gotosocial/vendor/github.com/jackc/pgproto3/v2/backend.go

209 lines
5 KiB
Go
Raw Normal View History

package pgproto3
import (
"encoding/binary"
"fmt"
"io"
)
// Backend acts as a server for the PostgreSQL wire protocol version 3.
type Backend struct {
cr ChunkReader
w io.Writer
// Frontend message flyweights
bind Bind
cancelRequest CancelRequest
_close Close
copyFail CopyFail
copyData CopyData
copyDone CopyDone
describe Describe
execute Execute
flush Flush
2021-11-27 14:26:58 +00:00
functionCall FunctionCall
gssEncRequest GSSEncRequest
parse Parse
query Query
sslRequest SSLRequest
startupMessage StartupMessage
sync Sync
terminate Terminate
2021-11-27 14:26:58 +00:00
bodyLen int
msgType byte
partialMsg bool
authType uint32
}
const (
minStartupPacketLen = 4 // minStartupPacketLen is a single 32-bit int version or code.
maxStartupPacketLen = 10000 // maxStartupPacketLen is MAX_STARTUP_PACKET_LENGTH from PG source.
)
// NewBackend creates a new Backend.
func NewBackend(cr ChunkReader, w io.Writer) *Backend {
return &Backend{cr: cr, w: w}
}
// 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 connection message. This method is used of the normal Receive method
// because the initial connection message is "special" and does not include the message type as the first byte. This
// will return either a StartupMessage, SSLRequest, GSSEncRequest, or CancelRequest.
func (b *Backend) ReceiveStartupMessage() (FrontendMessage, error) {
buf, err := b.cr.Next(4)
if err != nil {
return nil, err
}
msgSize := int(binary.BigEndian.Uint32(buf) - 4)
if msgSize < minStartupPacketLen || msgSize > maxStartupPacketLen {
return nil, fmt.Errorf("invalid length of startup packet: %d", msgSize)
}
buf, err = b.cr.Next(msgSize)
if err != nil {
return nil, translateEOFtoErrUnexpectedEOF(err)
}
code := binary.BigEndian.Uint32(buf)
switch code {
case ProtocolVersionNumber:
err = b.startupMessage.Decode(buf)
if err != nil {
return nil, err
}
return &b.startupMessage, nil
case sslRequestNumber:
err = b.sslRequest.Decode(buf)
if err != nil {
return nil, err
}
return &b.sslRequest, nil
case cancelRequestCode:
err = b.cancelRequest.Decode(buf)
if err != nil {
return nil, err
}
return &b.cancelRequest, nil
case gssEncReqNumber:
err = b.gssEncRequest.Decode(buf)
if err != nil {
return nil, err
}
return &b.gssEncRequest, nil
default:
return nil, fmt.Errorf("unknown startup message code: %d", code)
}
}
// Receive receives a message from the frontend. The returned message is only valid until the next call to Receive.
func (b *Backend) Receive() (FrontendMessage, error) {
if !b.partialMsg {
header, err := b.cr.Next(5)
if err != nil {
return nil, translateEOFtoErrUnexpectedEOF(err)
}
b.msgType = header[0]
b.bodyLen = int(binary.BigEndian.Uint32(header[1:])) - 4
b.partialMsg = true
}
var msg FrontendMessage
switch b.msgType {
case 'B':
msg = &b.bind
case 'C':
msg = &b._close
case 'D':
msg = &b.describe
case 'E':
msg = &b.execute
2021-11-27 14:26:58 +00:00
case 'F':
msg = &b.functionCall
case 'f':
msg = &b.copyFail
case 'd':
msg = &b.copyData
case 'c':
msg = &b.copyDone
case 'H':
msg = &b.flush
case 'P':
msg = &b.parse
case 'p':
switch b.authType {
case AuthTypeSASL:
msg = &SASLInitialResponse{}
case AuthTypeSASLContinue:
msg = &SASLResponse{}
case AuthTypeSASLFinal:
msg = &SASLResponse{}
case AuthTypeCleartextPassword, AuthTypeMD5Password:
fallthrough
default:
// to maintain backwards compatability
msg = &PasswordMessage{}
}
case 'Q':
msg = &b.query
case 'S':
msg = &b.sync
case 'X':
msg = &b.terminate
default:
return nil, fmt.Errorf("unknown message type: %c", b.msgType)
}
msgBody, err := b.cr.Next(b.bodyLen)
if err != nil {
return nil, translateEOFtoErrUnexpectedEOF(err)
}
b.partialMsg = false
err = msg.Decode(msgBody)
return msg, err
}
// SetAuthType sets the authentication type in the backend.
// Since multiple message types can start with 'p', SetAuthType allows
// contextual identification of FrontendMessages. For example, in the
// PG message flow documentation for PasswordMessage:
//
// Byte1('p')
//
// Identifies the message as a password response. Note that this is also used for
// GSSAPI, SSPI and SASL response messages. The exact message type can be deduced from
// the context.
//
// Since the Frontend does not know about the state of a backend, it is important
// to call SetAuthType() after an authentication request is received by the Frontend.
func (b *Backend) SetAuthType(authType uint32) error {
switch authType {
case AuthTypeOk,
AuthTypeCleartextPassword,
AuthTypeMD5Password,
AuthTypeSCMCreds,
AuthTypeGSS,
AuthTypeGSSCont,
AuthTypeSSPI,
AuthTypeSASL,
AuthTypeSASLContinue,
AuthTypeSASLFinal:
b.authType = authType
default:
return fmt.Errorf("authType not recognized: %d", authType)
}
return nil
}