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FTP client trusts the host from PASV response by default
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Adapted patch from Jochen Wiedmann
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@garydgregory
garydgregory committed Nov 7, 2022
1 parent 387ee3e commit b0bff89
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Showing 4 changed files with 111 additions and 19 deletions.
2 changes: 1 addition & 1 deletion checkstyle.xml
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Expand Up @@ -49,7 +49,7 @@ limitations under the License.
</module>

<module name="LineLength">
<property name="max" value="132"/>
<property name="max" value="160"/>
</module>

<module name="TreeWalker">
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3 changes: 3 additions & 0 deletions src/changes/changes.xml
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Expand Up @@ -74,6 +74,9 @@ The <action> type attribute can be add,update,fix,remove.
<action type="fix" dev="ggregory" due-to="Arturo Bernal">
Use Math.min and Math.max method instead of manual calculations. #104.
</action>
<action type="fix" dev="ggregory" due-to="Jochen Wiedmann, Gary Gregory">
FTP client trusts the host from PASV response by default.
</action>
<!-- ADD -->
<action type="add" dev="ggregory" due-to="Gary Gregory">
[FTP] Add FTPClient.mdtmInstant(String).
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96 changes: 78 additions & 18 deletions src/main/java/org/apache/commons/net/ftp/FTPClient.java
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Expand Up @@ -295,10 +295,10 @@
* @see FTPFileEntryParserFactory
* @see DefaultFTPFileEntryParserFactory
* @see FTPClientConfig
*
* @see org.apache.commons.net.MalformedServerReplyException
*/
public class FTPClient extends FTP implements Configurable {

// @since 3.0
private static class CSL implements CopyStreamListener {

Expand Down Expand Up @@ -437,6 +437,18 @@ private static class PropertiesSingleton {
*/
public static final String FTP_SYSTEM_TYPE_DEFAULT = "org.apache.commons.net.ftp.systemType.default";

/**
* The system property that defines the default for {@link #isIpAddressFromPasvResponse()}. This property, if present, configures the default for the
* following: If the client receives the servers response for a PASV request, then that response will contain an IP address. If this property is true, then
* the client will use that IP address, as requested by the server. This is compatible to version {@code 3.8.0}, and before. If this property is false, or
* absent, then the client will ignore that IP address, and instead use the remote address of the control connection.
*
* @see #isIpAddressFromPasvResponse()
* @see #setIpAddressFromPasvResponse(boolean)
* @since 3.9.0
*/
public static final String FTP_IP_ADDRESS_FROM_PASV_RESPONSE = "org.apache.commons.net.ftp.ipAddressFromPasvResponse";

/**
* The name of an optional systemType properties file ({@value}), which is loaded
* using {@link Class#getResourceAsStream(String)}.<br>
Expand Down Expand Up @@ -625,6 +637,8 @@ static String parsePathname(final String reply)
/** Map of FEAT responses. If null, has not been initialized. */
private HashMap<String, Set<String>> featuresMap;

private boolean ipAddressFromPasvResponse = Boolean.parseBoolean(System.getProperty(FTPClient.FTP_IP_ADDRESS_FROM_PASV_RESPONSE));

/**
* Default FTPClient constructor. Creates a new FTPClient instance
* with the data connection mode set to
Expand Down Expand Up @@ -928,35 +942,44 @@ protected void _parseExtendedPassiveModeReply(String reply) throws MalformedServ
protected void _parsePassiveModeReply(final String reply) throws MalformedServerReplyException {
final Matcher m = PARMS_PAT.matcher(reply);
if (!m.find()) {
throw new MalformedServerReplyException(
"Could not parse passive host information.\nServer Reply: " + reply);
throw new MalformedServerReplyException("Could not parse passive host information.\nServer Reply: " + reply);
}

this.passiveHost = "0,0,0,0".equals(m.group(1)) ? _socket_.getInetAddress().getHostAddress()
: m.group(1).replace(',', '.'); // Fix up to look like IP address
int pasvPort;
// Fix up to look like IP address
String pasvHost = "0,0,0,0".equals(m.group(1)) ? _socket_.getInetAddress().getHostAddress() : m.group(1).replace(',', '.');

try {
final int oct1 = Integer.parseInt(m.group(2));
final int oct2 = Integer.parseInt(m.group(3));
passivePort = (oct1 << 8) | oct2;
pasvPort = (oct1 << 8) | oct2;
} catch (final NumberFormatException e) {
throw new MalformedServerReplyException(
"Could not parse passive port information.\nServer Reply: " + reply);
throw new MalformedServerReplyException("Could not parse passive port information.\nServer Reply: " + reply);
}

