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我试图找到一个示例来解释我如何使用 libwebsocket 实现客户端，但我没有得到任何令人信服的代码。有什么链接可以参考吗？

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2 回答 2

23

更正了Ren-Wei Luo的代码示例以使用libwebsockets 1.6

在 Ubuntu 14.04 上测试

示例-server.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>
#include <libwebsockets.h>

#define KGRN "\033[0;32;32m"
#define KCYN "\033[0;36m"
#define KRED "\033[0;32;31m"
#define KYEL "\033[1;33m"
#define KMAG "\033[0;35m"
#define KBLU "\033[0;32;34m"
#define KCYN_L "\033[1;36m"
#define RESET "\033[0m"

static int destroy_flag = 0;

static void INT_HANDLER(int signo) {
    destroy_flag = 1;
}

/* *
 * websocket_write_back: write the string data to the destination wsi.
 */
int websocket_write_back(struct lws *wsi_in, char *str, int str_size_in) 
{
    if (str == NULL || wsi_in == NULL)
        return -1;

    int n;
    int len;
    char *out = NULL;

    if (str_size_in < 1) 
        len = strlen(str);
    else
        len = str_size_in;

    out = (char *)malloc(sizeof(char)*(LWS_SEND_BUFFER_PRE_PADDING + len + LWS_SEND_BUFFER_POST_PADDING));
    //* setup the buffer*/
    memcpy (out + LWS_SEND_BUFFER_PRE_PADDING, str, len );
    //* write out*/
    n = lws_write(wsi_in, out + LWS_SEND_BUFFER_PRE_PADDING, len, LWS_WRITE_TEXT);

    printf(KBLU"[websocket_write_back] %s\n"RESET, str);
    //* free the buffer*/
    free(out);

    return n;
}


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

    switch (reason) {

        case LWS_CALLBACK_ESTABLISHED:
            printf(KYEL"[Main Service] Connection established\n"RESET);
            break;

        //* If receive a data from client*/
        case LWS_CALLBACK_RECEIVE:
            printf(KCYN_L"[Main Service] Server recvived:%s\n"RESET,(char *)in);

            //* echo back to client*/
            websocket_write_back(wsi ,(char *)in, -1);

            break;
    case LWS_CALLBACK_CLOSED:
            printf(KYEL"[Main Service] Client close.\n"RESET);
        break;

    default:
            break;
    }

    return 0;
}

struct per_session_data {
    int fd;
};

int main(void) {
    // server url will usd port 5000
    int port = 5000;
    const char *interface = NULL;
    struct lws_context_creation_info info;
    struct lws_protocols protocol;
    struct lws_context *context;
    // Not using ssl
    const char *cert_path = NULL;
    const char *key_path = NULL;
    // no special options
    int opts = 0;


    //* register the signal SIGINT handler */
    struct sigaction act;
    act.sa_handler = INT_HANDLER;
    act.sa_flags = 0;
    sigemptyset(&act.sa_mask);
    sigaction( SIGINT, &act, 0);

    //* setup websocket protocol */
    protocol.name = "my-echo-protocol";
    protocol.callback = ws_service_callback;
    protocol.per_session_data_size=sizeof(struct per_session_data);
    protocol.rx_buffer_size = 0;

    //* setup websocket context info*/
    memset(&info, 0, sizeof info);
    info.port = port;
    info.iface = interface;
    info.protocols = &protocol;
    info.extensions = lws_get_internal_extensions();
    info.ssl_cert_filepath = cert_path;
    info.ssl_private_key_filepath = key_path;
    info.gid = -1;
    info.uid = -1;
    info.options = opts;

    //* create libwebsocket context. */
    context = lws_create_context(&info);
    if (context == NULL) {
        printf(KRED"[Main] Websocket context create error.\n"RESET);
        return -1;
    }

    printf(KGRN"[Main] Websocket context create success.\n"RESET);

    //* websocket service */
    while ( !destroy_flag ) {
        lws_service(context, 50);
    }
    usleep(10);
    lws_context_destroy(context);

    return 0;
}

示例-client.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>
#include <libwebsockets.h>

#define KGRN "\033[0;32;32m"
#define KCYN "\033[0;36m"
#define KRED "\033[0;32;31m"
#define KYEL "\033[1;33m"
#define KBLU "\033[0;32;34m"
#define KCYN_L "\033[1;36m"
#define KBRN "\033[0;33m"
#define RESET "\033[0m"

static int destroy_flag = 0;
static int connection_flag = 0;
static int writeable_flag = 0;

static void INT_HANDLER(int signo) {
    destroy_flag = 1;
}

struct session_data {
    int fd;
};

struct pthread_routine_tool {
    struct lws_context *context;
    struct lws *wsi;
};

static int websocket_write_back(struct lws *wsi_in, char *str, int str_size_in) 
{
    if (str == NULL || wsi_in == NULL)
        return -1;

    int n;
    int len;
    char *out = NULL;

    if (str_size_in < 1) 
        len = strlen(str);
    else
        len = str_size_in;

    out = (char *)malloc(sizeof(char)*(LWS_SEND_BUFFER_PRE_PADDING + len + LWS_SEND_BUFFER_POST_PADDING));
    //* setup the buffer*/
    memcpy (out + LWS_SEND_BUFFER_PRE_PADDING, str, len );
    //* write out*/
    n = lws_write(wsi_in, out + LWS_SEND_BUFFER_PRE_PADDING, len, LWS_WRITE_TEXT);

    printf(KBLU"[websocket_write_back] %s\n"RESET, str);
    //* free the buffer*/
    free(out);

