parseServicesLine() method is called by
* getPortNumberForTcpIpService() to parse a non-comment line
* in the /etc/services file and save the values.
*
* @param line
* A line to compare from the /etc/services file.
*
* @param tcpipService
* The name of a TCP/IP "well-known" service found in the
* /etc/services file
*
* @param tcpipClass
* Either "tcp" or "udp", depending on the TCP/IP service desired.
*
* @return
* A port number for a TCP or UDP service (depending on tcpipClass).
* Return -1 on error.
*/
static private int parseServicesLine( String line
, String tcpipService
, String tcpipClass) {
// Parse line
StringTokenizer st = new StringTokenizer(line, " \t/#");
// First get the name on the line (parameter 1):
if (! st.hasMoreTokens()) {
return -1; // error
}
String name = st.nextToken().trim();
// Next get the service name on the line (parameter 2):
if (! st.hasMoreTokens()) {
return -1; // error
}
String portValue = st.nextToken().trim();
// Finally get the class on the line (parameter 3):
if (! st.hasMoreTokens()) {
return -1; // error
}
String classValue = st.nextToken().trim();
// Class doesn't match--reject:
if (! classValue.equals(tcpipClass)) {
return -1; // error
}
// Return port number, if name on this line matches:
if (name.equals(tcpipService)) {
try { // Convert the port number string to integer
return (Integer.parseInt(portValue));
} catch (NumberFormatException nfe) {
// Ignore corrupt /etc/services lines:
return -1; // error
}
} else {
return -1; // no match
}
}
/**
* The getServiceByName() method
* Search the /etc/services file for a service name and class.
* Return the port number.
* * For example, given this line in /etc/services, *
* farkle 4545/udp
*
* In this example, a search for service "farkle" and class "udp"
* will return 4545.
*
* @param tcpipService
* The name of a TCP/IP "well-known" service found in the
* /etc/services file
*
* @param tcpipClass
* Either "tcp" or "udp", depending on the TCP/IP service desired.
*
* @return
* A port number for a TCP or UDP service
* (depending on tcpipClass).
* Return -1 on error.
*/
static public int getServiceByName( String tcpipService
, String tcpipClass) {
int port = -1;
// Look for our service, line-by-line:
try {
String line;
BufferedReader br = new BufferedReader(
new InputStreamReader(new FileInputStream(SERVICES_FILENAME)));
// Read /etc/services file.
// Skip comments and empty lines.
while ( ((line = br.readLine()) != null)
&&
(port == -1)
) {
if ((line.length() != 0) && (line.charAt(0) != '#')) {
port = parseServicesLine(line, tcpipService, tcpipClass);
}
}
br.close();
return (port); // port number (or -1 on error)
} catch (IOException ioe) {
// File doesn't exist or is otherwise not available. Keep defaults
// error
return -1;
}
}
/**
* This main() method is for use as an "internal test driver only".
* To test this class, execute:
*
* java GetServiceByName [tcpipService tcpipClass]
*
* where: "service" - is a TCP/IP service name for which the port
* number is desired
* "class" - is the TCP/IP class (either tcp or udp)
*
* Example:
*
* java GetServiceByName ftp tcp
*
* @param tcpipService The service name for which the port number is
* desired.
* @param tcpipClass The TCP/IP class (either "tcp" or "udp")
*/
public static void main(String[] args) throws IOException {
int portUserTest, portOk, portFail;
int errorCount = 0;
try {
// -----------------------------------
// Check for arguments on command line
// -----------------------------------
if ((args.length != 0) && (args.length != 2)) {
System.err.println(
"Test driver for this class\n\n" +
"Usage: \n" +
" java GetServiceByName [