internal/pkg/testdata: check network

This validates hostNet state.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/pkg/exec_test.go

@@ -1,6 +1,6 @@
 package pkg_test
 
-//go:generate go build -tags testtool -ldflags "-extldflags='-static'" -o testdata/testtool ./testdata
+//go:generate env CGO_ENABLED=0 go build -tags testtool -o testdata/testtool ./testdata
 
 import (
 	_ "embed"

internal/pkg/testdata/main.go

@@ -3,10 +3,13 @@
 package main
 
 import (
+	"errors"
 	"log"
+	"net"
 	"os"
 	"path"
 	"slices"
+	"syscall"
 
 	"hakurei.app/container/fhs"
 	"hakurei.app/container/vfs"
@@ -67,6 +70,18 @@ func main() {
 		}
 	}
 
+	if _, err := net.Dial("tcp", "127.0.0.1:0"); err == nil {
+		log.Fatal("Dial unexpectedly succeeded")
+	} else if hostNet {
+		if !errors.Is(err, syscall.ECONNREFUSED) {
+			log.Fatalf("Dial: error = %v", err)
+		}
+	} else {
+		if !errors.Is(err, syscall.ENETUNREACH) {
+			log.Fatalf("Dial: error = %v", err)
+		}
+	}
+
 	log.Println(m)
 	if m.Root != "/sysroot" || m.Target != "/" {
 		log.Fatal("unexpected root mount entry")