Add a lot of documentation

authentication.go

@@ -8,6 +8,7 @@ import (
 	"github.com/pkg/errors"
 )
 
+// Authentication message type constants.
 const (
 	AuthTypeOk                = 0
 	AuthTypeCleartextPassword = 3
@@ -17,6 +18,10 @@ const (
 	AuthTypeSASLFinal         = 12
 )
 
+// Authentication is a message sent from the backend during the authentication process.
+//
+// There are multiple authentication messages that each begin with 'R'. This structure represents all such
+// authentication messages.
 type Authentication struct {
 	Type uint32
 
@@ -30,8 +35,11 @@ type Authentication struct {
 	SASLData []byte
 }
 
+// Backend identifies this message as sendable by the PostgreSQL backend.
 func (*Authentication) Backend() {}
 
+// Decode decodes src into dst. src must contain the complete message with the exception of the initial 1 byte message
+// type identifier and 4 byte message length.
 func (dst *Authentication) Decode(src []byte) error {
 	*dst = Authentication{Type: binary.BigEndian.Uint32(src[:4])}
 
@@ -58,6 +66,7 @@ func (dst *Authentication) Decode(src []byte) error {
 	return nil
 }
 
+// Encode encodes src into dst. dst will include the 1 byte message type identifier and the 4 byte message length.
 func (src *Authentication) Encode(dst []byte) []byte {
 	dst = append(dst, 'R')
 	sp := len(dst)

backend.go

@@ -7,6 +7,7 @@ import (
 	"github.com/pkg/errors"
 )
 
+// Backend acts as a server for the PostgreSQL wire protocol version 3.
 type Backend struct {
 	cr ChunkReader
 	w  io.Writer
@@ -30,15 +31,19 @@ type Backend struct {
 	partialMsg bool
 }
 
+// NewBackend creates a new Backend.
 func NewBackend(cr ChunkReader, w io.Writer) (*Backend, error) {
 	return &Backend{cr: cr, w: w}, nil
 }
 
+// Send sends a message to the frontend.
 func (b *Backend) Send(msg BackendMessage) error {
 	_, err := b.w.Write(msg.Encode(nil))
 	return err
 }
 
+// ReceiveStartupMessage receives the initial startup message. This method is used of the normal Receive method
+// because StartupMessage and SSLRequest are "special" and do not include the message type as the first byte.
 func (b *Backend) ReceiveStartupMessage() (*StartupMessage, error) {
 	buf, err := b.cr.Next(4)
 	if err != nil {
@@ -59,6 +64,7 @@ func (b *Backend) ReceiveStartupMessage() (*StartupMessage, error) {
 	return &b.startupMessage, nil
 }
 
+// Receive receives a message from the frontend.
 func (b *Backend) Receive() (FrontendMessage, error) {
 	if !b.partialMsg {
 		header, err := b.cr.Next(5)

backend_key_data.go

@@ -12,8 +12,11 @@ type BackendKeyData struct {
 	SecretKey uint32
 }
 
+// Backend identifies this message as sendable by the PostgreSQL backend.
 func (*BackendKeyData) Backend() {}
 
+// Decode decodes src into dst. src must contain the complete message with the exception of the initial 1 byte message
+// type identifier and 4 byte message length.
 func (dst *BackendKeyData) Decode(src []byte) error {
 	if len(src) != 8 {
 		return &invalidMessageLenErr{messageType: "BackendKeyData", expectedLen: 8, actualLen: len(src)}
@@ -25,6 +28,7 @@ func (dst *BackendKeyData) Decode(src []byte) error {
 	return nil
 }
 
+// Encode encodes src into dst. dst will include the 1 byte message type identifier and the 4 byte message length.
 func (src *BackendKeyData) Encode(dst []byte) []byte {
 	dst = append(dst, 'K')
 	dst = pgio.AppendUint32(dst, 12)
@@ -33,6 +37,7 @@ func (src *BackendKeyData) Encode(dst []byte) []byte {
 	return dst
 }
 
+// MarshalJSON implements encoding/json.Marshaler.
 func (src *BackendKeyData) MarshalJSON() ([]byte, error) {
 	return json.Marshal(struct {
 		Type      string

bind.go

@@ -17,8 +17,11 @@ type Bind struct {
 	ResultFormatCodes    []int16
 }
 
+// Frontend identifies this message as sendable by a PostgreSQL frontend.
 func (*Bind) Frontend() {}
 
+// Decode decodes src into dst. src must contain the complete message with the exception of the initial 1 byte message
+// type identifier and 4 byte message length.
 func (dst *Bind) Decode(src []byte) error {
 	*dst = Bind{}
 
@@ -103,6 +106,7 @@ func (dst *Bind) Decode(src []byte) error {
 	return nil
 }
 
+// Encode encodes src into dst. dst will include the 1 byte message type identifier and the 4 byte message length.
 func (src *Bind) Encode(dst []byte) []byte {
 	dst = append(dst, 'B')
 	sp := len(dst)
@@ -139,6 +143,7 @@ func (src *Bind) Encode(dst []byte) []byte {
 	return dst
 }
 
+// MarshalJSON implements encoding/json.Marshaler.
 func (src *Bind) MarshalJSON() ([]byte, error) {
 	formattedParameters := make([]map[string]string, len(src.Parameters))
 	for i, p := range src.Parameters {

bind_complete.go

@@ -6,8 +6,11 @@ import (
 
 type BindComplete struct{}
 
+// Backend identifies this message as sendable by the PostgreSQL backend.
 func (*BindComplete) Backend() {}
 
