mailgoserver/internal/abuseguard/abuseguard_test.go

package abuseguard

import (
	"net"
	"path/filepath"
	"strconv"
	"testing"

	"gopkg.in/ini.v1"

	"mailgoserver/internal/db"
)

func testCfg(t *testing.T, threshold int) *ini.File {
	t.Helper()
	cfg := ini.Empty()
	sec, _ := cfg.NewSection("Security")
	sec.NewKey("abuse_detection_enabled", "true")
	sec.NewKey("abuse_failure_threshold", strconv.Itoa(threshold))
	sec.NewKey("abuse_detection_window_minutes", "10")
	sec.NewKey("abuse_blacklist_base_hours", "12")
	sec.NewKey("abuse_blacklist_max_hours", "168")
	return cfg
}

func openTestDB(t *testing.T) *db.DB {
	t.Helper()
	database, err := db.Open(filepath.Join(t.TempDir(), "test.db"))
	if err != nil {
		t.Fatal(err)
	}
	t.Cleanup(func() { database.Close() })
	return database
}

func TestRecordFailureAndMaybeBlacklistTripsThreshold(t *testing.T) {
	database := openTestDB(t)
	cfg := testCfg(t, 3)
	const ip = "203.0.113.50"

	for i := 0; i < 2; i++ {
		database.LogAuthAttempt("sender", "victim@example.com", ip, false, "bad password")
		RecordFailureAndMaybeBlacklist(database, cfg, nil, ip)
	}
	if blocked, _ := database.IsIPBlacklisted(ip); blocked {
		t.Fatal("should not be blacklisted before threshold")
	}

	database.LogAuthAttempt("sender", "victim@example.com", ip, false, "bad password")
	RecordFailureAndMaybeBlacklist(database, cfg, nil, ip)

	blocked, err := database.IsIPBlacklisted(ip)
	if err != nil {
		t.Fatal(err)
	}
	if !blocked {
		t.Fatal("expected IP to be blacklisted after hitting the threshold")
	}
}

func TestRecordFailureAndMaybeBlacklistSkipsWhitelisted(t *testing.T) {
	database := openTestDB(t)
	cfg := testCfg(t, 2)
	const ip = "203.0.113.51"
	if err := database.AddAbuseWhitelist(ip, "trusted"); err != nil {
		t.Fatal(err)
	}

	for i := 0; i < 5; i++ {
		database.LogAuthAttempt("sender", "victim@example.com", ip, false, "bad password")
		RecordFailureAndMaybeBlacklist(database, cfg, nil, ip)
	}

	if blocked, _ := database.IsIPBlacklisted(ip); blocked {
		t.Fatal("whitelisted IP should never be blacklisted")
	}
}

// fakeListener yields exactly one already-open in-memory connection pair, then EOF-like
// closed errors, letting GuardListener's Accept loop be tested without real sockets.
type fakeListener struct {
	conns chan net.Conn
	done  chan struct{}
}

func newFakeListener(conns ...net.Conn) *fakeListener {
	ch := make(chan net.Conn, len(conns))
	for _, c := range conns {
		ch <- c
	}
	return &fakeListener{conns: ch, done: make(chan struct{})}
}

func (f *fakeListener) Accept() (net.Conn, error) {
	select {
	case c := <-f.conns:
		return c, nil
	case <-f.done:
		return nil, net.ErrClosed
	}
}
func (f *fakeListener) Close() error   { close(f.done); return nil }
func (f *fakeListener) Addr() net.Addr { return dummyAddr{} }

type dummyAddr struct{}

func (dummyAddr) Network() string { return "tcp" }
func (dummyAddr) String() string  { return "0.0.0.0:0" }

func TestGuardListenerRejectsBlacklistedIP(t *testing.T) {
	database := openTestDB(t)
	const blockedIP = "198.51.100.77"
	if err := database.AddManualBlacklistEntry(blockedIP, "test", 1); err != nil {
		t.Fatal(err)
	}

	blockedConn, blockedPeer := net.Pipe()
	defer blockedPeer.Close()

	inner := newFakeListener(&addrOverrideConn{Conn: blockedConn, remote: hostPortAddr(blockedIP)})
	guarded := GuardListener(inner, database, nil)

	go func() {
		guarded.Accept()
		inner.Close()
	}()

	// The blocked connection's peer end should observe the connection close rather
	// than any protocol banner, since GuardListener closes it before returning it.
	buf := make([]byte, 1)
	if _, err := blockedPeer.Read(buf); err == nil {
		t.Fatal("expected blocked connection to be closed by GuardListener, got readable data instead")
	}
}

type addrOverrideConn struct {
	net.Conn
	remote net.Addr
}

func (c *addrOverrideConn) RemoteAddr() net.Addr { return c.remote }

type hostPortAddr string

func (hostPortAddr) Network() string  { return "tcp" }
func (a hostPortAddr) String() string { return string(a) + ":12345" }