From e229c8c3d75d37d0dcd06a4313626d8df3477950 Mon Sep 17 00:00:00 2001
From: Ethan Buchman <ethan@coinculture.info>
Date: Thu, 9 Feb 2017 22:44:43 -0500
Subject: [PATCH] rpc: /commit

---
 rpc/core/blocks.go          | 23 +++++++++++++++++++++++
 rpc/core/pipe.go            |  4 +++-
 rpc/core/routes.go          |  9 +++++++++
 rpc/core/types/responses.go |  7 +++++++
 4 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/rpc/core/blocks.go b/rpc/core/blocks.go
index 115ca2a9c..f1e47d416 100644
--- a/rpc/core/blocks.go
+++ b/rpc/core/blocks.go
@@ -44,3 +44,26 @@ func Block(height int) (*ctypes.ResultBlock, error) {
 	block := blockStore.LoadBlock(height)
 	return &ctypes.ResultBlock{blockMeta, block}, nil
 }
+
+//-----------------------------------------------------------------------------
+
+func Commit(height int) (*ctypes.ResultCommit, error) {
+	if height == 0 {
+		return nil, fmt.Errorf("Height must be greater than 0")
+	}
+	storeHeight := blockStore.Height()
+	if height > storeHeight {
+		return nil, fmt.Errorf("Height must be less than or equal to the current blockchain height")
+	}
+
+	// If the next block has not been committed yet,
+	// use a non-canonical commit
+	if height == storeHeight+1 {
+		commit := blockStore.LoadSeenCommit(height)
+		return &ctypes.ResultCommit{commit, false}, nil
+	}
+
+	// Return the canonical commit (comes from the block at height+1)
+	commit := blockStore.LoadBlockCommit(height)
+	return &ctypes.ResultCommit{commit, true}, nil
+}
diff --git a/rpc/core/pipe.go b/rpc/core/pipe.go
index 356a2ff0d..16bd8f20f 100644
--- a/rpc/core/pipe.go
+++ b/rpc/core/pipe.go
@@ -5,10 +5,10 @@ import (
 	"github.com/tendermint/go-crypto"
 	"github.com/tendermint/go-p2p"
 
+	abci "github.com/tendermint/abci/types"
 	"github.com/tendermint/tendermint/consensus"
 	"github.com/tendermint/tendermint/proxy"
 	"github.com/tendermint/tendermint/types"
-	abci "github.com/tendermint/abci/types"
 )
 
 //-----------------------------------------------------
@@ -19,6 +19,8 @@ type BlockStore interface {
 	Height() int
 	LoadBlockMeta(height int) *types.BlockMeta
 	LoadBlock(height int) *types.Block
+	LoadSeenCommit(height int) *types.Commit
+	LoadBlockCommit(height int) *types.Commit
 }
 
 type Consensus interface {
diff --git a/rpc/core/routes.go b/rpc/core/routes.go
index 8396cd23c..643b2bf02 100644
--- a/rpc/core/routes.go
+++ b/rpc/core/routes.go
@@ -18,6 +18,7 @@ var Routes = map[string]*rpc.RPCFunc{
 	"blockchain":           rpc.NewRPCFunc(BlockchainInfoResult, "minHeight,maxHeight"),
 	"genesis":              rpc.NewRPCFunc(GenesisResult, ""),
 	"block":                rpc.NewRPCFunc(BlockResult, "height"),
+	"commit":               rpc.NewRPCFunc(CommitResult, "height"),
 	"validators":           rpc.NewRPCFunc(ValidatorsResult, ""),
 	"dump_consensus_state": rpc.NewRPCFunc(DumpConsensusStateResult, ""),
 	"unconfirmed_txs":      rpc.NewRPCFunc(UnconfirmedTxsResult, ""),
@@ -107,6 +108,14 @@ func BlockResult(height int) (ctypes.TMResult, error) {
 	}
 }
 
+func CommitResult(height int) (ctypes.TMResult, error) {
+	if r, err := Commit(height); err != nil {
+		return nil, err
+	} else {
+		return r, nil
+	}
+}
+
 func ValidatorsResult() (ctypes.TMResult, error) {
 	if r, err := Validators(); err != nil {
 		return nil, err
diff --git a/rpc/core/types/responses.go b/rpc/core/types/responses.go
index 1a5deaeab..b68f169a4 100644
--- a/rpc/core/types/responses.go
+++ b/rpc/core/types/responses.go
@@ -23,6 +23,11 @@ type ResultBlock struct {
 	Block     *types.Block     `json:"block"`
 }
 
+type ResultCommit struct {
+	Commit    *types.Commit `json:"commit"`
+	Canonical bool          `json:"canonical"`
+}
+
 type ResultStatus struct {
 	NodeInfo          *p2p.NodeInfo `json:"node_info"`
 	PubKey            crypto.PubKey `json:"pub_key"`
@@ -106,6 +111,7 @@ const (
 	ResultTypeGenesis        = byte(0x01)
 	ResultTypeBlockchainInfo = byte(0x02)
 	ResultTypeBlock          = byte(0x03)
+	ResultTypeCommit         = byte(0x04)
 
 	// 0x2 bytes are for the network
 	ResultTypeStatus    = byte(0x20)
@@ -148,6 +154,7 @@ var _ = wire.RegisterInterface(
 	wire.ConcreteType{&ResultGenesis{}, ResultTypeGenesis},
 	wire.ConcreteType{&ResultBlockchainInfo{}, ResultTypeBlockchainInfo},
 	wire.ConcreteType{&ResultBlock{}, ResultTypeBlock},
+	wire.ConcreteType{&ResultCommit{}, ResultTypeCommit},
 	wire.ConcreteType{&ResultStatus{}, ResultTypeStatus},
 	wire.ConcreteType{&ResultNetInfo{}, ResultTypeNetInfo},
 	wire.ConcreteType{&ResultDialSeeds{}, ResultTypeDialSeeds},