Update connect-go dependency to latest (#126)

Some of the updated behavior in connect-go tickled some bugs in
vanguard, which were caught by the tests. These issues are fixed
in this change:

1. When the `envelopingReader` was transforming an un-enveloped body
(for Connect unary) to an enveloped one, it would include an extra,
second, invalid envelope(!!). This wasn't previously caught because the
older version of connect-go only tried to read a single request for
unary RPCs and then effectively ignored the rest of the body. The newer
connect-go validates that the client isn't erroneously sending more than
one message, which brought this bug to light.
2. The "content-type" response header was not being correctly set when
translating a Connect unary error (JSON response body) to gRPC. This
wasn't previously caught because the older version of connect-go failed
to validate the response content-type. The newer version does validate
the content-type, so complains when it is empty since it should always
be set for gRPC and gRPC-Web responses (even if the body is empty).
3. If the "content-length" header was set, the vanguard transcoder was
failing to correctly enforce the max buffer size limit. This wasn't
previously caught because the older connect-go never set the
"content-length" header; but now it will be set for unary and
server-stream operations, which tickled this bug. Luckily, we had a test
case to catch it.

The other changes necessary to get tests to pass were changes to make
vanguard's test code more robust:
1. It was using `assert.Equal` on a `*connect.Error`, which may contain
`proto.Message` instances if there are error details, which do not
correctly compare with `assert.Error`. I've extract the comparison to a
helper that checks all of the error properties and uses `protocmp` to
compare the message values.
2. It was assuming a content-type of "application/grpc+proto" for gRPC
requests with a proto codec, but the newer connect-go version will now
shorten this to simply "application/grpc". So the assertions here were
relaxed accordingly.

go.mod

@@ -6,7 +6,7 @@ require (
 	buf.build/gen/go/connectrpc/eliza/connectrpc/go v1.11.1-20230822171018-8b8b971d6fde.1
 	buf.build/gen/go/connectrpc/eliza/grpc/go v1.3.0-20230822171018-8b8b971d6fde.1
 	buf.build/gen/go/connectrpc/eliza/protocolbuffers/go v1.31.0-20230822171018-8b8b971d6fde.1
-	connectrpc.com/connect v1.14.0
+	connectrpc.com/connect v1.16.2
 	connectrpc.com/grpcreflect v1.2.0
 	github.com/google/go-cmp v0.5.9
 	github.com/stretchr/testify v1.8.4

go.sum

@@ -391,8 +391,8 @@ cloud.google.com/go/workflows v1.6.0/go.mod h1:6t9F5h/unJz41YqfBmqSASJSXccBLtD1V
 cloud.google.com/go/workflows v1.7.0/go.mod h1:JhSrZuVZWuiDfKEFxU0/F1PQjmpnpcoISEXH2bcHC3M=
 cloud.google.com/go/workflows v1.8.0/go.mod h1:ysGhmEajwZxGn1OhGOGKsTXc5PyxOc0vfKf5Af+to4M=
 cloud.google.com/go/workflows v1.9.0/go.mod h1:ZGkj1aFIOd9c8Gerkjjq7OW7I5+l6cSvT3ujaO/WwSA=
-connectrpc.com/connect v1.14.0 h1:PDS+J7uoz5Oui2VEOMcfz6Qft7opQM9hPiKvtGC01pA=
-connectrpc.com/connect v1.14.0/go.mod h1:uoAq5bmhhn43TwhaKdGKN/bZcGtzPW1v+ngDTn5u+8s=
+connectrpc.com/connect v1.16.2 h1:ybd6y+ls7GOlb7Bh5C8+ghA6SvCBajHwxssO2CGFjqE=
+connectrpc.com/connect v1.16.2/go.mod h1:n2kgwskMHXC+lVqb18wngEpF95ldBHXjZYJussz5FRc=
 connectrpc.com/grpcreflect v1.2.0 h1:Q6og1S7HinmtbEuBvARLNwYmTbhEGRpHDhqrPNlmK+U=
 connectrpc.com/grpcreflect v1.2.0/go.mod h1:nwSOKmE8nU5u/CidgHtPYk1PFI3U9ignz7iDMxOYkSY=
 dmitri.shuralyov.com/gpu/mtl v0.0.0-20190408044501-666a987793e9/go.mod h1:H6x//7gZCb22OMCxBHrMx7a5I7Hp++hsVxbQ4BYO7hU=

protocol_grpc.go

@@ -357,6 +357,7 @@ func grpcAddRequestMeta(contentTypePrefix string, meta requestMeta, headers http
 
 func grpcAddResponseMeta(contentTypePrefix string, meta responseMeta, headers http.Header) int {
 	if meta.end != nil {
+		headers.Set("Content-Type", contentTypePrefix+meta.codec)
 		grpcWriteEndToTrailers(meta.end, headers)
 		return http.StatusOK
 	}

protocol_grpc_test.go

@@ -25,8 +25,10 @@ import (
 	"unicode/utf8"
 
