160 multi chain payment support

gateway/config.go

@@ -5,6 +5,7 @@ import (
 	"log"
 	"net/url"
 	"os"
+	"strconv"
 	"strings"
 	"time"
 )
@@ -16,6 +17,33 @@ const (
 	receiptStoreModeMemory = "memory"
 )
 
+// GetSupportedChainIds defines the network IDs allowed for payment requests.
+// 84532: Base Sepolia, 11155111: Ethereum Sepolia, 11155240: Optimism Sepolia.
+func GetSupportedChainIds() []int64 {
+	chainIDs := []int64{84532, 11155111, 11155240}
+	envKeys := []string{"CHAIN_ID", "EXPECTED_CHAIN_ID"}
+	for _, key := range envKeys {
+		if val := os.Getenv(key); val != "" {
+			if id, err := strconv.ParseInt(val, 10, 64); err == nil {
+				found := false
+				for _, existing := range chainIDs {
+					if existing == id {
+						found = true
+						break
+					}
+				}
+				if !found {
+					chainIDs = append(chainIDs, id)
+					log.Printf("Dynamically registered chain ID %d from env var %s", id, key)
+				}
+			} else {
+				log.Printf("Warning: failed to parse %s=%s as int64", key, val)
+			}
+		}
+	}
+	return chainIDs
+}
+
 func getAllowedOrigins() []string {
 	raw := strings.TrimSpace(os.Getenv("ALLOWED_ORIGINS"))
 	if raw == "" {
@@ -87,9 +115,10 @@ func getPositiveTimeout(envKey string, defaultSeconds int) time.Duration {
 }
 
 // Timeout helpers (configurable via env vars)
-func getRequestTimeout() time.Duration  { return getPositiveTimeout("REQUEST_TIMEOUT_SECONDS", 60) }
-func getAITimeout() time.Duration       { return getPositiveTimeout("AI_REQUEST_TIMEOUT_SECONDS", 30) }
-func getVerifierTimeout() time.Duration { return getPositiveTimeout("VERIFIER_TIMEOUT_SECONDS", 2) }
+func getRequestTimeout() time.Duration    { return getPositiveTimeout("REQUEST_TIMEOUT_SECONDS", 60) }
+func getAITimeout() time.Duration         { return getPositiveTimeout("AI_REQUEST_TIMEOUT_SECONDS", 30) }
+func getVerifierTimeout() time.Duration   { return getPositiveTimeout("VERIFIER_TIMEOUT_SECONDS", 2) }
 func getHealthCheckTimeout() time.Duration {
 	return getPositiveTimeout("HEALTH_CHECK_TIMEOUT_SECONDS", 2)
 }
+

gateway/openapi.yaml

@@ -371,6 +371,12 @@ components:
         chainId:
           type: integer
           example: 84532
+        supportedChainIds:
+          type: array
+          items:
+            type: integer
+            format: int64
+          description: List of supported blockchain network chain IDs for this payment challenge context.
         timestamp:
           type: integer
           format: uint64
@@ -456,7 +462,7 @@ components:
           format: date-time
         payment:
           type: object
-          required: [payer, recipient, amount, token, chainId, nonce]
+          required: [payer, recipient, amount, token, chainId, supportedChainIds, nonce]
           properties:
             payer:
               type: string
@@ -473,6 +479,12 @@ components:
             chainId:
               type: integer
               example: 84532
+            supportedChainIds:
+              type: array
+              items:
+                type: integer
+                format: int64
+              description: List of supported blockchain network chain IDs for this payment challenge context.
             nonce:
               type: string
               example: "550e8400-e29b-41d4-a716-446655440000"
@@ -489,3 +501,5 @@ components:
             response_hash:
               type: string
               example: sha256:...
+
+

gateway/receipt.go

@@ -24,12 +24,13 @@ type Receipt struct {
 
 // PaymentDetails contains payment-related information
 type PaymentDetails struct {
-	Payer     string `json:"payer"`
-	Recipient string `json:"recipient"`
-	Amount    string `json:"amount"`
-	Token     string `json:"token"`
-	ChainID   int    `json:"chainId"`
-	Nonce     string `json:"nonce"`
+	Payer      string  `json:"payer"`
+	Recipient  string  `json:"recipient"`
+	Amount     string  `json:"amount"`
+	Token      string  `json:"token"`
+	ChainID    int64   `json:"chainId"`
+	ChainIDs   []int64 `json:"supportedChainIds"` // Advertises multi-chain capability
+	Nonce      string  `json:"nonce"`
 }
 
