Apply JCS before signature validation (#54)

consts.go

@@ -2,5 +2,5 @@ package inngestgo
 
 const (
 	SDKLanguage = "go"
-	SDKVersion  = "0.5.4"
+	SDKVersion  = "0.7.3"
 )

handler.go

@@ -774,7 +774,13 @@ func (h *handler) trust(
 		return
 	}
 
-	w.Header().Add("X-Inngest-Signature", Sign(ctx, time.Now(), []byte(key), byt))
+	resSig, err := Sign(ctx, time.Now(), []byte(key), byt)
+	if err != nil {
+		_ = publicerr.WriteHTTP(w, err)
+		return
+	}
+
+	w.Header().Add("X-Inngest-Signature", resSig)
 	w.WriteHeader(200)
 	_, err = w.Write(byt)
 	if err != nil {

handler_test.go

@@ -494,7 +494,7 @@ func TestIntrospection(t *testing.T) {
 		r := require.New(t)
 
 		reqBody := []byte("")
-		sig := Sign(context.Background(), time.Now(), []byte(testKey), reqBody)
+		sig, _ := Sign(context.Background(), time.Now(), []byte(testKey), reqBody)
 		req, err := http.NewRequest(http.MethodGet, server.URL, bytes.NewReader(reqBody))
 		r.NoError(err)
 		req.Header.Set("X-Inngest-Signature", sig)
@@ -531,7 +531,7 @@ func TestIntrospection(t *testing.T) {
 
 		reqBody := []byte("")
 		invalidKey := "deadbeef"
-		sig := Sign(context.Background(), time.Now(), []byte(invalidKey), reqBody)
+		sig, _ := Sign(context.Background(), time.Now(), []byte(invalidKey), reqBody)
 		req, err := http.NewRequest(http.MethodGet, server.URL, bytes.NewReader(reqBody))
 		r.NoError(err)
 		req.Header.Set("X-Inngest-Signature", sig)
@@ -591,7 +591,7 @@ func handlerPost(t *testing.T, url string, r *sdkrequest.Request) *http.Response
 	t.Helper()
 
 	body := marshalRequest(t, r)
-	sig := Sign(context.Background(), time.Now(), []byte(testKey), body)
+	sig, _ := Sign(context.Background(), time.Now(), []byte(testKey), body)
 
 	req, err := http.NewRequest(http.MethodPost, url, bytes.NewReader(body))
 	require.NoError(t, err)

signature.go

@@ -10,6 +10,9 @@ import (
 	"regexp"
 	"strconv"
 	"time"
+
+	"github.com/gowebpki/jcs"
+	"github.com/inngest/inngest/pkg/logger"
 )
 
 var (
@@ -22,9 +25,17 @@ var (
 )
 
 // Sign signs a request body with the given key at the given timestamp.
-func Sign(ctx context.Context, at time.Time, key, body []byte) string {
+func Sign(ctx context.Context, at time.Time, key, body []byte) (string, error) {
 	key = normalizeKey(key)
 
+	var err error
+	if len(body) > 0 {
+		body, err = jcs.Transform(body)
+		if err != nil {
+			logger.StdlibLogger(ctx).Warn("failed to canonicalize body", "error", err)
+		}
+	}
+
 	ts := at.Unix()
 	if at.IsZero() {
 		ts = time.Now().Unix()
@@ -36,7 +47,7 @@ func Sign(ctx context.Context, at time.Time, key, body []byte) string {
 	// timing attacks.
 	_, _ = mac.Write([]byte(fmt.Sprintf("%d", ts)))
 	sig := hex.EncodeToString(mac.Sum(nil))
-	return fmt.Sprintf("t=%d&s=%s", ts, sig)
+	return fmt.Sprintf("t=%d&s=%s", ts, sig), nil
 }
 
 // validateSignature ensures that the signature for the given body is signed with
@@ -58,7 +69,10 @@ func validateSignature(ctx context.Context, sig string, key, body []byte) (bool,
 		return false, ErrExpiredSignature
 	}
 
-	actual := Sign(ctx, ts, key, body)
+	actual, err := Sign(ctx, ts, key, body)
+	if err != nil {
+		return false, err
+	}
 	if actual != sig {
 		return false, ErrInvalidSignature
 	}

signature_test.go

@@ -10,7 +10,7 @@ import (
 )
 
 var (
-	testBody        = []byte(`hey!  if you're reading this come work with us: careers@inngest.com`)
+	testBody        = []byte(`{"msg": "hey!  if you're reading this come work with us: careers@inngest.com"}`)
 	testKey         = "signkey-test-12345678"
 	testKeyFallback = "signkey-test-00000000"
 )
@@ -23,9 +23,9 @@ func TestSign(t *testing.T) {
 		keyA := []byte("signkey-test-12345678")
 		keyB := []byte("signkey-prod-12345678")
 		keyC := []byte("12345678")
-		a := Sign(ctx, at, keyA, testBody)
-		b := Sign(ctx, at, keyB, testBody)
-		c := Sign(ctx, at, keyC, testBody)
+		a, _ := Sign(ctx, at, keyA, testBody)
+		b, _ := Sign(ctx, at, keyB, testBody)
+		c, _ := Sign(ctx, at, keyC, testBody)
 		require.Equal(t, a, b)
 		require.Equal(t, a, c)
 	})
@@ -54,7 +54,7 @@ func TestValidateSignature(t *testing.T) {
 
 		t.Run("with the wrong key it fails", func(t *testing.T) {
 			at := time.Now()
-			sig := Sign(ctx, at, []byte(testKey), testBody)
+			sig, _ := Sign(ctx, at, []byte(testKey), testBody)
 
 			ok, _, err := ValidateSignature(ctx, sig, "signkey-test-lolwtf", "", testBody)
 			require.False(t, ok)
@@ -64,7 +64,7 @@ func TestValidateSignature(t *testing.T) {
 
 	t.Run("with the same key and within a reasonable time it succeeds", func(t *testing.T) {
 		at := time.Now().Add(-5 * time.Second)
-		sig := Sign(ctx, at, []byte(testKey), testBody)
+		sig, _ := Sign(ctx, at, []byte(testKey), testBody)
 
 		ok, _, err := ValidateSignature(ctx, sig, testKey, "", testBody)
 		require.True(t, ok)