zephyr/subsys/net/lib/http/http_server_http2.c

/*
 * Copyright (c) 2023, Emna Rekik
 * Copyright (c) 2024 Nordic Semiconductor ASA
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#include <errno.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>

#include <zephyr/fs/fs.h>
#include <zephyr/fs/fs_interface.h>
#include <zephyr/kernel.h>
#include <zephyr/logging/log.h>
#include <zephyr/net/http/service.h>

LOG_MODULE_DECLARE(net_http_server, CONFIG_NET_HTTP_SERVER_LOG_LEVEL);

#include "headers/server_internal.h"

static const char content_404[] = {
#ifdef INCLUDE_HTML_CONTENT
#include "not_found_page.html.gz.inc"
#endif
};

static bool is_header_flag_set(uint8_t flags, uint8_t mask)
{
	return (flags & mask) != 0;
}

static void clear_header_flag(uint8_t *flags, uint8_t mask)
{
	*flags &= ~mask;
}

static void print_http_frames(struct http_client_ctx *client)
{
#if defined(PRINT_COLOR)
	const char *bold = "\033[1m";
	const char *reset = "\033[0m";
	const char *green = "\033[32m";
	const char *blue = "\033[34m";
#else
	const char *bold = "";
	const char *reset = "";
	const char *green = "";
	const char *blue = "";
#endif

	struct http2_frame *frame = &client->current_frame;

	LOG_DBG("%s=====================================%s", green, reset);
	LOG_DBG("%sReceived %s Frame :%s", bold, get_frame_type_name(frame->type), reset);
	LOG_DBG("  %sLength:%s %u", blue, reset, frame->length);
	LOG_DBG("  %sType:%s %u (%s)", blue, reset, frame->type, get_frame_type_name(frame->type));
	LOG_DBG("  %sFlags:%s %u", blue, reset, frame->flags);
	LOG_DBG("  %sStream Identifier:%s %u", blue, reset, frame->stream_identifier);
	LOG_DBG("%s=====================================%s", green, reset);
}

static struct http2_stream_ctx *find_http_stream_context(
			struct http_client_ctx *client, uint32_t stream_id)
{
	ARRAY_FOR_EACH(client->streams, i) {
		if (client->streams[i].stream_id == stream_id) {
			return &client->streams[i];
		}
	}

	return NULL;
}

static struct http2_stream_ctx *allocate_http_stream_context(
			struct http_client_ctx *client, uint32_t stream_id)
{
	ARRAY_FOR_EACH(client->streams, i) {
		if (client->streams[i].stream_state == HTTP2_STREAM_IDLE) {
			client->streams[i].stream_id = stream_id;
			client->streams[i].stream_state = HTTP2_STREAM_OPEN;
			client->streams[i].window_size =
				HTTP_SERVER_INITIAL_WINDOW_SIZE;
			client->streams[i].headers_sent = false;
			client->streams[i].end_stream_sent = false;
			return &client->streams[i];
		}
	}

	return NULL;
}

static void release_http_stream_context(struct http_client_ctx *client,
					uint32_t stream_id)
{
	ARRAY_FOR_EACH(client->streams, i) {
		if (client->streams[i].stream_id == stream_id) {
			client->streams[i].stream_id = 0;
			client->streams[i].stream_state = HTTP2_STREAM_IDLE;
			client->streams[i].current_detail = NULL;
			break;
		}
	}
}

static int add_header_field(struct http_client_ctx *client, uint8_t **buf,
			    size_t *buflen, const char *name, const char *value)
{
	int ret;

	client->header_field.name = name;
	client->header_field.name_len = strlen(name);
	client->header_field.value = value;
	client->header_field.value_len = strlen(value);

	ret = http_hpack_encode_header(*buf, *buflen, &client->header_field);
	if (ret < 0) {
		LOG_DBG("Failed to encode header, err %d", ret);
		return ret;
	}

	*buf += ret;
	*buflen -= ret;

	return 0;
}

static void encode_frame_header(uint8_t *buf, uint32_t payload_len,
				enum http2_frame_type frame_type,
				uint8_t flags, uint32_t stream_id)
{
	sys_put_be24(payload_len, &buf[HTTP2_FRAME_LENGTH_OFFSET]);
	buf[HTTP2_FRAME_TYPE_OFFSET] = frame_type;
	buf[HTTP2_FRAME_FLAGS_OFFSET] = flags;
	sys_put_be32(stream_id, &buf[HTTP2_FRAME_STREAM_ID_OFFSET]);
}

static int send_headers_frame(struct http_client_ctx *client, enum http_status status,
			      uint32_t stream_id, struct http_resource_detail *detail_common,
			      uint8_t flags, const struct http_header *extra_headers,
			      size_t extra_headers_count)
{
	uint8_t headers_frame[CONFIG_HTTP_SERVER_HTTP2_MAX_HEADER_FRAME_LEN];
	uint8_t status_str[4];
	uint8_t *buf = headers_frame + HTTP2_FRAME_HEADER_SIZE;
	size_t buflen = sizeof(headers_frame) - HTTP2_FRAME_HEADER_SIZE;
	bool content_encoding_sent = false;
	bool content_type_sent = false;
	size_t payload_len;
	int ret;

	ret = snprintf(status_str, sizeof(status_str), "%d", status);
	if (ret > sizeof(status_str) - 1) {
		return -EINVAL;
	}

	ret = add_header_field(client, &buf, &buflen, ":status", status_str);
	if (ret < 0) {
		return ret;
	}

	for (size_t i = 0; i < extra_headers_count; i++) {
		const struct http_header *hdr = &extra_headers[i];

		if (strcasecmp(hdr->name, "content-encoding") == 0) {
			content_encoding_sent = true;
		}

		if (strcasecmp(hdr->name, "content-type") == 0) {
			content_type_sent = true;
		}

		ret = add_header_field(client, &buf, &buflen, hdr->name, hdr->value);
		if (ret < 0) {
			return ret;
		}
	}

	if (!content_encoding_sent && detail_common && detail_common->content_encoding != NULL) {
		ret = add_header_field(client, &buf, &buflen, "content-encoding",
				       detail_common->content_encoding);
		if (ret < 0) {
			return ret;
		}
	}

	if (!content_type_sent && detail_common && detail_common->content_type != NULL) {
		ret = add_header_field(client, &buf, &buflen, "content-type",
				       detail_common->content_type);
		if (ret < 0) {
			return ret;
		}
	}

	payload_len = sizeof(headers_frame) - buflen - HTTP2_FRAME_HEADER_SIZE;
	flags |= HTTP2_FLAG_END_HEADERS;

	encode_frame_header(headers_frame, payload_len, HTTP2_HEADERS_FRAME,
			    flags, stream_id);

	ret = http_server_sendall(client, headers_frame,
				  payload_len + HTTP2_FRAME_HEADER_SIZE);
	if (ret < 0) {
		LOG_DBG("Cannot write to socket (%d)", ret);
		return ret;
	}

