Merge pull request #2498 from oasislabs/pro-wh/feature/xferwl

go staking: undisable transfers for some senders

.changelog/2498.feature.md

@@ -0,0 +1,7 @@
+Undisable transfers for some senders.
+
+Ostensibly for faucet purposes while we run the rest of the network with transfers disabled,
+this lets us identify a whitelist of accounts from which we allow transfers when otherwise transfers are disabled.
+
+Configure this with a map of allowed senders' public keys -> `true` in the new `undisable_transfers_from` field in the
+staking consensus parameters object along with `"disable_transfers": true`.

go/consensus/tendermint/apps/staking/transactions.go

@@ -2,13 +2,25 @@ package staking
 
 import (
 	"github.com/oasislabs/oasis-core/go/common/cbor"
+	"github.com/oasislabs/oasis-core/go/common/crypto/signature"
 	"github.com/oasislabs/oasis-core/go/common/quantity"
 	"github.com/oasislabs/oasis-core/go/consensus/tendermint/abci"
 	"github.com/oasislabs/oasis-core/go/consensus/tendermint/api"
 	stakingState "github.com/oasislabs/oasis-core/go/consensus/tendermint/apps/staking/state"
 	staking "github.com/oasislabs/oasis-core/go/staking/api"
 )
 
+func isTransferPermitted(params *staking.ConsensusParameters, fromID signature.PublicKey) (permitted bool) {
+	permitted = true
+	if params.DisableTransfers {
+		permitted = false
+		if params.UndisableTransfersFrom != nil && params.UndisableTransfersFrom[fromID] {
+			permitted = true
+		}
+	}
+	return
+}
+
 func (app *stakingApplication) transfer(ctx *abci.Context, state *stakingState.MutableState, xfer *staking.Transfer) error {
 	if ctx.IsCheckOnly() {
 		return nil
@@ -23,11 +35,11 @@ func (app *stakingApplication) transfer(ctx *abci.Context, state *stakingState.M
 		return err
 	}
 
-	if params.DisableTransfers {
+	fromID := ctx.TxSigner()
+	if !isTransferPermitted(params, fromID) {
 		return staking.ErrForbidden
 	}
 
-	fromID := ctx.TxSigner()
 	from := state.Account(fromID)
 
 	if fromID.Equal(xfer.To) {

go/staking/api/api.go

@@ -410,8 +410,9 @@ type ConsensusParameters struct {
 	GasCosts                          transaction.Costs                   `json:"gas_costs,omitempty"`
 	MinDelegationAmount               quantity.Quantity                   `json:"min_delegation,omitempty"`
 
-	DisableTransfers  bool `json:"disable_transfers,omitempty"`
-	DisableDelegation bool `json:"disable_delegation,omitempty"`
+	DisableTransfers       bool                         `json:"disable_transfers,omitempty"`
+	DisableDelegation      bool                         `json:"disable_delegation,omitempty"`
+	UndisableTransfersFrom map[signature.PublicKey]bool `json:"undisable_transfers_from,omitempty"`
 }
 
 const (