使用linux c开源库libwebsockets编写的websocket客户端

<一>: 背景

19年中旬做的一个嵌入式项目, 应用层需要有一个心跳的功能, 当时决定用websocket协议, 所以当时就研究了下libwebsockets的使用. 网上的资料并不多, 当时只能研究开源库提供的测试代码, 然后改改后就合并到项目里了. 这几天又把libwebsockets重新编译了下, 顺手重新写了一个简单的websocket客户端. 主要包含了以下三个功能:

1): 定时发送心跳数据;

2): 掉网重连;

3): 是否使用ssl;

代码如<二>, 不足之处请多指教.

<二>: 代码

WebsocketClient.h如下:

#ifndef WEBSOCKET_CLIENT_H
#define WEBSOCKET_CLIENT_H#include <string.h>
#include <libwebsockets.h>#define _THIS_ "this"
#define _ADDR_ "addr"
#define _PORT_ "port"
#define _PATH_ "path"
#define _SSL_  "ssl"class WebsocketClient;
typedef struct ClientData {struct lws_context *context;struct lws_vhost *vhost;struct lws *client_wsi;const char **addr;int *port;const char **path;int *ssl;WebsocketClient *wsc;
}_ClientData;class WebsocketClient
{
public:WebsocketClient();~WebsocketClient(){if (mContext != NULL){lws_context_destroy(mContext);mContext = NULL;}}public:bool Start(int argc, const char **argv);private:bool init(int argc, const char **argv);public:char msg[1024];private:struct lws_context *mContext;struct lws_protocol_vhost_options lpvoAddr; // 地址struct lws_protocol_vhost_options lpvoPort; // 端口struct lws_protocol_vhost_options lpvoPath; // 路径struct lws_protocol_vhost_options lpvoSSL;  // 是否使用sslstruct lws_protocol_vhost_options lpvoThis; // 传递的本类struct lws_protocol_vhost_options lpvo;
};#endif // WEBSOCKET_CLIENT_H

WebsocketClient.cpp如下:


