使用libwebsocket搭建websocket服務器實例

 

                                                       webcomm與前端的通訊-websocket服務器操作流程

 

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

#define MAX_PAYLOAD_SIZE	(4096)

/** 開啓確認纔有重發的機制 */
typedef struct comm_packet {
	void 		*content; 				/* is malloc'd */
	size_t 		content_len;
	uint8_t		enable_ack;				/* 是否需要響應 0：不需要響應 1：需要響應 */
	uint8_t		retry_cnt;				/* 重發的次數(ms)    */	
} comm_packet_t;

/* one of these created for each message */
typedef struct msg {
	comm_packet_t	*payload; /* is malloc'd */
	size_t 			len;
} msg_t;

/* one of these is created for each client connecting to us */
struct per_session_data__cetwebsocket {
	struct per_session_data__cetwebsocket *pss_list;
	struct lws *wsi;
	uint32_t tail;
	
	struct lws_ring *ring; 		/* ringbuffer holding unsent messages */	
};

/* one of these is created for each vhost our protocol is used with */
struct per_vhost_data__cetwebsocket {
	struct lws_context *context;
	struct lws_vhost *vhost;
	const struct lws_protocols *protocol;

	struct per_session_data__cetwebsocket *pss_list; /* linked-list of live pss*/
};

static int
callback_protocol_cetwebsocket_server(struct lws *wsi, enum lws_callback_reasons reason,
			void *user, void *in, size_t len);

#define LWS_PLUGIN_PROTOCOL_CETWEBSOCKET \
	{ \
		"cet-webserver", /* "cet-webserver" */ \
		callback_protocol_cetwebsocket_server, \
		sizeof(struct per_session_data__cetwebsocket), \
		2048, \
		0, NULL, 0 \
	}

static struct lws_protocols sg_protocols[] = {
	{ "http", lws_callback_http_dummy, 0, 0 }, 
	LWS_PLUGIN_PROTOCOL_CETWEBSOCKET,
	{ NULL, NULL, 0, 0 } /* terminator */
};

static int sg_interrupted = 0;

/* destroys the message when everyone has had a copy of it */
static void
cetwebsocket_destroy_message(void *_msg)
{
	msg_t *message = _msg;
	comm_packet_t *ppacket = (comm_packet_t *)message->payload;

	free(ppacket->content);
	ppacket->content = NULL;
	free(message->payload);
	message->payload = NULL;
	message->len = 0;
}

static struct per_session_data__cetwebsocket **
cetwebsocket_traverse_find(struct per_vhost_data__cetwebsocket *vhd, 
				struct per_session_data__cetwebsocket *pss)
{	
	ASSERT_PARAM_CHECK(vhd, NULL);
	ASSERT_PARAM_CHECK(pss, NULL);

	struct per_session_data__cetwebsocket **ppss = NULL;

	for (ppss = &(vhd->pss_list); *ppss; ppss = &((*ppss)->pss_list)) {
		if ((*ppss) == pss) {
			return ppss;
		}
	}

	return NULL;
}

static struct per_session_data__cetwebsocket *
cetwebsocket_client_remove(struct per_vhost_data__cetwebsocket *vhd, 
				struct per_session_data__cetwebsocket *pss)
{	
	ASSERT_PARAM_CHECK(vhd, NULL);
	ASSERT_PARAM_CHECK(pss, NULL);

	struct per_session_data__cetwebsocket **ppss = NULL;

	if (NULL != (ppss = cetwebsocket_traverse_find(vhd, pss))) {
		lws_ring_destroy(pss->ring);
		*ppss = pss->pss_list;		
		return *ppss;
	}

	return pss;
}

static int 
cetwebsocket_insert_ring(struct per_session_data__cetwebsocket *pss, const char *func_id, 
		const char *mid, uint8_t enable_ack, const void *content, int contentlen)
{	
	int n = 0;
	msg_t amsg;
	
	ASSERT_PARAM_CHECK(pss, -1);
	ASSERT_PARAM_CHECK(content, -1);
	
	n = (int)lws_ring_get_count_free_elements(pss->ring);	
	if (!n) {
		return -1;
	}
	
	memset(&amsg, 0x00, sizeof(amsg));
	/* notice we over-allocate by LWS_PRE */
	amsg.payload = calloc(sizeof(char), sizeof(comm_packet_t));
	if (!amsg.payload) {
		return -1;
	}
	
