Add ledger entry diff to simulateTransaction response

.github/actions/setup-integration-tests/action.yml

@@ -53,6 +53,9 @@ runs:
       sudo apt-get remove -y moby-compose
       sudo apt-get install -y docker-compose-plugin
 
+      # add alias for docker compose
+      ln -f -s /usr/libexec/docker/cli-plugins/docker-compose /usr/local/bin/docker-compose
+
       echo "Docker Compose Version:"
       docker-compose version
 

.github/workflows/soroban-rpc.yml

@@ -107,7 +107,6 @@ jobs:
       matrix:
         os: [ubuntu-20.04, ubuntu-22.04]
         go: [1.22]
-        test: ['.*CLI.*', '^Test(([^C])|(C[^L])|(CL[^I])).*$']
     runs-on: ${{ matrix.os }}
     env:
       SOROBAN_RPC_INTEGRATION_TESTS_ENABLED: true
@@ -127,4 +126,4 @@ jobs:
       - name: Run Soroban RPC Integration Tests
         run: |
           make install_rust
-          go test -race -run '${{ matrix.test }}' -timeout 60m -v ./cmd/soroban-rpc/internal/test/...
+          go test -race -timeout 60m -v ./cmd/soroban-rpc/internal/test/...

cmd/soroban-rpc/internal/methods/simulate_transaction.go

@@ -3,7 +3,10 @@ package methods
 import (
 	"context"
 	"encoding/base64"
+	"encoding/json"
+	"errors"
 	"fmt"
+	"strings"
 
 	"github.com/creachadair/jrpc2"
 	"github.com/creachadair/jrpc2/handler"
@@ -34,6 +37,108 @@ type RestorePreamble struct {
 	TransactionData string `json:"transactionData"` // SorobanTransactionData XDR in base64
 	MinResourceFee  int64  `json:"minResourceFee,string"`
 }
+type LedgerEntryChangeType int
+
+const (
+	LedgerEntryChangeTypeCreated LedgerEntryChangeType = iota + 1
+	LedgerEntryChangeTypeUpdated
+	LedgerEntryChangeTypeDeleted
+)
+
+var (
+	LedgerEntryChangeTypeName = map[LedgerEntryChangeType]string{
+		LedgerEntryChangeTypeCreated: "created",
+		LedgerEntryChangeTypeUpdated: "updated",
+		LedgerEntryChangeTypeDeleted: "deleted",
+	}
+	LedgerEntryChangeTypeValue = map[string]LedgerEntryChangeType{
+		"created": LedgerEntryChangeTypeCreated,
+		"updated": LedgerEntryChangeTypeUpdated,
+		"deleted": LedgerEntryChangeTypeDeleted,
+	}
+)
+
+func (l LedgerEntryChangeType) String() string {
+	return LedgerEntryChangeTypeName[l]
+}
+
+func (l LedgerEntryChangeType) MarshalJSON() ([]byte, error) {
+	return json.Marshal(l.String())
+}
+
+func (l *LedgerEntryChangeType) Parse(s string) error {
+	s = strings.TrimSpace(strings.ToLower(s))
+	value, ok := LedgerEntryChangeTypeValue[s]
+	if !ok {
+		return fmt.Errorf("%q is not a valid ledger entry change type", s)
+	}
+	*l = value
+	return nil
+}
+
+func (l *LedgerEntryChangeType) UnmarshalJSON(data []byte) (err error) {
+	var s string
+	if err := json.Unmarshal(data, &s); err != nil {
+		return err
+	}
+	return l.Parse(s)
+}
+
+func (l *LedgerEntryChange) FromXDRDiff(diff preflight.XDRDiff) error {
+	beforePresent := len(diff.Before) > 0
+	afterPresent := len(diff.After) > 0
+	var (
+		entryXDR   []byte
+		changeType LedgerEntryChangeType
+	)
+	switch {
+	case beforePresent:
+		entryXDR = diff.Before
+		if afterPresent {
+			changeType = LedgerEntryChangeTypeUpdated
+		} else {
+			changeType = LedgerEntryChangeTypeDeleted
+		}
+	case afterPresent:
+		entryXDR = diff.After
+		changeType = LedgerEntryChangeTypeCreated
+	default:
+		return errors.New("missing before and after")
+	}
+	var entry xdr.LedgerEntry
+
+	if err := xdr.SafeUnmarshal(entryXDR, &entry); err != nil {
+		return err
+	}
+	key, err := entry.LedgerKey()
+	if err != nil {
+		return err
+	}
+	keyB64, err := xdr.MarshalBase64(key)
+	if err != nil {
+		return err
+	}
+	l.Type = changeType
+	l.Key = keyB64
+	if beforePresent {
+		before := base64.StdEncoding.EncodeToString(diff.Before)
+		l.Before = &before
+	}
+	if afterPresent {
+		after := base64.StdEncoding.EncodeToString(diff.After)
+		l.After = &after
+	}
+	return nil
+}
+
+// LedgerEntryChange designates a change in a ledger entry. Before and After cannot be be omitted at the same time.
+// If Before is omitted, it constitutes a creation, if After is omitted, it constitutes a delation.
+type LedgerEntryChange struct {
+	Type   LedgerEntryChangeType
+	Key    string  // LedgerEntryKey in base64
+	Before *string `json:"before"` // LedgerEntry XDR in base64
+	After  *string `json:"after"`  // LedgerEntry XDR in base64
+}
 