	return 0;
}

static int send_data_frame(struct http_client_ctx *client, const char *payload,
			   size_t length, uint32_t stream_id, uint8_t flags)
{
	uint8_t frame_header[HTTP2_FRAME_HEADER_SIZE];
	int ret;

	encode_frame_header(frame_header, length, HTTP2_DATA_FRAME,
			    is_header_flag_set(flags, HTTP2_FLAG_END_STREAM) ?
			    HTTP2_FLAG_END_STREAM : 0,
			    stream_id);

	ret = http_server_sendall(client, frame_header, sizeof(frame_header));
	if (ret < 0) {
		LOG_DBG("Cannot write to socket (%d)", ret);
	} else {
		if (payload != NULL && length > 0) {
			ret = http_server_sendall(client, payload, length);
			if (ret < 0) {
				LOG_DBG("Cannot write to socket (%d)", ret);
			}
		}
	}

	return ret;
}

int send_settings_frame(struct http_client_ctx *client, bool ack)
{
	uint8_t settings_frame[HTTP2_FRAME_HEADER_SIZE +
			       2 * sizeof(struct http2_settings_field)];
	struct http2_settings_field *setting;
	size_t len;
	int ret;

	if (ack) {
		encode_frame_header(settings_frame, 0,
				    HTTP2_SETTINGS_FRAME,
				    HTTP2_FLAG_SETTINGS_ACK, 0);
		len = HTTP2_FRAME_HEADER_SIZE;
	} else {
		encode_frame_header(settings_frame,
				    2 * sizeof(struct http2_settings_field),
				    HTTP2_SETTINGS_FRAME, 0, 0);

		setting = (struct http2_settings_field *)
			(settings_frame + HTTP2_FRAME_HEADER_SIZE);
		UNALIGNED_PUT(htons(HTTP2_SETTINGS_HEADER_TABLE_SIZE),
			      &setting->id);
		UNALIGNED_PUT(0, &setting->value);

		setting++;
		UNALIGNED_PUT(htons(HTTP2_SETTINGS_MAX_CONCURRENT_STREAMS),
			      &setting->id);
		UNALIGNED_PUT(htonl(CONFIG_HTTP_SERVER_MAX_STREAMS),
			      &setting->value);

		len = HTTP2_FRAME_HEADER_SIZE +
		      2 * sizeof(struct http2_settings_field);
	}

	ret = http_server_sendall(client, settings_frame, len);
	if (ret < 0) {
		LOG_DBG("Cannot write to socket (%d)", ret);
		return ret;
	}

	return 0;
}

int send_window_update_frame(struct http_client_ctx *client,
			     struct http2_stream_ctx *stream)
{
	uint8_t window_update_frame[HTTP2_FRAME_HEADER_SIZE +
				    sizeof(uint32_t)];
	uint32_t window_update;
	uint32_t stream_id;
	int ret;

	if (stream != NULL) {
		window_update = HTTP_SERVER_INITIAL_WINDOW_SIZE - stream->window_size;
		stream->window_size = HTTP_SERVER_INITIAL_WINDOW_SIZE;
		stream_id = stream->stream_id;
	} else {
		window_update = HTTP_SERVER_INITIAL_WINDOW_SIZE - client->window_size;
		client->window_size = HTTP_SERVER_INITIAL_WINDOW_SIZE;
		stream_id = 0;
	}

	encode_frame_header(window_update_frame, sizeof(uint32_t),
			    HTTP2_WINDOW_UPDATE_FRAME,
			    0, stream_id);
	sys_put_be32(window_update,
		     window_update_frame + HTTP2_FRAME_HEADER_SIZE);

	ret = http_server_sendall(client, window_update_frame,
				  sizeof(window_update_frame));
	if (ret < 0) {
		LOG_DBG("Cannot write to socket (%d)", ret);
		return ret;
	}

	return 0;
}

static int send_http2_404(struct http_client_ctx *client,
			  struct http2_frame *frame)
{
	int ret;

	ret = send_headers_frame(client, HTTP_404_NOT_FOUND, frame->stream_identifier, NULL, 0,
				 NULL, 0);
	if (ret < 0) {
		LOG_DBG("Cannot write to socket (%d)", ret);
		return ret;
	}

	ret = send_data_frame(client, content_404, sizeof(content_404),
			      frame->stream_identifier,
			      HTTP2_FLAG_END_STREAM);
	if (ret < 0) {
		LOG_DBG("Cannot write to socket (%d)", ret);
	}

	return ret;
}

static int send_http2_409(struct http_client_ctx *client,
			  struct http2_frame *frame)
{
	int ret;

	ret = send_headers_frame(client, HTTP_409_CONFLICT, frame->stream_identifier, NULL,
				 HTTP2_FLAG_END_STREAM, NULL, 0);
	if (ret < 0) {
		LOG_DBG("Cannot write to socket (%d)", ret);
	}

	return ret;
}

static int handle_http2_static_resource(
	struct http_resource_detail_static *static_detail,
	struct http2_frame *frame, struct http_client_ctx *client)
{
	const char *content_200;
	size_t content_len;
	int ret;

	if (!(static_detail->common.bitmask_of_supported_http_methods & BIT(HTTP_GET))) {
		return -ENOTSUP;
	}

	if (client->current_stream == NULL) {
		return -ENOENT;
	}

	content_200 = static_detail->static_data;
	content_len = static_detail->static_data_len;

	ret = send_headers_frame(client, HTTP_200_OK, frame->stream_identifier,
				 &static_detail->common, 0, NULL, 0);
	if (ret < 0) {
		LOG_DBG("Cannot write to socket (%d)", ret);
		goto out;
	}

	client->current_stream->headers_sent = true;

	ret = send_data_frame(client, content_200, content_len,
			      frame->stream_identifier,
			      HTTP2_FLAG_END_STREAM);
	if (ret < 0) {
		LOG_DBG("Cannot write to socket (%d)", ret);
		goto out;
	}

	client->current_stream->end_stream_sent = true;

out:
	return ret;
}

static int handle_http2_static_fs_resource(struct http_resource_detail_static_fs *static_fs_detail,
					   struct http2_frame *frame,
					   struct http_client_ctx *client)
{
	int ret;
	struct fs_file_t file;
	char fname[HTTP_SERVER_MAX_URL_LENGTH];
	char content_type[HTTP_SERVER_MAX_CONTENT_TYPE_LEN] = "text/html";
	struct http_resource_detail res_detail = {
		.bitmask_of_supported_http_methods =
			static_fs_detail->common.bitmask_of_supported_http_methods,
		.content_type = content_type,
		.path_len = static_fs_detail->common.path_len,
		.type = static_fs_detail->common.type,
	};
	bool gzipped;
	int len;
	int remaining;
	char tmp[64];

	if (!(static_fs_detail->common.bitmask_of_supported_http_methods & BIT(HTTP_GET))) {
		return -ENOTSUP;
	}

	if (client->current_stream == NULL) {
		return -ENOENT;
	}

	/* get filename and content-type from url */
	len = strlen(client->url_buffer);
	if (len == 1) {
		/* url is just the leading slash, use index.html as filename */
		snprintk(fname, sizeof(fname), "%s/index.html", static_fs_detail->fs_path);
	} else {
		http_server_get_content_type_from_extension(client->url_buffer, content_type,
							    sizeof(content_type));
		snprintk(fname, sizeof(fname), "%s%s", static_fs_detail->fs_path,
			 client->url_buffer);
	}