	/* notice we over-allocate by LWS_PRE */
	amsg.payload->content = calloc(sizeof(char), LWS_PRE + contentlen + 1);
	if (!amsg.payload->content) {
		return -1;
	}
	
	amsg.payload->enable_ack	= enable_ack;
	amsg.payload->retry_cnt		= 0;
	amsg.payload->content_len	= contentlen;
	amsg.len = amsg.payload->content_len + sizeof(comm_packet_t);

	memcpy((char *)amsg.payload->content + LWS_PRE, content, contentlen);
	/** 將實時消息插入到環形緩存中 */
	if (!lws_ring_insert(pss->ring, &amsg, 1)) {
		cetwebsocket_destroy_message(&amsg);
		return -1;
	}
	
	return 0;
}

static comm_packet_t *
cetwebsocket_get_packet(struct lws_ring *ring, uint32_t *tail)
{
	msg_t	*pmsg = NULL;

	ASSERT_PARAM_CHECK(ring, NULL);
	
	pmsg = (msg_t *)lws_ring_get_element(ring, tail);

	return (NULL == pmsg)? NULL : (comm_packet_t *)pmsg->payload;
}
					
static int
cetwebsocket_response_handler(struct per_session_data__cetwebsocket *pss, const char *mid)
{	
	comm_packet_t *ppacket;

	ASSERT_PARAM_CHECK(pss, -1);
	ASSERT_PARAM_CHECK(mid, -1);

	ppacket = cetwebsocket_get_packet(pss->ring, &pss->tail);			
	if (NULL == ppacket)
		return -1;
				
	if (ppacket->enable_ack) {	// ack respense
		if (0 == strcmp(mid, ppacket->mid)) {
			lws_ring_consume_single_tail(pss->ring, &pss->tail, 1);			
		}
	} else {
		; // not ack respense
	}
			
	return 0;
}

static int
cetwebsocket_server_create(struct lws *wsi)
{		
	struct per_vhost_data__cetwebsocket *vhd = NULL;

	vhd = (struct per_vhost_data__cetwebsocket *)lws_protocol_vh_priv_zalloc(lws_get_vhost(wsi),
				lws_get_protocol(wsi), sizeof(struct per_vhost_data__cetwebsocket));
	vhd->context = lws_get_context(wsi);
	vhd->protocol = lws_get_protocol(wsi);
	vhd->vhost = lws_get_vhost(wsi);
	vhd->pss_debug_count = 0;	
	vhd->pss_other_count = 0;
	vhd->pss_list = NULL;
	sg_ptr_websockets->vhost = vhd;
	
	return 0;
}

static int
cetwebsocket_session_create(struct lws *wsi, struct per_vhost_data__cetwebsocket *vhd, 
				struct per_session_data__cetwebsocket *pss)
{	
	char	*cookie_id = NULL;
	char 	buffer[FIELDS_SIZE] = {0};

	ASSERT_PARAM_CHECK(wsi, -1);
	ASSERT_PARAM_CHECK(vhd, -1);
	ASSERT_PARAM_CHECK(pss, -1);
	
	pss->tail = 0;
	pss->wsi = wsi;
	pss->ring = lws_ring_create(sizeof(msg_t), (FIELDS_SIZE), cetwebsocket_destroy_message);		
	if (!pss->ring) {			
		return -1;
	}
			
	lws_ll_fwd_insert(pss, pss_list, vhd->pss_list);
		
	return 0;
}

static int
cetwebsocket_server_write(struct lws *wsi, struct per_vhost_data__cetwebsocket *vhd, 
				struct per_session_data__cetwebsocket *pss)
{		
	int 	len;
	comm_packet_t *ppacket;
	
