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Attempt to detect external IP changes more accurately #374

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Aug 24, 2021
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Attempt to detect external IP changes more accurately #374

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34 changes: 28 additions & 6 deletions src/libp2p_transport_tcp.erl
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Original file line number Diff line number Diff line change
Expand Up @@ -482,6 +482,8 @@ handle_info({handle_identify, Session, {ok, Identify}}, State) ->
lager:notice("handle identify failed ~p ~p ~p", [What, Why, Stack]),
{noreply, State}
end;
handle_info({stungun_retry,Addr}, State) ->
handle_info(stungun_retry, State#state{resolved_addresses = State#state.resolved_addresses -- [{failed, Addr}]});
handle_info(stungun_retry, State=#state{observed_addrs=Addrs, tid=TID, stun_txns=StunTxns}) ->
case most_observed_addr(Addrs) of
{ok, ObservedAddr} ->
Expand Down Expand Up @@ -543,13 +545,13 @@ handle_info({stungun_nat, TxnID, NatType}, State=#state{tid=TID, stun_txns=StunT
{PeerAddr, ObservedAddr} = lists:nth(rand:uniform(length(Peers)), Peers),
%% finally, as this is a 'negative' result, schedule a retry in the future in case
%% our peers are wrong or lying to us
TimerRef = erlang:send_after(timer:minutes(30), self(), stungun_retry),
TimerRef = erlang:send_after(timer:minutes(30), self(), {stungun_retry, ResolvedAddr}),
NewState = attempt_port_forward_discovery(ObservedAddr, PeerAddr, State#state{stun_txns=remove_stun_txn(TxnID, StunTxns),
relay_monitor = Ref,
stungun_timeout_count = 0,
stungun_timer = TimerRef,
nat_type=NatType,
resolved_addresses=[ResolvedAddr|State#state.resolved_addresses]}),
resolved_addresses=[{failed, ResolvedAddr}|State#state.resolved_addresses]}),
{noreply, NewState}
end
end;
Expand Down Expand Up @@ -584,6 +586,8 @@ handle_info({stungun_reply, TxnID, LocalAddr}, State=#state{tid=TID, stun_txns=S
lager:info("Got dial back confirmation of observed address ~p", [ObservedAddr]),
case libp2p_config:lookup_listener(TID, LocalAddr) of
{ok, ListenerPid} ->
%% remove any prior stungun discovered addresses, if any
[ true = libp2p_config:remove_listener(TID, MultiAddr) || {resolved, MultiAddr} <- State#state.resolved_addresses ],
libp2p_config:insert_listener(TID, [ObservedAddr], ListenerPid),
%% don't need to start relay here, stop any we already have
libp2p_relay_server:stop(libp2p_swarm:swarm(TID)),
Expand All @@ -597,11 +601,12 @@ handle_info({stungun_reply, TxnID, LocalAddr}, State=#state{tid=TID, stun_txns=S
end,
libp2p_peerbook:update_nat_type(libp2p_swarm:peerbook(TID), NatType),
erlang:cancel_timer(State#state.stungun_timer),
ResolvedAddrs = [E || {resolved, _MultiAddr}=E <- State#state.resolved_addresses ],
%% clear the txnid so the timeout won't fire
{noreply, State#state{stun_txns=remove_stun_txn(TxnID, StunTxns),
nat_type=NatType,
stungun_timeout_count=0,
resolved_addresses=[ObservedAddr|State#state.resolved_addresses]}};
resolved_addresses=[{resolved, ObservedAddr}|State#state.resolved_addresses -- ResolvedAddrs]}};
false ->
%% don't clear the txnid so the stungun timeout will still be handled
lager:notice("unable to determine listener pid for ~p", [LocalAddr]),
Expand Down Expand Up @@ -960,6 +965,23 @@ distinct_observed_addrs(Addrs) ->
end, {[], []}, sets:to_list(Addrs)),
lists:usort(DistinctAddresses).

distinct_observed_addrs_for_ip(Addrs, ThisAddr) ->
{DistinctAddresses, _} = lists:foldl(fun({Reporter, Addr}, {Addresses, Reporters}) ->
case lists:member(Reporter, Reporters) of
true ->
{Addresses, Reporters};
false ->
%% check it shares the same IP as the supplied address
case hd(multiaddr:protocols(Addr)) == hd(multiaddr:protocols(ThisAddr)) of
true ->
{[Addr|Addresses], [Reporter|Reporters]};
false ->
{Addresses, Reporters}
end
end
end, {[], []}, sets:to_list(Addrs)),
lists:usort(DistinctAddresses).

-spec record_observed_addr(string(), string(), #state{}) -> #state{}.
record_observed_addr(_, _, State=#state{negotiated_nat=NegotiatedNat, nat_type=NatType}) when NegotiatedNat == true; NatType /= unknown ->
%% we have a upnp address, do nothing
Expand All @@ -972,7 +994,7 @@ record_observed_addr(PeerAddr, ObservedAddr, State=#state{tid=TID, observed_addr
false ->
% check if another peer has seen this address and we're not running a stun txn for this address
HasStunTxn = lists:member(ObservedAddr, maps:values(StunTxns)),
IsResolved = lists:member(ObservedAddr, State#state.resolved_addresses),
IsResolved = lists:keymember(ObservedAddr, 2, State#state.resolved_addresses),
case is_observed_addr(ObservedAddr, ObservedAddrs) of
true ->
case HasStunTxn orelse IsResolved of
Expand Down Expand Up @@ -1003,7 +1025,7 @@ record_observed_addr(PeerAddr, ObservedAddr, State=#state{tid=TID, observed_addr
lager:info("peer ~p informed us of our observed address ~p", [PeerAddr, ObservedAddr]),
%% check if we have `Limit' + 1 distinct observed addresses
%% make it an exact check so we don't do this constantly
case length(distinct_observed_addrs(ObservedAddresses)) == 3 of
case length(distinct_observed_addrs_for_ip(ObservedAddresses, ObservedAddr)) == 3 of
true ->
lager:info("Saw 3 distinct observed addresses, assuming symmetric NAT"),
libp2p_peerbook:update_nat_type(libp2p_swarm:peerbook(TID), symmetric),
Expand All @@ -1030,7 +1052,7 @@ attempt_port_forward_discovery(ObservedAddr, PeerAddr, State=#state{tid=TID, stu
{PeerPath, TxnID} = libp2p_stream_stungun:mk_stun_txn(list_to_integer(PortStr)),
[{"ip4", IP}, {"tcp", _}] = multiaddr:protocols(ObservedAddr),
ObservedAddr1 = "/ip4/"++IP++"/tcp/"++PortStr,
case lists:member(ObservedAddr1, State#state.resolved_addresses) of
case lists:keymember(ObservedAddr1, 2, State#state.resolved_addresses) of
true ->
%% we don't need to try this again
StateAcc;
Expand Down