DEV: h2: fix h2-tracer.lua nil value index

Nick Ramirez reported the following error while testing the h2-tracer.lua
script:

  Lua filter 'h2-tracer' : [state-id 0] runtime error: /etc/haproxy/h2-tracer.lua:227: attempt to index a nil value (field '?') from /etc/haproxy/h2-tracer.lua:227: in function line 109.

It is caused by h2ff indexing with an out of bound value. Indeed, h2ff
is indexed with the frame type, which can potentially be > 9 (not common
nor observed during Willy's tests), while h2ff only defines indexes from
0 to 9.

The fix was provided by Willy, it consists in skipping h2ff indexing if
frame type is > 9. It was confirmed that doing so fixes the error.

diff --git a/dev/h2/h2-tracer.lua b/dev/h2/h2-tracer.lua
index 71643bb623532ac8c01c71ed117cbf207c9d4c22..b31ee15f2480559b5f1ed77e459deebfd523dca7 100644 (file)
--- a/dev/h2/h2-tracer.lua
+++ b/dev/h2/h2-tracer.lua
@@ -224,7 +224,7 @@ function Dec:tcp_payload(txn, chn)
         ff = ""
         for i = 7, 0, -1 do
             if (((self.st[dir].fflg >> i) & 1) ~= 0) then
-                if h2ff[self.st[dir].ftyp][i] ~= nil then
+                if self.st[dir].ftyp <= 9 and h2ff[self.st[dir].ftyp][i] ~= nil then
                     ff = ff .. ((ff == "") and "" or "+")
                     ff = ff .. h2ff[self.st[dir].ftyp][i]
                 else