	ASSERT_PARAM_CHECK(wsi, -1);
	ASSERT_PARAM_CHECK(vhd, -1);
	ASSERT_PARAM_CHECK(pss, -1);

	if (NULL == cetwebsocket_traverse_find(vhd, pss)) {
		return -1;
	}

	if (NULL == (ppacket = cetwebsocket_get_packet(pss->ring, &pss->tail))) {
		return -1;
	}
			
	len = lws_write(wsi, ((unsigned char *)ppacket->content) + LWS_PRE, 
		ppacket->content_len, LWS_WRITE_TEXT);
	if (len < (int)ppacket->content_len) {
		return -1;
	}
		
	if (!ppacket->enable_ack || ppacket->retry_cnt > RETRY_MAX_CNT) {		
		lws_ring_consume_single_tail(pss->ring, &pss->tail, 1);
	}
		
	return 0;
}
	
static int
callback_protocol_cetwebsocket_server(struct lws *wsi, enum lws_callback_reasons reason,
			void *user, void *in, size_t len)
{
	struct per_session_data__cetwebsocket *pss = (struct per_session_data__cetwebsocket *)user;
	struct per_vhost_data__cetwebsocket *vhd = sg_ptr_websockets->vhost;
	
	switch (reason) {
	case LWS_CALLBACK_PROTOCOL_INIT:		
		cetwebsocket_server_create(wsi);
		break;

	case LWS_CALLBACK_PROTOCOL_DESTROY:
		break;

	case LWS_CALLBACK_ESTABLISHED:
	{	
		cetwebsocket_session_create(wsi, vhd, pss);
		break;
	}
	case LWS_CALLBACK_CLOSED:		
		cetwebsocket_client_remove(vhd, pss);
		break;

	case LWS_CALLBACK_SERVER_WRITEABLE:
	{	
		cetwebsocket_server_write(wsi, vhd, pss);
		break;
	}
	case LWS_CALLBACK_RECEIVE:
	{	
		if (vhd->pss_list) {		
			cetwebsocket_server_receive(wsi, vhd, pss, in, len);
		}		
		break;
	}
	default:
		break;
	}

	return 0;
}

static int
cetwebsocket_retry_writable_handler(struct per_vhost_data__cetwebsocket *vhost)
{
	boolean 		is_writable = true;
	comm_packet_t 	*ppacket = NULL;	
	struct per_session_data__cetwebsocket *pss = NULL;
	
	ASSERT_PARAM_CHECK(vhost, -1);
	
	for (pss = vhost->pss_list; pss; pss = pss->pss_list) {
		ppacket = cetwebsocket_get_packet(pss->ring, &pss->tail);			
		if (NULL == ppacket)
			continue;

		if (ppacket->enable_ack) {
			if (ppacket->retry_cnt <= RETRY_MAX_CNT) {
				ppacket->retry_cnt += 1;
			} else {
				is_writable = false;
			}
		}

		if (true == is_writable) {
			lws_callback_on_writable(pss->wsi);
		}
	}
	
	return 0;
}

int main(int argc, char * const argv[])
{
	struct lws_context_creation_info info;
	struct lws_context *context;	
	int n = 0/* , logs = LLL_USER | LLL_ERR | LLL_WARN | LLL_NOTICE
			| LLL_INFO | LLL_PARSER | LLL_HEADER | LLL_EXT 
			| LLL_CLIENT | LLL_LATENCY | LLL_DEBUG */
			/* 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 */;

		
	lws_set_log_level(0, NULL);
	memset(&info, 0, sizeof info); /* otherwise uninitialized garbage */
	info.port = 7681;
	info.protocols = sg_protocols;
	info.vhost_name = "localhost";
	info.ws_ping_pong_interval = 10;
	info.options = LWS_SERVER_OPTION_HTTP_HEADERS_SECURITY_BEST_PRACTICES_ENFORCE;
	info.options |= LWS_SERVER_OPTION_DO_SSL_GLOBAL_INIT;
	info.ssl_cert_filepath = ME_GOAHEAD_SSL_CERTIFICATE;
	info.ssl_private_key_filepath = ME_GOAHEAD_SSL_KEY;

	context = lws_create_context(&info);
	if (!context) {
		return NULL;
	}
		
	while (n >= 0 && !sg_interrupted) {	
		n = lws_service(context, 0);
		lws_cancel_service(context);		
	}
	lws_context_destroy(context);

	return NULL;
}