implement openssh config behavior to handle append, prepend and removal of algorithms

src/main/java/com/jcraft/jsch/OpenSSHConfig.java

@@ -29,16 +29,20 @@ LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 
 package com.jcraft.jsch;
 
-import java.io.InputStream;
-import java.io.Reader;
-import java.io.StringReader;
 import java.io.BufferedReader;
 import java.io.IOException;
+import java.io.Reader;
+import java.io.StringReader;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.Paths;
+import java.util.Arrays;
 import java.util.Hashtable;
+import java.util.List;
+import java.util.Set;
 import java.util.Vector;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
 
 /**
  * This class implements ConfigRepository interface, and parses
@@ -64,7 +68,7 @@ LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  *   <li>CompressionLevel</li>
  *   <li>ForwardAgent</li>
  *   <li>RequestTTY</li>
- *   <li>ServerAliveInterval</li>  
+ *   <li>ServerAliveInterval</li>
  *   <li>LocalForward</li>
  *   <li>RemoteForward</li>
  *   <li>ClearAllForwardings</li>
@@ -74,6 +78,11 @@ LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  */
 public class OpenSSHConfig implements ConfigRepository {
 
+  private static final Set<String> keysWithListAdoption = Stream
+      .of("KexAlgorithms", "Ciphers", "HostbasedAcceptedAlgorithms",
+          "HostKeyAlgorithms", "MACs", "PubkeyAcceptedAlgorithms", "CASignatureAlgorithms", "PubkeyAcceptedKeyTypes")
+      .map(String::toUpperCase).collect(Collectors.toSet());
+
   /**
    * Parses the given string, and returns an instance of ConfigRepository.
    *
@@ -143,6 +152,15 @@ public Config getConfig(String host) {
     return new MyConfig(host);
   }
 
+  /**
+   * Returns mapping of jsch config property names to OpenSSH property names.
+   *
+   * @return map
+   */
+  public static Hashtable<String, String> getKeymap() {
+    return keymap;
+  }
+
   private static final Hashtable<String, String> keymap = new Hashtable<>();
   static {
     keymap.put("kex", "KexAlgorithms");
@@ -192,6 +210,7 @@ else if(negate){
     }
 
     private String find(String key) {
+      String originalKey=key;
       if(keymap.get(key)!=null) {
         key = keymap.get(key);
       }
@@ -223,6 +242,24 @@ private String find(String key) {
         }
       }
       */
+
+      if (keysWithListAdoption.contains(key) && value != null && (value.startsWith("+") || value.startsWith("-") || value.startsWith("^"))) {
+
+        String origConfig = JSch.getConfig(originalKey).trim();
+
+        if (value.startsWith("+")) {
+          value=origConfig + "," + value.substring(1);
+        } else if (value.startsWith("-")) {
+          List<String> algList = Arrays.stream(Util.split(origConfig,",")).collect(Collectors.toList());
+          for (String alg : Util.split(value.substring(1),",")) {
+            algList.remove(alg.trim());
+          }
+          value = String.join(",", algList);
+        } else if (value.startsWith("^")) {
+          value = value.substring(1).trim() + "," + origConfig;
+        }
+      }
+
       return value;
     }
 
@@ -242,7 +279,7 @@ private String[] multiFind(String key) {
           }
         }
       }
-      String[] result = new String[value.size()]; 
+      String[] result = new String[value.size()];
       value.toArray(result);
       return result;
     }

src/test/java/com/jcraft/jsch/OpenSSHConfigTest.java

@@ -1,22 +1,86 @@
 package com.jcraft.jsch;
 
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
+
 import java.io.IOException;
 import java.net.URISyntaxException;
 import java.nio.file.Paths;
+import java.util.Map;
+import java.util.Optional;
+import java.util.stream.Collectors;
 