+// Decode decodes src into dst. src must contain the complete message with the exception of the initial 1 byte message
+// type identifier and 4 byte message length.
 func (dst *BindComplete) Decode(src []byte) error {
 	if len(src) != 0 {
 		return &invalidMessageLenErr{messageType: "BindComplete", expectedLen: 0, actualLen: len(src)}
@@ -16,10 +19,12 @@ func (dst *BindComplete) Decode(src []byte) error {
 	return nil
 }
 
+// Encode encodes src into dst. dst will include the 1 byte message type identifier and the 4 byte message length.
 func (src *BindComplete) Encode(dst []byte) []byte {
 	return append(dst, '2', 0, 0, 0, 4)
 }
 
+// MarshalJSON implements encoding/json.Marshaler.
 func (src *BindComplete) MarshalJSON() ([]byte, error) {
 	return json.Marshal(struct {
 		Type string

chunkreader.go

@@ -13,6 +13,7 @@ type ChunkReader interface {
 	Next(n int) (buf []byte, err error)
 }
 
+// NewChunkReader creates and returns a new default ChunkReader.
 func NewChunkReader(r io.Reader) ChunkReader {
 	return chunkreader.New(r)
 }

close.go

@@ -12,8 +12,11 @@ type Close struct {
 	Name       string
 }
 
+// Frontend identifies this message as sendable by a PostgreSQL frontend.
 func (*Close) Frontend() {}
 
+// Decode decodes src into dst. src must contain the complete message with the exception of the initial 1 byte message
+// type identifier and 4 byte message length.
 func (dst *Close) Decode(src []byte) error {
 	if len(src) < 2 {
 		return &invalidMessageFormatErr{messageType: "Close"}
@@ -32,6 +35,7 @@ func (dst *Close) Decode(src []byte) error {
 	return nil
 }
 
+// Encode encodes src into dst. dst will include the 1 byte message type identifier and the 4 byte message length.
 func (src *Close) Encode(dst []byte) []byte {
 	dst = append(dst, 'C')
 	sp := len(dst)
@@ -46,6 +50,7 @@ func (src *Close) Encode(dst []byte) []byte {
 	return dst
 }
 
+// MarshalJSON implements encoding/json.Marshaler.
 func (src *Close) MarshalJSON() ([]byte, error) {
 	return json.Marshal(struct {
 		Type       string

close_complete.go

@@ -6,8 +6,11 @@ import (
 
 type CloseComplete struct{}
 
+// Backend identifies this message as sendable by the PostgreSQL backend.
 func (*CloseComplete) Backend() {}
 
+// Decode decodes src into dst. src must contain the complete message with the exception of the initial 1 byte message
+// type identifier and 4 byte message length.
 func (dst *CloseComplete) Decode(src []byte) error {
 	if len(src) != 0 {
 		return &invalidMessageLenErr{messageType: "CloseComplete", expectedLen: 0, actualLen: len(src)}
@@ -16,10 +19,12 @@ func (dst *CloseComplete) Decode(src []byte) error {
 	return nil
 }
 
+// Encode encodes src into dst. dst will include the 1 byte message type identifier and the 4 byte message length.
 func (src *CloseComplete) Encode(dst []byte) []byte {
 	return append(dst, '3', 0, 0, 0, 4)
 }
 
+// MarshalJSON implements encoding/json.Marshaler.
 func (src *CloseComplete) MarshalJSON() ([]byte, error) {
 	return json.Marshal(struct {
 		Type string

command_complete.go

@@ -11,8 +11,11 @@ type CommandComplete struct {
 	CommandTag []byte
 }
 
+// Backend identifies this message as sendable by the PostgreSQL backend.
 func (*CommandComplete) Backend() {}
 
+// Decode decodes src into dst. src must contain the complete message with the exception of the initial 1 byte message
+// type identifier and 4 byte message length.
 func (dst *CommandComplete) Decode(src []byte) error {
 	idx := bytes.IndexByte(src, 0)
 	if idx != len(src)-1 {
@@ -24,6 +27,7 @@ func (dst *CommandComplete) Decode(src []byte) error {
 	return nil
 }
 
+// Encode encodes src into dst. dst will include the 1 byte message type identifier and the 4 byte message length.
 func (src *CommandComplete) Encode(dst []byte) []byte {
 	dst = append(dst, 'C')
 	sp := len(dst)
@@ -37,6 +41,7 @@ func (src *CommandComplete) Encode(dst []byte) []byte {
 	return dst
 }
 
+// MarshalJSON implements encoding/json.Marshaler.
 func (src *CommandComplete) MarshalJSON() ([]byte, error) {
 	return json.Marshal(struct {
 		Type       string

copy_both_response.go

@@ -13,8 +13,11 @@ type CopyBothResponse struct {
 	ColumnFormatCodes []uint16
 }
 
+// Backend identifies this message as sendable by the PostgreSQL backend.
 func (*CopyBothResponse) Backend() {}
 
+// Decode decodes src into dst. src must contain the complete message with the exception of the initial 1 byte message
+// type identifier and 4 byte message length.
 func (dst *CopyBothResponse) Decode(src []byte) error {
 	buf := bytes.NewBuffer(src)
 
@@ -39,6 +42,7 @@ func (dst *CopyBothResponse) Decode(src []byte) error {
 	return nil
 }
 
+// Encode encodes src into dst. dst will include the 1 byte message type identifier and the 4 byte message length.
 func (src *CopyBothResponse) Encode(dst []byte) []byte {
 	dst = append(dst, 'W')
 	sp := len(dst)
@@ -54,6 +58,7 @@ func (src *CopyBothResponse) Encode(dst []byte) []byte {
 	return dst
 }
 