 // ServiceDetails contains service-related information
@@ -53,7 +54,8 @@ type ReceiptStore interface {
 	Close() error
 }
 
-// GenerateReceipt creates a new receipt for a successful payment
+// GenerateReceipt creates a new receipt for a successful payment, 
+// wiring in the global SupportedChainIDs registry.
 func GenerateReceipt(payment PaymentContext, payer string, endpoint string, reqBody, respBody []byte) (*SignedReceipt, error) {
 	receiptID, err := generateReceiptID()
 	if err != nil {
@@ -69,7 +71,8 @@ func GenerateReceipt(payment PaymentContext, payer string, endpoint string, reqB
 			Recipient: payment.Recipient,
 			Amount:    payment.Amount,
 			Token:     payment.Token,
-			ChainID:   payment.ChainID,
+			ChainID:   int64(payment.ChainID), // Fixed: Explicit int64 type cast resolves compiler type mismatch
+			ChainIDs:  SupportedChainIDs,      // Inject multi-chain registry
 			Nonce:     payment.Nonce,
 		},
 		Service: ServiceDetails{
@@ -83,9 +86,7 @@ func GenerateReceipt(payment PaymentContext, payer string, endpoint string, reqB
 }
 
 // generateReceiptID generates a unique receipt ID with "rcpt_" prefix
-// Returns error if random generation fails to prevent predictable IDs
 func generateReceiptID() (string, error) {
-	// Generate 6 random bytes (12 hex characters)
 	bytes := make([]byte, 6)
 	if _, err := rand.Read(bytes); err != nil {
 		return "", fmt.Errorf("failed to generate random receipt ID: %w", err)
@@ -96,42 +97,30 @@ func generateReceiptID() (string, error) {
 // hashData computes SHA-256 hash of data and returns hex-encoded string
 func hashData(data []byte) string {
 	if len(data) == 0 {
-		return "sha256:e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855" // Empty hash
+		return "sha256:e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
 	}
 	hash := sha256.Sum256(data)
 	return "sha256:" + hex.EncodeToString(hash[:])
 }
 
 // signReceipt signs a receipt using the server's private key
-// NOTE: Go's json.Marshal is deterministic for structs - fields are always
-// serialized in the order they are defined in the struct, ensuring consistent output.
-// This guarantees consistent signatures across multiple marshaling operations.
 func signReceipt(receipt Receipt) (*SignedReceipt, error) {
-	// Get server's private key
 	privateKey, err := getServerPrivateKey()
 	if err != nil {
 		return nil, fmt.Errorf("failed to load server private key: %w", err)
 	}
 
-	// Serialize receipt deterministically
-	// json.Marshal outputs struct fields in their declaration order
 	receiptBytes, err := json.Marshal(receipt)
 	if err != nil {
 		return nil, fmt.Errorf("failed to marshal receipt: %w", err)
 	}
 
-	// Hash the receipt using Keccak256 (Ethereum-compatible)
 	hash := crypto.Keccak256Hash(receiptBytes)
-
-	// Sign the hash using ECDSA
-	// SECURITY: crypto.Sign uses constant-time operations from go-ethereum's secp256k1 implementation
-	// This prevents timing attacks that could leak private key information
 	signature, err := crypto.Sign(hash.Bytes(), privateKey)
 	if err != nil {
 		return nil, fmt.Errorf("failed to sign receipt: %w", err)
 	}
 
-	// Get server's public key for verification
 	publicKey := privateKey.Public().(*ecdsa.PublicKey)
 	publicKeyBytes := crypto.FromECDSAPub(publicKey)