Add Group Join request and response pair.

errors.go

@@ -37,6 +37,9 @@ var ErrShuttingDown = errors.New("kafka: message received by producer in process
 // ErrMessageTooLarge is returned when the next message to consume is larger than the configured Consumer.Fetch.Max
 var ErrMessageTooLarge = errors.New("kafka: message is larger than Consumer.Fetch.Max")
 
+// ErrMessageTooLarge is returned when a JoinGroup request returns a protocol type that is not supported by sarama.
+var ErrUnknownGroupProtocol = errors.New("kafka: encountered an unknown group protocol")
+
 // PacketEncodingError is returned from a failure while encoding a Kafka packet. This can happen, for example,
 // if you try to encode a string over 2^15 characters in length, since Kafka's encoding rules do not permit that.
 type PacketEncodingError struct {

join_group_request.go

@@ -0,0 +1,127 @@
+package sarama
+
+type JoinGroupRequest struct {
+	GroupId        string
+	SessionTimeout int32
+	MemberId       string
+	ProtocolType   string
+	GroupProtocols []GroupProtocol
+}
+
+func (r *JoinGroupRequest) encode(pe packetEncoder) error {
+	if err := pe.putString(r.GroupId); err != nil {
+		return err
+	}
+	pe.putInt32(r.SessionTimeout)
+	if err := pe.putString(r.MemberId); err != nil {
+		return err
+	}
+	if err := pe.putString(r.ProtocolType); err != nil {
+		return err
+	}
+
+	if err := pe.putArrayLength(len(r.GroupProtocols)); err != nil {
+		return err
+	}
+	for _, groupProtocol := range r.GroupProtocols {
+		if err := groupProtocol.encodeGroupProtocol(pe); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func (r *JoinGroupRequest) decode(pd packetDecoder) (err error) {
+	r.GroupId, err = pd.getString()
+	if err != nil {
+		return
+	}
+
+	r.SessionTimeout, err = pd.getInt32()
+	if err != nil {
+		return
+	}
+
+	r.MemberId, err = pd.getString()
+	if err != nil {
+		return
+	}
+
+	r.ProtocolType, err = pd.getString()
+	if err != nil {
+		return
+	}
+
+	switch r.ProtocolType {
+	case "consumer":
+		n, err := pd.getArrayLength()
+		if err != nil {
+			return err
+		}
+
+		r.GroupProtocols = make([]GroupProtocol, n)
+		for i := 0; i < n; i++ {
+			r.GroupProtocols[i] = new(ConsumerGroupProtocol)
+			if err := r.GroupProtocols[i].decodeGroupProtocol(pd); err != nil {
+				return nil
+			}
+		}
+
+	default:
+		return ErrUnknownGroupProtocol
+	}
+
+	return nil
+}
+
+func (r *JoinGroupRequest) key() int16 {
+	return 11
+}
+
+func (r *JoinGroupRequest) version() int16 {
+	return 0
+}
+
+type GroupProtocol interface {
+	encodeGroupProtocol(packetEncoder) error
+	decodeGroupProtocol(packetDecoder) error
+}
+
+type ConsumerGroupProtocol struct {
+	ProtocolName string
+	Version      int16
+	Subscription []string
+	UserData     []byte
+}
+
+func (cgp *ConsumerGroupProtocol) encodeGroupProtocol(pe packetEncoder) error {
+	if err := pe.putString(cgp.ProtocolName); err != nil {
+		return err
+	}
+	pe.putInt16(cgp.Version)
+	if err := pe.putStringArray(cgp.Subscription); err != nil {
+		return err
+	}
+	return pe.putBytes(cgp.UserData)
+}
+
+func (cgp *ConsumerGroupProtocol) decodeGroupProtocol(pd packetDecoder) (err error) {
+	cgp.ProtocolName, err = pd.getString()
+	if err != nil {
+		return
+	}
+
+	cgp.Version, err = pd.getInt16()
+	if err != nil {
+		return
+	}
+
+	cgp.Subscription, err = pd.getStringArray()
+	if err != nil {
+		return
+	}
+
+	cgp.UserData, err = pd.getBytes()
+	return
+}

