test/e2e: fix ncat tests

These tests are flaking for unknown reasons. One problem could be ncat
did not bound the port before we connect to it. Simple fix do not use
ncat and just use the golang API to listen on the port without the
extra ncat process. This should be race free in theory.
Also do not run the nc container in the background, we want to see the
errors from the ncat process in the container.

And because both tests do the same thing deduplicate them into one that
just uses a loop to create both tests.

Fixes #23263

Signed-off-by: Paul Holzinger <pholzing@redhat.com>

test/e2e/run_networking_test.go

@@ -3,10 +3,12 @@ package integration
 import (
 	"encoding/json"
 	"fmt"
+	"io"
 	"net"
 	"os"
 	"strconv"
 	"strings"
+	"sync"
 	"syscall"
 
 	"github.com/containernetworking/plugins/pkg/ns"
@@ -543,56 +545,58 @@ EXPOSE 2004-2005/tcp`, ALPINE)
 		}
 	})
 
-	It("podman run network bind to 127.0.0.1", func() {
+	for _, local := range []bool{true, false} {
-		slirp4netnsHelp := SystemExec("slirp4netns", []string{"--help"})
+		local := local
-		Expect(slirp4netnsHelp).Should(ExitCleanly())
+		testName := "HostIP"
-		networkConfiguration := "slirp4netns:outbound_addr=127.0.0.1,allow_host_loopback=true"
+		if local {
-		port := strconv.Itoa(GetPort())
+			testName = "127.0.0.1"
-
-		if strings.Contains(slirp4netnsHelp.OutputToString(), "outbound-addr") {
-			ncListener := StartSystemExec("nc", []string{"-v", "-n", "-l", "-p", port})
-			session := podmanTest.Podman([]string{"run", "--network", networkConfiguration, "-dt", ALPINE, "nc", "-w", "2", "10.0.2.2", port})
-			session.WaitWithDefaultTimeout()
-			ncListener.WaitWithDefaultTimeout()
-
-			Expect(session).Should(ExitCleanly())
-			Expect(ncListener).Should(Exit(0))
-			Expect(ncListener.ErrorToString()).To(ContainSubstring("Connection from 127.0.0.1"))
-		} else {
-			session := podmanTest.Podman([]string{"run", "--network", networkConfiguration, "-dt", ALPINE, "nc", "-w", "2", "10.0.2.2", port})
-			session.WaitWithDefaultTimeout()
-			Expect(session).To(ExitWithError(125, "outbound_addr not supported"))
 		}
-	})
+		It(fmt.Sprintf("podman run network slirp4netns bind to %s", testName), func() {
-
+			ip := "127.0.0.1"
-	It("podman run network bind to HostIP", func() {
+			if !local {
 				// Determine our likeliest outgoing IP address
 				conn, err := net.Dial("udp", "8.8.8.8:80")
 				Expect(err).ToNot(HaveOccurred())
 
 				defer conn.Close()
-		ip := conn.LocalAddr().(*net.UDPAddr).IP
+				ip = conn.LocalAddr().(*net.UDPAddr).IP.String()
+			}
 			port := strconv.Itoa(GetPort())
 
-		slirp4netnsHelp := SystemExec("slirp4netns", []string{"--help"})
+			networkConfiguration := fmt.Sprintf("slirp4netns:outbound_addr=%s,allow_host_loopback=true", ip)
-		Expect(slirp4netnsHelp).Should(ExitCleanly())
-		networkConfiguration := fmt.Sprintf("slirp4netns:outbound_addr=%s,allow_host_loopback=true", ip.String())
 
-		if strings.Contains(slirp4netnsHelp.OutputToString(), "outbound-addr") {
+			listener, err := net.Listen("tcp", ":"+port)
-			ncListener := StartSystemExec("nc", []string{"-v", "-n", "-l", "-p", port})
+			Expect(err).ToNot(HaveOccurred())
-			session := podmanTest.Podman([]string{"run", "--network", networkConfiguration, ALPINE, "nc", "-w", "2", "10.0.2.2", port})
+			defer listener.Close()
-			session.Wait(30)
-			ncListener.Wait(30)
 
+			msg := RandomString(10)
+			wg := &sync.WaitGroup{}
+			wg.Add(1)
+			// now use a new goroutine to start accepting connection in the background and make the checks there
+			go func() {
+				defer GinkgoRecover()
+				defer wg.Done()
+				conn, err := listener.Accept()
+				Expect(err).ToNot(HaveOccurred(), "accept new connection")
+				defer conn.Close()
+				addr := conn.RemoteAddr()
+				// addr will be in the form ip:port, we don't care about the port as it is random
+				Expect(addr.String()).To(HavePrefix(ip+":"), "remote address")
+				gotBytes, err := io.ReadAll(conn)
+				Expect(err).ToNot(HaveOccurred(), "read from connection")
+				Expect(string(gotBytes)).To(Equal(msg), "received correct message from container")
+			}()
+
+			session := podmanTest.Podman([]string{"run", "--network", networkConfiguration, ALPINE, "sh", "-c", "echo -n " + msg + " | nc -w 30 10.0.2.2 " + port})
+			session.WaitWithDefaultTimeout()
 			Expect(session).Should(ExitCleanly())
-			Expect(ncListener).Should(Exit(0))
+
-			Expect(ncListener.ErrorToString()).To(ContainSubstring("Connection from " + ip.String()))
+			// explicitly close the socket here before we wait to unlock Accept() calls in case of hangs
-		} else {
+			listener.Close()
-			session := podmanTest.Podman([]string{"run", "--network", networkConfiguration, ALPINE, "nc", "-w", "2", "10.0.2.2", port})
+			// wait for the checks in the goroutine to be done
-			session.Wait(30)
+			wg.Wait()
-			Expect(session).To(ExitWithError(125, "outbound_addr not supported"))
-		}
 		})
+	}
 
 	It("podman run network expose ports in image metadata", func() {
 		session := podmanTest.Podman([]string{"create", "--name", "test", "-t", "-P", NGINX_IMAGE})