From e2aebf5c529e84968498148d7ca5199ea5b1456a Mon Sep 17 00:00:00 2001
From: Warren He <w@oasislabs.com>
Date: Fri, 20 Dec 2019 16:40:59 -0800
Subject: [PATCH 1/2] go staking: undisable transfers for some senders

---
 .../tendermint/apps/staking/transactions.go      | 16 ++++++++++++++--
 go/staking/api/api.go                            |  5 +++--
 2 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/go/consensus/tendermint/apps/staking/transactions.go b/go/consensus/tendermint/apps/staking/transactions.go
index ab57988e14d..e1d2462b822 100644
--- a/go/consensus/tendermint/apps/staking/transactions.go
+++ b/go/consensus/tendermint/apps/staking/transactions.go
@@ -2,6 +2,7 @@ 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"
@@ -9,6 +10,17 @@ import (
 	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) {
diff --git a/go/staking/api/api.go b/go/staking/api/api.go
index 2c65597d5bc..3d002a1d17c 100644
--- a/go/staking/api/api.go
+++ b/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 (

From 65a3db6e6c13a4fdeb98cde41dc58efcc9929db1 Mon Sep 17 00:00:00 2001
From: Warren He <w@oasislabs.com>
Date: Mon, 23 Dec 2019 10:52:32 -0800
Subject: [PATCH 2/2] add changelog

---
 .changelog/2498.feature.md | 7 +++++++
 1 file changed, 7 insertions(+)
 create mode 100644 .changelog/2498.feature.md

diff --git a/.changelog/2498.feature.md b/.changelog/2498.feature.md
new file mode 100644
index 00000000000..78f378f0aef
--- /dev/null
+++ b/.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`.