In deciding whether to relay a proposal or validation, a server would
consider whether it was issued by a validator on that server's UNL.
While both trusted proposals and validations were always relayed,
the code prioritized relaying of untrusted proposals over untrusted
validations. While not technically incorrect, validations are
generally more "valuable" because they are required during the
consensus process, whereas proposals are not, strictly, required.
The commit introduces two new configuration options, allowing server
operators to fine-tune the relaying behavior:
The `[relay_proposals]` option controls the relaying behavior for
proposals received by this server. It has two settings: "trusted"
and "all" and the default is "trusted".
The `[relay_validations]` options controls the relaying behavior for
validations received by this server. It has two settings: "trusted"
and "all" and the default is "all".
This change does not require an amendment as it does not affect
transaction processing.
The sfLedgerSequence field is designated as optional in the object
template but it is effectively required and validations which do not
include it were, correctly, rejected.
This commit migrates the check outside of the peer code and into the
constructor used for validations being deserialized for the network.
Furthermore, the code will generate an error if a validation that is
generated by a server does not include the field.
This commit introduces the "HardenedValidations" amendment which,
if enabled, allows validators to include additional information in
their validations that can increase the robustness of consensus.
Specifically, the commit introduces a new optional field that can
be set in validation messages can be used to attest to the hash of
the latest ledger that a validator considers to be fully validated.
Additionally, the commit leverages the previously introduced "cookie"
field to improve the robustness of the network by making it possible
for servers to automatically detect accidental misconfiguration which
results in two or more validators using the same validation key.
Each validator will generate a random cookie on startup that it will
include in each of its validations. This will allow validators to detect
when more than one validator is accidentally operating with the same
validation keys.
These changes use the hash of the consensus transaction set when
characterizing the mismatch between a locally built ledger and fully
validated network ledger. This allows detection of non-determinism in
transaction process, in which consensus succeeded, but a node somehow
generated a different subsequent ledger.
These changes augment the Validations class with a LedgerTrie to better
track the history of support for validated ledgers. This improves the
selection of the preferred working ledger for consensus. The Validations
class now tracks both full and partial validations. Partial validations
are only used to determine the working ledger; full validations are
required for any quorum related function. Validators are also now
explicitly restricted to sending validations with increasing ledger
sequence number.
