I'm doing a simple send/receive and in order to execute each request in a thread I've set up my handler function like so:

UPDATE: Using std::thread and properly closing socket after use. I'm not using a loop for reading atm because I'm just sending small test messages that are well below the 1024 buffer limit. Unfortunately, I'm still getting odd data for the ip and port.

int P2PServer::socketReceiveHandler(int s) {
    struct sockaddr_in *sin = (struct sockaddr_in *)&s;
    
    char buffer[1024] = {0};
    int reader;
    reader = read(s, buffer, 1024);
    if (reader <= 0) {
        return 0;
    } else {
        std::cout << reader << std::endl; // let's see
    }

    char ip[INET_ADDRSTRLEN];
    int port=0;
    inet_ntop(AF_INET, &(sin->sin_addr), ip, sizeof(ip));
    port = htons(sin->sin_port);
    strcpy(ip, inet_ntoa(sin->sin_addr));
    printf ("Connection from %s:%d\n", ip, port);

    printf("Connection from: %d.%d.%d.%d", buffer[197], buffer[198], buffer[199], buffer[200]);
    //int port = 0;                         // Start with zero
    port |= buffer[204] & 0xFF;             // Assign first byte to port using bitwise or.
    port <<= 8;                             // Shift the bits left by 8 
    port |= buffer[205] & 0xFF;             // (so the byte from before is on the correct position)
    printf(" Port: %d\n\n", port);


    char const* message = "I am an amazing server!";
    std::cout << "received: " << buffer << std::endl; 
    send(s, message, strlen(message) , 0 );
    printf("Server : Message has been sent ! \n");

    if (close(s) == -1) {
        p2putils::logit("Close problems");
        std::cout << "errno: " << errno << std::endl;
    }
    
    return 0;
}

The function is called like so:

std::thread peerThread (&P2PServer::socketReceiveHandler,this, incomingSocket);
peerThread.join();

Here's the output from the server:

./p2pserver 127.0.0.1 10001
Node usage for peers: ./p2pserver <ip> <port> <masternode>
If this is not the master node, restart with 3rd parameter
P2P Server: 127.0.0.1 is listening on PORT: 10001
 

Waiting for incoming connections...
23
Connection from 8.233.176.178:0
Connection from: 0.0.0.0 Port: 0

received: I am an amazing client.
Server : Message has been sent ! 
 

Waiting for incoming connections...

Here's the output from the client:

./p2pserver 127.0.0.1 10002 127.0.0.1
P2P Server: 127.0.0.1 is listening on PORT: 10002
Client : Message has been sent ! 
I am an amazing server!
 

Waiting for incoming connections...

CodePudding user response：

So the function that saved the day is getpeername()

Here's my working solution:

int P2PServer::socketReceiveHandler(int s) {
    struct sockaddr_in addr;
    
    char buffer[1024] = {0};
    int reader;
    reader = read(s, buffer, 1024);
    if (reader <= 0)
        return 0;

    socklen_t len;
    len = sizeof(addr);
    getpeername(s, (struct sockaddr*)&addr, &len);
    std::cout << "Connection from: " 
              << inet_ntoa(addr.sin_addr) 
              << " : " 
              << ntohs(addr.sin_port) << std::endl;

    char const* message = "I am an amazing server!";
    std::cout << "received: " << buffer << std::endl; 
    send(s, message, strlen(message) , 0 );
    printf("Server : Message has been sent ! \n");

    if (close(s) == -1) {
        p2putils::logit("Close problems");
        std::cout << "errno: " << errno << std::endl;
    }
    
    return 0;
}

The partial output is as follows:

P2P Server: 127.0.0.1 is listening on PORT: 10001
 

Waiting for incoming connections...
Connection from: 127.0.0.1 : 58560