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package response
import (
"errors"
"fmt"
"net"
"strings"
"time"
)
// Upgrade takes a hijacked HTTP connection and sends the HTTP 101 Switching Protocols headers for protocolName.
func Upgrade(hijackedConn net.Conn, protocolName string) error {
// Write the status line and upgrade header by hand since w.WriteHeader() would fail after Hijack().
sb := strings.Builder{}
sb.WriteString("HTTP/1.1 101 Switching Protocols\r\n")
sb.WriteString(fmt.Sprintf("Upgrade: %s\r\n", protocolName))
sb.WriteString("Connection: Upgrade\r\n\r\n")
_ = hijackedConn.SetWriteDeadline(time.Now().Add(time.Second * 5))
n, err := hijackedConn.Write([]byte(sb.String()))
_ = hijackedConn.SetWriteDeadline(time.Time{}) // Cancel deadline.
if err != nil {
return fmt.Errorf("Failed writing upgrade headers: %w", err)
}
if n != sb.Len() {
return errors.New("Failed writing upgrade headers")
}
return nil
}
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