org.apache.sshd.sftp.client.SftpVersionSelector Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.apache.sshd.sftp.client;
import java.util.Collection;
import java.util.List;
import java.util.Objects;
import java.util.stream.Stream;
import java.util.stream.StreamSupport;
import org.apache.sshd.client.session.ClientSession;
import org.apache.sshd.common.NamedResource;
import org.apache.sshd.common.util.GenericUtils;
import org.apache.sshd.common.util.NumberUtils;
import org.apache.sshd.common.util.ValidateUtils;
/**
* @author Apache MINA SSHD Project
*/
@FunctionalInterface
public interface SftpVersionSelector {
/**
* An {@link SftpVersionSelector} that returns the current version
*/
NamedVersionSelector CURRENT = new NamedVersionSelector("CURRENT", (session, initial, current, available) -> current);
/**
* An {@link SftpVersionSelector} that returns the maximum available version
*/
NamedVersionSelector MAXIMUM = new NamedVersionSelector(
"MAXIMUM",
(session, initial, current, available) -> GenericUtils.stream(available).mapToInt(Integer::intValue).max()
.orElse(current));
/**
* An {@link SftpVersionSelector} that returns the minimum available version
*/
NamedVersionSelector MINIMUM = new NamedVersionSelector(
"MINIMUM",
(session, initial, current, available) -> GenericUtils.stream(available).mapToInt(Integer::intValue).min()
.orElse(current));
/**
* @param session The {@link ClientSession} through which the SFTP connection is made
* @param initial If {@code true} then this is the initial version sent via {@code SSH_FXP_INIT} otherwise it is
* a re-negotiation.
* @param current The current version negotiated with the server
* @param available Extra versions available - may be empty and/or contain only the current one
* @return The new requested version - if same as current, then nothing is done
*/
int selectVersion(ClientSession session, boolean initial, int current, List available);
/**
* Creates a selector the always returns the requested (fixed version) regardless of what the current or reported
* available versions are. If the requested version is not reported as available then an exception will be
* eventually thrown by the client during re-negotiation phase.
*
* @param version The requested version
* @return The {@link NamedVersionSelector} wrapping the requested version
*/
static NamedVersionSelector fixedVersionSelector(int version) {
return new NamedVersionSelector(Integer.toString(version), (session, initial, current, available) -> version);
}
/**
* Selects a version in order of preference - if none of the preferred versions is listed as available then an
* exception is thrown when the {@link SftpVersionSelector#selectVersion(ClientSession, boolean, int, List)} method
* is invoked
*
* @param preferred The preferred versions in decreasing order of preference (i.e., most preferred is 1st) - may
* not be {@code null}/empty
* @return A {@link NamedVersionSelector} that attempts to select the most preferred version that is also
* listed as available.
*/
static NamedVersionSelector preferredVersionSelector(int... preferred) {
return preferredVersionSelector(NumberUtils.asList(preferred));
}
/**
* Selects a version in order of preference - if none of the preferred versions is listed as available then an
* exception is thrown when the {@link SftpVersionSelector#selectVersion(ClientSession, boolean, int, List)} method
* is invoked
*
* @param preferred The preferred versions in decreasing order of preference (i.e., most preferred is 1st)
* @return A {@link NamedVersionSelector} that attempts to select the most preferred version that is also
* listed as available.
*/
static NamedVersionSelector preferredVersionSelector(Iterable preferred) {
ValidateUtils.checkNotNullAndNotEmpty((Collection) preferred, "Empty preferred versions");
return new NamedVersionSelector(
GenericUtils.join(preferred, ','),
(session, initial, current, available) -> StreamSupport.stream(preferred.spliterator(), false)
.mapToInt(Number::intValue)
.filter(v -> (v == current) || available.contains(v))
.findFirst()
.orElseThrow(() -> new IllegalStateException(
"Preferred versions (" + preferred + ") not available: " + available)));
}
/**
* Parses the input string to see if it matches one of the "known" selectors names (case insensitive). If
* not, then checks if it is a single number and uses it as a {@link #fixedVersionSelector(int) fixed} version.
* Otherwise, assumes a comma separated list of versions in preferred order.
*
* @param selector The selector value - if {@code null}/empty then returns {@link #CURRENT}
* @return Parsed {@link NamedVersionSelector}
*/
static NamedVersionSelector resolveVersionSelector(String selector) {
if (GenericUtils.isEmpty(selector)) {
return SftpVersionSelector.CURRENT;
} else if (selector.equalsIgnoreCase(SftpVersionSelector.CURRENT.getName())) {
return SftpVersionSelector.CURRENT;
} else if (selector.equalsIgnoreCase(SftpVersionSelector.MINIMUM.getName())) {
return SftpVersionSelector.MINIMUM;
} else if (selector.equalsIgnoreCase(SftpVersionSelector.MAXIMUM.getName())) {
return SftpVersionSelector.MAXIMUM;
} else if (NumberUtils.isIntegerNumber(selector)) {
return SftpVersionSelector.fixedVersionSelector(Integer.parseInt(selector));
} else {
String[] preferred = GenericUtils.split(selector, ',');
int[] prefs = Stream.of(preferred).mapToInt(Integer::parseInt).toArray();
return SftpVersionSelector.preferredVersionSelector(prefs);
}
}
/**
* Wraps a {@link SftpVersionSelector} and assigns it a name. Note: {@link NamedVersionSelector} are
* considered equal if they are assigned the same name - case insensitive
*
* @author Apache MINA SSHD Project
*/
class NamedVersionSelector implements SftpVersionSelector, NamedResource {
protected final SftpVersionSelector selector;
private final String name;
public NamedVersionSelector(String name, SftpVersionSelector selector) {
this.name = ValidateUtils.checkNotNullAndNotEmpty(name, "No name provided");
this.selector = Objects.requireNonNull(selector, "No delegate selector provided");
}
@Override
public int selectVersion(ClientSession session, boolean initial, int current, List available) {
return selector.selectVersion(session, initial, current, available);
}
@Override
public String getName() {
return name;
}
@Override
public int hashCode() {
return GenericUtils.hashCode(getName(), Boolean.TRUE);
}
@Override
public boolean equals(Object obj) {
if (obj == null) {
return false;
}
if (obj == this) {
return true;
}
if (getClass() != obj.getClass()) {
return false;
}
return NamedResource.safeCompareByName(this, (NamedVersionSelector) obj, false) == 0;
}
@Override
public String toString() {
return getName();
}
}
}
© 2015 - 2024 Weber Informatics LLC | Privacy Policy