-import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.*;
 
 class OpenSSHConfigTest {
 
-    @org.junit.jupiter.api.Test
+    Map<String, String> keyMap = OpenSSHConfig.getKeymap().entrySet().stream().collect(Collectors.toMap(entry->entry.getValue().toUpperCase(), Map.Entry::getKey, (s, s2) -> s2));
+
+    @Test
     void parseFile() throws IOException, URISyntaxException {
         final String configFile = Paths.get(ClassLoader.getSystemResource("config").toURI()).toFile().getAbsolutePath();
         final OpenSSHConfig openSSHConfig = OpenSSHConfig.parseFile(configFile);
         final ConfigRepository.Config config = openSSHConfig.getConfig("host2");
         assertNotNull(config);
         assertEquals("foobar", config.getUser());
         assertEquals("host2.somewhere.edu", config.getHostname());
-        assertEquals("~/.ssh/old_keys/host2_key",config.getValue("IdentityFile"));
+        assertEquals("~/.ssh/old_keys/host2_key", config.getValue("IdentityFile"));
     }
+
+    @ParameterizedTest
+    @ValueSource(strings = {"MACs", "Macs"})
+    void parseMacsCaseInsensitive(String key) throws IOException {
+        OpenSSHConfig parse = OpenSSHConfig.parse(key + " someValue");
+        ConfigRepository.Config config = parse.getConfig("");
+        assertEquals("someValue", config.getValue("mac.c2s"));
+        assertEquals("someValue", config.getValue("mac.s2c"));
+    }
+
+    @Test
+    void appendKexAlgorithms() throws IOException {
+        OpenSSHConfig parse = OpenSSHConfig.parse("KexAlgorithms +diffie-hellman-group1-sha1");
+        ConfigRepository.Config kex = parse.getConfig("");
+        assertEquals(JSch.getConfig("kex") + "," + "diffie-hellman-group1-sha1", kex.getValue("kex"));
+    }
+
+    @ParameterizedTest
+    @ValueSource(strings = {"KexAlgorithms", "Ciphers", "HostKeyAlgorithms", "MACs", "PubkeyAcceptedAlgorithms", "PubkeyAcceptedKeyTypes"})
+    void appendAlgorithms(String key) throws IOException {
+        OpenSSHConfig parse = OpenSSHConfig.parse(key + " +someValue,someValue1");
+        ConfigRepository.Config config = parse.getConfig("");
+        String mappedKey = Optional.ofNullable(keyMap.get(key.toUpperCase())).orElse(key);
+        assertEquals(JSch.getConfig(mappedKey) + "," + "someValue,someValue1", config.getValue(mappedKey));
+    }
+
+    @ParameterizedTest
+    @ValueSource(strings = {"KexAlgorithms", "Ciphers", "HostKeyAlgorithms", "MACs", "PubkeyAcceptedAlgorithms", "PubkeyAcceptedKeyTypes"})
+    void prependAlgorithms(String key) throws IOException {
+        OpenSSHConfig parse = OpenSSHConfig.parse(key + " ^someValue,someValue1");
+        ConfigRepository.Config config = parse.getConfig("");
+        String mappedKey = Optional.ofNullable(keyMap.get(key.toUpperCase())).orElse(key);
+        assertEquals("someValue,someValue1,"+JSch.getConfig(mappedKey) , config.getValue(mappedKey));
+    }
+
+    @Test
+    void prependKexAlgorithms() throws IOException {
+        OpenSSHConfig parse = OpenSSHConfig.parse("KexAlgorithms ^diffie-hellman-group1-sha1");
+        ConfigRepository.Config kex = parse.getConfig("");
+        assertEquals("diffie-hellman-group1-sha1," + JSch.getConfig("kex"), kex.getValue("kex"));
+    }
+
+    @Test
+    void removeKexAlgorithm() throws IOException {
+        OpenSSHConfig parse = OpenSSHConfig.parse("KexAlgorithms -ecdh-sha2-nistp256");
+        ConfigRepository.Config kex = parse.getConfig("");
+        assertEquals(JSch.getConfig("kex").replaceAll(",ecdh-sha2-nistp256", ""), kex.getValue("kex"));
+    }
+
+    @Test
+    void replaceKexAlgorithms() throws IOException {
+        OpenSSHConfig parse = OpenSSHConfig.parse("KexAlgorithms diffie-hellman-group1-sha1");
+        ConfigRepository.Config kex = parse.getConfig("");
+        assertEquals("diffie-hellman-group1-sha1", kex.getValue("kex"));
+    }
+
 }