fix: validate TX builder inputs

Fixes #180

Signed-off-by: Aurora Gaffney <aurora@blinklabs.io>

Author: agaffney

.gitignore

@@ -26,6 +26,7 @@ go.work.sum
 
 # Program binary
 /vpn-indexer
+/vpn-cli
 
 # Local data dir
 /.vpn-indexer

internal/api/tx.go

@@ -17,6 +17,7 @@ package api
 import (
 	"encoding/hex"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"log/slog"
@@ -79,8 +80,14 @@ func (a *Api) handleTxSignup(w http.ResponseWriter, r *http.Request) {
 			"error",
 			err,
 		)
-		w.WriteHeader(http.StatusInternalServerError)
-		_, _ = w.Write([]byte(`{"error":"Internal server error"}`))
+		var validationErr txbuilder.InputValidationError
+		if errors.As(err, &validationErr) {
+			w.WriteHeader(http.StatusBadRequest)
+			_, _ = w.Write([]byte(fmt.Sprintf(`{"error":"Invalid request: %s"}`, validationErr)))
+		} else {
+			w.WriteHeader(http.StatusInternalServerError)
+			_, _ = w.Write([]byte(`{"error":"Internal server error"}`))
+		}
 		return
 	}
 
@@ -146,8 +153,14 @@ func (a *Api) handleTxRenew(w http.ResponseWriter, r *http.Request) {
 			"error",
 			err,
 		)
-		w.WriteHeader(http.StatusInternalServerError)
-		_, _ = w.Write([]byte(`{"error":"Internal server error"}`))
+		var validationErr txbuilder.InputValidationError
+		if errors.As(err, &validationErr) {
+			w.WriteHeader(http.StatusBadRequest)
+			_, _ = w.Write([]byte(fmt.Sprintf(`{"error":"Invalid request: %s"}`, validationErr)))
+		} else {
+			w.WriteHeader(http.StatusInternalServerError)
+			_, _ = w.Write([]byte(`{"error":"Internal server error"}`))
+		}
 		return
 	}
 
@@ -210,8 +223,14 @@ func (a *Api) handleTxTransfer(w http.ResponseWriter, r *http.Request) {
 			"error",
 			err,
 		)
-		w.WriteHeader(http.StatusInternalServerError)
-		_, _ = w.Write([]byte(`{"error":"Internal server error"}`))
+		var validationErr txbuilder.InputValidationError
+		if errors.As(err, &validationErr) {
+			w.WriteHeader(http.StatusBadRequest)
+			_, _ = w.Write([]byte(fmt.Sprintf(`{"error":"Invalid request: %s"}`, validationErr)))
+		} else {
+			w.WriteHeader(http.StatusInternalServerError)
+			_, _ = w.Write([]byte(`{"error":"Internal server error"}`))
+		}
 		return
 	}
 

internal/txbuilder/renew.go

@@ -18,7 +18,6 @@ import (
 	"bytes"
 	"context"
 	"encoding/hex"
-	"errors"
 	"fmt"
 	"time"
 
@@ -41,6 +40,10 @@ func BuildRenewTransferTx(
 	price int,
 	duration int,
 ) ([]byte, error) {
+	// Validate inputs
+	if paymentAddress == "" {
+		return nil, NewInputValidationError("empty payment address provided")
+	}
 	cfg := config.GetConfig()
 	cc, err := apolloBackend()
 	if err != nil {
@@ -58,15 +61,15 @@ func BuildRenewTransferTx(
 	// Decode payment address
 	paymentAddr, err := serAddress.DecodeAddress(paymentAddress)
 	if err != nil {
-		return nil, fmt.Errorf("payment address: %w", err)
+		return nil, NewInputValidationError("failed to decode payment address")
 	}
 	// Determine owner credential
 	// Use existing owner for client by default
 	ownerCredential := client.Credential
 	if ownerAddress != "" && ownerAddress != paymentAddress {
 		ownerAddr, err := serAddress.DecodeAddress(ownerAddress)
 		if err != nil {
-			return nil, fmt.Errorf("owner address: %w", err)
+			return nil, NewInputValidationError("failed to decode owner address")
 		}
 		ownerCredential = ownerAddr.PaymentPart
 	}
@@ -113,7 +116,7 @@ func BuildRenewTransferTx(
 		return nil, fmt.Errorf("choose input UTxOs: %w", err)
 	}
 	if len(inputUtxos) == 0 {
-		return nil, errors.New("no input UTxOs found")
+		return nil, NewInputValidationError("no input UTxOs found")
 	}
 	// Lookup UTxO for client asset
 	clientUtxo, err := cc.GetUtxoFromRef(
@@ -130,7 +133,7 @@ func BuildRenewTransferTx(
 	if price > 0 && duration > 0 {
 		selectionId, err = determinePlanSelection(refData, price, duration)
 		if err != nil {
-			return nil, fmt.Errorf("determine plan selection: %w", err)
+			return nil, NewInputValidationError("could not determine plan selection from provided price/duration")
 		}
 	}
 	// Get last known slot

