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Microsoft JDBC Driver for SQL Server.
/*
* Microsoft JDBC Driver for SQL Server Copyright(c) Microsoft Corporation All rights reserved. This program is made
* available under the terms of the MIT License. See the LICENSE file in the project root for more information.
*/
package com.microsoft.sqlserver.jdbc.dns;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
/**
* Represents a DNS SRV Record.
*/
public class DNSRecordSRV implements Comparable {
private static final Pattern PATTERN = Pattern.compile("^([0-9]+) ([0-9]+) ([0-9]+) (.+)$");
private final int priority;
/**
* Parses a DNS SRC Record from a DNS String record.
*
* @param record
* the record to parse
* @return a not null DNS Record
* @throws IllegalArgumentException
* if record is not correct and cannot be parsed
*/
public static DNSRecordSRV parseFromDNSRecord(String record) {
Matcher m = PATTERN.matcher(record);
if (!m.matches()) {
throw new IllegalArgumentException("record '" + record + "' cannot be matched as a valid DNS SRV Record");
}
try {
int priority = Integer.parseInt(m.group(1));
int weight = Integer.parseInt(m.group(2));
int port = Integer.parseInt(m.group(3));
String serverName = m.group(4);
// Avoid issues with Kerberos SPN when fully qualified records ends with '.'
if (serverName.endsWith(".")) {
serverName = serverName.substring(0, serverName.length() - 1);
}
return new DNSRecordSRV(priority, weight, port, serverName);
} catch (IllegalArgumentException err) {
throw err;
} catch (Exception err) {
throw new IllegalArgumentException("Failed to parse DNS SRV record '" + record + "'", err);
}
}
@Override
public String toString() {
return String.format("DNS.SRV[pri=%d w=%d port=%d h='%s']", priority, weight, port, serverName);
}
/**
* Constructs a DNSRecordSRV.
*
* @param priority
* is lowest
* @param weight
* 1 at minimum
* @param port
* the port of service
* @param serverName
* the host
* @throws IllegalArgumentException
* if priority {@literal <} 0 or weight {@literal <=} 1
*/
public DNSRecordSRV(int priority, int weight, int port, String serverName) {
if (priority < 0) {
throw new IllegalArgumentException("priority must be >= 0, but was: " + priority);
}
this.priority = priority;
if (weight < 0) {
// Weight == 0 is OK to disable load balancing, but not below
throw new IllegalArgumentException("weight must be >= 0, but was: " + weight);
}
this.weight = weight;
if (port < 0 || port > 65535) {
throw new IllegalArgumentException("port must be between 0 and 65535, but was: " + port);
}
this.port = port;
if (serverName == null || serverName.trim().isEmpty()) {
throw new IllegalArgumentException("hostname is not supposed to be null or empty in a SRV Record");
}
this.serverName = serverName;
}
private final int weight;
private final int port;
private final String serverName;
@Override
public int hashCode() {
return serverName.hashCode();
}
@Override
public boolean equals(Object other) {
if (other == this) {
return true;
}
if (!(other instanceof DNSRecordSRV)) {
return false;
}
DNSRecordSRV r = (DNSRecordSRV) other;
return port == r.port && weight == r.weight && priority == r.priority && serverName.equals(r.serverName);
}
@Override
public int compareTo(DNSRecordSRV o) {
if (o == null) {
return 1;
}
int p = Integer.compare(priority, o.priority);
if (p != 0) {
return p;
}
p = Integer.compare(weight, o.weight);
if (p != 0) {
return p;
}
p = Integer.compare(port, o.port);
if (p != 0) {
return p;
}
return serverName.compareTo(o.serverName);
}
/**
* Returns the priority of DNS SRV record.
*
* @return a positive priority, where lowest values have to be considered first.
*/
public int getPriority() {
return priority;
}
/**
* Returns the weight of DNS record from 0 to 65535.
*
* @return The weight, higher value means higher probability of selecting the given record for a given priority.
*/
public int getWeight() {
return weight;
}
/**
* Returns the IP port of record.
*
* @return a value from 1 to 65535.
*/
public int getPort() {
return port;
}
/**
* Returns the DNS server name.
*
* @return a not null server name.
*/
public String getServerName() {
return serverName;
}
}