Auxiliary application: 'psocks', a simple SOCKS server.

This is built more or less entirely out of pieces I already had. The
SOCKS server code is provided by the dynamic forwarding code in
portfwd.c. When that accepts a connection request, it wants to talk to
an SSH ConnectionLayer, which is already a trait with interchangeable
implementations - so I just provide one of my own which only supports
the lportfwd_open() method. And that in turn returns an SshChannel
object, with a special trait implementation all of whose methods
just funnel back to an ordinary Socket.

Result: you get a Socket-to-Socket SOCKS implementation with no SSH
anywhere, and even a minimal amount of need to _pretend_ internally to
be an SSH implementation.

Additional features include the ability to log all the traffic in the
form of diagnostics to standard error, or log each direction of each
connection separately to a file, or for anything more general, to log
each direction of each connection through a pipe to a subcommand that
can filter out whatever you think are the interesting parts. Also, you
can spawn a subcommand after the SOCKS server is set up, and terminate
automatically when that subcommand does - e.g. you might use this to
wrap the execution of a single SOCKS-using program.

This is a modernisation of a diagnostic utility I've had kicking
around out-of-tree for a long time. With all of last year's
refactorings, it now becomes feasible to keep it in-tree without
needing huge amounts of scaffolding. Also, this version runs on
Windows, which is more than the old one did. (On Windows I haven't
implemented the subprocess parts, although there's no reason I
_couldn't_.)

As well as diagnostic uses, this may also be useful in some situations
as a thing to forward ports to: PuTTY doesn't currently support
reverse dynamic port forwarding (in which the remote listening port
acts as a SOCKS server), but you could get the same effect by
forwarding a remote port to a local instance of this. (Although, of
course, that's nothing you couldn't achieve using any other SOCKS
server.)

Author: sgtatham

.gitignore

@@ -40,6 +40,7 @@
 /psusan
 /osxlaunch
 /uppity
+/psocks
 /unix/PuTTY.app
 /unix/Pterm.app
 /fuzzterm

Recipe

@@ -411,15 +411,22 @@ uppity   : [UT] uxserver SSHSERVER UXMISC uxsignal uxnoise uxgss uxnogtk
 psusan   : [UT] uxpsusan SSHSERVER UXMISC uxsignal uxnoise nogss uxnogtk
          + uxpty uxsftpserver ux_x11 uxagentsock procnet uxcliloop
 
+PSOCKS   = psocks portfwd conf sshutils logging proxy nocproxy timing callback
+         + time tree234 version errsock be_misc norand MISC
+psocks   : [C] PSOCKS winsocks wincons winproxy winnet winmisc winselcli
+         + winhsock winhandl winmiscs winnohlp wincliloop LIBS
+psocks   : [UT] PSOCKS uxsocks uxcons uxproxy uxnet uxmisc uxpoll uxsel uxnogtk
+         + uxpeer uxfdsock uxcliloop uxsignal
+
 # ----------------------------------------------------------------------
 # On Windows, provide a means of removing local test binaries that we
 # aren't going to actually ship. (I prefer this to not building them
 # in the first place, so that we find out about build breakage early.)
 !begin vc
 cleantestprogs:
-	-del $(BUILDDIR)testcrypt.exe
+	-del $(BUILDDIR)testcrypt.exe $(BUILDDIR)psocks.exe
 !end
 !begin clangcl
 cleantestprogs:
-	-rm -f $(BUILDDIR)testcrypt.exe
+	-rm -f $(BUILDDIR)testcrypt.exe $(BUILDDIR)psocks.exe
 !end