 type SimulateTransactionResponse struct {
 	Error           string                       `json:"error,omitempty"`
@@ -43,6 +148,7 @@ type SimulateTransactionResponse struct {
 	Results         []SimulateHostFunctionResult `json:"results,omitempty"`         // an array of the individual host function call results
 	Cost            SimulateTransactionCost      `json:"cost,omitempty"`            // the effective cpu and memory cost of the invoked transaction execution.
 	RestorePreamble *RestorePreamble             `json:"restorePreamble,omitempty"` // If present, it indicates that a prior RestoreFootprint is required
+	StateChanges    []LedgerEntryChange          `json:"stateChanges,omitempty"`    // If present, it indicates how the state (ledger entries) will change as a result of the transaction execution.
 	LatestLedger    uint32                       `json:"latestLedger"`
 }
 
@@ -149,6 +255,11 @@ func NewSimulateTransactionHandler(logger *log.Entry, ledgerEntryReader db.Ledge
 			}
 		}
 
+		stateChanges := make([]LedgerEntryChange, len(result.LedgerEntryDiff))
+		for i := 0; i < len(stateChanges); i++ {
+			stateChanges[i].FromXDRDiff(result.LedgerEntryDiff[i])
+		}
+
 		return SimulateTransactionResponse{
 			Error:           result.Error,
 			Results:         results,
@@ -161,6 +272,7 @@ func NewSimulateTransactionHandler(logger *log.Entry, ledgerEntryReader db.Ledge
 			},
 			LatestLedger:    latestLedger,
 			RestorePreamble: restorePreamble,
+			StateChanges:    stateChanges,
 		}
 	})
 }

cmd/soroban-rpc/internal/preflight/preflight.go

@@ -105,6 +105,11 @@ type PreflightParameters struct {
 	EnableDebug       bool
 }
 
+type XDRDiff struct {
+	Before []byte // optional before XDR
+	After  []byte // optional after XDR
+}
+
 type Preflight struct {
 	Error                     string
 	Events                    [][]byte // DiagnosticEvents XDR
@@ -116,6 +121,7 @@ type Preflight struct {
 	MemoryBytes               uint64
 	PreRestoreTransactionData []byte // SorobanTransactionData XDR
 	PreRestoreMinFee          int64
+	LedgerEntryDiff           []XDRDiff
 }
 
 func CXDR(xdr []byte) C.xdr_t {
@@ -138,6 +144,16 @@ func GoXDRVector(xdrVector C.xdr_vector_t) [][]byte {
 	return result
 }
 