	/* open file, if it exists */
	ret = http_server_find_file(fname, sizeof(fname), &client->data_len, &gzipped);
	if (ret < 0) {
		LOG_ERR("fs_stat %s: %d", fname, ret);

		ret = send_headers_frame(client, HTTP_404_NOT_FOUND, frame->stream_identifier, NULL,
					 0, NULL, 0);
		if (ret < 0) {
			LOG_DBG("Cannot write to socket (%d)", ret);
		}
		return ret;
	}
	fs_file_t_init(&file);
	ret = fs_open(&file, fname, FS_O_READ);
	if (ret < 0) {
		LOG_ERR("fs_open %s: %d", fname, ret);
		if (ret < 0) {
			return ret;
		}
	}

	/* send headers */
	if (gzipped) {
		res_detail.content_encoding = "gzip";
	}
	ret = send_headers_frame(client, HTTP_200_OK, frame->stream_identifier, &res_detail, 0,
				 NULL, 0);
	if (ret < 0) {
		LOG_DBG("Cannot write to socket (%d)", ret);
		goto out;
	}

	client->current_stream->headers_sent = true;

	/* read and send file */
	remaining = client->data_len;
	while (remaining > 0) {
		len = fs_read(&file, tmp, sizeof(tmp));
		if (len < 0) {
			LOG_ERR("Filesystem read error (%d)", len);
			goto out;
		}

		remaining -= len;
		ret = send_data_frame(client, tmp, len, frame->stream_identifier,
				      (remaining > 0) ? 0 : HTTP2_FLAG_END_STREAM);
		if (ret < 0) {
			LOG_DBG("Cannot write to socket (%d)", ret);
			goto out;
		}
	}

	client->current_stream->end_stream_sent = true;

out:
	/* close file */
	fs_close(&file);

	return ret;
}

static int http2_dynamic_response(struct http_client_ctx *client, struct http2_frame *frame,
				  struct http_response_ctx *rsp, enum http_data_status data_status,
				  struct http_resource_detail_dynamic *dynamic_detail)
{
	int ret;
	uint8_t flags = 0;
	bool final_response = http_response_is_final(rsp, data_status);

	if (client->current_stream->headers_sent && (rsp->header_count > 0 || rsp->status != 0)) {
		LOG_WRN("Already sent headers, dropping new headers and/or response code");
	}

	/* Send headers and response code if not already sent */
	if (!client->current_stream->headers_sent) {
		/* Use '200 OK' status if not specified by application */
		if (rsp->status == 0) {
			rsp->status = 200;
		}

		if (rsp->status < HTTP_100_CONTINUE ||
		    rsp->status > HTTP_511_NETWORK_AUTHENTICATION_REQUIRED) {
			LOG_DBG("Invalid HTTP status code: %d", rsp->status);
			return -EINVAL;
		}

		if (rsp->headers == NULL && rsp->header_count > 0) {
			LOG_DBG("NULL headers, but count is > 0");
			return -EINVAL;
		}

		if (final_response && rsp->body_len == 0) {
			flags |= HTTP2_FLAG_END_STREAM;
			client->current_stream->end_stream_sent = true;
		}

		ret = send_headers_frame(client, rsp->status, frame->stream_identifier,
					 (struct http_resource_detail *)dynamic_detail, flags,
					 rsp->headers, rsp->header_count);
		if (ret < 0) {
			return ret;
		}

		client->current_stream->headers_sent = true;
	}

	/* Send body data if provided */
	if (rsp->body != NULL && rsp->body_len > 0) {
		if (final_response) {
			flags |= HTTP2_FLAG_END_STREAM;
			client->current_stream->end_stream_sent = true;
		}

		ret = send_data_frame(client, rsp->body, rsp->body_len, frame->stream_identifier,
				      flags);
		if (ret < 0) {
			return ret;
		}
	}

	return 0;
}

static int dynamic_get_req_v2(struct http_resource_detail_dynamic *dynamic_detail,
			      struct http_client_ctx *client)
{
	int ret, len;
	char *ptr;
	struct http2_frame *frame = &client->current_frame;
	enum http_data_status status;
	struct http_request_ctx request_ctx;
	struct http_response_ctx response_ctx;

	if (client->current_stream == NULL) {
		return -ENOENT;
	}

	/* Start of GET params */
	ptr = &client->url_buffer[dynamic_detail->common.path_len];
	len = strlen(ptr);
	status = HTTP_SERVER_DATA_FINAL;

	do {
		memset(&response_ctx, 0, sizeof(response_ctx));
		populate_request_ctx(&request_ctx, ptr, len, &client->header_capture_ctx);

		ret = dynamic_detail->cb(client, status, &request_ctx, &response_ctx,
					 dynamic_detail->user_data);
		if (ret < 0) {
			return ret;
		}

		ret = http2_dynamic_response(client, frame, &response_ctx, status, dynamic_detail);
		if (ret < 0) {
			return ret;
		}

		/* URL params are passed in the first cb only */
		len = 0;
	} while (!http_response_is_final(&response_ctx, status));

	if (!client->current_stream->end_stream_sent) {
		client->current_stream->end_stream_sent = true;
		ret = send_data_frame(client, NULL, 0, frame->stream_identifier,
				      HTTP2_FLAG_END_STREAM);
		if (ret < 0) {
			LOG_DBG("Cannot send last frame (%d)", ret);
		}
	}

	dynamic_detail->holder = NULL;

	return ret;
}

static int dynamic_post_req_v2(struct http_resource_detail_dynamic *dynamic_detail,
			       struct http_client_ctx *client, bool headers_only)
{
	int ret = 0;
	char *ptr = client->cursor;
	size_t data_len;
	enum http_data_status status;
	struct http2_frame *frame = &client->current_frame;
	struct http_request_ctx request_ctx;
	struct http_response_ctx response_ctx;
	struct http_header_capture_ctx *request_headers_ctx =
		headers_only ? &client->header_capture_ctx : NULL;

	if (dynamic_detail == NULL) {
		return -ENOENT;
	}

	if (client->current_stream == NULL) {
		return -ENOENT;
	}

	if (headers_only) {
		data_len = 0;
	} else {
		data_len = MIN(frame->length, client->data_len);
		frame->length -= data_len;
		client->cursor += data_len;
		client->data_len -= data_len;
	}

	if (frame->length == 0 && is_header_flag_set(frame->flags, HTTP2_FLAG_END_STREAM) &&
	    !headers_only) {
		status = HTTP_SERVER_DATA_FINAL;
	} else {
		status = HTTP_SERVER_DATA_MORE;
	}

	memset(&response_ctx, 0, sizeof(response_ctx));
	populate_request_ctx(&request_ctx, ptr, data_len, request_headers_ctx);

	ret = dynamic_detail->cb(client, status, &request_ctx, &response_ctx,
				 dynamic_detail->user_data);
	if (ret < 0) {
		return ret;
	}

