feat(encoding): support protocol buffers (#117)

Author: abemedia

README.md

@@ -171,6 +171,13 @@ MIME: `application/toml`
 Parses TOML requests & encodes responses as TOML. Use the `toml` tag in your request & response
 structs.
 
+#### Protocol Buffers
+
+MIME: `application/protobuf`
+
+Parses protobuf requests & encodes responses as protobuf. Use pointer types generated with `protoc`
+as your request & response structs.
+
 ### Adding custom encoding
 
 Adding your own is easy. See [encoding/json/json.go](./encoding/json/json.go).

encoding/protobuf/protobuf.go

@@ -0,0 +1,42 @@
+package protobuf
+
+import (
+	"reflect"
+
+	"github.com/abemedia/go-don"
+	"github.com/abemedia/go-don/encoding"
+	"google.golang.org/protobuf/proto"
+)
+
+var messageType = reflect.TypeOf((*proto.Message)(nil)).Elem()
+
+func unmarshal(b []byte, v any) error {
+	// TODO: Cache reflect results to improve performance.
+	elem := reflect.ValueOf(v).Elem()
+	if elem.Type().Implements(messageType) && elem.IsNil() {
+		elem.Set(reflect.New(elem.Type().Elem()))
+		v = elem.Interface()
+	}
+
+	m, ok := v.(proto.Message)
+	if !ok {
+		return don.ErrUnsupportedMediaType
+	}
+	return proto.Unmarshal(b, m)
+}
+
+func marshal(v any) ([]byte, error) {
+	m, ok := v.(proto.Message)
+	if !ok {
+		return nil, don.ErrNotAcceptable
+	}
+	return proto.Marshal(m)
+}
+
+func init() {
+	mediaType := "application/protobuf"
+	alias := "application/x-protobuf"
+
+	encoding.RegisterDecoder(unmarshal, mediaType, alias)
+	encoding.RegisterEncoder(marshal, mediaType, alias)
+}

encoding/protobuf/protobuf_test.go

@@ -0,0 +1,49 @@
+package protobuf_test
+
+import (
+	"errors"
+	"testing"
+
+	"github.com/abemedia/go-don"
+	"github.com/abemedia/go-don/encoding"
+	"github.com/abemedia/go-don/encoding/protobuf/testdata"
+	"github.com/abemedia/go-don/internal/test"
+	"github.com/abemedia/go-don/pkg/httptest"
+)
+
+//go:generate protoc testdata/test.proto --go_out=. --go_opt=paths=source_relative
+
+var opt = test.EncodingOptions[*testdata.Item]{
+	Mime:   "application/protobuf",
+	Raw:    "\n\x03bar",
+	Parsed: &testdata.Item{Foo: "bar"},
+}
+
+func TestProtobuf(t *testing.T) {
+	test.Encoding(t, opt)
+}
+
+func TestProtobufError(t *testing.T) {
+	ctx := httptest.NewRequest("", "", "", nil)
+	v := "test"
+
+	t.Run("Decode", func(t *testing.T) {
+		dec := encoding.GetDecoder("application/protobuf")
+		err := dec(ctx, &v)
+		if !errors.Is(err, don.ErrUnsupportedMediaType) {
+			t.Fatal("should fail")
+		}
+	})
+
+	t.Run("Encode", func(t *testing.T) {
+		enc := encoding.GetEncoder("application/protobuf")
+		err := enc(ctx, &v)
+		if !errors.Is(err, don.ErrNotAcceptable) {
+			t.Fatal("should fail")
+		}
+	})
+}
+
+func BenchmarkProtobuf(b *testing.B) {
+	test.BenchmarkEncoding(b, opt)
+}

encoding/protobuf/testdata/test.pb.go

@@ -0,0 +1,5 @@
+syntax = "proto3";
+
+option go_package = "github.com/abemedia/go-don/encoding/protobuf/testdata";
+
+message Item { string foo = 1; }

encoding/protobuf/testdata/test.proto

@@ -9,6 +9,7 @@ require (
 	github.com/pelletier/go-toml v1.9.5
 	github.com/valyala/fasthttp v1.47.0
 	github.com/vmihailenco/msgpack/v5 v5.3.5
+	google.golang.org/protobuf v1.30.0
 	gopkg.in/yaml.v3 v3.0.1
 )
 

go.mod

@@ -10,6 +10,8 @@ github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/goccy/go-json v0.10.2 h1:CrxCmQqYDkv1z7lO7Wbh2HN93uovUHgrECaO5ZrCXAU=
 github.com/goccy/go-json v0.10.2/go.mod h1:6MelG93GURQebXPDq3khkgXZkazVtN9CRI+MGFi0w8I=
+github.com/golang/protobuf v1.5.0/go.mod h1:FsONVRAS9T7sI+LIUmWTfcYkHO4aIWwzhcaSAoJOfIk=
+github.com/google/go-cmp v0.5.5/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
 github.com/google/go-cmp v0.5.9 h1:O2Tfq5qg4qc4AmwVlvv0oLiVAGB7enBSJ2x2DqQFi38=
 github.com/google/go-cmp v0.5.9/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/klauspost/compress v1.15.0/go.mod h1:/3/Vjq9QcHkK5uEr5lBEmyoZ1iFhe47etQ6QUkpK6sk=
@@ -75,6 +77,10 @@ golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtn
 golang.org/x/tools v0.1.12/go.mod h1:hNGJHUnrk76NpqgfD5Aqm5Crs+Hm0VOH/i9J2+nxYbc=
 golang.org/x/tools v0.6.0/go.mod h1:Xwgl3UAJ/d3gWutnCtw505GrjyAbvKui8lOU390QaIU=
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+google.golang.org/protobuf v1.26.0-rc.1/go.mod h1:jlhhOSvTdKEhbULTjvd4ARK9grFBp09yW+WbY/TyQbw=
+google.golang.org/protobuf v1.30.0 h1:kPPoIgf3TsEvrm0PFe15JQ+570QVxYzEvvHqChK+cng=
+google.golang.org/protobuf v1.30.0/go.mod h1:HV8QOd/L58Z+nl8r43ehVNZIU/HEI6OcFqwMG9pJV4I=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=