121 lines
3.4 KiB
Go
121 lines
3.4 KiB
Go
package pgproto3
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import (
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"encoding/hex"
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"errors"
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"fmt"
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"github.com/jackc/pgx/v5/internal/pgio"
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)
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// maxMessageBodyLen is the maximum length of a message body in bytes. See PG_LARGE_MESSAGE_LIMIT in the PostgreSQL
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// source. It is defined as (MaxAllocSize - 1). MaxAllocSize is defined as 0x3fffffff.
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const maxMessageBodyLen = (0x3fffffff - 1)
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// Message is the interface implemented by an object that can decode and encode
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// a particular PostgreSQL message.
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type Message interface {
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// Decode is allowed and expected to retain a reference to data after
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// returning (unlike encoding.BinaryUnmarshaler).
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Decode(data []byte) error
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// Encode appends itself to dst and returns the new buffer.
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Encode(dst []byte) ([]byte, error)
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}
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// FrontendMessage is a message sent by the frontend (i.e. the client).
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type FrontendMessage interface {
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Message
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Frontend() // no-op method to distinguish frontend from backend methods
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}
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// BackendMessage is a message sent by the backend (i.e. the server).
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type BackendMessage interface {
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Message
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Backend() // no-op method to distinguish frontend from backend methods
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}
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type AuthenticationResponseMessage interface {
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BackendMessage
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AuthenticationResponse() // no-op method to distinguish authentication responses
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}
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type invalidMessageLenErr struct {
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messageType string
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expectedLen int
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actualLen int
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}
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func (e *invalidMessageLenErr) Error() string {
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return fmt.Sprintf("%s body must have length of %d, but it is %d", e.messageType, e.expectedLen, e.actualLen)
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}
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type invalidMessageFormatErr struct {
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messageType string
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details string
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}
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func (e *invalidMessageFormatErr) Error() string {
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return fmt.Sprintf("%s body is invalid %s", e.messageType, e.details)
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}
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type writeError struct {
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err error
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safeToRetry bool
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}
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func (e *writeError) Error() string {
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return fmt.Sprintf("write failed: %s", e.err.Error())
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}
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func (e *writeError) SafeToRetry() bool {
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return e.safeToRetry
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}
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func (e *writeError) Unwrap() error {
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return e.err
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}
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type ExceededMaxBodyLenErr struct {
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MaxExpectedBodyLen int
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ActualBodyLen int
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}
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func (e *ExceededMaxBodyLenErr) Error() string {
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return fmt.Sprintf("invalid body length: expected at most %d, but got %d", e.MaxExpectedBodyLen, e.ActualBodyLen)
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}
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// getValueFromJSON gets the value from a protocol message representation in JSON.
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func getValueFromJSON(v map[string]string) ([]byte, error) {
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if v == nil {
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return nil, nil
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}
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if text, ok := v["text"]; ok {
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return []byte(text), nil
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}
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if binary, ok := v["binary"]; ok {
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return hex.DecodeString(binary)
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}
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return nil, errors.New("unknown protocol representation")
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}
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// beginMessage begines a new message of type t. It appends the message type and a placeholder for the message length to
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// dst. It returns the new buffer and the position of the message length placeholder.
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func beginMessage(dst []byte, t byte) ([]byte, int) {
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dst = append(dst, t)
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sp := len(dst)
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dst = pgio.AppendInt32(dst, -1)
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return dst, sp
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}
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// finishMessage finishes a message that was started with beginMessage. It computes the message length and writes it to
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// dst[sp]. If the message length is too large it returns an error. Otherwise it returns the final message buffer.
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func finishMessage(dst []byte, sp int) ([]byte, error) {
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messageBodyLen := len(dst[sp:])
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if messageBodyLen > maxMessageBodyLen {
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return nil, errors.New("message body too large")
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}
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pgio.SetInt32(dst[sp:], int32(messageBodyLen))
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return dst, nil
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}
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