19f7cb23c8
add a new functionality to the agnhost image to run a server that closes the connections received by sending a RST. If a TCP servers closes the connection before all the socket is read, it sends a RST. This implementations just reads only one byte from the connection and closes it after that, that means that in order for this to work the client has to send at least 2 bytes of data. Using a simple curl is enough to trigger a RST: curl http://127.0.0.1:8080 curl: (56) Recv failure: Connection reset by peer Change-Id: I238fba0f790f2c92b37c732f51910a8b125f65db
79 lines
1.9 KiB
Go
79 lines
1.9 KiB
Go
/*
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Copyright 2023 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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// A small utility to send RST on the TCP connection
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// Ref: https://gosamples.dev/connection-reset-by-peer/
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package tcpreset
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import (
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"fmt"
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"log"
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"net"
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"os"
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"os/signal"
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"syscall"
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"github.com/spf13/cobra"
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)
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// CmdTCPReset is used by agnhost Cobra.
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var CmdTCPReset = &cobra.Command{
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Use: "tcp-reset",
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Short: "Serves on a tcp port and RST the connections received",
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Long: `Serves on a tcp port and RST the connections received.`,
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Args: cobra.MaximumNArgs(0),
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Run: main,
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}
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var (
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port int
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)
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func init() {
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CmdTCPReset.Flags().IntVar(&port, "port", 8080, "Port number.")
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}
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func main(cmd *cobra.Command, args []string) {
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listener, err := net.Listen("tcp", fmt.Sprintf(":%d", port))
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if err != nil {
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log.Fatalf("Error from net.Listen(): %s", err)
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}
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go func() {
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for {
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conn, err := listener.Accept()
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if err != nil {
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log.Fatalf("Error from Accept(): %s", err)
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}
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// if there are still data in the buffer to read
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// and the connection is closed, it will send a RST.
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buf := make([]byte, 1)
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conn.Read(buf)
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conn.Close()
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log.Printf("TCP request from %s", conn.RemoteAddr().String())
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}
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}()
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log.Printf("Serving on port %d.\n", port)
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signals := make(chan os.Signal, 1)
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signal.Notify(signals, syscall.SIGTERM)
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sig := <-signals
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log.Printf("Shutting down after receiving signal: %s.\n", sig)
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log.Printf("Awaiting pod deletion.\n")
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}
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