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Trampoline routing.

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- trampoline is enabled by default in config, to prevent download of `gossip_db`.
   (if disabled, `gossip_db` will be downloaded, regardless of the existence of channels)
 - if trampoline is enabled:
    - the wallet can only open channels with trampoline nodes
    - already-existing channels with non-trampoline nodes are frozen for sending.
 - there are two types of trampoline payments: legacy and end-to-end (e2e).
 - we decide to perform legacy or e2e based on the invoice:
    - we use trampoline_routing_opt in features to detect Eclair and Phoenix invoices
    - we use trampoline_routing_hints to detect Electrum invoices
 - when trying a legacy payment, we add a second trampoline to the path to preserve privacy.
   (we fall back to a single trampoline if the payment fails for all trampolines)
 - the trampoline list is hardcoded, it will remain so until `trampoline_routing_opt` feature flag is in INIT.
 - there are currently only two nodes in the hardcoded list, it would be nice to have more.
 - similar to Phoenix, we find the fee/cltv by trial-and-error.
    - if there is a second trampoline in the path, we use the same fee for both.
    - the final spec should add fee info in error messages, so we will be able to fine-tune fees
This commit is contained in:
ThomasV
2020-11-11 11:03:31 +01:00
parent f4fe80dfd1
commit ded449233e
19 changed files with 541 additions and 107 deletions
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10
electrum/lnutil.py
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@@ -949,6 +949,15 @@ class LnFeatures(IntFlag):
_ln_feature_contexts[OPTION_SUPPORT_LARGE_CHANNEL_OPT] = (LNFC.INIT | LNFC.NODE_ANN | LNFC.CHAN_ANN_ALWAYS_EVEN)
_ln_feature_contexts[OPTION_SUPPORT_LARGE_CHANNEL_REQ] = (LNFC.INIT | LNFC.NODE_ANN | LNFC.CHAN_ANN_ALWAYS_EVEN)
OPTION_TRAMPOLINE_ROUTING_REQ = 1 << 50
OPTION_TRAMPOLINE_ROUTING_OPT = 1 << 51
# We do not set trampoline_routing_opt in invoices, because the spec is not ready.
# This ensures that current version of Phoenix can pay us
# It also prevents Electrum from using t_tags from future implementations
_ln_feature_contexts[OPTION_TRAMPOLINE_ROUTING_REQ] = (LNFC.INIT | LNFC.NODE_ANN) # | LNFC.INVOICE)
_ln_feature_contexts[OPTION_TRAMPOLINE_ROUTING_OPT] = (LNFC.INIT | LNFC.NODE_ANN) # | LNFC.INVOICE)
def validate_transitive_dependencies(self) -> bool:
# for all even bit set, set corresponding odd bit:
features = self # copy
@@ -1014,6 +1023,7 @@ LN_FEATURES_IMPLEMENTED = (
| LnFeatures.OPTION_STATIC_REMOTEKEY_OPT | LnFeatures.OPTION_STATIC_REMOTEKEY_REQ
| LnFeatures.VAR_ONION_OPT | LnFeatures.VAR_ONION_REQ
| LnFeatures.PAYMENT_SECRET_OPT | LnFeatures.PAYMENT_SECRET_REQ
| LnFeatures.OPTION_TRAMPOLINE_ROUTING_OPT | LnFeatures.OPTION_TRAMPOLINE_ROUTING_REQ
)