service/state: Implement balance verification against AppHash

docs/adr/adr-004-state-interaction.md

@@ -69,9 +69,54 @@ type StateAccessor interface {
 
 ### Verification of Balances
 In order to check that the balances returned via the `AccountBalance` query are correct, it is necessary to also request
-Merkle proofs from the celestia-app and verify them against the latest head's `AppHash`. In order for the `StateAccessor`
-to do this, it would need access to the `header.Store`'s `Head()` method in order to get the latest known header of the 
-node and check its `AppHash`.
+Merkle proofs from celestia-app and verify them against the latest head's `AppHash`.
+
+In order for the `StateAccessor` to do this, it would need access to the `header.Getter`'s `Head()` method in order to get the latest known header of the node and check its `AppHash`.
+Then, instead of performing a regular `gRPC` query against the celestia-app's bank module, it would perform an ABCI request query via RPC as such: 
+
+```go
+  prefixedAccountKey := append(bank_types.CreateAccountBalancesPrefix(addr.Bytes()), []byte(app.BondDenom)...)
+  abciReq := abci.RequestQuery{
+      Path:   fmt.Sprintf("store/%s/key", bank_types.StoreKey),
+      // we request the balance at the block *previous* to the current head as
+      // the AppHash committed to the head is calculated by applying the previous
+      // block's transaction list, not the current block, meaning the head's AppHash
+      // is actually a result of the previous block's transactions.
+      Height: head.Height - 1,
+      Data:   prefixedAccountKey,
+      // we set this value to `true` in order to get proofs in the response
+      // that we can use to verify against the head's AppHash.
+      Prove:  true,
+  }
+  result, err := ca.rpcCli.ABCIQueryWithOptions(ctx, abciReq.Path, abciReq.Data,  rpc_client.ABCIQueryOptions{})
+  if err != nil {
+      return nil, err
+  }
+```
+
+The result of the above request will contain the balance of the queried address and proofs that can be used to verify 
+the returned balance against the current head's `AppHash`. The proofs are returned as the type `crypto.ProofOps` which 
+itself is not really functional until converted into a more useful wrapper, `MerkleProof`, provided by the `ibc-go`
+[23-commitment/types pkg](https://github.com/cosmos/ibc-go/blob/main/modules/core/23-commitment/types/utils.go#L10).
+
+Using `types.ConvertProofs()` returns a `types.MerkleProof` that wraps a chain of commitment proofs with which you can
+verify the membership of the returned balance in the tree of the given root (the `AppHash` from the head), as such: 
+
+```go
+ // convert proofs into a more digestible format
+ merkleproof, err := proof_utils.ConvertProofs(result.Response.GetProofOps())
+ if err != nil {
+     return nil, err
+ }
+ root := proof_utils.NewMerkleRoot(head.AppHash)
+ // VerifyMembership expects the path as:
+ // []string{<store key of module>, <actual key corresponding to requested value>}
+ path := proof_utils.NewMerklePath(bank_types.StoreKey, string(prefixedAccountKey))
+ err = merkleproof.VerifyMembership(proof_utils.GetSDKSpecs(), root, path, result.Response.Value)
+ if err != nil {
+     return nil, err
+ }
+```
 
 ### Availability of `StateService` during sync
 The `Syncer` in the `header`  package provides one public method, `Finished()`, that indicates whether the syncer has 

go.mod

@@ -11,6 +11,8 @@ require (
 	github.com/celestiaorg/nmt v0.10.0
 	github.com/celestiaorg/rsmt2d v0.5.0
 	github.com/cosmos/cosmos-sdk v0.46.0-beta2.0.20220418184507-c53157dd63f6
+	github.com/cosmos/cosmos-sdk/api v0.1.0
+	github.com/cosmos/ibc-go/v4 v4.0.0-rc0
 	github.com/dgraph-io/badger/v2 v2.2007.4
 	github.com/gammazero/workerpool v1.1.2
 	github.com/gogo/protobuf v1.3.3
@@ -61,7 +63,7 @@ require (
 	filippo.io/edwards25519 v1.0.0-rc.1 // indirect
 	github.com/99designs/keyring v1.1.6 // indirect
 	github.com/Workiva/go-datastructures v1.0.53 // indirect
-	github.com/armon/go-metrics v0.3.10 // indirect
+	github.com/armon/go-metrics v0.4.0 // indirect
 	github.com/aws/aws-sdk-go v1.40.45 // indirect
 	github.com/benbjohnson/clock v1.3.0 // indirect
 	github.com/beorn7/perks v1.0.1 // indirect
@@ -107,7 +109,6 @@ require (
 	github.com/fsnotify/fsnotify v1.5.4 // indirect
 	github.com/gammazero/deque v0.1.0 // indirect
 	github.com/go-kit/kit v0.12.0 // indirect
-	github.com/go-playground/validator/v10 v10.4.1 // indirect
 	github.com/go-task/slim-sprig v0.0.0-20210107165309-348f09dbbbc0 // indirect
 	github.com/godbus/dbus v0.0.0-20190726142602-4481cbc300e2 // indirect
 	github.com/godbus/dbus/v5 v5.0.4 // indirect

