From 19f7cb23c8caba63620ccffd763d0d961556d9a4 Mon Sep 17 00:00:00 2001 From: Antonio Ojea Date: Wed, 3 May 2023 20:49:28 +0000 Subject: [PATCH] e2e agnhost functionality to RST TCP connections 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 --- test/images/agnhost/README.md | 23 +++++++ test/images/agnhost/VERSION | 2 +- test/images/agnhost/agnhost.go | 2 + test/images/agnhost/tcp-reset/tcp_reset.go | 78 ++++++++++++++++++++++ 4 files changed, 104 insertions(+), 1 deletion(-) create mode 100644 test/images/agnhost/tcp-reset/tcp_reset.go diff --git a/test/images/agnhost/README.md b/test/images/agnhost/README.md index ab4fe8bd44a..459d3213e1d 100644 --- a/test/images/agnhost/README.md +++ b/test/images/agnhost/README.md @@ -621,6 +621,29 @@ Usage: kubectl exec test-agnhost -- /agnhost serve-hostname [--tcp] [--udp] [--http] [--close] [--port ] ``` +### tcp-reset + +Starts a simple TCP servers that reads only one byte of the connection and then closes it, +having the effect of sending a TCP RST to the client. + +The subcommand can accept the following flags: + +- `port` (default: `8080`): The port number to listen to. + +Usage: + +```console + kubectl exec test-agnhost -- /agnhost tcp-reset [--port ] +``` + +Important: This behavior only works if the client send more than 1 byte and is OS +dependant, it is guaranteed to work on Linux. + +```console +echo -n 1 | nc 192.168.1.4:8080 # FIN +echo -n 12 | nc 192.168.1.4:8080 # RST +``` + ### test-webserver Starts a simple HTTP fileserver which serves any file specified in the URL path, if it exists. diff --git a/test/images/agnhost/VERSION b/test/images/agnhost/VERSION index 7cd20263835..f454b8169e3 100644 --- a/test/images/agnhost/VERSION +++ b/test/images/agnhost/VERSION @@ -1 +1 @@ -2.43 +2.44 diff --git a/test/images/agnhost/agnhost.go b/test/images/agnhost/agnhost.go index bfc0f190d65..7f32499a14e 100644 --- a/test/images/agnhost/agnhost.go +++ b/test/images/agnhost/agnhost.go @@ -45,6 +45,7 @@ import ( "k8s.io/kubernetes/test/images/agnhost/porter" resconsumerctrl "k8s.io/kubernetes/test/images/agnhost/resource-consumer-controller" servehostname "k8s.io/kubernetes/test/images/agnhost/serve-hostname" + tcpreset "k8s.io/kubernetes/test/images/agnhost/tcp-reset" testwebserver "k8s.io/kubernetes/test/images/agnhost/test-webserver" "k8s.io/kubernetes/test/images/agnhost/webhook" ) @@ -81,6 +82,7 @@ func main() { rootCmd.AddCommand(resconsumerctrl.CmdResourceConsumerController) rootCmd.AddCommand(servehostname.CmdServeHostname) rootCmd.AddCommand(testwebserver.CmdTestWebserver) + rootCmd.AddCommand(tcpreset.CmdTCPReset) rootCmd.AddCommand(webhook.CmdWebhook) rootCmd.AddCommand(openidmetadata.CmdTestServiceAccountIssuerDiscovery) rootCmd.AddCommand(grpchealthchecking.CmdGrpcHealthChecking) diff --git a/test/images/agnhost/tcp-reset/tcp_reset.go b/test/images/agnhost/tcp-reset/tcp_reset.go new file mode 100644 index 00000000000..a7ab5edb3c9 --- /dev/null +++ b/test/images/agnhost/tcp-reset/tcp_reset.go @@ -0,0 +1,78 @@ +/* +Copyright 2023 The Kubernetes Authors. + +Licensed under the Apache License, Version 2.0 (the "License"); +you may not use this file except in compliance with the License. +You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + +Unless required by applicable law or agreed to in writing, software +distributed under the License is distributed on an "AS IS" BASIS, +WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +See the License for the specific language governing permissions and +limitations under the License. +*/ + +// A small utility to send RST on the TCP connection +// Ref: https://gosamples.dev/connection-reset-by-peer/ + +package tcpreset + +import ( + "fmt" + "log" + "net" + "os" + "os/signal" + "syscall" + + "github.com/spf13/cobra" +) + +// CmdTCPReset is used by agnhost Cobra. +var CmdTCPReset = &cobra.Command{ + Use: "tcp-reset", + Short: "Serves on a tcp port and RST the connections received", + Long: `Serves on a tcp port and RST the connections received.`, + Args: cobra.MaximumNArgs(0), + Run: main, +} + +var ( + port int +) + +func init() { + CmdTCPReset.Flags().IntVar(&port, "port", 8080, "Port number.") +} + +func main(cmd *cobra.Command, args []string) { + + listener, err := net.Listen("tcp", fmt.Sprintf(":%d", port)) + if err != nil { + log.Fatalf("Error from net.Listen(): %s", err) + } + go func() { + for { + conn, err := listener.Accept() + if err != nil { + log.Fatalf("Error from Accept(): %s", err) + } + // if there are still data in the buffer to read + // and the connection is closed, it will send a RST. + buf := make([]byte, 1) + conn.Read(buf) + conn.Close() + log.Printf("TCP request from %s", conn.RemoteAddr().String()) + } + }() + + log.Printf("Serving on port %d.\n", port) + signals := make(chan os.Signal, 1) + signal.Notify(signals, syscall.SIGTERM) + sig := <-signals + log.Printf("Shutting down after receiving signal: %s.\n", sig) + log.Printf("Awaiting pod deletion.\n") + +}