	/* For POST the application might not send a response until all data has been received.
	 * Don't send a default response until the application has had a chance to respond.
	 */
	if (http_response_is_provided(&response_ctx)) {
		ret = http2_dynamic_response(client, frame, &response_ctx, status, dynamic_detail);
		if (ret < 0) {
			return ret;
		}
	}

	/* Once all data is transferred to application, repeat cb until response is complete */
	while (!http_response_is_final(&response_ctx, status) && status == HTTP_SERVER_DATA_FINAL) {
		memset(&response_ctx, 0, sizeof(response_ctx));
		populate_request_ctx(&request_ctx, ptr, 0, request_headers_ctx);

		ret = dynamic_detail->cb(client, status, &request_ctx, &response_ctx,
					 dynamic_detail->user_data);
		if (ret < 0) {
			return ret;
		}

		ret = http2_dynamic_response(client, frame, &response_ctx, status, dynamic_detail);
		if (ret < 0) {
			return ret;
		}
	}

	/* At end of stream, ensure response is sent and terminated */
	if (frame->length == 0 && !client->current_stream->end_stream_sent &&
	    is_header_flag_set(frame->flags, HTTP2_FLAG_END_STREAM)) {
		if (client->current_stream->headers_sent) {
			ret = send_data_frame(client, NULL, 0, frame->stream_identifier,
					      HTTP2_FLAG_END_STREAM);
		} else {
			memset(&response_ctx, 0, sizeof(response_ctx));
			response_ctx.final_chunk = true;
			ret = http2_dynamic_response(client, frame, &response_ctx,
						     HTTP_SERVER_DATA_FINAL, dynamic_detail);
		}

		if (ret < 0) {
			LOG_DBG("Cannot send last frame (%d)", ret);
		}

		client->current_stream->end_stream_sent = true;
		dynamic_detail->holder = NULL;
	}

	return ret;
}

static int handle_http2_dynamic_resource(
	struct http_resource_detail_dynamic *dynamic_detail,
	struct http2_frame *frame, struct http_client_ctx *client)
{
	uint32_t user_method;
	int ret;

	if (dynamic_detail->cb == NULL) {
		return -ESRCH;
	}

	user_method = dynamic_detail->common.bitmask_of_supported_http_methods;

	if (!(BIT(client->method) & user_method)) {
		return -ENOPROTOOPT;
	}

	if (dynamic_detail->holder != NULL && dynamic_detail->holder != client) {
		ret = send_http2_409(client, frame);
		if (ret < 0) {
			return ret;
		}

		return enter_http_done_state(client);
	}

	dynamic_detail->holder = client;

	switch (client->method) {
	case HTTP_GET:
		if (user_method & BIT(HTTP_GET)) {
			return dynamic_get_req_v2(dynamic_detail, client);
		}

		goto not_supported;

	case HTTP_POST:
		/* The data will come in DATA frames. Remember the detail ptr
		 * which needs to be known when passing data to application.
		 */
		if (user_method & BIT(HTTP_POST)) {
			client->current_stream->current_detail =
				(struct http_resource_detail *)dynamic_detail;

			/* If there are any header fields to pass to the application, call the
			 * dynamic handler now with the header data so that this may be cleared to
			 * re-use for any other concurrent streams
			 */
			if (IS_ENABLED(CONFIG_HTTP_SERVER_CAPTURE_HEADERS)) {
				ret = dynamic_post_req_v2(dynamic_detail, client, true);
				if (ret < 0) {
					return ret;
				}
			}
			break;
		}

		goto not_supported;

not_supported:
	default:
		LOG_DBG("HTTP method %s (%d) not supported.",
			http_method_str(client->method),
			client->method);

		return -ENOTSUP;
	}

	return 0;
}

int enter_http2_request(struct http_client_ctx *client)
{
	int ret;

	client->server_state = HTTP_SERVER_FRAME_HEADER_STATE;
	client->data_len -= sizeof(HTTP2_PREFACE) - 1;
	client->cursor += sizeof(HTTP2_PREFACE) - 1;

	/* HTTP/2 client preface received, send server preface
	 * (settings frame).
	 */
	if (!client->preface_sent) {
		ret = send_settings_frame(client, false);
		if (ret < 0) {
			return ret;
		}

		client->preface_sent = true;
	}

	return 0;
}

static int enter_http_frame_settings_state(struct http_client_ctx *client)
{
	client->server_state = HTTP_SERVER_FRAME_SETTINGS_STATE;

	return 0;
}

static int enter_http_frame_data_state(struct http_client_ctx *client)
{
	struct http2_frame *frame = &client->current_frame;
	struct http2_stream_ctx *stream;

	if (frame->stream_identifier == 0) {
		LOG_DBG("Stream ID 0 is forbidden for data frames.");
		return -EBADMSG;
	}

	stream = find_http_stream_context(client, frame->stream_identifier);
	if (stream == NULL) {
		LOG_DBG("No stream context found for ID %d",
			frame->stream_identifier);
		return -EBADMSG;
	}

	if (stream->stream_state != HTTP2_STREAM_OPEN &&
	    stream->stream_state != HTTP2_STREAM_HALF_CLOSED_REMOTE) {
		LOG_DBG("Stream ID %d in a wrong state %d", stream->stream_id,
			stream->stream_state);
		return -EBADMSG;
	}

	stream->window_size -= frame->length;
	client->window_size -= frame->length;
	client->server_state = HTTP_SERVER_FRAME_DATA_STATE;
	client->current_stream = stream;

	return 0;
}

static int enter_http_frame_headers_state(struct http_client_ctx *client)
{
	struct http2_frame *frame = &client->current_frame;
	struct http2_stream_ctx *stream;

	stream = find_http_stream_context(client, frame->stream_identifier);
	if (!stream) {
		LOG_DBG("|| stream ID ||  %d", frame->stream_identifier);

		stream = allocate_http_stream_context(client, frame->stream_identifier);
		if (!stream) {
			LOG_DBG("No available stream slots. Connection closed.");

			return -ENOMEM;
		}
	}

	client->current_stream = stream;

	if (!is_header_flag_set(frame->flags, HTTP2_FLAG_END_HEADERS)) {
		client->expect_continuation = true;
	} else {
		client->expect_continuation = false;
	}

	if (IS_ENABLED(CONFIG_HTTP_SERVER_CAPTURE_HEADERS)) {
		/* Reset header capture state for new headers frame */
		client->header_capture_ctx.count = 0;
		client->header_capture_ctx.cursor = 0;
		client->header_capture_ctx.status = HTTP_HEADER_STATUS_OK;
		client->header_capture_ctx.current_stream = stream;
	}