+// MarshalJSON implements encoding/json.Marshaler.
 func (src *CopyBothResponse) MarshalJSON() ([]byte, error) {
 	return json.Marshal(struct {
 		Type              string

copy_data.go

@@ -11,14 +11,20 @@ type CopyData struct {
 	Data []byte
 }
 
-func (*CopyData) Backend()  {}
+// Backend identifies this message as sendable by the PostgreSQL backend.
+func (*CopyData) Backend() {}
+
+// Frontend identifies this message as sendable by a PostgreSQL frontend.
 func (*CopyData) Frontend() {}
 
+// Decode decodes src into dst. src must contain the complete message with the exception of the initial 1 byte message
+// type identifier and 4 byte message length.
 func (dst *CopyData) Decode(src []byte) error {
 	dst.Data = src
 	return nil
 }
 
+// Encode encodes src into dst. dst will include the 1 byte message type identifier and the 4 byte message length.
 func (src *CopyData) Encode(dst []byte) []byte {
 	dst = append(dst, 'd')
 	dst = pgio.AppendInt32(dst, int32(4+len(src.Data)))
@@ -26,6 +32,7 @@ func (src *CopyData) Encode(dst []byte) []byte {
 	return dst
 }
 
+// MarshalJSON implements encoding/json.Marshaler.
 func (src *CopyData) MarshalJSON() ([]byte, error) {
 	return json.Marshal(struct {
 		Type string

copy_done.go

@@ -7,8 +7,11 @@ import (
 type CopyDone struct {
 }
 
+// Backend identifies this message as sendable by the PostgreSQL backend.
 func (*CopyDone) Backend() {}
 
+// Decode decodes src into dst. src must contain the complete message with the exception of the initial 1 byte message
+// type identifier and 4 byte message length.
 func (dst *CopyDone) Decode(src []byte) error {
 	if len(src) != 0 {
 		return &invalidMessageLenErr{messageType: "CopyDone", expectedLen: 0, actualLen: len(src)}
@@ -17,10 +20,12 @@ func (dst *CopyDone) Decode(src []byte) error {
 	return nil
 }
 
+// Encode encodes src into dst. dst will include the 1 byte message type identifier and the 4 byte message length.
 func (src *CopyDone) Encode(dst []byte) []byte {
 	return append(dst, 'c', 0, 0, 0, 4)
 }
 
+// MarshalJSON implements encoding/json.Marshaler.
 func (src *CopyDone) MarshalJSON() ([]byte, error) {
 	return json.Marshal(struct {
 		Type string

copy_fail.go

@@ -11,8 +11,11 @@ type CopyFail struct {
 	Message string
 }
 
+// Frontend identifies this message as sendable by a PostgreSQL frontend.
 func (*CopyFail) Frontend() {}
 
+// Decode decodes src into dst. src must contain the complete message with the exception of the initial 1 byte message
+// type identifier and 4 byte message length.
 func (dst *CopyFail) Decode(src []byte) error {
 	idx := bytes.IndexByte(src, 0)
 	if idx != len(src)-1 {
@@ -24,6 +27,7 @@ func (dst *CopyFail) Decode(src []byte) error {
 	return nil
 }
 
+// Encode encodes src into dst. dst will include the 1 byte message type identifier and the 4 byte message length.
 func (src *CopyFail) Encode(dst []byte) []byte {
 	dst = append(dst, 'f')
 	sp := len(dst)
@@ -37,6 +41,7 @@ func (src *CopyFail) Encode(dst []byte) []byte {
 	return dst
 }
 
+// MarshalJSON implements encoding/json.Marshaler.
 func (src *CopyFail) MarshalJSON() ([]byte, error) {
 	return json.Marshal(struct {
 		Type    string

copy_in_response.go

@@ -13,8 +13,11 @@ type CopyInResponse struct {
 	ColumnFormatCodes []uint16
 }
 
+// Backend identifies this message as sendable by the PostgreSQL backend.
 func (*CopyInResponse) Backend() {}
 
+// Decode decodes src into dst. src must contain the complete message with the exception of the initial 1 byte message
+// type identifier and 4 byte message length.
 func (dst *CopyInResponse) Decode(src []byte) error {
 	buf := bytes.NewBuffer(src)
 
@@ -39,6 +42,7 @@ func (dst *CopyInResponse) Decode(src []byte) error {
 	return nil
 }
 
+// Encode encodes src into dst. dst will include the 1 byte message type identifier and the 4 byte message length.
 func (src *CopyInResponse) Encode(dst []byte) []byte {
 	dst = append(dst, 'G')
 	sp := len(dst)
@@ -54,6 +58,7 @@ func (src *CopyInResponse) Encode(dst []byte) []byte {
 	return dst
 }
 
+// MarshalJSON implements encoding/json.Marshaler.
 func (src *CopyInResponse) MarshalJSON() ([]byte, error) {
 	return json.Marshal(struct {
 		Type              string

copy_out_response.go

@@ -15,6 +15,8 @@ type CopyOutResponse struct {
 
 func (*CopyOutResponse) Backend() {}
 
+// Decode decodes src into dst. src must contain the complete message with the exception of the initial 1 byte message
+// type identifier and 4 byte message length.
 func (dst *CopyOutResponse) Decode(src []byte) error {
 	buf := bytes.NewBuffer(src)
 
@@ -39,6 +41,7 @@ func (dst *CopyOutResponse) Decode(src []byte) error {
 	return nil
 }
 
+// Encode encodes src into dst. dst will include the 1 byte message type identifier and the 4 byte message length.
 func (src *CopyOutResponse) Encode(dst []byte) []byte {
 	dst = append(dst, 'H')
 	sp := len(dst)
@@ -56,6 +59,7 @@ func (src *CopyOutResponse) Encode(dst []byte) []byte {
 	return dst
 }
 
