The Annoyance Filter.pdf - Fourmilab

§202 ANNOYANCE-FILTER POP3 PROXY SERVER CLASS DEFINITION 169
202. Once we’ve determined the IP address of the POP3 server, we next need to open a socket
connection to it on the TCP/IP port on which it listens.
〈 Open connection to server 202 〉 ≡
struct sockaddr in serverHost ;
serverHost .sin family = AF_INET;
serverSocket = socket (AF_INET, SOCK_STREAM, 0);
if (serverSocket < 0) {
perror ("POP3Proxy␣opening␣socket␣to␣POP␣server");
cstat = −1;
}
else {
if (popProxyTrace ) {
cerr ≪ "POP3:␣serverSocket␣opened." ≪ endl ;
}
serverHost .sin port = htons (serverPort );
memcpy ((char ∗) &serverHost .sin addr .s addr , (char ∗)(&serverIP ), sizeof
serverHost .sin addr .s addr );
errno = 0;
do {
cstat = connect (serverSocket , (struct sockaddr ∗) &(serverHost ), sizeof serverHost );
if (popProxyTrace ) {
cerr ≪ "POP3:␣serverSocket␣connected." ≪ endl ;
}
if (cstat ≡ 0) {
if (popProxyTrace ) {
cerr ≪ "POP3:␣Connected␣to␣POP␣server␣on␣" ≪ inet ntoa (serverHost .sin addr ) ≪
":" ≪ ntohs (serverHost .sin port ) ≪ endl ;
}
break;
}
else {
perror ("POP3Proxy␣connection␣to␣POP␣server␣failed");
}
} while (errno ≡ EINTR);
if (cstat < 0) {
cerr ≪ "POP3Proxy:␣Cannot␣connect␣to␣POP3␣server␣" ≪ serverName .c str ( ) ≪ endl ;
}
}
This code is used in section 200.