This commit checks that the size of the bech32 encoded invoice is not
greater than 7092 bytes, which is the maximum number of bytes that can
fit into a QR code. This mitigates a potential DoS vector where an attacker
could craft a very large bech32 invoice string containing an absurd amount
of route and/or hop hints. If sent to an application that processes
payment requests, this would allocate a burdensome amount of memory
due to the public key parsing for each route/hop hint.
For a 1.7MB payment request, this yielded about 38MB in allocations
from just parsing public keys:
```
45.51MB 7.31% 92.07% 45.51MB 7.31% math/big.nat.make
25.50MB 4.09% 96.16% 25.50MB 4.09% github.com/lightningnetwork/lnd/zpay32.bech32VerifyChecksum
1MB 0.16% 96.32% 39.50MB 6.34% github.com/lightningnetwork/lnd/zpay32.parseRouteHint
1MB 0.16% 96.48% 33.50MB 5.38% github.com/btcsuite/btcd/btcec.decompressPoint
0.50MB 0.08% 96.56% 7.50MB 1.20% crypto/elliptic.(*CurveParams).doubleJacobian
0.50MB 0.08% 96.64% 38MB 6.10% github.com/btcsuite/btcd/btcec.ParsePubKey
0 0% 96.64% 12MB 1.93% crypto/ecdsa.Verify
0 0% 96.64% 8MB 1.28% crypto/elliptic.(*CurveParams).ScalarBaseMult
0 0% 96.64% 12MB 1.93% crypto/elliptic.(*CurveParams).ScalarMult
```
With this change, memory usage will be far lower as decoding will exit
early with an error if the invoice is too large.
In this commit, we update the router and link to support users
updating the max HTLC policy for their channels. By updating these internal
systems before updating the RPC server and lncli, we protect users from
being shown an option that doesn't actually work.
The policy update logic that resided part in the gossiper and
part in the rpc server is extracted into its own object.
This prepares for additional validation logic to be added for policy
updates that would otherwise make the gossiper heavier.
It is also a small first step towards separation of our own channel data
from the rest of the graph.
As a preparation for making the gossiper less responsible for validating
and supplementing local channel policy updates, this commits moves the
on-the-fly max htlc migration up the call tree. The plan for a follow up
commit is to move it out of the gossiper completely for local channel
updates, so that we don't need to return a list of final applied policies
anymore.
Since the ErrorCodes are not part of the spec, they cannot be read by
other implementations.
Instead of only sending the error code we therefore send the complete
error message. This will have the same effect at the client, as it will
just get the full error instead of the code indicating which error it
is. It will also be compatible with other impls.
Note that the GRPC error codes will change, since we don't set them
anymore.
Now that the link will remain ineligible until it receives
channel_reestablish from the remote peer, we can remove the channel
reestablish timeout entirely.
This commit modifies the link's EligibleToForward() method only return
true once the peers have successfully exchanged channel reestablish
messages. This is a preliminary step to increasing the reestablish
timeout, ensuring the switch won't try to forward over links while
we're waiting for the remote peer to resume the connection.
Since we will now wait to deliver the event after channel reestablish,
notifying when the link is added to the switch will no longer be
sufficient. Later, we will add receiving reestablish as an additional
requirement for EligibleToForward returning true.
The inactive ntfn is also moved, to ensure that we don't fire inactive
notifications if no corresponding active notification was sent.
This commit applies the same cd /tmp prefix to installations for all
dependencies. It also corrects the previous behavior, which requires the
cd /tmp to be in the same command, and not separate statements.