+// MarshalJSON implements encoding/json.Marshaler.
 func (src *CopyOutResponse) MarshalJSON() ([]byte, error) {
 	return json.Marshal(struct {
 		Type              string

data_row.go

@@ -12,8 +12,11 @@ type DataRow struct {
 	Values [][]byte
 }
 
+// Backend identifies this message as sendable by the PostgreSQL backend.
 func (*DataRow) Backend() {}
 
+// Decode decodes src into dst. src must contain the complete message with the exception of the initial 1 byte message
+// type identifier and 4 byte message length.
 func (dst *DataRow) Decode(src []byte) error {
 	if len(src) < 2 {
 		return &invalidMessageFormatErr{messageType: "DataRow"}
@@ -59,6 +62,7 @@ func (dst *DataRow) Decode(src []byte) error {
 	return nil
 }
 
+// Encode encodes src into dst. dst will include the 1 byte message type identifier and the 4 byte message length.
 func (src *DataRow) Encode(dst []byte) []byte {
 	dst = append(dst, 'D')
 	sp := len(dst)
@@ -80,6 +84,7 @@ func (src *DataRow) Encode(dst []byte) []byte {
 	return dst
 }
 
+// MarshalJSON implements encoding/json.Marshaler.
 func (src *DataRow) MarshalJSON() ([]byte, error) {
 	formattedValues := make([]map[string]string, len(src.Values))
 	for i, v := range src.Values {

describe.go

@@ -12,8 +12,11 @@ type Describe struct {
 	Name       string
 }
 
+// Frontend identifies this message as sendable by a PostgreSQL frontend.
 func (*Describe) Frontend() {}
 
+// Decode decodes src into dst. src must contain the complete message with the exception of the initial 1 byte message
+// type identifier and 4 byte message length.
 func (dst *Describe) Decode(src []byte) error {
 	if len(src) < 2 {
 		return &invalidMessageFormatErr{messageType: "Describe"}
@@ -32,6 +35,7 @@ func (dst *Describe) Decode(src []byte) error {
 	return nil
 }
 
+// Encode encodes src into dst. dst will include the 1 byte message type identifier and the 4 byte message length.
 func (src *Describe) Encode(dst []byte) []byte {
 	dst = append(dst, 'D')
 	sp := len(dst)
@@ -46,6 +50,7 @@ func (src *Describe) Encode(dst []byte) []byte {
 	return dst
 }
 
+// MarshalJSON implements encoding/json.Marshaler.
 func (src *Describe) MarshalJSON() ([]byte, error) {
 	return json.Marshal(struct {
 		Type       string

doc.go

@@ -1,2 +1,4 @@
 // Package pgproto3 is a encoder and decoder of the PostgreSQL wire protocol version 3.
+//
+// See https://www.postgresql.org/docs/current/protocol-message-formats.html for meanings of the different messages.
 package pgproto3

empty_query_response.go

@@ -6,8 +6,11 @@ import (
 
 type EmptyQueryResponse struct{}
 
+// Backend identifies this message as sendable by the PostgreSQL backend.
 func (*EmptyQueryResponse) Backend() {}
 
+// Decode decodes src into dst. src must contain the complete message with the exception of the initial 1 byte message
+// type identifier and 4 byte message length.
 func (dst *EmptyQueryResponse) Decode(src []byte) error {
 	if len(src) != 0 {
 		return &invalidMessageLenErr{messageType: "EmptyQueryResponse", expectedLen: 0, actualLen: len(src)}
@@ -16,10 +19,12 @@ func (dst *EmptyQueryResponse) Decode(src []byte) error {
 	return nil
 }
 
+// Encode encodes src into dst. dst will include the 1 byte message type identifier and the 4 byte message length.
 func (src *EmptyQueryResponse) Encode(dst []byte) []byte {
 	return append(dst, 'I', 0, 0, 0, 4)
 }
 
+// MarshalJSON implements encoding/json.Marshaler.
 func (src *EmptyQueryResponse) MarshalJSON() ([]byte, error) {
 	return json.Marshal(struct {
 		Type string

error_response.go

@@ -28,8 +28,11 @@ type ErrorResponse struct {
 	UnknownFields map[byte]string
 }
 
+// Backend identifies this message as sendable by the PostgreSQL backend.
 func (*ErrorResponse) Backend() {}
 
+// Decode decodes src into dst. src must contain the complete message with the exception of the initial 1 byte message
+// type identifier and 4 byte message length.
 func (dst *ErrorResponse) Decode(src []byte) error {
 	*dst = ErrorResponse{}
 
@@ -103,6 +106,7 @@ func (dst *ErrorResponse) Decode(src []byte) error {
 	return nil
 }
 
+// Encode encodes src into dst. dst will include the 1 byte message type identifier and the 4 byte message length.
 func (src *ErrorResponse) Encode(dst []byte) []byte {
 	return append(dst, src.marshalBinary('E')...)
 }

execute.go

@@ -13,8 +13,11 @@ type Execute struct {
 	MaxRows uint32
 }
 
+// Frontend identifies this message as sendable by a PostgreSQL frontend.
 func (*Execute) Frontend() {}
 
+// Decode decodes src into dst. src must contain the complete message with the exception of the initial 1 byte message
+// type identifier and 4 byte message length.
 func (dst *Execute) Decode(src []byte) error {
 	buf := bytes.NewBuffer(src)
 
@@ -32,6 +35,7 @@ func (dst *Execute) Decode(src []byte) error {
 	return nil
 }
 
+// Encode encodes src into dst. dst will include the 1 byte message type identifier and the 4 byte message length.
 func (src *Execute) Encode(dst []byte) []byte {
 	dst = append(dst, 'E')
 	sp := len(dst)
@@ -47,6 +51,7 @@ func (src *Execute) Encode(dst []byte) []byte {
 	return dst
 }
 
