C语言主从Socket间时间戳通信故障排查求助

错误码10014对应Windows Socket的WSAEFAULT错误，核心问题出在recvfrom的参数传递上：

• recvfrom的第6个参数（地址长度）要求传入指针，因为函数会在调用后更新这个值为实际接收到的地址长度。你直接传了server_address_size（一个int值），这会导致系统尝试向无效内存地址写入数据，触发错误。

另外你的sendto也存在不合理之处：用sizeof(buffer)作为发送长度会把整个1024字节的缓冲区都发出去，包括字符串后面的垃圾数据，正确做法应该发送实际的字符串长度（strlen(buffer)+1，+1是为了带上字符串终止符）。

修正后的代码 #

发送函数修正 #

void sendSyncMessage(SOCKET clientSocket, struct sockaddr_in client_address)
{
    SYSTEMTIME systemTime;
    char buffer[1024];

    GetLocalTime(&systemTime);

    sprintf(buffer, "SYNC:%04d-%02d-%02d %02d:%02d:%02d",  
        systemTime.wYear, systemTime.wMonth, systemTime.wDay,
        systemTime.wHour, systemTime.wMinute, systemTime.wSecond);

    printf("The current timestamp : %s\n", buffer);

    // 发送实际字符串长度，而非整个缓冲区大小
    int sendLen = strlen(buffer) + 1;
    sendto(clientSocket, buffer, sendLen, 0, 
        (struct sockaddr*)&client_address, sizeof(client_address));
}

接收函数修正 #

void receiveSyncMessage(SOCKET server_socket)
{
    struct sockaddr_in server_address;
    int server_address_size = sizeof(server_address);
    char buffer[1024];

    // 最后一个参数传地址长度变量的指针
    int bytesReceived = recvfrom(server_socket, buffer, sizeof(buffer), 0, 
        (struct sockaddr*)&server_address, &server_address_size);
    if (bytesReceived == SOCKET_ERROR) {
        fprintf(stderr, "Receive failed: %ld\n", WSAGetLastError());
    }
    else{
        buffer[bytesReceived] = '\0';
        printf("Received Sync timestamp: %s\n", buffer);
        printf("Bytes received: %d\n", bytesReceived);
     }    
}

额外注意事项 #

• 确保接收端的socket已经正确绑定到127.0.0.1:4455，并且处于可用状态
• 发送端的目标地址（client_address）要正确设置：sin_family设为AF_INET，sin_addr设为inet_addr("127.0.0.1")，sin_port用htons(4455)转换为网络字节序
• 建议检查sendto的返回值，确认数据是否发送成功

内容的提问来源于stack exchange，提问作者Varun Bhat