2 files changed, 289 insertions, 0 deletions
diff --git a/app/src/main/java/net/sourceforge/jsocks/server/ServerAuthenticator.java b/app/src/main/java/net/sourceforge/jsocks/server/ServerAuthenticator.java
new file mode 100644
index 0000000..cb7f0af
--- /dev/null
+++ b/app/src/main/java/net/sourceforge/jsocks/server/ServerAuthenticator.java
@@ -0,0 +1,120 @@
+package net.sourceforge.jsocks.server;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.net.DatagramPacket;
+import java.net.Socket;
+
+import net.sourceforge.jsocks.ProxyMessage;
+import net.sourceforge.jsocks.UDPEncapsulation;
+
+/**
+ Classes implementing this interface should provide socks server with
+ authentication and authorization of users.
+**/
+public interface ServerAuthenticator{
+
+   /**
+     This method is called when a new connection accepted by the server.
+     <p>
+     At this point no data have been extracted from the connection. It is
+     responsibility of this method to ensure that the next byte in the
+     stream after this method have been called is the first byte of the
+     socks request message. For SOCKSv4 there is no authentication data and
+     the first byte in the stream is part of the request. With SOCKSv5 however
+     there is an authentication data first. It is expected that implementaions
+     will process this authentication data. 
+     <p>
+     If authentication was successful an instance of ServerAuthentication
+     should be returned, it later will be used by the server to perform
+     authorization and some other things. If authentication fails null should
+     be returned, or an exception may be thrown.
+
+     @param s Accepted Socket.
+     @return An instance of ServerAuthenticator to be used for this connection
+     or null
+   */
+   ServerAuthenticator startSession(Socket s) throws IOException;
+
+   /**
+    This method should return input stream which should be used on the
+    accepted socket.
+    <p>
+    SOCKSv5 allows to have multiple authentication methods, and these methods
+    might require some kind of transformations being made on the data.
+    <p>
+    This method is called on the object returned from the startSession
+    function.
+   */
+   InputStream getInputStream();
+   /**
+    This method should return output stream to use to write to the accepted
+    socket.
+    <p>
+    SOCKSv5 allows to have multiple authentication methods, and these methods
+    might require some kind of transformations being made on the data.
+    <p>
+    This method is called on the object returned from the startSession
+    function.
+   */
+   OutputStream getOutputStream();
+
+   /**
+    This method should return UDPEncapsulation, which should be used
+    on the datagrams being send in/out.
+    <p>
+    If no transformation should be done on the datagrams, this method
+    should return null.
+    <p>
+    This method is called on the object returned from the startSession
+    function.
+   */
+
+   UDPEncapsulation getUdpEncapsulation();
+
+   /**
+    This method is called when a request have been read.
+    <p>
+    Implementation should decide wether to grant request or not. Returning
+    true implies granting the request, false means request should be rejected.
+    <p>
+    This method is called on the object returned from the startSession
+    function.
+    @param msg Request message.
+    @return true to grant request, false to reject it.
+   */
+   boolean checkRequest(ProxyMessage msg);
+
+   /**
+    This method is called when datagram is received by the server.
+    <p>
+    Implementaions should decide wether it should be forwarded or dropped.
+    It is expecteed that implementation will use datagram address and port
+    information to make a decision, as well as anything else. Address and
+    port of the datagram are always correspond to remote machine. It is
+    either destination or source address. If out is true address is destination
+    address, else it is a source address, address of the machine from which
+    datagram have been received for the client.
+    <p>
+    Implementaions should return true if the datagram is to be forwarded, and
+    false if the datagram should be dropped.
+    <p>
+    This method is called on the object returned from the startSession
+    function.
+
+    @param out If true the datagram is being send out(from the client),
+               otherwise it is an incoming datagram.
+    @return True to forward datagram false drop it silently.
+   */
+   boolean checkRequest(DatagramPacket dp, boolean out);
+
+   /**
+    This method is called when session is completed. Either due to normal
+    termination or due to any error condition.
+    <p>
+    This method is called on the object returned from the startSession
+    function.
+   */
+   void endSession();
+}
diff --git a/app/src/main/java/net/sourceforge/jsocks/server/ServerAuthenticatorNone.java b/app/src/main/java/net/sourceforge/jsocks/server/ServerAuthenticatorNone.java
new file mode 100644
index 0000000..e4edbe7
--- /dev/null
+++ b/app/src/main/java/net/sourceforge/jsocks/server/ServerAuthenticatorNone.java
@@ -0,0 +1,169 @@
+package net.sourceforge.jsocks.server;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.io.PushbackInputStream;
+import java.net.Socket;
+
+import net.sourceforge.jsocks.ProxyMessage;
+import net.sourceforge.jsocks.UDPEncapsulation;
+
+/**
+ An implementation of ServerAuthenticator, which does <b>not</b> do
+ any authentication.
