17. Sockets

//-----------------------------


//Pike doesn't normally use packed IP addresses. Strings such as "204.148.40.9" are used literally.


// -----------------------------


// DNS lookups can be done with gethostbyname() and gethostbyaddr()

[string host,array ip,array alias] = gethostbyname("www.example.com");
// ip[0] is a string "192.0.32.10"


//-----------------------------

//-----------------------------

Stdio.File sock=Stdio.File();
if (!sock->connect(remote_host,remote_port)) //Connection failed. Error code is in sock->errno() .

{
    werror("Couldn't connect to %s:%d: %s\n",remote_host,remote_port,strerror(sock->errno()));
    return 1;
}
sock->write("Hello, world!"); //Send something to the socket

string answer=sock->read(); //Read until the remote side disconnects. Use sock->read(1024,1) to read only some (up to 1KB here).

sock->close(); //Not necessary if the sock object goes out of scope here.


//-----------------------------

//-----------------------------

Stdio.Port mainsock=Stdio.Port();
if (!mainsock->bind(server_port))
{
    werror("Couldn't be a tcp server on port %d: %s\n",server_port,strerror(mainsock->errno()));
    return 1;
}
while (1)
{
    Stdio.File sock=mainsock->accept();
    if (!sock) break;
    // sock is the new connection

    // if you don't do anything and just let sock expire, the client connection will be closed

}
//-----------------------------

//-----------------------------

sock->write("What is your name?\n");
string response=sock->read(1024,1); //Reads up to 1KB or whatever is available (minimum 1 byte).

//Buffered reads:

Stdio.FILE sock2=Stdio.FILE(); sock2->assign(sock);
string response=sock2->gets();
//-----------------------------


//-----------------------------

//-----------------------------

string other_end=sock->query_address(); //eg "10.1.1.1 123"

//-----------------------------

//-----------------------------

sock->close("r");   //Close the read direction

sock->close("w");   //Close the write direction

sock->close("rw");  //Shut down both directions

sock->close();      //Close completely

//-----------------------------

//-----------------------------


//Forking is generally unnecessary in Pike, as the driver works more efficiently with other models.

//-----------------------------

//-----------------------------


//Incomplete. There's multiple ways to do this, including:

//1) Threaded server (works like forking but clients can share global state if desired)

//2) Multiplexing using select()

//3) Callback mode (puts the sockets under the control of a Backend which uses select())

//-----------------------------

//-----------------------------

Stdio.Port mainsock=Stdio.Port();
if (!mainsock->bind(server_port))
{
    werror("Couldn't be a tcp server on port %d: %s\n",server_port,strerror(mainsock->errno()));
    return 1;
}
while (1)
{
    Stdio.File sock=mainsock->accept();
    if (!sock) break;
    string localaddr=sock->query_address(1); //Is the IP address and port connected to.

    //The IP will be that of one of your interfaces, and the port should be equal to server_port

}
//-----------------------------

//-----------------------------

if (!System.chroot("/var/daemon")) werror("Unable to chroot to /var/daemon: %s\n",strerror(errno()));
//Incomplete (I don't fork in Pike). See predef::fork() and Process.create_process() for details.

//-----------------------------

//-----------------------------

//The best way to restart the server is to adopt a microkernel concept and restart only the parts of

//the server that need updating. However, if you must reload, see Process.exec()

//-----------------------------