	client->server_state = HTTP_SERVER_FRAME_HEADERS_STATE;

	return 0;
}

static int enter_http_frame_continuation_state(struct http_client_ctx *client)
{
	struct http2_frame *frame = &client->current_frame;

	if (!is_header_flag_set(frame->flags, HTTP2_FLAG_END_HEADERS)) {
		client->expect_continuation = true;
	} else {
		client->expect_continuation = false;
	}

	client->server_state = HTTP_SERVER_FRAME_CONTINUATION_STATE;

	return 0;
}

static int enter_http_frame_window_update_state(struct http_client_ctx *client)
{
	client->server_state = HTTP_SERVER_FRAME_WINDOW_UPDATE_STATE;

	return 0;
}

static int enter_http_frame_priority_state(struct http_client_ctx *client)
{
	client->server_state = HTTP_SERVER_FRAME_PRIORITY_STATE;

	return 0;
}

static int enter_http_frame_rst_stream_state(struct http_client_ctx *client)
{
	client->server_state = HTTP_SERVER_FRAME_RST_STREAM_STATE;

	return 0;
}

static int enter_http_frame_goaway_state(struct http_client_ctx *client)
{
	client->server_state = HTTP_SERVER_FRAME_GOAWAY_STATE;

	return 0;
}

int handle_http_frame_header(struct http_client_ctx *client)
{
	int ret;

	LOG_DBG("HTTP_SERVER_FRAME_HEADER");

	ret = parse_http_frame_header(client, client->cursor, client->data_len);
	if (ret < 0) {
		return ret;
	}

	client->cursor += HTTP2_FRAME_HEADER_SIZE;
	client->data_len -= HTTP2_FRAME_HEADER_SIZE;

	print_http_frames(client);

	if (client->expect_continuation &&
	    client->current_frame.type != HTTP2_CONTINUATION_FRAME) {
		LOG_ERR("Continuation frame expected");
		return -EBADMSG;
	}

	client->current_stream = NULL;

	switch (client->current_frame.type) {
	case HTTP2_DATA_FRAME:
		return enter_http_frame_data_state(client);
	case HTTP2_HEADERS_FRAME:
		return enter_http_frame_headers_state(client);
	case HTTP2_CONTINUATION_FRAME:
		return enter_http_frame_continuation_state(client);
	case HTTP2_SETTINGS_FRAME:
		return enter_http_frame_settings_state(client);
	case HTTP2_WINDOW_UPDATE_FRAME:
		return enter_http_frame_window_update_state(client);
	case HTTP2_RST_STREAM_FRAME:
		return enter_http_frame_rst_stream_state(client);
	case HTTP2_GOAWAY_FRAME:
		return enter_http_frame_goaway_state(client);
	case HTTP2_PRIORITY_FRAME:
		return enter_http_frame_priority_state(client);
	default:
		return enter_http_done_state(client);
	}

	return 0;
}

/* This feature is theoretically obsoleted in RFC9113, but curl for instance
 * still uses it, so implement as described in RFC7540.
 */
int handle_http1_to_http2_upgrade(struct http_client_ctx *client)
{
	static const char switching_protocols[] =
		"HTTP/1.1 101 Switching Protocols\r\n"
		"Connection: Upgrade\r\n"
		"Upgrade: h2c\r\n"
		"\r\n";
	struct http2_frame *frame = &client->current_frame;
	struct http_resource_detail *detail;
	struct http2_stream_ctx *stream;
	int path_len;
	int ret;

	/* Create an artificial Data frame, so that we can proceed with HTTP2
	 * processing. The HTTP/1.1 request that is sent prior to upgrade is
	 * assigned a stream identifier of 1.
	 */
	frame->stream_identifier = 1;
	frame->type = HTTP2_DATA_FRAME;
	frame->length = client->http1_frag_data_len;
	if (client->parser_state == HTTP1_MESSAGE_COMPLETE_STATE) {
		frame->flags = HTTP2_FLAG_END_STREAM;
	} else {
		frame->flags = 0;
	}

	/* Allocate stream. */
	stream = find_http_stream_context(client, frame->stream_identifier);
	if (stream == NULL) {
		stream = allocate_http_stream_context(client, frame->stream_identifier);
		if (!stream) {
			LOG_DBG("No available stream slots. Connection closed.");
			return -ENOMEM;
		}
	}

	client->current_stream = stream;

	if (!client->preface_sent) {
		ret = http_server_sendall(client, switching_protocols,
					  sizeof(switching_protocols) - 1);
		if (ret < 0) {
			goto error;
		}

		/* The first HTTP/2 frame sent by the server MUST be a server connection
		 * preface.
		 */
		ret = send_settings_frame(client, false);
		if (ret < 0) {
			goto error;
		}

		client->preface_sent = true;
	}

	detail = get_resource_detail(client->url_buffer, &path_len, false);
	if (detail != NULL) {
		detail->path_len = path_len;

		if (detail->type == HTTP_RESOURCE_TYPE_STATIC) {
			ret = handle_http2_static_resource(
				(struct http_resource_detail_static *)detail,
				frame, client);
			if (ret < 0) {
				goto error;
			}
		} else if (detail->type == HTTP_RESOURCE_TYPE_STATIC_FS) {
			ret = handle_http2_static_fs_resource(
				(struct http_resource_detail_static_fs *)detail, frame, client);
			if (ret < 0) {
				goto error;
			}
		} else if (detail->type == HTTP_RESOURCE_TYPE_DYNAMIC) {
			ret = handle_http2_dynamic_resource(
				(struct http_resource_detail_dynamic *)detail,
				frame, client);
			if (ret < 0) {
				goto error;
			}

			if (client->method == HTTP_POST) {
				ret = dynamic_post_req_v2(
					(struct http_resource_detail_dynamic *)detail, client,
					false);
				if (ret < 0) {
					goto error;
				}
			}

		}
	} else {
		ret = send_http2_404(client, frame);
		if (ret < 0) {
			goto error;
		}
	}

	/* Only after the complete HTTP1 payload has been processed, switch
	 * to HTTP2.
	 */
	if (client->parser_state == HTTP1_MESSAGE_COMPLETE_STATE) {
		release_http_stream_context(client, frame->stream_identifier);
		client->current_detail = NULL;
		client->server_state = HTTP_SERVER_PREFACE_STATE;
		client->cursor += client->data_len;
		client->data_len = 0;
	}

	return 0;

error:
	return ret;
}

static int parse_http_frame_padded_field(struct http_client_ctx *client)
{
	struct http2_frame *frame = &client->current_frame;

	if (client->data_len == 0) {
		return -EAGAIN;
	}

	frame->padding_len = *client->cursor;
	client->cursor++;
	client->data_len--;
	frame->length--;

	if (frame->length <= frame->padding_len) {
		return -EBADMSG;
	}

	/* Subtract the padding length from frame length now to simplify
	 * payload processing. Padding will be handled based on
	 * frame->padding_len in a separate state.
	 */
	frame->length -= frame->padding_len;

