[DIRMINA-987] SOCKS5 Proxy handler can not handle unresolved computer names

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Incomplete
• Affects Version/s: 2.0.7
• Component/s: Handler
• Assignee: Unassigned
• Reporter: Michael Reinecke
• Created: 26/Sep/14 08:29
• Updated: 04/May/19 17:38
• Resolved: 04/May/19 17:38

Description

We are using Mina 2.0.7 to access an server through an Socks5 proxy. This worked fine as long as we use a direct IP address of the endpoint, but once we use the computer name, a nullpointer exception would occur. I searched through the source code and found the cause.
If Java can not resolve the computer name, then the handler will switch to the else branch, which tries to access the host value from the request. But to construct the Socks5 Request, you HAVE to set an INetAddress and CAN NOT set the host directly.
One feature of Socks5 is the ability to resolve the hostname by the proxy which may not be resolvable by others and therefor it is not required to resolve the name on our side. So the fastest way to fix this was to add the code in the '//---' in the else branch.

I am sure there are smarter ways to handle this problem, like extracting the host name in the SocksProxyRequest constructor and set it to the host variable. But as far as I do not know the complete infrastructure of MINA and the resulting consequences, I used this approach .

Yours,
Michael Reinecke

<...>
SocksProxyRequest soxx = new SocksProxyRequest(
SocksProxyConstants.SOCKS_VERSION_5,
SocksProxyConstants.ESTABLISH_TCPIP_STREAM,
new InetSocketAddress("endpoint-name", 666),
"username"); <...>

package org.apache.mina.proxy.handlers.socks;
<...>
public class Socks5LogicHandler extends AbstractSocksLogicHandler { <...>
private IoBuffer encodeProxyRequestPacket(final SocksProxyRequest request) throws UnsupportedEncodingException {
int len = 6;
InetSocketAddress adr = request.getEndpointAddress();
byte addressType = 0;
byte[] host = null;

if (adr != null && !adr.isUnresolved()) {
if (adr.getAddress() instanceof Inet6Address)

{ len += 16; addressType = SocksProxyConstants.IPV6_ADDRESS_TYPE; }

else if (adr.getAddress() instanceof Inet4Address)

{ len += 4; addressType = SocksProxyConstants.IPV4_ADDRESS_TYPE; }

} else {
host = request.getHost() != null ? request.getHost().getBytes("ASCII") : null;
// — The proxy will take care of the destination in Socks5
if(host == null && adr != null)

{ host = adr.getHostName().getBytes("ASCII"); }

// —
if (host != null)

{ len += 1 + host.length; addressType = SocksProxyConstants.DOMAIN_NAME_ADDRESS_TYPE; }

else

{ throw new IllegalArgumentException("SocksProxyRequest object " + "has no suitable endpoint information"); }

}
<...>
}