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remote.go
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remote.go
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package sqldb
import (
"context"
"crypto/rand"
"encoding/base64"
"errors"
"fmt"
"net"
"time"
"github.com/gorilla/websocket"
"github.com/rs/zerolog/log"
"encr.dev/cli/internal/platform"
"encr.dev/pkg/pgproxy"
)
// OneshotProxy listens on a random port for a single connection, and proxies that connection to a remote db.
// It reports the one-time password and port to use.
// Once a connection has been established, it stops listening.
func OneshotProxy(appSlug, envSlug string) (port int, passwd string, err error) {
ln, err := net.Listen("tcp", "localhost:0")
if err != nil {
return 0, "", err
}
var passwdBytes [8]byte
if _, err := rand.Read(passwdBytes[:]); err != nil {
return 0, "", err
}
passwd = base64.RawURLEncoding.EncodeToString(passwdBytes[:])
go oneshotServer(context.Background(), ln, passwd, appSlug, envSlug)
return ln.Addr().(*net.TCPAddr).Port, passwd, nil
}
func oneshotServer(ctx context.Context, ln net.Listener, passwd, appSlug, envSlug string) error {
proxy := &pgproxy.SingleBackendProxy{
RequirePassword: passwd != "",
FrontendTLS: nil,
DialBackend: func(ctx context.Context, startup *pgproxy.StartupData) (pgproxy.LogicalConn, error) {
if startup.Password != passwd {
return nil, fmt.Errorf("bad password")
}
startupData := startup.Raw.Encode(nil)
ws, err := platform.DBConnect(ctx, appSlug, envSlug, startup.Database, startupData)
if err != nil {
var e platform.Error
if errors.As(err, &e) && e.HTTPCode == 404 {
return nil, pgproxy.DatabaseNotFoundError{Database: startup.Database}
}
return nil, err
}
conn := &WebsocketLogicalConn{Conn: ws}
return conn, nil
},
}
return proxy.Serve(ctx, ln)
}
type WebsocketLogicalConn struct {
*websocket.Conn
buf []byte
}
var _ pgproxy.LogicalConn = (*WebsocketLogicalConn)(nil)
func (c *WebsocketLogicalConn) Write(p []byte) (int, error) {
err := c.Conn.WriteMessage(websocket.BinaryMessage, p)
if err != nil {
return 0, err
}
return len(p), nil
}
func (c *WebsocketLogicalConn) Read(p []byte) (int, error) {
// If we have remaining data from the previous message we received
// from the stream, simply return that.
if len(c.buf) > 0 {
n := copy(p, c.buf)
c.buf = c.buf[n:]
return n, nil
}
// No more buffered data, wait for a new message from the stream.
for {
typ, data, err := c.Conn.ReadMessage()
if err != nil {
return 0, err
} else if typ != websocket.BinaryMessage {
continue
}
// Read as much data as possible directly to the waiting caller.
// Anything remaining beyond that gets buffered until the next Read call.
n := copy(p, data)
c.buf = data[n:]
return n, nil
}
}
func (c *WebsocketLogicalConn) Cancel(req *pgproxy.CancelData) error {
enc := base64.StdEncoding
data := req.Raw.Encode(nil)
encoded := make([]byte, enc.EncodedLen(len(data)))
enc.Encode(encoded, data)
log.Info().Msgf("sending cancel request %x", data)
return c.Conn.WriteMessage(websocket.TextMessage, encoded)
}
func (c *WebsocketLogicalConn) SetDeadline(t time.Time) error {
_ = c.Conn.SetReadDeadline(t)
err := c.Conn.SetWriteDeadline(t)
return err
}