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

/*
 * lws-minimal-http-client-post
 *
 * 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 and POST.
 *
 * It POSTs both form data and a file to the form at
 * https://libwebsockets.org/testserver/formtest and dumps
 * the html page received generated by the POST handler.
 */

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

static int interrupted;
static struct lws *client_wsi;

struct pss {
	char boundary[32];
	char body_part;
};

static int
callback_http(struct lws *wsi, enum lws_callback_reasons reason,
	      void *user, void *in, size_t len)
{
	struct pss *pss = (struct pss *)user;
	char buf[LWS_PRE + 1024], *start = &buf[LWS_PRE], *p = start,
		*end = &buf[sizeof(buf) - 1];
	uint8_t **up, *uend;
	uint32_t r;
	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;

	/* ...callbacks related to receiving the result... */

	case LWS_CALLBACK_ESTABLISHED_CLIENT_HTTP:
		lwsl_user("LWS_CALLBACK_ESTABLISHED_CLIENT_HTTP: response %d\n",
				lws_http_client_http_response(wsi));
		break;

	case LWS_CALLBACK_RECEIVE_CLIENT_HTTP_READ:
		lwsl_user("RECEIVE_CLIENT_HTTP_READ: read %d\n", (int)len);
		lwsl_hexdump_notice(in, len);
		return 0; /* don't passthru */

	case LWS_CALLBACK_RECEIVE_CLIENT_HTTP:
		n = sizeof(buf) - LWS_PRE;
		if (lws_http_client_read(wsi, &p, &n) < 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;

	/* ...callbacks related to generating the POST... */

	case LWS_CALLBACK_CLIENT_APPEND_HANDSHAKE_HEADER:
		lwsl_user("LWS_CALLBACK_CLIENT_APPEND_HANDSHAKE_HEADER\n");
		up = (uint8_t **)in;
		uend = *up + len - 1;

		/* generate a random boundary string */

		lws_get_random(lws_get_context(wsi), &r, sizeof(r));
		lws_snprintf(pss->boundary, sizeof(pss->boundary) - 1,
				"---boundary-%08x", r);

		n = lws_snprintf(buf, sizeof(buf) - 1,
			"multipart/form-data; boundary=%s", pss->boundary);
		if (lws_add_http_header_by_token(wsi,
				WSI_TOKEN_HTTP_CONTENT_TYPE,
				(uint8_t *)buf, n, up, uend))
			return 1;
		/*
		 * Notice because we are sending multipart/form-data we can
		 * usually rely on the server to understand where the form
		 * payload ends without having to give it an overall
		 * content-length (which can be troublesome to compute ahead
		 * of generating the data to send).
		 *
		 * Tell lws we are going to send the body next...
		 */
		lws_client_http_body_pending(wsi, 1);
		lws_callback_on_writable(wsi);
		break;

	case LWS_CALLBACK_CLIENT_HTTP_WRITEABLE:
		lwsl_user("LWS_CALLBACK_CLIENT_HTTP_WRITEABLE\n");
		n = LWS_WRITE_HTTP;

		/*
		 * For a small body like this, we could prepare it in memory and
		 * send it all at once.  But to show how to handle, eg,
		 * arbitrary-sized file payloads, or huge form-data fields, the
		 * sending is done in multiple passes through the event loop.
		 */

		switch (pss->body_part++) {
		case 0:
			/* notice every usage of the boundary starts with -- */
			p += lws_snprintf(p, end - p, "--%s\xd\xa"
				"content-disposition: "
					"form-data; name=\"text\"\xd\xa"
				"\xd\xa"
				"my text field"
				"\xd\xa", pss->boundary);
			break;
		case 1:
			p += lws_snprintf(p, end - p,
				"--%s\xd\xa"
				"content-disposition: form-data; name=\"file\";"
				"filename=\"myfile.txt\"\xd\xa"
				"content-type: text/plain\xd\xa"
				"\xd\xa"
					"This is the contents of the "
					"uploaded file.\xd\xa"
				"\xd\xa", pss->boundary);
			break;
		case 2:
			p += lws_snprintf(p, end - p, "--%s--\xd\xa",
					  pss->boundary);
			lws_client_http_body_pending(wsi, 0);
			 /* necessary to support H2, it means we will write no
			  * more on this stream */
			n = LWS_WRITE_HTTP_FINAL;
			break;

		default:
			/*
			 * We can get extra callbacks here, if nothing to do,
			 * then do nothing.
			 */
			return 0;
		}

		if (lws_write(wsi, (uint8_t *)start, lws_ptr_diff(p, start), n)
				!= lws_ptr_diff(p, start))
			return 1;

		if (n != LWS_WRITE_HTTP_FINAL)
			lws_callback_on_writable(wsi);

		return 0;

	default:
		break;
	}

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

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

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

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

	signal(SIGINT, sigint_handler);
	lws_set_log_level(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 */, NULL);

	lwsl_user("LWS minimal http client - POST\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 = "./libwebsockets.org.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 = "libwebsockets.org";
	i.path = "/testserver/formtest";
	i.ssl_connection = /* LCCSCF_NOT_H2 | */ LCCSCF_USE_SSL;
	i.host = i.address;
	i.origin = i.address;
	i.method = "POST";

	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;
}