The Annoyance Filter.pdf - Fourmilab

166 POP3 PROXY SERVER CLASS DEFINITION ANNOYANCE-FILTER §197
197. In order to accept connections, we need to create a socket, listenSocket which is bound to the
port address on which we listen. We accept connections from any IP address. The acceptConnections
must be called to activate the socket before connections may be processed.
〈 Class implementations 11 〉 +≡
#ifdef POP3_PROXY_SERVER
bool POP3Proxy ::acceptConnections (int maxBacklog )
{
struct sockaddr in name ;
listenSocket = socket (AF_INET, SOCK_STREAM, 0);
if (listenSocket < 0) {
perror ("POP3Proxy␣opening␣socket␣to␣listen␣for␣connections");
listenSocket = −1;
return false ;
} /∗ Create name with wildcards. ∗/
name .sin family = AF_INET;
name .sin addr .s addr = INADDR_ANY;
name .sin port = htons (popProxyPort );
if (bind (listenSocket , (struct sockaddr ∗) &name , sizeof name ) < 0) {
close (listenSocket );
perror ("POP3Proxy␣binding␣socket␣to␣listen␣for␣connections");
listenSocket = −1;
return false ;
}
if (listen (listenSocket , maxBacklog ) < 0) {
close (listenSocket );
perror ("POP3Proxy␣calling␣listen␣for␣connection␣socket");
listenSocket = −1;
return false ;
}
signal (SIGPIPE, absentPlumber ); /∗ Catch ”broken pipe” signals from disconnects ∗/
opened = true ;
return opened ;
}
#endif
198. The serviceConnection method waits for the next client connection to the listenSocket , accepts
it, and then conducts the dialogue with the client.
〈 Class implementations 11 〉 +≡
#ifdef POP3_PROXY_SERVER
bool POP3Proxy ::serviceConnection (void)
{
assert(opened );
int clientSocket ; /∗ Socket for talking to client ∗/
struct sockaddr in from ; /∗ Client IP address ∗/
socklen t fromlen ; /∗ Length of client address ∗/
〈 Wait for next client connection and accept it 199 〉;
〈 Conduct dialogue with client 200 〉;
return true ;
}
#endif