	/* Clear the padded flag, this indicates that padding field was
	 * already parsed.
	 */
	clear_header_flag(&frame->flags, HTTP2_FLAG_PADDED);

	return 0;
}

static int parse_http_frame_priority_field(struct http_client_ctx *client)
{
	struct http2_frame *frame = &client->current_frame;

	if (client->data_len < HTTP2_HEADERS_FRAME_PRIORITY_LEN) {
		return -EAGAIN;
	}

	/* Priority signalling is deprecated by RFC 9113, however it still
	 * should be expected to receive, just drop the bytes.
	 */
	client->cursor += HTTP2_HEADERS_FRAME_PRIORITY_LEN;
	client->data_len -= HTTP2_HEADERS_FRAME_PRIORITY_LEN;
	frame->length -= HTTP2_HEADERS_FRAME_PRIORITY_LEN;

	/* Clear the priority flag, this indicates that priority field was
	 * already parsed.
	 */
	clear_header_flag(&frame->flags, HTTP2_FLAG_PRIORITY);

	return 0;
}

int handle_http_frame_data(struct http_client_ctx *client)
{
	struct http2_frame *frame = &client->current_frame;
	int ret;

	LOG_DBG("HTTP_SERVER_FRAME_DATA_STATE");

	if (client->current_stream->current_detail == NULL) {
		/* There is no handler */
		LOG_DBG("No dynamic handler found.");
		(void)send_http2_404(client, frame);
		return -ENOENT;
	}

	if (is_header_flag_set(frame->flags, HTTP2_FLAG_PADDED)) {
		ret = parse_http_frame_padded_field(client);
		if (ret < 0) {
			return ret;
		}
	}

	ret = dynamic_post_req_v2(
		(struct http_resource_detail_dynamic *)client->current_stream->current_detail,
		client, false);
	if (ret < 0 && ret == -ENOENT) {
		ret = send_http2_404(client, frame);
	}

	if (ret < 0) {
		return ret;
	}

	if (frame->length == 0) {
		struct http2_stream_ctx *stream =
			find_http_stream_context(client, frame->stream_identifier);

		if (stream == NULL) {
			LOG_DBG("No stream context found for ID %d",
				frame->stream_identifier);
			return -EBADMSG;
		}

		ret = send_window_update_frame(client, stream);
		if (ret < 0) {
			return ret;
		}

		ret = send_window_update_frame(client, NULL);
		if (ret < 0) {
			return ret;
		}

		if (is_header_flag_set(frame->flags, HTTP2_FLAG_END_STREAM)) {
			client->current_stream->current_detail = NULL;
			release_http_stream_context(client, frame->stream_identifier);
		}

		/* Whole frame consumed, expect next one. */
		if (frame->padding_len > 0) {
			client->server_state = HTTP_SERVER_FRAME_PADDING_STATE;
		} else {
			client->server_state = HTTP_SERVER_FRAME_HEADER_STATE;
		}
	}

	return 0;
}

static void check_user_request_headers_http2(struct http_header_capture_ctx *ctx,
					     struct http_hpack_header_buf *hdr_buf)
{
	size_t required_len;
	char *dest = &ctx->buffer[ctx->cursor];
	size_t remaining = sizeof(ctx->buffer) - ctx->cursor;
	struct http_header *current_header = &ctx->headers[ctx->count];

	STRUCT_SECTION_FOREACH(http_header_name, header) {
		required_len = hdr_buf->name_len + hdr_buf->value_len + 2;

		if (hdr_buf->name_len == strlen(header->name) &&
		    (strncasecmp(hdr_buf->name, header->name, hdr_buf->name_len) == 0)) {
			if (ctx->count == ARRAY_SIZE(ctx->headers)) {
				LOG_DBG("Header '%s' dropped: not enough slots", header->name);
				ctx->status = HTTP_HEADER_STATUS_DROPPED;
				break;
			}

			if (remaining < required_len) {
				LOG_DBG("Header '%s' dropped: buffer too small", header->name);
				ctx->status = HTTP_HEADER_STATUS_DROPPED;
				break;
			}

			/* Copy header name from user-registered header to make HTTP1/HTTP2
			 * transparent to the user - they do not need a case-insensitive comparison
			 * to check which header was matched.
			 */
			memcpy(dest, header->name, hdr_buf->name_len);
			dest[hdr_buf->name_len] = '\0';
			current_header->name = dest;
			ctx->cursor += (hdr_buf->name_len + 1);
			dest += (hdr_buf->name_len + 1);

			/* Copy header value */
			memcpy(dest, hdr_buf->value, hdr_buf->value_len);
			dest[hdr_buf->value_len] = '\0';
			current_header->value = dest;
			ctx->cursor += (hdr_buf->value_len + 1);

			ctx->count++;
			break;
		}
	}
}

static int process_header(struct http_client_ctx *client,
			  struct http_hpack_header_buf *header)
{
	if (IS_ENABLED(CONFIG_HTTP_SERVER_CAPTURE_HEADERS)) {
		check_user_request_headers_http2(&client->header_capture_ctx, header);
	}

	if (header->name_len == (sizeof(":method") - 1) &&
	    memcmp(header->name, ":method", header->name_len) == 0) {
		/* TODO Improve string to method conversion */
		if (header->value_len == (sizeof("GET") - 1) &&
			memcmp(header->value, "GET", header->value_len) == 0) {
			client->method = HTTP_GET;
		} else if (header->value_len == (sizeof("POST") - 1) &&
				memcmp(header->value, "POST", header->value_len) == 0) {
			client->method = HTTP_POST;
		} else {
			/* Unknown method */
			return -EBADMSG;
		}
	} else if (header->name_len == (sizeof(":path") - 1) &&
		   memcmp(header->name, ":path", header->name_len) == 0) {
		if (header->value_len > sizeof(client->url_buffer) - 1) {
			/* URL too long to handle */
			return -ENOBUFS;
		}

		memcpy(client->url_buffer, header->value, header->value_len);
		client->url_buffer[header->value_len] = '\0';
	} else if (header->name_len == (sizeof("content-type") - 1) &&
		   memcmp(header->name, "content-type", header->name_len) == 0) {
		if (header->value_len > sizeof(client->content_type) - 1) {
			/* Content-type too long to handle */
			return -ENOBUFS;
		}

		memcpy(client->content_type, header->value, header->value_len);
		client->content_type[header->value_len] = '\0';
	} else if (header->name_len == (sizeof("content-length") - 1) &&
		   memcmp(header->name, "content-length", header->name_len) == 0) {
		char len_str[16] = { 0 };
		char *endptr;
		unsigned long len;

		memcpy(len_str, header->value, MIN(sizeof(len_str), header->value_len));
		len_str[sizeof(len_str) - 1] = '\0';

		len = strtoul(len_str, &endptr, 10);
		if (*endptr != '\0') {
			return -EINVAL;
		}

		client->content_len = (size_t)len;
	} else {
		/* Just ignore for now. */
		LOG_DBG("Ignoring field %.*s", (int)header->name_len, header->name);
	}

	return 0;
}

static int handle_incomplete_http_header(struct http_client_ctx *client)
{
	struct http2_frame *frame = &client->current_frame;
	size_t extra_len, prev_frame_len;
	int ret;

	if (client->data_len < frame->length) {
		/* Still did not receive entire frame content */
		return -EAGAIN;
	}

	if (!client->expect_continuation) {
		/* Failed to parse header field while the frame is complete
		 * and no continuation frame is expected - report protocol
		 * error.
		 */
		LOG_ERR("Incomplete header field");
		return -EBADMSG;
	}

