From dae73eaa9ca8651857aefe56cb46332fce1ee240 Mon Sep 17 00:00:00 2001
From: Paul Greenberg <greenpau@outlook.com>
Date: Mon, 3 Aug 2020 10:59:40 -0400
Subject: [PATCH] rule: add String() method

Before this commit: the printing of a rule results in
a pointer address.

After this commit: the printing of a rules results in
a human-readable text.

Resolves: #104

Signed-off-by: Paul Greenberg <greenpau@outlook.com>
---
 .gitignore       |  1 +
 README.md        |  8 ++++++++
 expr/verdict.go  | 43 +++++++++++++++++++++++++++++++++++++++++++
 nftables_test.go | 15 +++++++++++++++
 nftables_test.sh |  3 +++
 5 files changed, 70 insertions(+)
 create mode 100644 .gitignore
 create mode 100755 nftables_test.sh

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..35417a1
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+nftables.test
diff --git a/README.md b/README.md
index a722eb5..a89d3f6 100644
--- a/README.md
+++ b/README.md
@@ -21,4 +21,12 @@ the data types/API will be identified as more functionality is added.
 
 Contributions are very welcome!
 
+### Testing Changes
 
+Run the following commands to test your changes:
+
+```bash
+go test ./...
+go test -c github.com/google/nftables
+sudo ./nftables.test -test.v -run_system_tests
+```
diff --git a/expr/verdict.go b/expr/verdict.go
index b166a19..3cb8893 100644
--- a/expr/verdict.go
+++ b/expr/verdict.go
@@ -24,6 +24,15 @@ import (
 	"golang.org/x/sys/unix"
 )
 
+const (
+	NFT_DROP   = 0
+	NFT_ACCEPT = 1
+	NFT_STOLEN = 2
+	NFT_QUEUE  = 3
+	NFT_REPEAT = 4
+	NFT_STOP   = 5
+)
+
 // This code assembles the verdict structure, as expected by the
 // nftables netlink API.
 // For further information, consult:
@@ -126,3 +135,37 @@ func (e *Verdict) unmarshal(data []byte) error {
 	}
 	return ad.Err()
 }
+
+func (e *Verdict) String() string {
+	var v string
+	switch e.Kind {
+	case unix.NFT_RETURN:
+		v = "return" // -0x5
+	case unix.NFT_GOTO:
+		v = "goto" // -0x4
+	case unix.NFT_JUMP:
+		v = "jump" // NFT_JUMP = -0x3
+	case unix.NFT_BREAK:
+		v = "break" // NFT_BREAK = -0x2
+	case unix.NFT_CONTINUE:
+		v = "continue" // NFT_CONTINUE = -0x1
+	case NFT_DROP:
+		v = "drop"
+	case NFT_ACCEPT:
+		v = "accept"
+	case NFT_STOLEN:
+		v = "stolen"
+	case NFT_QUEUE:
+		v = "queue"
+	case NFT_REPEAT:
+		v = "repeat"
+	case NFT_STOP:
+		v = "stop"
+	default:
+		v = fmt.Sprintf("verdict %v", e.Kind)
+	}
+	if e.Chain != "" {
+		return v + " " + e.Chain
+	}
+	return v
+}
diff --git a/nftables_test.go b/nftables_test.go
index c12d7a4..c1c0f9d 100644
--- a/nftables_test.go
+++ b/nftables_test.go
@@ -252,12 +252,27 @@ func TestRuleOperations(t *testing.T) {
 		expr.VerdictDrop,
 	}
 
+	wantStrings := []string{
+		"queue",
+		"accept",
+		"queue",
+		"accept",
+		"drop",
+		"drop",
+	}
+
 	for i, r := range rules {
 		rr, _ := r.Exprs[0].(*expr.Verdict)
 
 		if rr.Kind != want[i] {
 			t.Fatalf("bad verdict kind at %d", i)
 		}
+
+		if rr.String() != wantStrings[i] {
+			t.Fatalf("bad verdict string at %d: %s (received) vs. %s (expected)", i, rr.String(), wantStrings[i])
+		}
+
+		t.Logf("%s", rr)
 	}
 }
 
diff --git a/nftables_test.sh b/nftables_test.sh
new file mode 100755
index 0000000..4601557
--- /dev/null
+++ b/nftables_test.sh
@@ -0,0 +1,3 @@
+go test ./...
+go test -c github.com/google/nftables
+sudo ./nftables.test -test.v -run_system_tests