Return all packets when Expect fails.

PiperOrigin-RevId: 305466309

2 files changed, 29 insertions, 22 deletions

diff --git a/test/packetimpact/testbench/connections.go b/test/packetimpact/testbench/connections.go
index 579da59c3..ed8689fd3 100644
--- a/test/packetimpact/testbench/connections.go
+++ b/test/packetimpact/testbench/connections.go
@@ -21,6 +21,7 @@ import (
 	"fmt"
 	"math/rand"
 	"net"
+	"strings"
 	"testing"
 	"time"
 
@@ -233,19 +234,23 @@ func (conn *TCPIPv4) RecvFrame(timeout time.Duration) Layers {
 
 // Expect a packet that matches the provided tcp within the timeout specified.
 // If it doesn't arrive in time, it returns nil.
-func (conn *TCPIPv4) Expect(tcp TCP, timeout time.Duration) *TCP {
+func (conn *TCPIPv4) Expect(tcp TCP, timeout time.Duration) (*TCP, error) {
 	// We cannot implement this directly using ExpectFrame as we cannot specify
 	// the Payload part.
 	deadline := time.Now().Add(timeout)
+	var allTCP []string
 	for {
-		timeout = time.Until(deadline)
-		if timeout <= 0 {
-			return nil
+		var gotTCP *TCP
+		if timeout = time.Until(deadline); timeout > 0 {
+			gotTCP = conn.Recv(timeout)
+		}
+		if gotTCP == nil {
+			return nil, fmt.Errorf("got %d packets:\n%s", len(allTCP), strings.Join(allTCP, "\n"))
 		}
-		gotTCP := conn.Recv(timeout)
 		if tcp.match(gotTCP) {
-			return gotTCP
+			return gotTCP, nil
 		}
+		allTCP = append(allTCP, gotTCP.String())
 	}
 }
 
@@ -284,10 +289,11 @@ func (conn *TCPIPv4) Handshake() {
 	conn.Send(TCP{Flags: Uint8(header.TCPFlagSyn)})
 
 	// Wait for the SYN-ACK.
-	conn.SynAck = conn.Expect(TCP{Flags: Uint8(header.TCPFlagSyn | header.TCPFlagAck)}, time.Second)
-	if conn.SynAck == nil {
-		conn.t.Fatalf("didn't get synack during handshake")
+	synAck, err := conn.Expect(TCP{Flags: Uint8(header.TCPFlagSyn | header.TCPFlagAck)}, time.Second)
+	if synAck == nil {
+		conn.t.Fatalf("didn't get synack during handshake: %s", err)
 	}
+	conn.SynAck = synAck
 
 	// Send an ACK.
 	conn.Send(TCP{Flags: Uint8(header.TCPFlagAck)})
@@ -427,19 +433,20 @@ func (conn *UDPIPv4) Recv(timeout time.Duration) *UDP {
 
 // Expect a packet that matches the provided udp within the timeout specified.
 // If it doesn't arrive in time, the test fails.
-func (conn *UDPIPv4) Expect(udp UDP, timeout time.Duration) *UDP {
+func (conn *UDPIPv4) Expect(udp UDP, timeout time.Duration) (*UDP, error) {
 	deadline := time.Now().Add(timeout)
+	var allUDP []string
 	for {
-		timeout = time.Until(deadline)
-		if timeout <= 0 {
-			return nil
+		var gotUDP *UDP
+		if timeout = time.Until(deadline); timeout > 0 {
+			gotUDP = conn.Recv(timeout)
 		}
-		gotUDP := conn.Recv(timeout)
 		if gotUDP == nil {
-			return nil
+			return nil, fmt.Errorf("got %d packets:\n%s", len(allUDP), strings.Join(allUDP, "\n"))
 		}
 		if udp.match(gotUDP) {
-			return gotUDP
+			return gotUDP, nil
 		}
+		allUDP = append(allUDP, gotUDP.String())
 	}
 }
diff --git a/test/packetimpact/tests/fin_wait2_timeout_test.go b/test/packetimpact/tests/fin_wait2_timeout_test.go
index 2b3f39045..90e16ef65 100644
--- a/test/packetimpact/tests/fin_wait2_timeout_test.go
+++ b/test/packetimpact/tests/fin_wait2_timeout_test.go
@@ -47,20 +47,20 @@ func TestFinWait2Timeout(t *testing.T) {
 			}
 			dut.Close(acceptFd)
 
-			if gotOne := conn.Expect(tb.TCP{Flags: tb.Uint8(header.TCPFlagFin | header.TCPFlagAck)}, time.Second); gotOne == nil {
-				t.Fatal("expected a FIN-ACK within 1 second but got none")
+			if _, err := conn.Expect(tb.TCP{Flags: tb.Uint8(header.TCPFlagFin | header.TCPFlagAck)}, time.Second); err != nil {
+				t.Fatalf("expected a FIN-ACK within 1 second but got none: %s", err)
 			}
 			conn.Send(tb.TCP{Flags: tb.Uint8(header.TCPFlagAck)})
 
 			time.Sleep(5 * time.Second)
 			conn.Send(tb.TCP{Flags: tb.Uint8(header.TCPFlagAck)})
 			if tt.linger2 {
-				if gotOne := conn.Expect(tb.TCP{Flags: tb.Uint8(header.TCPFlagRst)}, time.Second); gotOne == nil {
-					t.Fatal("expected a RST packet within a second but got none")
+				if _, err := conn.Expect(tb.TCP{Flags: tb.Uint8(header.TCPFlagRst)}, time.Second); err != nil {
+					t.Fatalf("expected a RST packet within a second but got none: %s", err)
 				}
 			} else {
-				if gotOne := conn.Expect(tb.TCP{Flags: tb.Uint8(header.TCPFlagRst)}, 10*time.Second); gotOne != nil {
-					t.Fatal("expected no RST packets within ten seconds but got one")
+				if _, err := conn.Expect(tb.TCP{Flags: tb.Uint8(header.TCPFlagRst)}, 10*time.Second); err == nil {
+					t.Fatalf("expected no RST packets within ten seconds but got one: %s", err)
 				}
 			}
 		})