go.sum

@@ -106,8 +106,8 @@ github.com/apache/thrift v0.13.0/go.mod h1:cp2SuWMxlEZw2r+iP2GNCdIi4C1qmUzdZFSVb
 github.com/armon/circbuf v0.0.0-20150827004946-bbbad097214e/go.mod h1:3U/XgcO3hCbHZ8TKRvWD2dDTCfh9M9ya+I9JpbB7O8o=
 github.com/armon/consul-api v0.0.0-20180202201655-eb2c6b5be1b6/go.mod h1:grANhF5doyWs3UAsr3K4I6qtAmlQcZDesFNEHPZAzj8=
 github.com/armon/go-metrics v0.0.0-20180917152333-f0300d1749da/go.mod h1:Q73ZrmVTwzkszR9V5SSuryQ31EELlFMUz1kKyl939pY=
-github.com/armon/go-metrics v0.3.10 h1:FR+drcQStOe+32sYyJYyZ7FIdgoGGBnwLl+flodp8Uo=
-github.com/armon/go-metrics v0.3.10/go.mod h1:4O98XIr/9W0sxpJ8UaYkvjk10Iff7SnFrb4QAOwNTFc=
+github.com/armon/go-metrics v0.4.0 h1:yCQqn7dwca4ITXb+CbubHmedzaQYHhNhrEXLYUeEe8Q=
+github.com/armon/go-metrics v0.4.0/go.mod h1:E6amYzXo6aW1tqzoZGT755KkbgrJsSdpwZ+3JqfkOG4=
 github.com/armon/go-radix v0.0.0-20180808171621-7fddfc383310/go.mod h1:ufUuZ+zHj4x4TnLV4JWEpy2hxWSpsRywHrMgIH9cCH8=
 github.com/aryann/difflib v0.0.0-20170710044230-e206f873d14a/go.mod h1:DAHtR1m6lCRdSC2Tm3DSWRPvIPr6xNKyeHdqDQSQT+A=
 github.com/aws/aws-lambda-go v1.13.3/go.mod h1:4UKl9IzQMoD+QF79YdCuzCwp8VbmG4VAQwij/eHl5CU=
@@ -234,6 +234,7 @@ github.com/cosmos/btcutil v1.0.4/go.mod h1:Ffqc8Hn6TJUdDgHBwIZLtrLQC1KdJ9jGJl/Tv
 github.com/cosmos/cosmos-proto v1.0.0-alpha7 h1:yqYUOHF2jopwZh4dVQp3xgqwftE5/2hkrwIV6vkUbO0=
 github.com/cosmos/cosmos-proto v1.0.0-alpha7/go.mod h1:dosO4pSAbJF8zWCzCoTWP7nNsjcvSUBQmniFxDg5daw=
 github.com/cosmos/cosmos-sdk/api v0.1.0 h1:xfSKM0e9p+EJTMQnf5PbWE6VT8ruxTABIJ64Rd064dE=
+github.com/cosmos/cosmos-sdk/api v0.1.0/go.mod h1:CupqQBskAOiTXO1XDZ/wrtWzN/wTxUvbQmOqdUhR8wI=
 github.com/cosmos/cosmos-sdk/db v1.0.0-beta.1 h1:6YvzjQtc+cDwCe9XwYPPa8zFCxNG79N7vmCjpK+vGOg=
 github.com/cosmos/cosmos-sdk/errors v1.0.0-beta.3 h1:Ep7FHNViVwwGnwLFEPewZYsyN2CJNVMmMvFmtNQtbnw=
 github.com/cosmos/cosmos-sdk/errors v1.0.0-beta.3/go.mod h1:HFea93YKmoMJ/mNKtkSeJZDtyJ4inxBsUK928KONcqo=
@@ -243,6 +244,8 @@ github.com/cosmos/gorocksdb v1.2.0 h1:d0l3jJG8M4hBouIZq0mDUHZ+zjOx044J3nGRskwTb4
 github.com/cosmos/gorocksdb v1.2.0/go.mod h1:aaKvKItm514hKfNJpUJXnnOWeBnk2GL4+Qw9NHizILw=
 github.com/cosmos/iavl v0.18.0 h1:02ur4vnalMR2GuWCFNkuseUcl/BCVmg9tOeHOGiZOkE=
 github.com/cosmos/iavl v0.18.0/go.mod h1:L0VZHfq0tqMNJvXlslGExaaiZM7eSm+90Vh9QUbp6j4=
+github.com/cosmos/ibc-go/v4 v4.0.0-rc0 h1:zeMr6PNE7L300AcGkrMwRvtp62/RpGc7qU1LwhUcPKc=
+github.com/cosmos/ibc-go/v4 v4.0.0-rc0/go.mod h1:4LK+uPycPhebJrJ8ebIqvsMEZ0lVRVNTiEyeI9zfB0U=
 github.com/cosmos/ledger-cosmos-go v0.11.1 h1:9JIYsGnXP613pb2vPjFeMMjBI5lEDsEaF6oYorTy6J4=
 github.com/cosmos/ledger-cosmos-go v0.11.1/go.mod h1:J8//BsAGTo3OC/vDLjMRFLW6q0WAaXvHnVc7ZmE8iUY=
 github.com/cosmos/ledger-go v0.9.2 h1:Nnao/dLwaVTk1Q5U9THldpUMMXU94BOTWPddSmVB6pI=
@@ -373,7 +376,6 @@ github.com/go-playground/universal-translator v0.17.0 h1:icxd5fm+REJzpZx7ZfpaD87
 github.com/go-playground/universal-translator v0.17.0/go.mod h1:UkSxE5sNxxRwHyU+Scu5vgOQjsIJAF8j9muTVoKLVtA=
 github.com/go-playground/validator/v10 v10.2.0/go.mod h1:uOYAAleCW8F/7oMFd6aG0GOhaH6EGOAJShg8Id5JGkI=
 github.com/go-playground/validator/v10 v10.4.1 h1:pH2c5ADXtd66mxoE0Zm9SUhxE20r7aM3F26W0hOn+GE=
-github.com/go-playground/validator/v10 v10.4.1/go.mod h1:nlOn6nFhuKACm19sB/8EGNn9GlaMV7XkbRSipzJ0Ii4=
 github.com/go-sql-driver/mysql v1.4.0/go.mod h1:zAC/RDZ24gD3HViQzih4MyKcchzm+sOG5ZlKdlhCg5w=
 github.com/go-stack/stack v1.8.0/go.mod h1:v0f6uXyyMGvRgIKkXu+yp6POWl0qKG85gN/melR3HDY=
 github.com/go-task/slim-sprig v0.0.0-20210107165309-348f09dbbbc0 h1:p104kn46Q8WdvHunIJ9dAyjPVtrBPhSr3KT2yUst43I=

