Merge 1e48c1007e into 6f574e7fd1

One of the biggest barriers to adopt the netlink format for nftables is
the complexity of writing bytecode.

This commits adds a tool that allows to take an nftables dump and
generate the corresponding golang code and validating that the generated
code produces the exact same output.

Change-Id: I491b35e0d8062de33c67091dd4126d843b231838
Signed-off-by: Antonio Ojea <aojea@google.com>

expr/expr.go

@@ -209,6 +209,8 @@ func exprFromName(name string) Any {
 		e = &CtTimeout{}
 	case "fib":
 		e = &Fib{}
+	case "numgen":
+		e = &Numgen{}
 	}
 	return e
 }

internal/nf2go/main.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"bytes"
+	"context"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -12,6 +13,7 @@ import (
 	"regexp"
 	"runtime"
 	"strings"
+	"time"
 
 	"github.com/google/go-cmp/cmp"
 	"github.com/google/nftables"
@@ -69,6 +71,7 @@ func main() {
 	pf("\n")
 	pf("\tvar expressions []expr.Any\n")
 	pf("\tvar chain *nftables.Chain\n")
+	pf("\tvar table *nftables.Table\n")
 
 	tables, err := n.ListTables()
 	if err != nil {
@@ -81,7 +84,9 @@ func main() {
 	}
 
 	for _, table := range tables {
-		pf("\ttable:= n.AddTable(&nftables.Table{Family: %s,Name: \"%s\"})\n", TableFamilyString(table.Family), table.Name)
+		log.Printf("processing table: %s", table.Name)
+
+		pf("\ttable = n.AddTable(&nftables.Table{Family: %s,Name: \"%s\"})\n", TableFamilyString(table.Family), table.Name)
 		for _, chain := range chains {
 			if chain.Table.Name != table.Name {
 				continue
@@ -120,74 +125,78 @@ func main() {
 				pf("\t})\n")
 			}
 		}
+	}
 
-		pf("\n\tif err:= n.Flush(); err!= nil {\n")
-		pf("\t\tlog.Fatalf(\"fail to flush rules: %v\", err)\n")
-		pf("\t}\n\n")
-		pf("\tfmt.Println(\"nft ruleset applied.\")\n")
-		pf("}\n")
+	pf("\n\tif err:= n.Flush(); err!= nil {\n")
+	pf("\t\tlog.Fatal(err)\n")
+	pf("\t}\n\n")
+	pf("\tfmt.Println(\"nft ruleset applied.\")\n")
+	pf("}\n")
 
-		// Program nftables using your Go code
-		if err := flushNFTRuleset(); err != nil {
-			log.Fatalf("Failed to flush nftables ruleset: %v", err)
-		}
+	// Program nftables using your Go code
+	if err := flushNFTRuleset(); err != nil {
+		log.Fatalf("Failed to flush nftables ruleset: %v", err)
+	}
 
-		// Create the output file
-		// Create a temporary directory
-		tempDir, err := ioutil.TempDir("", "nftables_gen")
-		if err != nil {
-			log.Fatal(err)
-		}
-		defer os.RemoveAll(tempDir) // Clean up the temporary directory
+	// Create the output file
+	// Create a temporary directory
+	tempDir, err := ioutil.TempDir("", "nftables_gen")
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer os.RemoveAll(tempDir) // Clean up the temporary directory
 
-		// Create the temporary Go file
-		tempGoFile := filepath.Join(tempDir, "nftables_recreate.go")
-		f, err := os.Create(tempGoFile)
-		if err != nil {
-			log.Fatal(err)
-		}
-		defer f.Close()
+	// Create the temporary Go file
+	tempGoFile := filepath.Join(tempDir, "nftables_recreate.go")
+	f, err := os.Create(tempGoFile)
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer f.Close()
 
-		fmt.Println("Generated code:")
+	mw := io.MultiWriter(f, os.Stdout)
+	buf.WriteTo(mw)
 
-		mw := io.MultiWriter(f, os.Stdout)
-		buf.WriteTo(mw)
+	// Format the generated code
+	log.Printf("formating file: %s", tempGoFile)
+	cmd := exec.Command("gofmt", "-w", "-s", tempGoFile)
+	output, err := cmd.CombinedOutput()
+	if err != nil {
+		log.Fatalf("gofmt error: %v\nOutput: %s", err, output)
+	}
 
-		// Format the generated code
-		cmd := exec.Command("gofmt", "-w", "-s", tempGoFile)
-		output, err := cmd.CombinedOutput()
-		if err != nil {
-			log.Fatalf("gofmt error: %v\nOutput: %s", err, output)
-		}
+	// Run the generated code
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
 
-		// Run the generated code
-		cmd = exec.Command("go", "run", tempGoFile)
-		output, err = cmd.CombinedOutput()
-		if err != nil {
-			log.Fatalf("Execution error: %v\nOutput: %s", err, output)
-		}
+	log.Printf("executing file: %s", tempGoFile)
+	cmd = exec.CommandContext(ctx, "go", "run", tempGoFile)
+	output, err = cmd.CombinedOutput()
+	if err != nil {
+		log.Fatalf("Execution error: %v\nOutput: %s", err, output)
+	}
 
-		// Retrieve nftables state using nft
-		actualOutput, err := listNFTRuleset()
-		if err != nil {
-			log.Fatalf("Failed to list nftables ruleset: %v\noutput:%s", err, actualOutput)
-		}
+	// Retrieve nftables state using nft
+	log.Printf("obtain current ruleset: %s", tempGoFile)
+	actualOutput, err := listNFTRuleset()
+	if err != nil {
+		log.Fatalf("Failed to list nftables ruleset: %v\noutput:%s", err, actualOutput)
+	}
 
-		expectedOutput, err := os.ReadFile(filename)
-		if err != nil {
-			log.Fatalf("Failed to list nftables ruleset: %v\noutput:%s", err, actualOutput)
-		}
+	expectedOutput, err := os.ReadFile(filename)
+	if err != nil {
+		log.Fatalf("Failed to list nftables ruleset: %v\noutput:%s", err, actualOutput)
+	}
 
-		if !compareMultilineStringsIgnoreIndentation(string(expectedOutput), actualOutput) {
-			log.Printf("Expected output:\n%s", string(expectedOutput))
-			log.Printf("Actual output:\n%s", actualOutput)
+	if !compareMultilineStringsIgnoreIndentation(string(expectedOutput), actualOutput) {
+		log.Printf("Expected output:\n%s", string(expectedOutput))
+		log.Printf("Actual output:\n%s", actualOutput)
 
-			log.Fatalf("nftables ruleset mismatch:\n%s", cmp.Diff(string(expectedOutput), actualOutput))
-		}
+		log.Fatalf("nftables ruleset mismatch:\n%s", cmp.Diff(string(expectedOutput), actualOutput))
+	}
 
-		if err := flushNFTRuleset(); err != nil {
-			log.Fatalf("Failed to flush nftables ruleset: %v", err)
-		}
+	if err := flushNFTRuleset(); err != nil {
+		log.Fatalf("Failed to flush nftables ruleset: %v", err)
 	}
 }