 	"connectrpc.com/connect"
+	"github.com/google/go-cmp/cmp"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+	"google.golang.org/protobuf/testing/protocmp"
 	"google.golang.org/protobuf/types/known/wrapperspb"
 )
 
@@ -45,7 +47,7 @@ func TestGRPCErrorWriter(t *testing.T) {
 	assert.Empty(t, rec.Body.Bytes())
 
 	got := grpcExtractErrorFromTrailer(rec.Header())
-	assert.Equal(t, cerr, got)
+	compareErrors(t, cerr, got)
 
 	// Now again, but this time an error with details
 	errDetail, err := connect.NewErrorDetail(&wrapperspb.StringValue{Value: "foo"})
@@ -60,7 +62,7 @@ func TestGRPCErrorWriter(t *testing.T) {
 	assert.Empty(t, rec.Body.Bytes())
 
 	got = grpcExtractErrorFromTrailer(rec.Header())
-	assert.Equal(t, cerr, got)
+	compareErrors(t, cerr, got)
 }
 
 func TestGRPCEncodeTimeoutQuick(t *testing.T) {
@@ -144,3 +146,24 @@ func TestGRPCEncodeTimeout(t *testing.T) {
 	timeout = grpcEncodeTimeout(-1 * time.Hour)
 	assert.Equal(t, "0n", timeout)
 }
+
+func compareErrors(t *testing.T, got, want *connect.Error) {
+	t.Helper()
+	assert.Equal(t, want.Code(), got.Code(), "wrong code")
+	assert.Equal(t, want.Message(), got.Message(), "wrong message")
+	wantDetails := want.Details()
+	gotDetails := got.Details()
+	if !assert.Len(t, wantDetails, len(gotDetails), "wrong number of details") {
+		return
+	}
+	for i, wantDetail := range wantDetails {
+		gotDetail := gotDetails[i]
+		if assert.Equal(t, wantDetail.Type(), gotDetail.Type(), "wrong detail type at index %d", i) {
+			wantedMsg, err := wantDetail.Value()
+			require.NoError(t, err, "failed to deserialize wanted detail at index %d", i)
+			gotMsg, err := gotDetail.Value()
+			require.NoError(t, err, "failed to deserialize got detail at index %d", i)
+			require.Empty(t, cmp.Diff(wantedMsg, gotMsg, protocmp.Transform()))
+		}
+	}
+}

transcoder.go

@@ -854,8 +854,18 @@ func (r *envelopingReader) prepareNext() error {
 		r.envRemain = 0
 		return nil
 	case r.rw.op.clientEnveloper == nil:
+		if r.current != nil {
+			// If there is no enveloping, the entire body is part of a single
+			// message. And we've already prepared that message once. So there
+			// is no more.
+			return io.EOF
+		}
 		env.compressed = r.rw.op.client.reqCompression != nil
 		if r.rw.op.contentLen != -1 {
+			limit := int64(r.rw.op.methodConf.maxMsgBufferBytes)
+			if r.rw.op.contentLen > limit {
+				return bufferLimitError(limit)
+			}
 			r.current = &hardLimitReader{r: r.r, rw: r.rw, limit: r.rw.op.contentLen, makeError: contentLengthError}
 			env.length = uint32(r.rw.op.contentLen)
 		} else {

vanguard_test.go

@@ -916,13 +916,21 @@ func protocolAssertMiddleware(
 		var wantHdr map[string][]string
 		switch protocol {
 		case ProtocolGRPC:
+			wantContentType := []string{"application/grpc+" + codec}
+			if codec == CodecProto {
+				wantContentType = append(wantContentType, "application/grpc")
+			}
 			wantHdr = map[string][]string{
-				"Content-Type":  {"application/grpc+" + codec},
+				"Content-Type":  wantContentType,
 				"Grpc-Encoding": allowedCompression,
 			}
 		case ProtocolGRPCWeb:
+			wantContentType := []string{"application/grpc-web+" + codec}
+			if codec == CodecProto {
+				wantContentType = append(wantContentType, "application/grpc-web")
+			}
 			wantHdr = map[string][]string{
-				"Content-Type":  {"application/grpc-web+" + codec},
+				"Content-Type":  wantContentType,
 				"Grpc-Encoding": allowedCompression,
 			}
 		case ProtocolConnect: