The Annoyance Filter.pdf - Fourmilab

§199 ANNOYANCE-FILTER POP3 PROXY SERVER CLASS DEFINITION 167
199. First of all, we have to camp on the listenSocket with accept until somebody connects to it. At
that point we obtain the clientSocket we’ll use to conduct the dialogue with the client.
〈 Wait for next client connection and accept it 199 〉 ≡
errno = 0;
do {
fromlen = sizeof from ;
clientSocket = accept (listenSocket , (struct sockaddr ∗) &from , &fromlen );
if (clientSocket ≥ 0) {
break;
}
} while (errno ≡ EINTR);
if (clientSocket < 0) {
perror ("POP3Proxy␣accepting␣connection␣from␣client");
return false ;
}
if (verbose ) {
cout ≪ "Accepting␣POP3␣connection␣from␣" ≪ inet ntoa (from .sin addr ) ≪ endl ;
}
This code is used in section 198.
200. Once a connection has been accepted, we use the clientSocket to conduct the dialogue until it’s
concluded.
〈 Conduct dialogue with client 200 〉 ≡
int clientLength , serverLength ;
char clientBuffer [POP_BUFFER], serverBuffer [POP_BUFFER];
int serverSocket ;
u int32 t serverIP ;
struct hostent ∗h;
int cstat = −1;
bool ok = true ;
string command , argument , reply ;
〈 Look up address of server 201 〉;
〈 Open connection to server 202 〉;
〈 Read the greeting from the server and relay to the client 203 〉;
〈 Conduct client/server dialogue 204 〉;
〈 Close the connection to the client and server 214 〉;
This code is used in section 198.