+<P>
+<FONT size="+3" color ="FF0000"> Warning!!</font><br> Should not be
+used on machines which are not behind the firewall.
+<p>
+It is only provided to make implementing other authentication schemes
+easier.<br>
+For Example: <tt><pre>
+   class MyAuth extends socks.server.ServerAuthenticator{
+    ...
+    public ServerAuthenticator startSession(java.net.Socket s){
+      if(!checkHost(s.getInetAddress()) return null;
+      return super.startSession(s);
+    }
+
+    boolean checkHost(java.net.Inetaddress addr){
+      boolean allow;
+      //Do it somehow
+      return allow;
+    }
+   }
+</pre></tt>
+*/
+public class ServerAuthenticatorNone implements ServerAuthenticator{
+
+   static final byte[] socks5response = {5,0};
+
+   InputStream in;
+   OutputStream out;
+
+   /**
+    Creates new instance of the ServerAuthenticatorNone.
+   */
+   public ServerAuthenticatorNone(){
+     this.in = null;
+     this.out = null;
+   }
+   /**
+    Constructs new ServerAuthenticatorNone object suitable for returning
+    from the startSession function.
+    @param in Input stream to return from getInputStream method.
+    @param out Output stream to return from getOutputStream method.
+   */
+   public ServerAuthenticatorNone(InputStream in, OutputStream out){
+      this.in = in;
+      this.out = out;
+   }
+   /**
+    Grants access to everyone.Removes authentication related bytes from
+    the stream, when a SOCKS5 connection is being made, selects an
+    authentication NONE.
+    */
+   public ServerAuthenticator startSession(Socket s)
+                                  throws IOException{
+
+     PushbackInputStream in =  new PushbackInputStream(s.getInputStream());
+     OutputStream out = s.getOutputStream();
+
+     int version = in.read();
+     if(version == 5){
+       if(!selectSocks5Authentication(in,out,0))
+          return null;
+     }else if(version == 4){
+       //Else it is the request message allready, version 4
+       in.unread(version);
+     }else
+       return null;
+     
+
+     return new ServerAuthenticatorNone(in,out);
+   }
+
+   /**
+     Get input stream.
+     @return Input stream speciefied in the constructor.
+   */
+   public InputStream getInputStream(){
+      return in;
+   }
+   /**
+     Get output stream.
+     @return Output stream speciefied in the constructor.
+   */
+   public OutputStream getOutputStream(){
+      return out;
+   }
+   /**
+     Allways returns null.
+     @return null
+   */
+   public UDPEncapsulation getUdpEncapsulation(){
+      return null;
+   }
+
+   /**
+    Allways returns true.
+   */
+   public boolean checkRequest(ProxyMessage msg){
+     return true;
+   }
+
+   /**
+    Allways returns true.
+   */
+   public boolean checkRequest(java.net.DatagramPacket dp, boolean out){
+     return true;
+   }
+
+   /**
+    Does nothing.
+    */
+   public void endSession(){
+   }
+
+   /**
+     Convinience routine for selecting SOCKSv5 authentication.
+     <p>
+     This method reads in authentication methods that client supports,
+     checks wether it supports given method. If it does, the notification
+     method is written back to client, that this method have been chosen
+     for authentication. If given method was not found, authentication
+     failure message is send to client ([5,FF]).
+     @param in Input stream, version byte should be removed from the stream
+               before calling this method.
+     @param out Output stream.
+     @param methodId Method which should be selected.
+     @return true if methodId was found, false otherwise.
+   */
+   static public boolean selectSocks5Authentication(InputStream in, 
+                                                    OutputStream out,
+                                                    int methodId)
+                                                    throws IOException{
+                                                    
+      int num_methods = in.read();
+      if (num_methods <= 0) return false;
+      byte method_ids[] = new byte[num_methods];
+      byte response[] = new byte[2];
+      boolean found = false;
+
+      response[0] = (byte) 5;    //SOCKS version
+      response[1] = (byte) 0xFF; //Not found, we are pessimistic
+
+      int bread = 0; //bytes read so far
+      while(bread < num_methods)
+         bread += in.read(method_ids,bread,num_methods-bread);
+
+      for(int i=0;i<num_methods;++i)
+         if(method_ids[i] == methodId){
+           found = true;
+           response[1] = (byte) methodId;
+           break;
+         }
+
+      out.write(response);
+      return found;
+   }
+}