
{
	interrupted = 1;
}

static int findswitch(int argc, char **argv, const char *val)
{
	while (--argc > 0) {
		if (!strcmp(argv[argc], val))
			return argc;
	}

	return 0;
}

int main(int argc, char **argv)
{
	struct lws_context_creation_info info;
	struct lws_client_connect_info i;
	struct lws_context *context;
	int logs = LLL_USER | LLL_ERR | LLL_WARN | LLL_NOTICE
		   /*
		    * For LLL_ verbosity above NOTICE to be built into lws,
		    * lws must have been configured and built with
		    * -DCMAKE_BUILD_TYPE=DEBUG instead of =RELEASE
		    *
		    * | LLL_INFO   | LLL_PARSER  | LLL_HEADER | LLL_EXT |
		    *   LLL_CLIENT | LLL_LATENCY | LLL_DEBUG
		    */ ;
	int n = 0, m;

	signal(SIGINT, sigint_handler);
	/* you can set the log level on commandline with, eg, -d 15 */
	m = findswitch(argc, argv, "-d");
	if (m && m + 1 < argc)
		logs = atoi(argv[m + 1]);

	lws_set_log_level(logs, NULL);
	lwsl_user("LWS minimal http client\n");

	memset(&info, 0, sizeof info); /* otherwise uninitialized garbage */
	info.options = LWS_SERVER_OPTION_DO_SSL_GLOBAL_INIT;
	info.port = CONTEXT_PORT_NO_LISTEN; /* we do not run any server */
	info.protocols = protocols;

#if defined(LWS_WITH_MBEDTLS)
	/*
	 * OpenSSL uses the system trust store.  mbedTLS has to be told which
	 * CA to trust explicitly.
	 */
	info.client_ssl_ca_filepath = "./warmcat.com.cer";
#endif

	context = lws_create_context(&info);
	if (!context) {
		lwsl_err("lws init failed\n");
		return 1;
	}

	memset(&i, 0, sizeof i); /* otherwise uninitialized garbage */
	i.context = context;

	i.port = 443;
	i.address = "warmcat.com";
	i.path = "/";
	i.host = i.address;
	i.origin = i.address;
	i.ssl_connection = /* LCCSCF_NOT_H2 | */ LCCSCF_USE_SSL;
	i.method = "GET";

	i.protocol = protocols[0].name;
	i.pwsi = &client_wsi;
	lws_client_connect_via_info(&i);

	while (n >= 0 && client_wsi && !interrupted)
		n = lws_service(context, 1000);

	lws_context_destroy(context);
	lwsl_user("Completed\n");

	return 0;
}