node/components.go

@@ -92,7 +92,7 @@ func baseComponents(cfg *Config, store Store) fx.Option {
 		fx.Invoke(invokeWatchdog(store.Path())),
 		p2p.Components(cfg.P2P),
 		// state components
-		statecomponents.Components(cfg.Core.IP, cfg.Core.GRPCPort, cfg.Key),
+		statecomponents.Components(cfg.Core, cfg.Key),
 		// RPC components
 		fx.Provide(rpc.Server(cfg.RPC)),
 	)

node/state/core.go

@@ -4,17 +4,19 @@ import (
 	"go.uber.org/fx"
 
 	apptypes "github.com/celestiaorg/celestia-app/x/payment/types"
+	"github.com/celestiaorg/celestia-node/header"
 	"github.com/celestiaorg/celestia-node/service/state"
 )
 
 // CoreAccessor constructs a new instance of state.Accessor over
 // a celestia-core connection.
 func CoreAccessor(
 	coreIP,
-	grpcPort string,
-) func(fx.Lifecycle, *apptypes.KeyringSigner) (state.Accessor, error) {
-	return func(lc fx.Lifecycle, signer *apptypes.KeyringSigner) (state.Accessor, error) {
-		ca := state.NewCoreAccessor(signer, coreIP, grpcPort)
+	coreRPC,
+	coreGRPC string,
+) func(fx.Lifecycle, *apptypes.KeyringSigner, header.Store) (state.Accessor, error) {
+	return func(lc fx.Lifecycle, signer *apptypes.KeyringSigner, getter header.Store) (state.Accessor, error) {
+		ca := state.NewCoreAccessor(signer, getter, coreIP, coreRPC, coreGRPC)
 		lc.Append(fx.Hook{
 			OnStart: ca.Start,
 			OnStop:  ca.Stop,

node/state/state.go

@@ -7,7 +7,9 @@ import (
 	"go.uber.org/fx"
 