	/* A header field can be split between two frames, i. e. header and
	 * continuation or two continuation frames. Because of this, the
	 * continuation frame header can be present in the stream in between
	 * header field data, so in such case we need to check for header here
	 * and remove it from the stream to unblock further processing of the
	 * header field.
	 */
	prev_frame_len = frame->length;
	extra_len = client->data_len - frame->length;
	ret = parse_http_frame_header(client, client->cursor + prev_frame_len,
				      extra_len);
	if (ret < 0) {
		return -EAGAIN;
	}

	/* Continuation frame expected. */
	if (frame->type != HTTP2_CONTINUATION_FRAME) {
		LOG_ERR("Continuation frame expected");
		return -EBADMSG;
	}

	print_http_frames(client);
	/* Now remove continuation frame header from the stream, and proceed
	 * with processing.
	 */
	extra_len -= HTTP2_FRAME_HEADER_SIZE;
	client->data_len -= HTTP2_FRAME_HEADER_SIZE;
	frame->length += prev_frame_len;
	memmove(client->cursor + prev_frame_len,
		client->cursor + prev_frame_len + HTTP2_FRAME_HEADER_SIZE,
		extra_len);

	return enter_http_frame_continuation_state(client);
}

static int handle_http_frame_headers_end_stream(struct http_client_ctx *client)
{
	struct http2_frame *frame = &client->current_frame;
	struct http_request_ctx request_ctx;
	struct http_response_ctx response_ctx;
	int ret = 0;

	if (client->current_stream == NULL) {
		return -ENOENT;
	}

	if (client->current_stream->current_detail == NULL) {
		goto out;
	}

	if (client->current_stream->current_detail->type == HTTP_RESOURCE_TYPE_DYNAMIC) {
		struct http_resource_detail_dynamic *dynamic_detail =
			(struct http_resource_detail_dynamic *)
				client->current_stream->current_detail;

		memset(&response_ctx, 0, sizeof(response_ctx));
		populate_request_ctx(&request_ctx, NULL, 0, NULL);

		ret = dynamic_detail->cb(client, HTTP_SERVER_DATA_FINAL, &request_ctx,
					 &response_ctx, dynamic_detail->user_data);
		if (ret < 0) {
			dynamic_detail->holder = NULL;
			goto out;
		}

		/* Force end stream */
		response_ctx.final_chunk = true;

		ret = http2_dynamic_response(client, frame, &response_ctx, HTTP_SERVER_DATA_FINAL,
					     dynamic_detail);
		dynamic_detail->holder = NULL;

		if (ret < 0) {
			goto out;
		}
	}

	if (!client->current_stream->headers_sent) {
		ret = send_headers_frame(client, HTTP_200_OK, frame->stream_identifier,
					 client->current_stream->current_detail,
					 HTTP2_FLAG_END_STREAM, NULL, 0);
		if (ret < 0) {
			LOG_DBG("Cannot write to socket (%d)", ret);
			goto out;
		}
	} else if (!client->current_stream->end_stream_sent) {
		ret = send_data_frame(client, NULL, 0, frame->stream_identifier,
				      HTTP2_FLAG_END_STREAM);
		if (ret < 0) {
			LOG_DBG("Cannot send last frame (%d)", ret);
		}
	}

	client->current_stream->current_detail = NULL;

out:
	release_http_stream_context(client, frame->stream_identifier);

	return ret;
}

int handle_http_frame_headers(struct http_client_ctx *client)
{
	struct http2_frame *frame = &client->current_frame;
	struct http_resource_detail *detail;
	int ret, path_len;

	LOG_DBG("HTTP_SERVER_FRAME_HEADERS");

	if (is_header_flag_set(frame->flags, HTTP2_FLAG_PADDED)) {
		ret = parse_http_frame_padded_field(client);
		if (ret < 0) {
			return ret;
		}
	}

	if (is_header_flag_set(frame->flags, HTTP2_FLAG_PRIORITY)) {
		ret = parse_http_frame_priority_field(client);
		if (ret < 0) {
			return ret;
		}
	}

	while (frame->length > 0) {
		struct http_hpack_header_buf *header = &client->header_field;
		size_t datalen = MIN(client->data_len, frame->length);

		ret = http_hpack_decode_header(client->cursor, datalen, header);
		if (ret <= 0) {
			if (ret == -EAGAIN) {
				ret = handle_incomplete_http_header(client);
			} else if (ret == 0) {
				ret = -EBADMSG;
			}

			return ret;
		}

		if (ret > frame->length) {
			LOG_ERR("Protocol error, frame length exceeded");
			return -EBADMSG;
		}

		frame->length -= ret;
		client->cursor += ret;
		client->data_len -= ret;

		LOG_DBG("Parsed header: %.*s %.*s", (int)header->name_len,
			header->name, (int)header->value_len, header->value);

		ret = process_header(client, header);
		if (ret < 0) {
			return ret;
		}
	}

	if (client->expect_continuation) {
		/* More headers to come in the continuation frame. */
		client->server_state = HTTP_SERVER_FRAME_HEADER_STATE;
		return 0;
	}

	detail = get_resource_detail(client->url_buffer, &path_len, false);
	if (detail != NULL) {
		detail->path_len = path_len;

		if (detail->type == HTTP_RESOURCE_TYPE_STATIC) {
			ret = handle_http2_static_resource(
				(struct http_resource_detail_static *)detail,
				frame, client);
			if (ret < 0) {
				return ret;
			}
		} else if (detail->type == HTTP_RESOURCE_TYPE_STATIC_FS) {
			ret = handle_http2_static_fs_resource(
				(struct http_resource_detail_static_fs *)detail, frame, client);
			if (ret < 0) {
				return ret;
			}
		} else if (detail->type == HTTP_RESOURCE_TYPE_DYNAMIC) {
			ret = handle_http2_dynamic_resource(
				(struct http_resource_detail_dynamic *)detail,
				frame, client);
			if (ret < 0) {
				return ret;
			}
		}

