Move most transport_opt() validation into diameter_config

Faulty configuration was previously passed directly on to watchdog and
peer_fsm processes, diameter:add_transport/2 happily returning ok and
the error resulting on failure of watchdog and/or peer_fsm processes.
Now check for errors before getting this far, returning {error, Reason}
from diameter:add_transport/2 when one is detected. There are still
some errors that can only be detected after transport start (eg. a
misbehaving callback) but most will be caught early.

1 files changed, 1 insertions, 3 deletions

diff --git a/lib/diameter/src/base/diameter_peer_fsm.erl b/lib/diameter/src/base/diameter_peer_fsm.erl
index 66342f7b62..3b8c49b7e8 100644
--- a/lib/diameter/src/base/diameter_peer_fsm.erl
+++ b/lib/diameter/src/base/diameter_peer_fsm.erl
@@ -198,6 +198,7 @@ i({Ack, WPid, {M, Ref} = T, Opts, {Mask,
     OnLengthErr = proplists:get_value(length_errors, Opts, exit),
     lists:member(OnLengthErr, [exit, handle, discard])
         orelse ?ERROR({invalid, {length_errors, OnLengthErr}}),
+    %% Error checking is for configuration added in old code.
 
     {TPid, Addrs} = start_transport(T, Rest, Svc),
 
@@ -212,9 +213,6 @@ i({Ack, WPid, {M, Ref} = T, Opts, {Mask,
 %% transports on the same service can use different local addresses.
 %% The local addresses are put into Host-IP-Address avps here when
 %% sending capabilities exchange messages.
-%%
-%% Invalid transport config may cause us to crash but note that the
-%% watchdog start (start/2) succeeds regardless.
 
 %% Wait for the caller to have a monitor to avoid a race with our
 %% death. (Since the exit reason is used in diameter_service.)