if (passiveNatWorkaroundStrategy != null) {
try {
final String newPassiveHost = passiveNatWorkaroundStrategy.resolve(this.passiveHost);
if (!this.passiveHost.equals(newPassiveHost)) {
fireReplyReceived(0,
"[Replacing PASV mode reply address " + this.passiveHost + " with " + newPassiveHost + "]\n");
this.passiveHost = newPassiveHost;
if (isIpAddressFromPasvResponse()) {
// Pre-3.9.0 behavior
if (passiveNatWorkaroundStrategy != null) {
try {
final String newPassiveHost = passiveNatWorkaroundStrategy.resolve(pasvHost);
if (!pasvHost.equals(newPassiveHost)) {
fireReplyReceived(0, "[Replacing PASV mode reply address " + this.passiveHost + " with " + newPassiveHost + "]\n");
pasvHost = newPassiveHost;
}
} catch (final UnknownHostException e) { // Should not happen as we are passing in an IP address
throw new MalformedServerReplyException("Could not parse passive host information.\nServer Reply: " + reply);
}
} catch (final UnknownHostException e) { // Should not happen as we are passing in an IP address
throw new MalformedServerReplyException(
"Could not parse passive host information.\nServer Reply: " + reply);
}
} else {
// Post-3.8 behavior
if (_socket_ == null) {
pasvHost = null; // For unit testing.
} else {
pasvHost = _socket_.getInetAddress().getHostAddress();
}
}
this.passiveHost = pasvHost;
this.passivePort = pasvPort;
}

/**
Expand Down Expand Up @@ -4140,4 +4163,41 @@ public boolean structureMount(final String pathname) throws IOException
{
return FTPReply.isPositiveCompletion(smnt(pathname));
}

/**
* Returns, whether the IP address from the server's response should be used.
* Until 3.9.0, this has always been the case. Beginning with 3.9.0,
* that IP address will be silently ignored, and replaced with the remote
* IP address of the control connection, unless this configuration option is
* given, which restores the old behavior. To enable this by default, use
* the system property {@link FTPClient#FTP_IP_ADDRESS_FROM_PASV_RESPONSE}.
* @return True, if the IP address from the server's response will be used
* (pre-3.9 compatible behavior), or false (ignore that IP address).
*
* @see FTPClient#FTP_IP_ADDRESS_FROM_PASV_RESPONSE
* @see #setIpAddressFromPasvResponse(boolean)
* @since 3.9.0
*/
public boolean isIpAddressFromPasvResponse() {
return ipAddressFromPasvResponse;
}

/**
* Sets whether the IP address from the server's response should be used.
* Until 3.9.0, this has always been the case. Beginning with 3.9.0,
* that IP address will be silently ignored, and replaced with the remote
* IP address of the control connection, unless this configuration option is
* given, which restores the old behavior. To enable this by default, use
* the system property {@link FTPClient#FTP_IP_ADDRESS_FROM_PASV_RESPONSE}.
*
* @param usingIpAddressFromPasvResponse True, if the IP address from the
* server's response should be used (pre-3.9.0 compatible behavior), or
* false (ignore that IP address).
* @see FTPClient#FTP_IP_ADDRESS_FROM_PASV_RESPONSE
* @see #isIpAddressFromPasvResponse
* @since 3.9.0
*/
public void setIpAddressFromPasvResponse(boolean usingIpAddressFromPasvResponse) {
this.ipAddressFromPasvResponse = usingIpAddressFromPasvResponse;
}
}
29 changes: 29 additions & 0 deletions src/test/java/org/apache/commons/net/ftp/FTPClientTest.java
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Expand Up @@ -37,6 +37,7 @@ private static class LocalClient extends FTPClient {
public String getSystemType() throws IOException {
return systemType;
}

public void setSystemType(final String type) {
systemType = type;
}
Expand Down Expand Up @@ -98,52 +99,80 @@ public void testParseClient() {

public void testParsePassiveModeReplyForLocalAddressWithNatWorkaround() throws Exception {
final FTPClient client = new PassiveNatWorkAroundLocalClient("8.8.8.8");
client.setIpAddressFromPasvResponse(true);
client._parsePassiveModeReply("227 Entering Passive Mode (172,16,204,138,192,22).");
assertEquals("8.8.8.8", client.getPassiveHost());
client.setIpAddressFromPasvResponse(false);
client._parsePassiveModeReply("227 Entering Passive Mode (172,16,204,138,192,22).");
assertNull(client.getPassiveHost());
}

