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

/*
 * lws-minimal-http-client
 *
 * Written in 2010-2019 by 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, bad = 1, status;
static struct lws *client_wsi;

static int
callback_http(struct lws *wsi, enum lws_callback_reasons reason,
	      void *user, void *in, size_t len)
{
	char val[32];
	int n;

	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;

	case LWS_CALLBACK_CLIENT_APPEND_HANDSHAKE_HEADER:
	{
		 unsigned char **p = (unsigned char **)in, *end = (*p) + len;

		 /*
		  * How to send a custom header in the request to the server
		  */

		 if (lws_add_http_header_by_name(wsi,
				 (const unsigned char *)"dnt",
				 (const unsigned char *)"1", 1, p, end))
			 return -1;
		break;
	}

	case LWS_CALLBACK_ESTABLISHED_CLIENT_HTTP:
		status = lws_http_client_http_response(wsi);
		lwsl_user("Connected with server response: %d\n", status);

		/*
		 * How to query custom headers (http 1.x only at the momemnt)
		 *
		 * warmcat.com sends a custom header "test-custom-header" for
		 * testing, it has the fixed value "hello".
		 */

		n = lws_hdr_custom_length(wsi, "test-custom-header:", 19);
		if (n < 0)
			lwsl_notice("%s: Can't find test-custom-header\n",
				    __func__);
		else {
			if (lws_hdr_custom_copy(wsi, val, sizeof(val),
						"test-custom-header:", 19) < 0)
				lwsl_notice("%s: custom header too long\n",
					    __func__);
			else
				lwsl_notice("%s: custom header: '%s'\n",
						__func__, val);
		}
		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;
		bad = status != 200;
		lws_cancel_service(lws_get_context(wsi)); /* abort poll wait */
		break;

	case LWS_CALLBACK_CLOSED_CLIENT_HTTP:
		client_wsi = NULL;
		bad = status != 200;
		lws_cancel_service(lws_get_context(wsi)); /* abort poll wait */
		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;
}

int main(int argc, const char **argv)
{
	struct lws_context_creation_info info;
	struct lws_client_connect_info i;
	struct lws_context *context;
	const char *p;
	int n = 0, 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
		    */ ;

	signal(SIGINT, sigint_handler);

	if ((p = lws_cmdline_option(argc, argv, "-d")))
		logs = atoi(p);

	lws_set_log_level(logs, NULL);
	lwsl_user("LWS minimal http client Custom Headers [-d<verbosity>] [-l] [--h1]\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;
	/*
	 * since we know this lws context is only ever going to be used with
	 * one client wsis / fds / sockets at a time, let lws know it doesn't
	 * have to use the default allocations for fd tables up to ulimit -n.
	 * It will just allocate for 1 internal and 1 (+ 1 http2 nwsi) that we
	 * will use.
	 */
	info.fd_limit_per_thread = 1 + 1 + 1;

#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;

	if (!lws_cmdline_option(argc, argv, "-n"))
		i.ssl_connection = LCCSCF_USE_SSL;

	if (lws_cmdline_option(argc, argv, "-l")) {
		i.port = 7681;
		i.address = "localhost";
		i.ssl_connection |= LCCSCF_ALLOW_SELFSIGNED;
	} else {
		i.port = 443;
		i.address = "warmcat.com";
	}

	/* currently custom headers receive only works with h1 */
	i.alpn = "http/1.1";

	i.path = "/";
	i.host = i.address;
	i.origin = i.address;
	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: %s\n", bad ? "failed" : "OK");

	return bad;
}