 	"github.com/celestiaorg/celestia-node/fraud"
+	"github.com/celestiaorg/celestia-node/header"
 	"github.com/celestiaorg/celestia-node/libs/fxutil"
+	"github.com/celestiaorg/celestia-node/node/core"
 	"github.com/celestiaorg/celestia-node/node/key"
 	"github.com/celestiaorg/celestia-node/node/services"
 	"github.com/celestiaorg/celestia-node/service/state"
@@ -17,17 +19,23 @@ var log = logging.Logger("state-access-constructor")
 
 // Components provides all components necessary to construct the
 // state service.
-func Components(coreIP, grpcPort string, cfg key.Config) fx.Option {
+func Components(coreCfg core.Config, keyCfg key.Config) fx.Option {
 	return fx.Options(
-		fx.Provide(Keyring(cfg)),
-		fx.Provide(CoreAccessor(coreIP, grpcPort)),
+		fx.Provide(Keyring(keyCfg)),
+		fx.Provide(CoreAccessor(coreCfg.IP, coreCfg.RPCPort, coreCfg.GRPCPort)),
 		fx.Provide(Service),
 	)
 }
 
 // Service constructs a new state.Service.
-func Service(ctx context.Context, lc fx.Lifecycle, accessor state.Accessor, fservice fraud.Service) *state.Service {
-	serv := state.NewService(accessor)
+func Service(
+	ctx context.Context,
+	lc fx.Lifecycle,
+	accessor state.Accessor,
+	store header.Store,
+	fservice fraud.Service,
+) *state.Service {
+	serv := state.NewService(accessor, store)
 	lifecycleCtx := fxutil.WithLifecycle(ctx, lc)
 	lc.Append(fx.Hook{
 		OnStart: func(startCtx context.Context) error {

service/rpc/endpoints.go

@@ -8,7 +8,7 @@ import (
 func (h *Handler) RegisterEndpoints(rpc *Server) {
 	// state endpoints
 	rpc.RegisterHandlerFunc(balanceEndpoint, h.handleBalanceRequest, http.MethodGet)
-	rpc.RegisterHandlerFunc(fmt.Sprintf("%s/{%s}", balanceEndpoint, addrKey), h.handleBalanceForAddrRequest,
+	rpc.RegisterHandlerFunc(fmt.Sprintf("%s/{%s}", balanceEndpoint, addrKey), h.handleBalanceRequest,
 		http.MethodGet)
 	rpc.RegisterHandlerFunc(submitTxEndpoint, h.handleSubmitTx, http.MethodPost)
 	rpc.RegisterHandlerFunc(submitPFDEndpoint, h.handleSubmitPFD, http.MethodPost)

service/rpc/state.go

@@ -8,6 +8,8 @@ import (
 
 	"github.com/cosmos/cosmos-sdk/types"
 	"github.com/gorilla/mux"
+
+	"github.com/celestiaorg/celestia-node/service/state"
 )
 
 const (
@@ -39,33 +41,24 @@ type transferRequest struct {
 }
 
 func (h *Handler) handleBalanceRequest(w http.ResponseWriter, r *http.Request) {
-	bal, err := h.state.Balance(r.Context())
-	if err != nil {
-		writeError(w, http.StatusInternalServerError, balanceEndpoint, err)
-		return
-	}
-	resp, err := json.Marshal(bal)
-	if err != nil {
-		writeError(w, http.StatusInternalServerError, balanceEndpoint, err)
-		return
-	}
-	_, err = w.Write(resp)
-	if err != nil {
-		log.Errorw("writing response", "endpoint", balanceEndpoint, "err", err)
-	}
-}
-
-func (h *Handler) handleBalanceForAddrRequest(w http.ResponseWriter, r *http.Request) {
+	var (
+		bal *state.Balance
+		err error
+	)
 	// read and parse request
 	vars := mux.Vars(r)
-	addrStr := vars[addrKey]
-	// convert address to Address type
-	addr, err := types.AccAddressFromBech32(addrStr)
-	if err != nil {
-		writeError(w, http.StatusBadRequest, balanceEndpoint, err)
-		return
+	addrStr, exists := vars[addrKey]
+	if exists {
+		// convert address to Address type
+		addr, addrerr := types.AccAddressFromBech32(addrStr)
+		if addrerr != nil {
+			writeError(w, http.StatusBadRequest, balanceEndpoint, addrerr)
+			return
+		}
+		bal, err = h.state.BalanceForAddress(r.Context(), addr)
+	} else {
+		bal, err = h.state.Balance(r.Context())
 	}
-	bal, err := h.state.BalanceForAddress(r.Context(), addr)
 	if err != nil {
 		writeError(w, http.StatusInternalServerError, balanceEndpoint, err)
 		return