@SuppressWarnings("deprecation") // testing deprecated code
public void testParsePassiveModeReplyForLocalAddressWithNatWorkaroundDisabled() throws Exception {
final FTPClient client = new PassiveNatWorkAroundLocalClient("8.8.8.8");
client.setPassiveNatWorkaround(false);
client.setIpAddressFromPasvResponse(true);
client._parsePassiveModeReply("227 Entering Passive Mode (172,16,204,138,192,22).");
assertEquals("172.16.204.138", client.getPassiveHost());
client.setIpAddressFromPasvResponse(false);
client._parsePassiveModeReply("227 Entering Passive Mode (172,16,204,138,192,22).");
assertNull(client.getPassiveHost());
}


public void testParsePassiveModeReplyForLocalAddressWithoutNatWorkaroundStrategy() throws Exception {
final FTPClient client = new PassiveNatWorkAroundLocalClient("8.8.8.8");
client.setPassiveNatWorkaroundStrategy(null);
client.setIpAddressFromPasvResponse(true);
client._parsePassiveModeReply("227 Entering Passive Mode (172,16,204,138,192,22).");
assertEquals("172.16.204.138", client.getPassiveHost());
client.setIpAddressFromPasvResponse(false);
client._parsePassiveModeReply("227 Entering Passive Mode (172,16,204,138,192,22).");
assertNull(client.getPassiveHost());
}

public void testParsePassiveModeReplyForLocalAddressWithSimpleNatWorkaroundStrategy() throws Exception {
final FTPClient client = new PassiveNatWorkAroundLocalClient("8.8.8.8");
client.setPassiveNatWorkaroundStrategy(hostname -> "4.4.4.4");
client.setIpAddressFromPasvResponse(true);
client._parsePassiveModeReply("227 Entering Passive Mode (172,16,204,138,192,22).");
assertEquals("4.4.4.4", client.getPassiveHost());
client.setIpAddressFromPasvResponse(false);
client._parsePassiveModeReply("227 Entering Passive Mode (172,16,204,138,192,22).");
assertNull(client.getPassiveHost());
}

public void testParsePassiveModeReplyForNonLocalAddressWithNatWorkaround() throws Exception {
final FTPClient client = new PassiveNatWorkAroundLocalClient("8.8.8.8");
client.setIpAddressFromPasvResponse(true);
client._parsePassiveModeReply("227 Entering Passive Mode (8,8,4,4,192,22).");
assertEquals("8.8.4.4", client.getPassiveHost());
client.setIpAddressFromPasvResponse(false);
client._parsePassiveModeReply("227 Entering Passive Mode (8,8,4,4,192,22).");
assertNull(client.getPassiveHost());
}

@SuppressWarnings("deprecation") // testing deprecated code
public void testParsePassiveModeReplyForNonLocalAddressWithNatWorkaroundDisabled() throws Exception {
final FTPClient client = new PassiveNatWorkAroundLocalClient("8.8.8.8");
client.setPassiveNatWorkaround(false);
client.setIpAddressFromPasvResponse(true);
client._parsePassiveModeReply("227 Entering Passive Mode (8,8,4,4,192,22).");
assertEquals("8.8.4.4", client.getPassiveHost());
client.setIpAddressFromPasvResponse(false);
client._parsePassiveModeReply("227 Entering Passive Mode (8,8,4,4,192,22).");
assertNull(client.getPassiveHost());
}

public void testParsePassiveModeReplyForNonLocalAddressWithoutNatWorkaroundStrategy() throws Exception {
final FTPClient client = new PassiveNatWorkAroundLocalClient("8.8.8.8");
client.setPassiveNatWorkaroundStrategy(null);
client.setIpAddressFromPasvResponse(true);
client._parsePassiveModeReply("227 Entering Passive Mode (8,8,4,4,192,22).");
assertEquals("8.8.4.4", client.getPassiveHost());
client.setIpAddressFromPasvResponse(false);
client._parsePassiveModeReply("227 Entering Passive Mode (8,8,4,4,192,22).");
assertNull(client.getPassiveHost());
}

public void testParserCachingNullKey() throws Exception {
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