+// MarshalJSON implements encoding/json.Marshaler.
 func (src *Execute) MarshalJSON() ([]byte, error) {
 	return json.Marshal(struct {
 		Type    string

flush.go

@@ -6,8 +6,11 @@ import (
 
 type Flush struct{}
 
+// Frontend identifies this message as sendable by a PostgreSQL frontend.
 func (*Flush) Frontend() {}
 
+// Decode decodes src into dst. src must contain the complete message with the exception of the initial 1 byte message
+// type identifier and 4 byte message length.
 func (dst *Flush) Decode(src []byte) error {
 	if len(src) != 0 {
 		return &invalidMessageLenErr{messageType: "Flush", expectedLen: 0, actualLen: len(src)}
@@ -16,10 +19,12 @@ func (dst *Flush) Decode(src []byte) error {
 	return nil
 }
 
+// Encode encodes src into dst. dst will include the 1 byte message type identifier and the 4 byte message length.
 func (src *Flush) Encode(dst []byte) []byte {
 	return append(dst, 'H', 0, 0, 0, 4)
 }
 
+// MarshalJSON implements encoding/json.Marshaler.
 func (src *Flush) MarshalJSON() ([]byte, error) {
 	return json.Marshal(struct {
 		Type string

frontend.go

@@ -7,6 +7,7 @@ import (
 	"github.com/pkg/errors"
 )
 
+// Frontend acts as a client for the PostgreSQL wire protocol version 3.
 type Frontend struct {
 	cr ChunkReader
 	w  io.Writer
@@ -41,15 +42,18 @@ type Frontend struct {
 	partialMsg bool
 }
 
+// NewFrontend creates a new Frontend.
 func NewFrontend(cr ChunkReader, w io.Writer) (*Frontend, error) {
 	return &Frontend{cr: cr, w: w}, nil
 }
 
+// Send sends a message to the backend.
 func (b *Frontend) Send(msg FrontendMessage) error {
 	_, err := b.w.Write(msg.Encode(nil))
 	return err
 }
 
+// Receive receives a message from the backend.
 func (b *Frontend) Receive() (BackendMessage, error) {
 	if !b.partialMsg {
 		header, err := b.cr.Next(5)

function_call_response.go

@@ -12,8 +12,11 @@ type FunctionCallResponse struct {
 	Result []byte
 }
 
+// Backend identifies this message as sendable by the PostgreSQL backend.
 func (*FunctionCallResponse) Backend() {}
 
+// Decode decodes src into dst. src must contain the complete message with the exception of the initial 1 byte message
+// type identifier and 4 byte message length.
 func (dst *FunctionCallResponse) Decode(src []byte) error {
 	if len(src) < 4 {
 		return &invalidMessageFormatErr{messageType: "FunctionCallResponse"}
@@ -35,6 +38,7 @@ func (dst *FunctionCallResponse) Decode(src []byte) error {
 	return nil
 }
 
+// Encode encodes src into dst. dst will include the 1 byte message type identifier and the 4 byte message length.
 func (src *FunctionCallResponse) Encode(dst []byte) []byte {
 	dst = append(dst, 'V')
 	sp := len(dst)
@@ -52,6 +56,7 @@ func (src *FunctionCallResponse) Encode(dst []byte) []byte {
 	return dst
 }
 
+// MarshalJSON implements encoding/json.Marshaler.
 func (src *FunctionCallResponse) MarshalJSON() ([]byte, error) {
 	var formattedValue map[string]string
 	var hasNonPrintable bool

no_data.go

@@ -6,8 +6,11 @@ import (
 
 type NoData struct{}
 
+// Backend identifies this message as sendable by the PostgreSQL backend.
 func (*NoData) Backend() {}
 
+// Decode decodes src into dst. src must contain the complete message with the exception of the initial 1 byte message
+// type identifier and 4 byte message length.
 func (dst *NoData) Decode(src []byte) error {
 	if len(src) != 0 {
 		return &invalidMessageLenErr{messageType: "NoData", expectedLen: 0, actualLen: len(src)}
@@ -16,10 +19,12 @@ func (dst *NoData) Decode(src []byte) error {
 	return nil
 }
 
+// Encode encodes src into dst. dst will include the 1 byte message type identifier and the 4 byte message length.
 func (src *NoData) Encode(dst []byte) []byte {
 	return append(dst, 'n', 0, 0, 0, 4)
 }
 
+// MarshalJSON implements encoding/json.Marshaler.
 func (src *NoData) MarshalJSON() ([]byte, error) {
 	return json.Marshal(struct {
 		Type string

notice_response.go

@@ -2,12 +2,16 @@ package pgproto3
 
 type NoticeResponse ErrorResponse
 
+// Backend identifies this message as sendable by the PostgreSQL backend.
 func (*NoticeResponse) Backend() {}
 
+// Decode decodes src into dst. src must contain the complete message with the exception of the initial 1 byte message
+// type identifier and 4 byte message length.
 func (dst *NoticeResponse) Decode(src []byte) error {
 	return (*ErrorResponse)(dst).Decode(src)
 }
 
+// Encode encodes src into dst. dst will include the 1 byte message type identifier and the 4 byte message length.
 func (src *NoticeResponse) Encode(dst []byte) []byte {
 	return append(dst, (*ErrorResponse)(src).marshalBinary('N')...)
 }

notification_response.go

@@ -14,8 +14,11 @@ type NotificationResponse struct {
 	Payload string
 }
 
+// Backend identifies this message as sendable by the PostgreSQL backend.
 func (*NotificationResponse) Backend() {}
 
