BSD套接字 - 使用send和recv

Question

我正在尝试使用bsd套接字在linux中实现一个简单的聊天程序.现在我只是尝试从客户端向服务器发送和接收一条消息.每当我运行代码时,recv返回-1并且errno代码为22.

服务器代码 -

struct sockaddr name;
char buf[80];

int main(int agrc, char** argv) {

    int sock, new_sd;   //sock is this socket, new_sd is connection socket
    int adrlen, cnt;

    name.sa_family = AF_UNIX;
    strcpy(name.sa_data, "/tmp/servsock");
    adrlen = strlen(name.sa_data) + sizeof(name.sa_family);

    sock = socket(AF_UNIX, SOCK_STREAM, 0);

    if (sock < 0) {
        cout<<"\nserver socket failure "<<errno;
        cout<<"\nServer: ";
        exit(1);
    }

    unlink("/tmp/servsock");
    if(bind (sock, &name, adrlen) < 0)
        cout<<"\nBind failure "<<errno;

    if(listen(sock, 5) < 0)
        cout<<"\nlisten error "<<errno;

    while(1) {
        if( new_sd = accept(sock, &name, (socklen_t*)&adrlen) < 0) {
            cout<<"\nserver accept failure "<<errno;
            exit(1);
        }

        char* buf = new char[14];

        if(recv(sock, buf, 14, 0) < 0) {
            cout<<"\nError receiving data "<<errno;
            exit(1);
        }
    }   //end while
    return 0;
}

客户代码 -

struct sockaddr name;

int main(int agrc, char** argv) {

    int sock, new_sd, adrlen, cnt;
    sock = socket(AF_UNIX, SOCK_STREAM, 0);

    if (sock < 0) {
        cout<<"\nserver socket failure "<<errno;
        cout<<"\nServer: ";
        exit(1);
    }

    //stuff for server socket
    name.sa_family = AF_UNIX;
    strcpy(name.sa_data, "/tmp/servsock");
    adrlen = strlen(name.sa_data) + sizeof(name.sa_family);

    if(connect(sock, &name, adrlen) < 0) {
        cout<<"\nclient connection failure "<<errno;
        exit(1);
    }

    cout<<"\nSuccessful connection from client 1";

    std::string buf = "\nClient 1 Here";

    if(send(sock, buf.c_str(), strlen(buf.c_str()), 0) < 0) {
        cout<<"\nError sending data from client 1 "<<errno;
        exit(1);
    }
    cout<<"\nExiting normally";
    return 0;
}

即使我在服务器端收到错误,我也没有在客户端获得错误消息 - 它只是正常退出.

根据 - http://www.workers.com.br/manuais/53/html/tcp53/mu/mu-7.htm,errno 22错误消息仅表示"无效参数".但我不知道究竟如何解释...如果一个论证无效,为什么它甚至会编译？

如果有人能指出我在这里做错了什么,我将非常感激.你想要指出的任何其他小笔记都会受到欢迎.谢谢你的帮助.

Answer 1

除了在你的代码中的所有其他问题,您要在错误的文件描述符读取-它应该是new_sd,不sock,这是一个服务器套接字,并只能accept()新的连接.

编辑0:

大嘘声:

if( new_sd = accept(sock, &name, (socklen_t*)&adrlen) < 0) { ...

这相当于:

if( new_sd = (accept(sock, &name, (socklen_t*)&adrlen) < 0)) {

所以new_sd获得完全错误的价值.一般的智慧不是将任务纳入条件.至少考虑使用高警告级别进行编译-Wall -pedantic.