#include "WebsocketClient.h"static const char *addr = "localhost", *path = "/";
static int port = 7681, ssl = 0;static int callBackFunc(struct lws *wsi, enum lws_callback_reasons reason, void *user, void *in, size_t len);
#define WEBSOCKET_CLIENT \
{ \"websocket-client", \callBackFunc, \0, \1024, \0, NULL, 0 \
}
static struct lws_protocols lProtocols[] = {WEBSOCKET_CLIENT,{ NULL, NULL, 0, 0 }};// 用于事件回调
static void scheduleCallBack(struct lws *wsi, int reason, int secs)
{lws_timed_callback_vh_protocol(lws_get_vhost(wsi), lws_get_protocol(wsi), reason, secs);
}// 连接服务
static int connectServer(_ClientData *ClientData)
{struct lws_client_connect_info lccInfo;memset(&lccInfo, 0, sizeof(lccInfo));char host[32];lws_snprintf(host, sizeof(host), "%s:%u", *ClientData->addr, *ClientData->port);lccInfo.context = ClientData->context;lccInfo.port = *ClientData->port;lccInfo.address = *ClientData->addr;lccInfo.path = *ClientData->path;lccInfo.host = host;lccInfo.origin = host;lccInfo.ssl_connection = *ClientData->ssl;lccInfo.vhost = ClientData->vhost;lccInfo.pwsi = &ClientData->client_wsi;lwsl_user("connecting to ws://%s:%d%s\n", lccInfo.address, lccInfo.port, lccInfo.path);return !lws_client_connect_via_info(&lccInfo);
}// lws_service回调
static int callBackFunc(struct lws *wsi, enum lws_callback_reasons reason, void *user, void *in, size_t len)
{_ClientData *clientData = (_ClientData *)lws_protocol_vh_priv_get(lws_get_vhost(wsi), lws_get_protocol(wsi));switch (reason) {case LWS_CALLBACK_PROTOCOL_INIT:lwsl_user("LWS_CALLBACK_PROTOCOL_INIT\n");clientData = (_ClientData *)lws_protocol_vh_priv_zalloc(lws_get_vhost(wsi), lws_get_protocol(wsi), sizeof(_ClientData));if (!clientData)return -1;clientData->context = lws_get_context(wsi);clientData->vhost = lws_get_vhost(wsi);clientData->port = (int *)lws_pvo_search((const struct lws_protocol_vhost_options *)in, _PORT_)->value;clientData->addr = (const char **)lws_pvo_search((const struct lws_protocol_vhost_options *)in, _ADDR_)->value;clientData->path = (const char **)lws_pvo_search((const struct lws_protocol_vhost_options *)in, _PATH_)->value;clientData->ssl = (int *)lws_pvo_search((const struct lws_protocol_vhost_options *)in, _SSL_)->value;char *pptr;pptr = (char *)lws_pvo_search((const struct lws_protocol_vhost_options *)in, _THIS_)->value;clientData->wsc = reinterpret_cast<WebsocketClient *>(pptr);if (connectServer(clientData))scheduleCallBack(wsi, LWS_CALLBACK_USER, 1);break;// 连接创建成功事件, 会调用: LWS_CALLBACK_TIMERcase LWS_CALLBACK_CLIENT_ESTABLISHED:lwsl_user("LWS_CALLBACK_CLIENT_ESTABLISHED\n");lws_set_timer_usecs(wsi, 5 * LWS_USEC_PER_SEC);break;// 写事件case LWS_CALLBACK_CLIENT_WRITEABLE:char *tmp;int sendLen, retLen;tmp = (char *)"{\"ping\":1,\"msg\":\"ping msg\"}";sendLen = strlen(tmp);char sendMsg[LWS_PRE + 1024];memcpy(sendMsg + LWS_PRE, tmp, sendLen);retLen = lws_write(wsi, ((unsigned char *)sendMsg) + LWS_PRE, sendLen, LWS_WRITE_TEXT);if (retLen < sendLen) {lwsl_err("sendMsg error\n");return -1;}lwsl_user("LWS_CALLBACK_CLIENT_WRITEABLE: %d, sendMsg: %s, sendLen: %d\n", reason, tmp, sendLen);break;// 收事件case LWS_CALLBACK_CLIENT_RECEIVE:lwsl_user("LWS_CALLBACK_CLIENT_RECEIVE: %d, receiveMsg: %s, receiveLen: %d\n", reason, in, len);memcpy(clientData->wsc->msg, (char *)in, len);lwsl_user("clientData->wsc->msg: %s\n", clientData->wsc->msg);break;// 连接错误事件, 会调用: LWS_CALLBACK_USERcase LWS_CALLBACK_CLIENT_CONNECTION_ERROR:lwsl_err("CLIENT_CONNECTION_ERROR\n");scheduleCallBack(wsi, LWS_CALLBACK_USER, 1);break;// 时间事件, 会调用: LWS_CALLBACK_CLIENT_WRITEABLEcase LWS_CALLBACK_TIMER:lws_callback_on_writable(wsi);lws_set_timer_usecs(wsi, 5 * LWS_USEC_PER_SEC);break;// 客户端session关闭事件case LWS_CALLBACK_CLIENT_CLOSED:lwsl_user("LWS_CALLBACK_CLIENT_CLOSED\n");lws_cancel_service(lws_get_context(wsi));scheduleCallBack(wsi, LWS_CALLBACK_USER, 1);break;// 自定义事件, 当前用于重连case LWS_CALLBACK_USER:lwsl_notice("%s: LWS_CALLBACK_USER\n", __func__);if (connectServer(clientData))scheduleCallBack(wsi, LWS_CALLBACK_USER, 1);break;default:break;}return 0;
}WebsocketClient::WebsocketClient()
{memset(msg, 0x00, sizeof(msg));lpvoAddr = {NULL, NULL, _ADDR_, (char *)((void *)&addr)};lpvoPort = {&lpvoAddr, NULL, _PORT_, (char *)((void *)&port)};lpvoPath = {&lpvoPort, NULL, _PATH_, (char *)((void *)&path)};lpvoSSL = {&lpvoPath, NULL, _SSL_, (char *)((void *)&ssl)};char *tmp = reinterpret_cast<char *>(this);lpvoThis = {&lpvoSSL, NULL, _THIS_, (char *)((void *)tmp)};lpvo = {NULL, &lpvoThis, "websocket-client", ""};
}bool WebsocketClient::init(int argc, const char **argv)
{struct lws_context_creation_info lcrInfo;memset(&lcrInfo, 0, sizeof lcrInfo);const char *tmpPtr = NULL;int logs = LLL_USER | LLL_ERR | LLL_WARN | LLL_NOTICE;// 连接地址if ((tmpPtr = lws_cmdline_option(argc, argv, "--addr")))addr = tmpPtr;// 连接端口if ((tmpPtr = lws_cmdline_option(argc, argv, "--port")))port = atoi(tmpPtr);// 虚拟路径if ((tmpPtr = lws_cmdline_option(argc, argv, "--path")))path = tmpPtr;// 是否使用sslif ((tmpPtr = lws_cmdline_option(argc, argv, "--ssl")))ssl = atoi(tmpPtr);if (ssl){if ((tmpPtr = lws_cmdline_option(argc, argv, "--ca_path"))){lcrInfo.client_ssl_ca_filepath = tmpPtr;  }      else {lwsl_err("cannot find ca_path\n");return false;}}// 日志输出等级if ((tmpPtr = lws_cmdline_option(argc, argv, "--log_level")))logs = atoi(tmpPtr);lws_set_log_level(logs, NULL);lcrInfo.port = CONTEXT_PORT_NO_LISTEN;  /* we do not run any server */lcrInfo.protocols = lProtocols;lcrInfo.pvo = &lpvo;lcrInfo.pt_serv_buf_size = 32 * 1024;lcrInfo.options = LWS_SERVER_OPTION_DO_SSL_GLOBAL_INIT | LWS_SERVER_OPTION_VALIDATE_UTF8;lcrInfo.fd_limit_per_thread = 1 + 1 + 1;mContext = lws_create_context(&lcrInfo);if (!mContext) {lwsl_err("lws init failed\n");return false;}return true;
}bool WebsocketClient::Start(int argc, const char **argv)
{if (!init(argc, argv)){return false;}while (!lws_service(mContext, 0));lws_context_destroy(mContext);return true;
}

测试文件main.cpp如下:

#include "WebsocketClient.h"int main(int argc, const char **argv)
{WebsocketClient websocketClient;if (!websocketClient.Start(argc, argv)){return -1;}return 0;
}

编译命令如下:

g++ main.cpp WebsocketClient.cpp -o main -lwebsockets -Wall -std=c++11

<三>: 测试

打开一个websocket服务, 如果没有, 可以根据上篇文章编译一个echo服务. 本测试就用自己编译的echo服务, 结果如下:

结束:

如果有什么问题, 大家可以一起讨论解决.

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使用linux c开源库libwebsockets编写的websocket客户端

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