+// Decode decodes src into dst. src must contain the complete message with the exception of the initial 1 byte message
+// type identifier and 4 byte message length.
 func (dst *NotificationResponse) Decode(src []byte) error {
 	buf := bytes.NewBuffer(src)
 
@@ -37,6 +40,7 @@ func (dst *NotificationResponse) Decode(src []byte) error {
 	return nil
 }
 
+// Encode encodes src into dst. dst will include the 1 byte message type identifier and the 4 byte message length.
 func (src *NotificationResponse) Encode(dst []byte) []byte {
 	dst = append(dst, 'A')
 	sp := len(dst)
@@ -52,6 +56,7 @@ func (src *NotificationResponse) Encode(dst []byte) []byte {
 	return dst
 }
 
+// MarshalJSON implements encoding/json.Marshaler.
 func (src *NotificationResponse) MarshalJSON() ([]byte, error) {
 	return json.Marshal(struct {
 		Type    string

parameter_description.go

@@ -12,8 +12,11 @@ type ParameterDescription struct {
 	ParameterOIDs []uint32
 }
 
+// Backend identifies this message as sendable by the PostgreSQL backend.
 func (*ParameterDescription) Backend() {}
 
+// Decode decodes src into dst. src must contain the complete message with the exception of the initial 1 byte message
+// type identifier and 4 byte message length.
 func (dst *ParameterDescription) Decode(src []byte) error {
 	buf := bytes.NewBuffer(src)
 
@@ -35,6 +38,7 @@ func (dst *ParameterDescription) Decode(src []byte) error {
 	return nil
 }
 
+// Encode encodes src into dst. dst will include the 1 byte message type identifier and the 4 byte message length.
 func (src *ParameterDescription) Encode(dst []byte) []byte {
 	dst = append(dst, 't')
 	sp := len(dst)
@@ -50,6 +54,7 @@ func (src *ParameterDescription) Encode(dst []byte) []byte {
 	return dst
 }
 
+// MarshalJSON implements encoding/json.Marshaler.
 func (src *ParameterDescription) MarshalJSON() ([]byte, error) {
 	return json.Marshal(struct {
 		Type          string

parameter_status.go

@@ -12,8 +12,11 @@ type ParameterStatus struct {
 	Value string
 }
 
+// Backend identifies this message as sendable by the PostgreSQL backend.
 func (*ParameterStatus) Backend() {}
 
+// Decode decodes src into dst. src must contain the complete message with the exception of the initial 1 byte message
+// type identifier and 4 byte message length.
 func (dst *ParameterStatus) Decode(src []byte) error {
 	buf := bytes.NewBuffer(src)
 
@@ -33,6 +36,7 @@ func (dst *ParameterStatus) Decode(src []byte) error {
 	return nil
 }
 
+// Encode encodes src into dst. dst will include the 1 byte message type identifier and the 4 byte message length.
 func (src *ParameterStatus) Encode(dst []byte) []byte {
 	dst = append(dst, 'S')
 	sp := len(dst)
@@ -48,6 +52,7 @@ func (src *ParameterStatus) Encode(dst []byte) []byte {
 	return dst
 }
 
+// MarshalJSON implements encoding/json.Marshaler.
 func (ps *ParameterStatus) MarshalJSON() ([]byte, error) {
 	return json.Marshal(struct {
 		Type  string

parse.go

@@ -14,8 +14,11 @@ type Parse struct {
 	ParameterOIDs []uint32
 }
 
+// Frontend identifies this message as sendable by a PostgreSQL frontend.
 func (*Parse) Frontend() {}
 
+// Decode decodes src into dst. src must contain the complete message with the exception of the initial 1 byte message
+// type identifier and 4 byte message length.
 func (dst *Parse) Decode(src []byte) error {
 	*dst = Parse{}
 
@@ -48,6 +51,7 @@ func (dst *Parse) Decode(src []byte) error {
 	return nil
 }
 
+// Encode encodes src into dst. dst will include the 1 byte message type identifier and the 4 byte message length.
 func (src *Parse) Encode(dst []byte) []byte {
 	dst = append(dst, 'P')
 	sp := len(dst)
@@ -68,6 +72,7 @@ func (src *Parse) Encode(dst []byte) []byte {
 	return dst
 }
 
+// MarshalJSON implements encoding/json.Marshaler.
 func (src *Parse) MarshalJSON() ([]byte, error) {
 	return json.Marshal(struct {
 		Type          string

parse_complete.go

@@ -6,8 +6,11 @@ import (
 
 type ParseComplete struct{}
 
+// Backend identifies this message as sendable by the PostgreSQL backend.
 func (*ParseComplete) Backend() {}
 
+// Decode decodes src into dst. src must contain the complete message with the exception of the initial 1 byte message
+// type identifier and 4 byte message length.
 func (dst *ParseComplete) Decode(src []byte) error {
 	if len(src) != 0 {
 		return &invalidMessageLenErr{messageType: "ParseComplete", expectedLen: 0, actualLen: len(src)}
@@ -16,10 +19,12 @@ func (dst *ParseComplete) Decode(src []byte) error {
 	return nil
 }
 
+// Encode encodes src into dst. dst will include the 1 byte message type identifier and the 4 byte message length.
 func (src *ParseComplete) Encode(dst []byte) []byte {
 	return append(dst, '1', 0, 0, 0, 4)
 }
 
+// MarshalJSON implements encoding/json.Marshaler.
 func (src *ParseComplete) MarshalJSON() ([]byte, error) {
 	return json.Marshal(struct {
 		Type string

password_message.go

@@ -11,8 +11,11 @@ type PasswordMessage struct {
 	Password string
 }
 
+// Frontend identifies this message as sendable by a PostgreSQL frontend.
 func (*PasswordMessage) Frontend() {}
 
