spregistry: fix UnpackIntoInterface bug for getProvider*

spregistry/contract.go

@@ -2,6 +2,7 @@ package spregistry
 
 import (
 	"context"
+	"encoding/json"
 	"fmt"
 	"math/big"
 	"strings"
@@ -349,19 +350,8 @@ func (c *Contract) GetProvider(ctx context.Context, providerID *big.Int) (*GetPr
 		return nil, fmt.Errorf("getProvider call failed: %w", err)
 	}
 
-	var res struct {
-		ProviderID *big.Int `abi:"providerId"`
-		Info       struct {
-			ServiceProvider common.Address `abi:"serviceProvider"`
-			Payee           common.Address `abi:"payee"`
-			Name            string         `abi:"name"`
-			Description     string         `abi:"description"`
-			IsActive        bool           `abi:"isActive"`
-		} `abi:"info"`
-	}
-
-	err = c.abi.UnpackIntoInterface(&res, "getProvider", result)
-	if err != nil {
+	var res getProviderByAddressOutput
+	if err := unpackSingleTuple(c.abi, "getProvider", result, &res); err != nil {
 		return nil, fmt.Errorf("failed to unpack getProvider result: %w", err)
 	}
 
@@ -391,19 +381,8 @@ func (c *Contract) GetProviderByAddress(ctx context.Context, addr common.Address
 		return nil, fmt.Errorf("getProviderByAddress call failed: %w", err)
 	}
 
-	var res struct {
-		ProviderID *big.Int `abi:"providerId"`
-		Info       struct {
-			ServiceProvider common.Address `abi:"serviceProvider"`
-			Payee           common.Address `abi:"payee"`
-			Name            string         `abi:"name"`
-			Description     string         `abi:"description"`
-			IsActive        bool           `abi:"isActive"`
-		} `abi:"info"`
-	}
-
-	err = c.abi.UnpackIntoInterface(&res, "getProviderByAddress", result)
-	if err != nil {
+	var res getProviderByAddressOutput
+	if err := unpackSingleTuple(c.abi, "getProviderByAddress", result, &res); err != nil {
 		return nil, fmt.Errorf("failed to unpack getProviderByAddress result: %w", err)
 	}
 
@@ -419,6 +398,44 @@ func (c *Contract) GetProviderByAddress(ctx context.Context, addr common.Address
 	}, nil
 }
 
+// getProviderByAddressOutput mirrors the (providerId, info) tuple
+// getProviderByAddress returns. Tagged for json round-trip via
+// unpackSingleTuple below.
+type getProviderByAddressOutput struct {
+	ProviderID *big.Int                       `json:"providerId"`
+	Info       getProviderByAddressOutputInfo `json:"info"`
+}
+
+type getProviderByAddressOutputInfo struct {
+	ServiceProvider common.Address `json:"serviceProvider"`
+	Payee           common.Address `json:"payee"`
+	Name            string         `json:"name"`
+	Description     string         `json:"description"`
+	IsActive        bool           `json:"isActive"`
+}
+
+// unpackSingleTuple decodes an ABI method's single-tuple return into dst
+// via abi.Unpack + json round-trip. UnpackIntoInterface mishandles this
+// shape; Unpack returns the right anonymous struct, json copies it into
+// dst by matching json tags. dst must be a pointer to a tagged struct.
+func unpackSingleTuple(parsed abi.ABI, method string, payload []byte, dst any) error {
+	out, err := parsed.Unpack(method, payload)
+	if err != nil {
+		return err
+	}
+	if len(out) != 1 {
+		return fmt.Errorf("%s: expected 1 output, got %d", method, len(out))
+	}
+	buf, err := json.Marshal(out[0])
+	if err != nil {
+		return fmt.Errorf("%s: marshal unpacked tuple: %w", method, err)
+	}
+	if err := json.Unmarshal(buf, dst); err != nil {
+		return fmt.Errorf("%s: decode into %T: %w", method, dst, err)
+	}
+	return nil
+}
+
 func (c *Contract) GetProviderIDByAddress(ctx context.Context, addr common.Address) (*big.Int, error) {
 	data, err := c.abi.Pack("getProviderIdByAddress", addr)
 	if err != nil {
@@ -446,10 +463,10 @@ func (c *Contract) GetProviderIDByAddress(ctx context.Context, addr common.Addre
 }
 
