# HG changeset patch
# User Augie Fackler <augie@google.com>
# Date 1435706357 14400
# Node ID d3d32643c0609e0e918aeaffa1fc03fd74c87cbe
# Parent  84518051bc3b851f736872df045d662de548b3c9
wireproto: correctly escape batched args and responses (issue4739)

This issue appears to be as old as wireproto batching itself: I can
reproduce the failure as far back as 08ef6b5f3715 trivially by
rebasing the test changes in this patch, which was back in the 1.9
era. I didn't test before that change, because prior to that the
testfile has a different name and I'm lazy.

Note that the test thought it was checking this case, but it actually
wasn't: it put a literal ; in the arg and response for its greet
command, but the mangle/unmangle step defined in the test meant that
instead of "Fo, =;o" going over the wire, "Gp-!><p" went instead,
which doesn't contain any special characters (those being [.=;]) and
thus not exercising the escaping. The test has been updated to use
pre-unmangled special characters, so the request is now "Fo+<:o",
which mangles to "Gp,=;p". I have confirmed that the test fails
without the adjustment to the escaping rules in wireproto.py.

No existing clients of RPC batching were depending on the old behavior
in any way. The only *actual* users of batchable RPCs in core were:

1) largefiles, wherein it batches up many statlfile calls. It sends
hexlified hashes over the wire and gets a 0, 1, or 2 back as a
response. No risk of special characters.

2) setdiscovery, which was using heads() and known(), both of which
communicate via hexlified nodes. Again, no risk of special characters.

Since the escaping functionality has been completely broken since it
was introduced, we know that it has no users. As such, we can change
the escaping mechanism without having to worry about backwards
compatibility issues.

For the curious, this was detected by chance: it happens that the
lz4-compressed text of a test file for remotefilelog compressed to
something containing a ;, which then caused the failure when I moved
remotefilelog to using batching for file content fetching.

diff -r 84518051bc3b -r d3d32643c060 mercurial/wireproto.py
--- a/mercurial/wireproto.py	Wed Jul 01 17:51:57 2015 -0500
+++ b/mercurial/wireproto.py	Tue Jun 30 19:19:17 2015 -0400
@@ -182,17 +182,17 @@
 
 def escapearg(plain):
     return (plain
-            .replace(':', '::')
-            .replace(',', ':,')
-            .replace(';', ':;')
-            .replace('=', ':='))
+            .replace(':', ':c')
+            .replace(',', ':o')
+            .replace(';', ':s')
+            .replace('=', ':e'))
 
 def unescapearg(escaped):
     return (escaped
-            .replace(':=', '=')
-            .replace(':;', ';')
-            .replace(':,', ',')
-            .replace('::', ':'))
+            .replace(':e', '=')
+            .replace(':s', ';')
+            .replace(':o', ',')
+            .replace(':c', ':'))
 
 # mapping of options accepted by getbundle and their types
 #
@@ -221,10 +221,11 @@
     def _submitbatch(self, req):
         cmds = []
         for op, argsdict in req:
-            args = ','.join('%s=%s' % p for p in argsdict.iteritems())
+            args = ','.join('%s=%s' % (escapearg(k), escapearg(v))
+                            for k, v in argsdict.iteritems())
             cmds.append('%s %s' % (op, args))
         rsp = self._call("batch", cmds=';'.join(cmds))
-        return rsp.split(';')
+        return [unescapearg(r) for r in rsp.split(';')]
     def _submitone(self, op, args):
         return self._call(op, **args)
 
diff -r 84518051bc3b -r d3d32643c060 tests/test-wireproto.py
--- a/tests/test-wireproto.py	Wed Jul 01 17:51:57 2015 -0500
+++ b/tests/test-wireproto.py	Tue Jun 30 19:19:17 2015 -0400
@@ -43,6 +43,6 @@
 
 print clt.greet("Foobar")
 b = clt.batch()
-fs = [b.greet(s) for s in ["Fo, =;o", "Bar"]]
+fs = [b.greet(s) for s in ["Fo, =;:<o", "Bar"]]
 b.submit()
 print [f.value for f in fs]
diff -r 84518051bc3b -r d3d32643c060 tests/test-wireproto.py.out
--- a/tests/test-wireproto.py.out	Wed Jul 01 17:51:57 2015 -0500
+++ b/tests/test-wireproto.py.out	Tue Jun 30 19:19:17 2015 -0400
@@ -1,2 +1,2 @@
 Hello, Foobar
-['Hello, Fo, =;o', 'Hello, Bar']
+['Hello, Fo, =;:<o', 'Hello, Bar']