+// Decode decodes src into dst. src must contain the complete message with the exception of the initial 1 byte message
+// type identifier and 4 byte message length.
 func (dst *PasswordMessage) Decode(src []byte) error {
 	buf := bytes.NewBuffer(src)
 
@@ -25,6 +28,7 @@ func (dst *PasswordMessage) Decode(src []byte) error {
 	return nil
 }
 
+// Encode encodes src into dst. dst will include the 1 byte message type identifier and the 4 byte message length.
 func (src *PasswordMessage) Encode(dst []byte) []byte {
 	dst = append(dst, 'p')
 	dst = pgio.AppendInt32(dst, int32(4+len(src.Password)+1))
@@ -35,6 +39,7 @@ func (src *PasswordMessage) Encode(dst []byte) []byte {
 	return dst
 }
 
+// MarshalJSON implements encoding/json.Marshaler.
 func (src *PasswordMessage) MarshalJSON() ([]byte, error) {
 	return json.Marshal(struct {
 		Type     string

portal_suspended.go

@@ -6,8 +6,11 @@ import (
 
 type PortalSuspended struct{}
 
+// Backend identifies this message as sendable by the PostgreSQL backend.
 func (*PortalSuspended) Backend() {}
 
+// Decode decodes src into dst. src must contain the complete message with the exception of the initial 1 byte message
+// type identifier and 4 byte message length.
 func (dst *PortalSuspended) Decode(src []byte) error {
 	if len(src) != 0 {
 		return &invalidMessageLenErr{messageType: "PortalSuspended", expectedLen: 0, actualLen: len(src)}
@@ -16,10 +19,12 @@ func (dst *PortalSuspended) Decode(src []byte) error {
 	return nil
 }
 
+// Encode encodes src into dst. dst will include the 1 byte message type identifier and the 4 byte message length.
 func (src *PortalSuspended) Encode(dst []byte) []byte {
 	return append(dst, 's', 0, 0, 0, 4)
 }
 
+// MarshalJSON implements encoding/json.Marshaler.
 func (src *PortalSuspended) MarshalJSON() ([]byte, error) {
 	return json.Marshal(struct {
 		Type string

query.go

@@ -11,8 +11,11 @@ type Query struct {
 	String string
 }
 
+// Frontend identifies this message as sendable by a PostgreSQL frontend.
 func (*Query) Frontend() {}
 
+// Decode decodes src into dst. src must contain the complete message with the exception of the initial 1 byte message
+// type identifier and 4 byte message length.
 func (dst *Query) Decode(src []byte) error {
 	i := bytes.IndexByte(src, 0)
 	if i != len(src)-1 {
@@ -24,6 +27,7 @@ func (dst *Query) Decode(src []byte) error {
 	return nil
 }
 
+// Encode encodes src into dst. dst will include the 1 byte message type identifier and the 4 byte message length.
 func (src *Query) Encode(dst []byte) []byte {
 	dst = append(dst, 'Q')
 	dst = pgio.AppendInt32(dst, int32(4+len(src.String)+1))
@@ -34,6 +38,7 @@ func (src *Query) Encode(dst []byte) []byte {
 	return dst
 }
 
+// MarshalJSON implements encoding/json.Marshaler.
 func (src *Query) MarshalJSON() ([]byte, error) {
 	return json.Marshal(struct {
 		Type   string

ready_for_query.go

@@ -8,8 +8,11 @@ type ReadyForQuery struct {
 	TxStatus byte
 }
 
+// Backend identifies this message as sendable by the PostgreSQL backend.
 func (*ReadyForQuery) Backend() {}
 
+// Decode decodes src into dst. src must contain the complete message with the exception of the initial 1 byte message
+// type identifier and 4 byte message length.
 func (dst *ReadyForQuery) Decode(src []byte) error {
 	if len(src) != 1 {
 		return &invalidMessageLenErr{messageType: "ReadyForQuery", expectedLen: 1, actualLen: len(src)}
@@ -20,10 +23,12 @@ func (dst *ReadyForQuery) Decode(src []byte) error {
 	return nil
 }
 
+// Encode encodes src into dst. dst will include the 1 byte message type identifier and the 4 byte message length.
 func (src *ReadyForQuery) Encode(dst []byte) []byte {
 	return append(dst, 'Z', 0, 0, 0, 5, src.TxStatus)
 }
 
+// MarshalJSON implements encoding/json.Marshaler.
 func (src *ReadyForQuery) MarshalJSON() ([]byte, error) {
 	return json.Marshal(struct {
 		Type     string

row_description.go

@@ -27,8 +27,11 @@ type RowDescription struct {
 	Fields []FieldDescription
 }
 
+// Backend identifies this message as sendable by the PostgreSQL backend.
 func (*RowDescription) Backend() {}
 
+// Decode decodes src into dst. src must contain the complete message with the exception of the initial 1 byte message
+// type identifier and 4 byte message length.
 func (dst *RowDescription) Decode(src []byte) error {
 
 	if len(src) < 2 {
@@ -74,6 +77,7 @@ func (dst *RowDescription) Decode(src []byte) error {
 	return nil
 }
 
+// Encode encodes src into dst. dst will include the 1 byte message type identifier and the 4 byte message length.
 func (src *RowDescription) Encode(dst []byte) []byte {
 	dst = append(dst, 'T')
 	sp := len(dst)
@@ -97,6 +101,7 @@ func (src *RowDescription) Encode(dst []byte) []byte {
 	return dst
 }
 