    return n;
}


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

    switch (reason) {

        case LWS_CALLBACK_CLIENT_ESTABLISHED:
            printf(KYEL"[Main Service] Connect with server success.\n"RESET);
            connection_flag = 1;
            break;

        case LWS_CALLBACK_CLIENT_CONNECTION_ERROR:
            printf(KRED"[Main Service] Connect with server error.\n"RESET);
            destroy_flag = 1;
            connection_flag = 0;
            break;

        case LWS_CALLBACK_CLOSED:
            printf(KYEL"[Main Service] LWS_CALLBACK_CLOSED\n"RESET);
            destroy_flag = 1;
            connection_flag = 0;
            break;

        case LWS_CALLBACK_CLIENT_RECEIVE:
            printf(KCYN_L"[Main Service] Client recvived:%s\n"RESET, (char *)in);

            if (writeable_flag)
                destroy_flag = 1;

            break;
        case LWS_CALLBACK_CLIENT_WRITEABLE :
            printf(KYEL"[Main Service] On writeable is called. send byebye message\n"RESET);
            websocket_write_back(wsi, "Byebye! See you later", -1);
            writeable_flag = 1;
            break;

        default:
            break;
    }

    return 0;
}

static void *pthread_routine(void *tool_in)
{
    struct pthread_routine_tool *tool = tool_in;

    printf(KBRN"[pthread_routine] Good day. This is pthread_routine.\n"RESET);

    //* waiting for connection with server done.*/
    while(!connection_flag)
        usleep(1000*20);

    //*Send greeting to server*/
    printf(KBRN"[pthread_routine] Server is ready. send a greeting message to server.\n"RESET); 
    websocket_write_back(tool->wsi, "Good day", -1);

    printf(KBRN"[pthread_routine] sleep 2 seconds then call onWritable\n"RESET);
    sleep(1);
    printf(KBRN"------------------------------------------------------\n"RESET);
    sleep(1);
    //printf(KBRN"[pthread_routine] sleep 2 seconds then call onWritable\n"RESET);

    //*involked wriable*/
    printf(KBRN"[pthread_routine] call on writable.\n"RESET);   
    lws_callback_on_writable(tool->wsi);

}

int main(void)
{
    //* register the signal SIGINT handler */
    struct sigaction act;
    act.sa_handler = INT_HANDLER;
    act.sa_flags = 0;
    sigemptyset(&act.sa_mask);
    sigaction( SIGINT, &act, 0);


    struct lws_context *context = NULL;
    struct lws_context_creation_info info;
    struct lws *wsi = NULL;
    struct lws_protocols protocol;

    memset(&info, 0, sizeof info);
    info.port = CONTEXT_PORT_NO_LISTEN;
    info.iface = NULL;
    info.protocols = &protocol;
    info.ssl_cert_filepath = NULL;
    info.ssl_private_key_filepath = NULL;
    info.extensions = lws_get_internal_extensions();
    info.gid = -1;
    info.uid = -1;
    info.options = 0;

    protocol.name  = "my-echo-protocol";
    protocol.callback = &ws_service_callback;
    protocol.per_session_data_size = sizeof(struct session_data);
    protocol.rx_buffer_size = 0;
    protocol.id = 0;
    protocol.user = NULL;

    context = lws_create_context(&info);
    printf(KRED"[Main] context created.\n"RESET);

    if (context == NULL) {
        printf(KRED"[Main] context is NULL.\n"RESET);
        return -1;
    }


    wsi = lws_client_connect(context, "localhost", 5000, 0,
            "/", "localhost:5000", NULL,
             protocol.name, -1);
    if (wsi == NULL) {
        printf(KRED"[Main] wsi create error.\n"RESET);
        return -1;
    }

    printf(KGRN"[Main] wsi create success.\n"RESET);

    struct pthread_routine_tool tool;
    tool.wsi = wsi;
    tool.context = context;

    pthread_t pid;
    pthread_create(&pid, NULL, pthread_routine, &tool);
    pthread_detach(pid);

    while(!destroy_flag)
    {
        lws_service(context, 50);
    }

    lws_context_destroy(context);

    return 0;
}

生成文件

.PHONY:clean

all:example-client example-server

example-client:example-client.c
    gcc example-client.c -o example-client -lpthread -lwebsockets

example-server:example-server.c
    gcc example-server.c -o example-server -lwebsockets

clean:
    -rm example-client example-server
于 2016-01-05T23:10:22.810 回答
6

2021-11-01 更新

最近几天，我收到了几个访问我以前在 Google Drive 上的 websocket 示例程序的请求。请注意，我在这篇文章中提到的示例写于 2015 年 8 月，其中 libwebsocket 库刚刚发布 1.5.0。我相信最新版本和 1.5.0 之间的机制肯定有很多变化。

从 2016 年开始，我改变了职业道路，不再使用 C 语言进行编码。因此，我不知道如何修改示例代码以适应 libwebsocket 的最新机制。

如果您仍然对我的示例感兴趣，这里是我的谷歌驱动器的更新链接。

原帖

我在纯 C 中使用 libwebsockets 编写了一个简单的回显服务器和客户端。

服务器端收到客户端的数据后会做回显。

建立连接后，客户端将向服务器写入 hello 消息。然后在休眠 2 秒后，客户端会调用 libwebsocket_callback_on_writable。你可以看看它是如何工作的。

我只是将代码上传到我的 Google 驱动器上。

我的谷歌驱动器链接

您可以在终端中使用以下命令编译代码。

gcc example-server.c -o example-server -lwebsockets

gcc example-client.c -o example-client -lpthread -lwebsockets

或者，只需在终端上使用make 。

于 2015-08-06T04:43:17.160 回答