internal/txbuilder/signup.go

@@ -45,6 +45,13 @@ func BuildSignupTx(
 	duration int,
 	region string,
 ) ([]byte, []byte, error) {
+	// Validate inputs
+	if region == "" {
+		return nil, nil, NewInputValidationError("empty region provided")
+	}
+	if paymentAddress == "" {
+		return nil, nil, NewInputValidationError("empty payment address provided")
+	}
 	cfg := config.GetConfig()
 	cc, err := apolloBackend()
 	if err != nil {
@@ -53,14 +60,14 @@ func BuildSignupTx(
 	// Decode payment address
 	paymentAddr, err := serAddress.DecodeAddress(paymentAddress)
 	if err != nil {
-		return nil, nil, fmt.Errorf("payment address: %w", err)
+		return nil, nil, NewInputValidationError("failed to decode payment address")
 	}
 	// Determine owner credential
 	ownerCredential := paymentAddr.PaymentPart
 	if ownerAddress != "" && ownerAddress != paymentAddress {
 		ownerAddr, err := serAddress.DecodeAddress(ownerAddress)
 		if err != nil {
-			return nil, nil, fmt.Errorf("owner address: %w", err)
+			return nil, nil, NewInputValidationError("failed to decode owner address")
 		}
 		ownerCredential = ownerAddr.PaymentPart
 	}
@@ -87,6 +94,16 @@ func BuildSignupTx(
 	default:
 		return nil, nil, errors.New("reference data not provided (missing deps.Ref and deps.DB)")
 	}
+	// Validate region
+	foundRegion := false
+	for _, refDataRegion := range refData.Regions {
+		if region == refDataRegion.Name {
+			foundRegion = true
+		}
+	}
+	if !foundRegion {
+		return nil, nil, NewInputValidationError("provided region not valid")
+	}
 	// Parse script ref
 	scriptRef, err := inputRefFromString(cfg.TxBuilder.ScriptRefInput)
 	if err != nil {
@@ -107,14 +124,14 @@ func BuildSignupTx(
 		return nil, nil, fmt.Errorf("choose input UTxOs: %w", err)
 	}
 	if len(inputUtxos) == 0 {
-		return nil, nil, errors.New("no input UTxOs found")
+		return nil, nil, NewInputValidationError("no input UTxOs found")
 	}
 	// Determine client ID from first selected input UTxO
 	clientId := clientIdFromInput(inputUtxos[0].Input)
 	// Determine plan selection ID from price/duration
 	selectionId, err := determinePlanSelection(refData, price, duration)
 	if err != nil {
-		return nil, nil, fmt.Errorf("determine plan selection: %w", err)
+		return nil, nil, NewInputValidationError("could not determine plan selection from provided price/duration")
 	}
 	// Get last known slot
 	curSlot, err := cc.LastBlockSlot()

internal/txbuilder/txbuilder.go

@@ -166,3 +166,18 @@ func determinePlanSelection(
 	}
 	return 0, errors.New("selection not found")
 }
+
+// InputValidationError is a custom error type representing input validation errors
+type InputValidationError struct {
+	msg string
+}
+
+func NewInputValidationError(msg string) error {
+	return InputValidationError{
+		msg: msg,
+	}
+}
+
+func (e InputValidationError) Error() string {
+	return e.msg
+}