+// MarshalJSON implements encoding/json.Marshaler.
 func (src *RowDescription) MarshalJSON() ([]byte, error) {
 	return json.Marshal(struct {
 		Type   string

sasl_initial_response.go

@@ -14,8 +14,11 @@ type SASLInitialResponse struct {
 	Data          []byte
 }
 
+// Frontend identifies this message as sendable by a PostgreSQL frontend.
 func (*SASLInitialResponse) Frontend() {}
 
+// Decode decodes src into dst. src must contain the complete message with the exception of the initial 1 byte message
+// type identifier and 4 byte message length.
 func (dst *SASLInitialResponse) Decode(src []byte) error {
 	*dst = SASLInitialResponse{}
 
@@ -35,6 +38,7 @@ func (dst *SASLInitialResponse) Decode(src []byte) error {
 	return nil
 }
 
+// Encode encodes src into dst. dst will include the 1 byte message type identifier and the 4 byte message length.
 func (src *SASLInitialResponse) Encode(dst []byte) []byte {
 	dst = append(dst, 'p')
 	sp := len(dst)
@@ -51,6 +55,7 @@ func (src *SASLInitialResponse) Encode(dst []byte) []byte {
 	return dst
 }
 
+// MarshalJSON implements encoding/json.Marshaler.
 func (src *SASLInitialResponse) MarshalJSON() ([]byte, error) {
 	return json.Marshal(struct {
 		Type          string

sasl_response.go

@@ -11,13 +11,17 @@ type SASLResponse struct {
 	Data []byte
 }
 
+// Frontend identifies this message as sendable by a PostgreSQL frontend.
 func (*SASLResponse) Frontend() {}
 
+// Decode decodes src into dst. src must contain the complete message with the exception of the initial 1 byte message
+// type identifier and 4 byte message length.
 func (dst *SASLResponse) Decode(src []byte) error {
 	*dst = SASLResponse{Data: src}
 	return nil
 }
 
+// Encode encodes src into dst. dst will include the 1 byte message type identifier and the 4 byte message length.
 func (src *SASLResponse) Encode(dst []byte) []byte {
 	dst = append(dst, 'p')
 	dst = pgio.AppendInt32(dst, int32(4+len(src.Data)))
@@ -27,6 +31,7 @@ func (src *SASLResponse) Encode(dst []byte) []byte {
 	return dst
 }
 
+// MarshalJSON implements encoding/json.Marshaler.
 func (src *SASLResponse) MarshalJSON() ([]byte, error) {
 	return json.Marshal(struct {
 		Type string

startup_message.go

@@ -19,8 +19,11 @@ type StartupMessage struct {
 	Parameters      map[string]string
 }
 
+// Frontend identifies this message as sendable by a PostgreSQL frontend.
 func (*StartupMessage) Frontend() {}
 
+// Decode decodes src into dst. src must contain the complete message with the exception of the initial 1 byte message
+// type identifier and 4 byte message length.
 func (dst *StartupMessage) Decode(src []byte) error {
 	if len(src) < 4 {
 		return errors.Errorf("startup message too short")
@@ -66,6 +69,7 @@ func (dst *StartupMessage) Decode(src []byte) error {
 	return nil
 }
 
+// Encode encodes src into dst. dst will include the 1 byte message type identifier and the 4 byte message length.
 func (src *StartupMessage) Encode(dst []byte) []byte {
 	sp := len(dst)
 	dst = pgio.AppendInt32(dst, -1)
@@ -84,6 +88,7 @@ func (src *StartupMessage) Encode(dst []byte) []byte {
 	return dst
 }
 
+// MarshalJSON implements encoding/json.Marshaler.
 func (src *StartupMessage) MarshalJSON() ([]byte, error) {
 	return json.Marshal(struct {
 		Type            string

sync.go

@@ -6,8 +6,11 @@ import (
 
 type Sync struct{}
 
+// Frontend identifies this message as sendable by a PostgreSQL frontend.
 func (*Sync) Frontend() {}
 
+// Decode decodes src into dst. src must contain the complete message with the exception of the initial 1 byte message
+// type identifier and 4 byte message length.
 func (dst *Sync) Decode(src []byte) error {
 	if len(src) != 0 {
 		return &invalidMessageLenErr{messageType: "Sync", expectedLen: 0, actualLen: len(src)}
@@ -16,10 +19,12 @@ func (dst *Sync) Decode(src []byte) error {
 	return nil
 }
 
+// Encode encodes src into dst. dst will include the 1 byte message type identifier and the 4 byte message length.
 func (src *Sync) Encode(dst []byte) []byte {
 	return append(dst, 'S', 0, 0, 0, 4)
 }
 
+// MarshalJSON implements encoding/json.Marshaler.
 func (src *Sync) MarshalJSON() ([]byte, error) {
 	return json.Marshal(struct {
 		Type string

terminate.go

@@ -6,8 +6,11 @@ import (
 
 type Terminate struct{}
 
+// Frontend identifies this message as sendable by a PostgreSQL frontend.
 func (*Terminate) Frontend() {}
 
+// Decode decodes src into dst. src must contain the complete message with the exception of the initial 1 byte message
+// type identifier and 4 byte message length.
 func (dst *Terminate) Decode(src []byte) error {
 	if len(src) != 0 {
 		return &invalidMessageLenErr{messageType: "Terminate", expectedLen: 0, actualLen: len(src)}
@@ -16,10 +19,12 @@ func (dst *Terminate) Decode(src []byte) error {
 	return nil
 }
 
+// Encode encodes src into dst. dst will include the 1 byte message type identifier and the 4 byte message length.
 func (src *Terminate) Encode(dst []byte) []byte {
 	return append(dst, 'X', 0, 0, 0, 4)
 }
 
+// MarshalJSON implements encoding/json.Marshaler.
 func (src *Terminate) MarshalJSON() ([]byte, error) {
 	return json.Marshal(struct {
 		Type string