C 套接字代码生成 ERRNO 24 消息

Question

我编写了一个 C 程序，希望将其用作基于 TCP/IP 的简单服务。该程序必须打开一个侦听 TCP 套接字。每当有人写入套接字时，我的程序都必须读取消息，做一些处理，然后发回一条不同的消息。该程序必须永远运行。

程序编译并运行s。（我使用的是 gcc 7.4.0）问题是，在成功处理了几千条消息后没有任何问题，程序开始打印：

...
 Connection FAILED :: Value of errno: 24
 Connection FAILED :: Value of errno: 24
 Connection FAILED :: Value of errno: 24
 Connection FAILED :: Value of errno: 24
...

Errno 24 的意思是“打开的文件描述符太多”，这让我想知道我的程序是否正在分配某些东西（套接字？内存？）并且稍后没有正确释放它。但是我找不到哪里错了。

让我向您展示我的代码。我遵循了我喜欢的教程，他们在一个结构中收集了所有相关的套接字信息：

typedef struct{
        int sock;
        struct sockaddr address;
        socklen_t addr_len;
} connection_t;

main()设置套接字，然后无限循环监听：

int main(int argc, char ** argv) {
        int             sock = -1;
        struct          sockaddr_in address;
        int             port = 12345;
        connection_t*   connection;


        // Create the listening socket
        sock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
        if (sock <= 0){
                fprintf(stderr, "%s: error: cannot create socket\n", argv[0]);
                return -3;
        }

        // Bind socket to port
        address.sin_family = AF_INET;
        address.sin_addr.s_addr = INADDR_ANY;
        address.sin_port = htons(port);
        if (bind(sock, (struct sockaddr *)&address, sizeof(struct sockaddr_in)) < 0){
                fprintf(stderr, "%s: error: cannot bind socket to port %d\n", argv[0], port);
                return -4;
        }

        // Listen on the port
        if (listen(sock, 5) < 0){
                fprintf(stderr, "%s: error: cannot listen on port\n", argv[0]);
                return -5;
        }

        // We're ready to go...!
        printf("%s: ready and listening\n", argv[0]);

        while (1){
                // Accept incoming connections
                connection = (connection_t *)malloc(sizeof(connection_t));
                connection->addr_len = 20;

                connection->sock = accept(sock, &connection->address, &connection->addr_len);

                if (connection->sock <= 0){
                        // ***********************************************
                        // ***  This is where the error happens!
                        printf("Connection FAILED :: Value of errno: %d\n ", errno);
                        // ***********************************************
                }
                else{
                        printf("SERVER...  New Msg received...\n");
                        readMsgAndReply( connection );
                }
                free(connection);
        }
        return 0;
}

您会注意到，当 accept() 无法成功接受新的传入连接时，我会收到“连接失败”消息 – 我希望我知道原因。

如果accept()成功，我的代码调用readMsgAndReply():

void readMsgAndReply( connection* conn ){

        char* buffer;
        char* reply = "Your Msg was received!";
        int ret, len, replyLen;
        long addr = 0;

        // First call to read() measures the length of the sent message
        ret = read(conn->sock, &len, sizeof(int));
        if( ret < 0 ){
                printf( "***readMsgAndReply() ERROR:  read() error\n" );
        }
        if( len > 0 ){
                addr = (long)((struct sockaddr_in *)&conn->address)->sin_addr.s_addr;
                buffer = (char *)malloc((len+1)*sizeof(char));
                buffer[len] = 0;

                // Second call to read() actually reads the message from the socket
                ret = read(conn->sock, buffer, len);
                if( ret < 0 ){
                        printf( "***readMsgAndReply() ERROR:  ret < 0\n");
                }
                else{
                        printf("***readMsgAndReply() message size :: %d\n",  len);
                        printf("***readMsgAndReply() is           :: \"%s\"\n", buffer);
                }

                // write reply message back to the client
                replyLen = write(conn->sock, reply, strlen(reply));
                if(replyLen > 0)
                        printf("===>  Reply written, %d bytes sent!\n", replyLen);
                else
                        printf("--->  No reply written\n");

                free(buffer);
        }
}

给你。此代码对于前几千条收到的消息运行良好，然后吐出 ERRNO 24。有人看到我做错了什么了吗？

Answer 1

在退出函数 readMsgAndReply 之前，您需要关闭套接字。

 close(connection->sock);

C 套接字代码生成 ERRNO 24 消息

C Socket Code Generates ERRNO 24 Messages

c

sockets

errno