The Annoyance Filter.pdf - Fourmilab

172 POP3 PROXY SERVER CLASS DEFINITION ANNOYANCE-FILTER §208
208. In order to determine whether the server will respond with a multi-line reply in addition to a
status line, we must examine the command and its arguments. The command, which is case-insensitive,
is forced to lower case to facilitate comparisons. Note that since we’ve already forwarded the request to
the server, it’s OK to diddle clientBuffer here.
〈 Parse request and argument into canonical form 208 〉 ≡
while ((clientLength > 0) ∧ isspace (clientBuffer [clientLength − 1])) {
clientLength −−;
}
command = argument = "";
int i;
for (i = 0; i < clientLength ; i++) {
if (isspace (clientBuffer [i])) {
break;
}
char ch = clientBuffer [i];
if (isalpha (ch ) ∧ isupper (ch )) {
ch = tolower (ch );
}
command += ch ;
}
while ((i < clientLength ) ∧ isspace (clientBuffer [i])) {
i++;
}
if (i < clientLength ) {
argument = string(clientBuffer + i, clientLength − i);
}
if (popProxyTrace ) {
cerr ≪ "POP3:␣Client␣command␣(" ≪ command ≪ ")␣␣Argument␣(" ≪ argument ≪ ")" ≪
endl ;
}
This code is used in section 204.