join_group_response.go

@@ -0,0 +1,111 @@
+package sarama
+
+type JoinGroupResponse struct {
+	ErrorCode     int16
+	GenerationId  int32
+	GroupProtocol string
+	LeaderId      string
+	MemberId      string
+	Members       []*GroupMember
+}
+
+func (r *JoinGroupResponse) encode(pe packetEncoder) error {
+	pe.putInt16(r.ErrorCode)
+	pe.putInt32(r.GenerationId)
+
+	if err := pe.putString(r.GroupProtocol); err != nil {
+		return err
+	}
+
+	if err := pe.putString(r.LeaderId); err != nil {
+		return err
+	}
+
+	if err := pe.putString(r.MemberId); err != nil {
+		return err
+	}
+
+	if err := pe.putArrayLength(len(r.Members)); err != nil {
+		return err
+	}
+	for _, member := range r.Members {
+		if err := member.encode(pe); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func (r *JoinGroupResponse) decode(pd packetDecoder) (err error) {
+	r.ErrorCode, err = pd.getInt16()
+	if err != nil {
+		return err
+	}
+
+	r.GenerationId, err = pd.getInt32()
+	if err != nil {
+		return err
+	}
+
+	r.GroupProtocol, err = pd.getString()
+	if err != nil {
+		return err
+	}
+
+	r.LeaderId, err = pd.getString()
+	if err != nil {
+		return err
+	}
+
+	r.MemberId, err = pd.getString()
+	if err != nil {
+		return err
+	}
+
+	n, err := pd.getArrayLength()
+	if err != nil {
+		return err
+	}
+
+	r.Members = make([]*GroupMember, n)
+	for i := 0; i < n; i++ {
+		r.Members[i] = new(GroupMember)
+		if err := r.Members[i].decode(pd); err != nil {
+			return nil
+		}
+	}
+
+	return nil
+}
+
+type GroupMember struct {
+	MemberId       string
+	MemberMetadata []byte
+}
+
+func (gm *GroupMember) encode(pe packetEncoder) error {
+	if err := pe.putString(gm.MemberId); err != nil {
+		return err
+	}
+
+	if err := pe.putBytes(gm.MemberMetadata); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (gm *GroupMember) decode(pd packetDecoder) (err error) {
+	gm.MemberId, err = pd.getString()
+	if err != nil {
+		return err
+	}
+
+	gm.MemberMetadata, err = pd.getBytes()
+	if err != nil {
+		return err
+	}
+
+	return nil
+}

packet_decoder.go

@@ -16,6 +16,7 @@ type packetDecoder interface {
 	getString() (string, error)
 	getInt32Array() ([]int32, error)
 	getInt64Array() ([]int64, error)
+	getStringArray() ([]string, error)
 
 	// Subsets
 	remaining() int

packet_encoder.go

@@ -15,6 +15,7 @@ type packetEncoder interface {
 	putBytes(in []byte) error
 	putRawBytes(in []byte) error
 	putString(in string) error
+	putStringArray(in []string) error
 	putInt32Array(in []int32) error
 	putInt64Array(in []int64) error
 

prep_encoder.go

@@ -66,6 +66,21 @@ func (pe *prepEncoder) putString(in string) error {
 	return nil
 }
 
+func (pe *prepEncoder) putStringArray(in []string) error {
+	err := pe.putArrayLength(len(in))
+	if err != nil {
+		return err
+	}
+
+	for _, str := range in {
+		if err := pe.putString(str); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
 func (pe *prepEncoder) putInt32Array(in []int32) error {
 	err := pe.putArrayLength(len(in))
 	if err != nil {

real_decoder.go

@@ -181,6 +181,33 @@ func (rd *realDecoder) getInt64Array() ([]int64, error) {
 	return ret, nil
 }
 
+func (rd *realDecoder) getStringArray() ([]string, error) {
+	if rd.remaining() < 4 {
+		rd.off = len(rd.raw)
+		return nil, ErrInsufficientData
+	}
+	n := int(binary.BigEndian.Uint32(rd.raw[rd.off:]))
+	rd.off += 4
+
+	if n == 0 {
+		return nil, nil
+	}
+
+	if n < 0 {
+		return nil, PacketDecodingError{"invalid array length"}
+	}
+
+	ret := make([]string, n)
+	for i := range ret {
+		if str, err := rd.getString(); err != nil {
+			return nil, err
+		} else {
+			ret[i] = str
+		}
+	}
+	return ret, nil
+}
+
 // subsets
 
 func (rd *realDecoder) remaining() int {

real_encoder.go

@@ -61,6 +61,21 @@ func (re *realEncoder) putString(in string) error {
 	return nil
 }
 
+func (re *realEncoder) putStringArray(in []string) error {
+	err := re.putArrayLength(len(in))
+	if err != nil {
+		return err
+	}
+
+	for _, val := range in {
+		if err := re.putString(val); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
 func (re *realEncoder) putInt32Array(in []int32) error {
 	err := re.putArrayLength(len(in))
 	if err != nil {