+func GoXDRDiffVector(xdrDiffVector C.xdr_diff_vector_t) []XDRDiff {
+	result := make([]XDRDiff, xdrDiffVector.len)
+	inputSlice := unsafe.Slice(xdrDiffVector.array, xdrDiffVector.len)
+	for i, v := range inputSlice {
+		result[i].Before = GoXDR(v.before)
+		result[i].After = GoXDR(v.after)
+	}
+	return result
+}
+
 func GetPreflight(ctx context.Context, params PreflightParameters) (Preflight, error) {
 	switch params.OpBody.Type {
 	case xdr.OperationTypeInvokeHostFunction:
@@ -259,6 +275,7 @@ func GoPreflight(result *C.preflight_result_t) Preflight {
 		MemoryBytes:               uint64(result.memory_bytes),
 		PreRestoreTransactionData: GoXDR(result.pre_restore_transaction_data),
 		PreRestoreMinFee:          int64(result.pre_restore_min_fee),
+		LedgerEntryDiff:           GoXDRDiffVector(result.ledger_entry_diff),
 	}
 	return preflight
 }

cmd/soroban-rpc/internal/test/simulate_transaction_test.go

@@ -260,6 +260,20 @@ func TestSimulateTransactionSucceeds(t *testing.T) {
 	assert.NoError(t, err)
 	assert.Equal(t, expectedXdr, resultXdr)
 
+	// Check state diff
+	assert.Len(t, result.StateChanges, 1)
+	assert.Nil(t, result.StateChanges[0].Before)
+	assert.NotNil(t, result.StateChanges[0].After)
+	assert.Equal(t, methods.LedgerEntryChangeTypeCreated, result.StateChanges[0].Type)
+	var after xdr.LedgerEntry
+	assert.NoError(t, xdr.SafeUnmarshalBase64(*result.StateChanges[0].After, &after))
+	assert.Equal(t, xdr.LedgerEntryTypeContractCode, after.Data.Type)
+	entryKey, err := after.LedgerKey()
+	assert.NoError(t, err)
+	entryKeyB64, err := xdr.MarshalBase64(entryKey)
+	assert.NoError(t, err)
+	assert.Equal(t, entryKeyB64, result.StateChanges[0].Key)
+
 	// test operation which does not have a source account
 	withoutSourceAccountOp := createInstallContractCodeOperation("", contractBinary)
 	params = txnbuild.TransactionParams{

cmd/soroban-rpc/lib/preflight.h

@@ -22,21 +22,32 @@ typedef struct xdr_vector_t {
     size_t len;
 } xdr_vector_t;
 
+typedef struct xdr_diff_t {
+    xdr_t before;
+    xdr_t after;
+} xdr_diff_t;
+
+typedef struct xdr_diff_vector_t {
+    xdr_diff_t  *array;
+    size_t len;
+} xdr_diff_vector_t;
+
 typedef struct resource_config_t {
     uint64_t instruction_leeway; // Allow this many extra instructions when budgeting
 } resource_config_t;
 
 typedef struct preflight_result_t {
-    char          *error; // Error string in case of error, otherwise null
-    xdr_vector_t  auth; // array of SorobanAuthorizationEntries
-    xdr_t         result; // XDR SCVal
-    xdr_t         transaction_data;
-    int64_t       min_fee; // Minimum recommended resource fee
-    xdr_vector_t  events; // array of XDR DiagnosticEvents
-    uint64_t      cpu_instructions;
-    uint64_t      memory_bytes;
-    xdr_t         pre_restore_transaction_data; // SorobanTransactionData XDR for a prerequired RestoreFootprint operation
-    int64_t       pre_restore_min_fee; // Minimum recommended resource fee for a prerequired RestoreFootprint operation
+    char             *error; // Error string in case of error, otherwise null
+    xdr_vector_t      auth; // array of SorobanAuthorizationEntries
+    xdr_t             result; // XDR SCVal
+    xdr_t             transaction_data;
+    int64_t           min_fee; // Minimum recommended resource fee
+    xdr_vector_t      events; // array of XDR DiagnosticEvents
+    uint64_t          cpu_instructions;
+    uint64_t          memory_bytes;
+    xdr_t             pre_restore_transaction_data; // SorobanTransactionData XDR for a prerequired RestoreFootprint operation
+    int64_t           pre_restore_min_fee; // Minimum recommended resource fee for a prerequired RestoreFootprint operation
+    xdr_diff_vector_t ledger_entry_diff; // Contains the ledger entry changes which would be caused by the transaction execution
 } preflight_result_t;
 
 preflight_result_t *preflight_invoke_hf_op(uintptr_t handle, // Go Handle to forward to SnapshotSourceGet