 type GetProviderWithProductResult struct {
-	ProviderID               *big.Int
-	ProviderInfo             RawProviderInfo
-	Product                  RawProduct
-	ProductCapabilityValues  [][]byte
+	ProviderID              *big.Int
+	ProviderInfo            RawProviderInfo
+	Product                 RawProduct
+	ProductCapabilityValues [][]byte
 }
 
 func (c *Contract) GetProviderWithProduct(ctx context.Context, providerID *big.Int, productType uint8) (*GetProviderWithProductResult, error) {

spregistry/contract_test.go

@@ -0,0 +1,77 @@
+package spregistry
+
+import (
+	"math/big"
+	"strings"
+	"testing"
+
+	"github.com/ethereum/go-ethereum/accounts/abi"
+	"github.com/ethereum/go-ethereum/common"
+)
+
+// TestUnpackSingleTuple_GetProviderByAddress exercises the unpack path
+// Contract.GetProviderByAddress uses, against a synthetic return blob.
+// Reproduces the calibnet bug if unpackSingleTuple regresses to
+// UnpackIntoInterface (which mishandles this shape).
+func TestUnpackSingleTuple_GetProviderByAddress(t *testing.T) {
+	parsedABI, err := abi.JSON(strings.NewReader(SPRegistryABIJSON))
+	if err != nil {
+		t.Fatalf("parse ABI: %v", err)
+	}
+
+	method, ok := parsedABI.Methods["getProviderByAddress"]
+	if !ok {
+		t.Fatalf("getProviderByAddress not found in ABI")
+	}
+
+	type infoT struct {
+		ServiceProvider common.Address `abi:"serviceProvider"`
+		Payee           common.Address `abi:"payee"`
+		Name            string         `abi:"name"`
+		Description     string         `abi:"description"`
+		IsActive        bool           `abi:"isActive"`
+	}
+	type outT struct {
+		ProviderID *big.Int `abi:"providerId"`
+		Info       infoT    `abi:"info"`
+	}
+	want := outT{
+		ProviderID: big.NewInt(24),
+		Info: infoT{
+			ServiceProvider: common.HexToAddress("0xE3e842B9D89ed2Ee3976b9b8916827302618c29e"),
+			Payee:           common.HexToAddress("0xE3e842B9D89ed2Ee3976b9b8916827302618c29e"),
+			Name:            "sp-playground",
+			Description:     "calibnet test SP",
+			IsActive:        true,
+		},
+	}
+
+	payload, err := method.Outputs.Pack(want)
+	if err != nil {
+		t.Fatalf("pack synthetic return: %v", err)
+	}
+
+	var got getProviderByAddressOutput
+	if err := unpackSingleTuple(parsedABI, "getProviderByAddress", payload, &got); err != nil {
+		t.Fatalf("unpackSingleTuple: %v", err)
+	}
+
+	if got.ProviderID == nil || got.ProviderID.Cmp(big.NewInt(24)) != 0 {
+		t.Errorf("ProviderID = %v, want 24", got.ProviderID)
+	}
+	if got.Info.ServiceProvider != want.Info.ServiceProvider {
+		t.Errorf("ServiceProvider = %s, want %s", got.Info.ServiceProvider, want.Info.ServiceProvider)
+	}
+	if got.Info.Payee != want.Info.Payee {
+		t.Errorf("Payee = %s, want %s", got.Info.Payee, want.Info.Payee)
+	}
+	if got.Info.Name != want.Info.Name {
+		t.Errorf("Name = %q, want %q", got.Info.Name, want.Info.Name)
+	}
+	if got.Info.Description != want.Info.Description {
+		t.Errorf("Description = %q, want %q", got.Info.Description, want.Info.Description)
+	}
+	if !got.Info.IsActive {
+		t.Errorf("IsActive = false, want true")
+	}
+}