	} else {
		ret = send_http2_404(client, frame);
		if (ret < 0) {
			return ret;
		}
	}

	if (is_header_flag_set(frame->flags, HTTP2_FLAG_END_STREAM)) {
		ret = handle_http_frame_headers_end_stream(client);
		if (ret < 0) {
			return ret;
		}
	}

	if (frame->padding_len > 0) {
		client->server_state = HTTP_SERVER_FRAME_PADDING_STATE;
	} else {
		client->server_state = HTTP_SERVER_FRAME_HEADER_STATE;
	}

	return 0;
}

int handle_http_frame_priority(struct http_client_ctx *client)
{
	struct http2_frame *frame = &client->current_frame;

	LOG_DBG("HTTP_SERVER_FRAME_PRIORITY_STATE");

	if (frame->length != HTTP2_PRIORITY_FRAME_LEN) {
		return -EBADMSG;
	}

	if (client->data_len < frame->length) {
		return -EAGAIN;
	}

	/* Priority signalling is deprecated by RFC 9113, however it still
	 * should be expected to receive, just drop the bytes.
	 */
	client->data_len -= HTTP2_PRIORITY_FRAME_LEN;
	client->cursor += HTTP2_PRIORITY_FRAME_LEN;

	client->server_state = HTTP_SERVER_FRAME_HEADER_STATE;

	return 0;
}

int handle_http_frame_rst_stream(struct http_client_ctx *client)
{
	struct http2_frame *frame = &client->current_frame;
	struct http2_stream_ctx *stream_ctx;
	uint32_t error_code;

	LOG_DBG("FRAME_RST_STREAM");

	if (frame->length != HTTP2_RST_STREAM_FRAME_LEN) {
		return -EBADMSG;
	}

	if (client->data_len < frame->length) {
		return -EAGAIN;
	}

	if (frame->stream_identifier == 0) {
		return -EBADMSG;
	}

	stream_ctx = find_http_stream_context(client, frame->stream_identifier);
	if (stream_ctx == NULL) {
		return -EBADMSG;
	}

	error_code = sys_get_be32(client->cursor);

	LOG_DBG("Stream %u reset with error code %u", stream_ctx->stream_id,
		error_code);

	release_http_stream_context(client, stream_ctx->stream_id);

	client->data_len -= HTTP2_RST_STREAM_FRAME_LEN;
	client->cursor += HTTP2_RST_STREAM_FRAME_LEN;

	client->server_state = HTTP_SERVER_FRAME_HEADER_STATE;

	return 0;
}

int handle_http_frame_settings(struct http_client_ctx *client)
{
	struct http2_frame *frame = &client->current_frame;
	int bytes_consumed;

	LOG_DBG("HTTP_SERVER_FRAME_SETTINGS");

	if (client->data_len < frame->length) {
		return -EAGAIN;
	}

	bytes_consumed = client->current_frame.length;
	client->data_len -= bytes_consumed;
	client->cursor += bytes_consumed;

	if (!is_header_flag_set(frame->flags, HTTP2_FLAG_SETTINGS_ACK)) {
		int ret;

		ret = send_settings_frame(client, true);
		if (ret < 0) {
			LOG_DBG("Cannot write to socket (%d)", ret);
			return ret;
		}
	}

	client->server_state = HTTP_SERVER_FRAME_HEADER_STATE;

	return 0;
}

int handle_http_frame_goaway(struct http_client_ctx *client)
{
	struct http2_frame *frame = &client->current_frame;
	int bytes_consumed;

	LOG_DBG("HTTP_SERVER_FRAME_GOAWAY");

	if (client->data_len < frame->length) {
		return -EAGAIN;
	}

	bytes_consumed = client->current_frame.length;
	client->data_len -= bytes_consumed;
	client->cursor += bytes_consumed;

	enter_http_done_state(client);

	return 0;
}

int handle_http_frame_window_update(struct http_client_ctx *client)
{
	struct http2_frame *frame = &client->current_frame;
	int bytes_consumed;

	LOG_DBG("HTTP_SERVER_FRAME_WINDOW_UPDATE");

	/* TODO Implement flow control, for now just ignore. */

	if (client->data_len < frame->length) {
		return -EAGAIN;
	}

	bytes_consumed = client->current_frame.length;
	client->data_len -= bytes_consumed;
	client->cursor += bytes_consumed;

	client->server_state = HTTP_SERVER_FRAME_HEADER_STATE;

	return 0;
}

int handle_http_frame_continuation(struct http_client_ctx *client)
{
	LOG_DBG("HTTP_SERVER_FRAME_CONTINUATION_STATE");
	client->server_state = HTTP_SERVER_FRAME_HEADERS_STATE;

	return 0;
}

int handle_http_frame_padding(struct http_client_ctx *client)
{
	struct http2_frame *frame = &client->current_frame;
	size_t bytes_consumed;

	if (client->data_len == 0) {
		return -EAGAIN;
	}

	bytes_consumed = MIN(client->data_len, frame->padding_len);
	client->data_len -= bytes_consumed;
	client->cursor += bytes_consumed;
	frame->padding_len -= bytes_consumed;

	if (frame->padding_len == 0) {
		client->server_state = HTTP_SERVER_FRAME_HEADER_STATE;
	}

	return 0;
}

const char *get_frame_type_name(enum http2_frame_type type)
{
	switch (type) {
	case HTTP2_DATA_FRAME:
		return "DATA";
	case HTTP2_HEADERS_FRAME:
		return "HEADERS";
	case HTTP2_PRIORITY_FRAME:
		return "PRIORITY";
	case HTTP2_RST_STREAM_FRAME:
		return "RST_STREAM";
	case HTTP2_SETTINGS_FRAME:
		return "SETTINGS";
	case HTTP2_PUSH_PROMISE_FRAME:
		return "PUSH_PROMISE";
	case HTTP2_PING_FRAME:
		return "PING";
	case HTTP2_GOAWAY_FRAME:
		return "GOAWAY";
	case HTTP2_WINDOW_UPDATE_FRAME:
		return "WINDOW_UPDATE";
	case HTTP2_CONTINUATION_FRAME:
		return "CONTINUATION";
	default:
		return "UNKNOWN";
	}
}

int parse_http_frame_header(struct http_client_ctx *client, const uint8_t *buffer,
			    size_t buflen)
{
	struct http2_frame *frame = &client->current_frame;

	if (buflen < HTTP2_FRAME_HEADER_SIZE) {
		return -EAGAIN;
	}

	frame->length = sys_get_be24(&buffer[HTTP2_FRAME_LENGTH_OFFSET]);
	frame->type = buffer[HTTP2_FRAME_TYPE_OFFSET];
	frame->flags = buffer[HTTP2_FRAME_FLAGS_OFFSET];
	frame->stream_identifier = sys_get_be32(
				&buffer[HTTP2_FRAME_STREAM_ID_OFFSET]);
	frame->stream_identifier &= HTTP2_FRAME_STREAM_ID_MASK;
	frame->padding_len = 0;

	LOG_DBG("Frame len %d type 0x%02x flags 0x%02x id %d",
		frame->length, frame->type, frame->flags, frame->stream_identifier);

	return 0;
}