feat(natpmp): rpc error contain all failed attempt messages

internal/natpmp/portmapping_test.go

@@ -49,7 +49,8 @@ func Test_Client_AddPortMapping(t *testing.T) {
 			initialConnectionDuration: time.Millisecond,
 			exchanges:                 []udpExchange{{close: true}},
 			err:                       ErrConnectionTimeout,
-			errMessage:                "executing remote procedure call: connection timeout: after 1ms",
+			errMessage: "executing remote procedure call: connection timeout: failed attempts: " +
+				"read udp 127.0.0.1:[1-9][0-9]{0,4}->127.0.0.1:[1-9][0-9]{0,4}: i/o timeout \\(try 1\\)",
 		},
 		"add_udp": {
 			ctx:                       context.Background(),

internal/natpmp/rpc.go

@@ -6,6 +6,8 @@ import (
 	"fmt"
 	"net"
 	"net/netip"
+	"sort"
+	"strings"
 	"time"
 )
 
@@ -65,9 +67,8 @@ func (c *Client) rpc(ctx context.Context, gateway netip.Addr,
 	// Note it does not double if the source IP mismatches the gateway IP.
 	connectionDuration := c.initialConnectionDuration
 
-	var totalRetryDuration time.Duration
-
 	var retryCount uint
+	var failedAttempts []string
 	for retryCount = 0; retryCount < c.maxRetries; retryCount++ {
 		deadline := time.Now().Add(connectionDuration)
 		err = connection.SetDeadline(deadline)
@@ -87,8 +88,8 @@ func (c *Client) rpc(ctx context.Context, gateway netip.Addr,
 			}
 			var netErr net.Error
 			if errors.As(err, &netErr) && netErr.Timeout() {
-				totalRetryDuration += connectionDuration
 				connectionDuration *= 2
+				failedAttempts = append(failedAttempts, netErr.Error())
 				continue
 			}
 			return nil, fmt.Errorf("reading from udp connection: %w", err)
@@ -98,6 +99,9 @@ func (c *Client) rpc(ctx context.Context, gateway netip.Addr,
 			// Upon receiving a response packet, the client MUST check the source IP
 			// address, and silently discard the packet if the address is not the
 			// address of the gateway to which the request was sent.
+			failedAttempts = append(failedAttempts,
+				fmt.Sprintf("received response from %s instead of gateway IP %s",
+					receivedRemoteAddress.IP, gatewayAddress.IP))
 			continue
 		}
 
@@ -106,8 +110,8 @@ func (c *Client) rpc(ctx context.Context, gateway netip.Addr,
 	}
 
 	if retryCount == c.maxRetries {
-		return nil, fmt.Errorf("%w: after %s",
-			ErrConnectionTimeout, totalRetryDuration)
+		return nil, fmt.Errorf("%w: failed attempts: %s",
+			ErrConnectionTimeout, dedupFailedAttempts(failedAttempts))
 	}
 
 	// Opcodes between 0 and 127 are client requests.  Opcodes from 128 to
@@ -121,3 +125,50 @@ func (c *Client) rpc(ctx context.Context, gateway netip.Addr,
 
 	return response, nil
 }
+
+func dedupFailedAttempts(failedAttempts []string) (errorMessage string) {
+	type data struct {
+		message string
+		indices []int
+	}
+	messageToData := make(map[string]data, len(failedAttempts))
+	for i, message := range failedAttempts {
+		metadata, ok := messageToData[message]
+		if !ok {
+			metadata.message = message
+		}
+		metadata.indices = append(metadata.indices, i)
+		sort.Slice(metadata.indices, func(i, j int) bool {
+			return metadata.indices[i] < metadata.indices[j]
+		})
+		messageToData[message] = metadata
+	}
+
+	// Sort by first index
+	dataSlice := make([]data, 0, len(messageToData))
+	for _, metadata := range messageToData {
+		dataSlice = append(dataSlice, metadata)
+	}
+	sort.Slice(dataSlice, func(i, j int) bool {
+		return dataSlice[i].indices[0] < dataSlice[j].indices[0]
+	})
+
+	dedupedFailedAttempts := make([]string, 0, len(dataSlice))
+	for _, data := range dataSlice {
+		newMessage := fmt.Sprintf("%s (%s)", data.message,
+			indicesToTryString(data.indices))
+		dedupedFailedAttempts = append(dedupedFailedAttempts, newMessage)
+	}
+	return strings.Join(dedupedFailedAttempts, "; ")
+}
+
+func indicesToTryString(indices []int) string {
+	if len(indices) == 1 {
+		return fmt.Sprintf("try %d", indices[0]+1)
+	}
+	tries := make([]string, len(indices))
+	for i, index := range indices {
+		tries[i] = fmt.Sprintf("%d", index+1)
+	}
+	return fmt.Sprintf("tries %s", strings.Join(tries, ", "))
+}

internal/natpmp/rpc_test.go

@@ -53,8 +53,9 @@ func Test_Client_rpc(t *testing.T) {
 			exchanges: []udpExchange{
 				{request: []byte{0, 1}, close: true},
 			},
-			err:        ErrConnectionTimeout,
-			errMessage: "connection timeout: after 1ms",
+			err: ErrConnectionTimeout,
+			errMessage: "connection timeout: failed attempts: " +
+				"read udp 127.0.0.1:[1-9][0-9]{0,4}->127.0.0.1:[1-9][0-9]{0,4}: i/o timeout \\(try 1\\)",
 		},
 		"response_too_small": {
 			ctx:                       context.Background(),
@@ -164,3 +165,40 @@ func Test_Client_rpc(t *testing.T) {
 		})
 	}
 }
+
+func Test_dedupFailedAttempts(t *testing.T) {
+	t.Parallel()
+
+	testCases := map[string]struct {
+		failedAttempts []string
+		expected       string
+	}{
+		"empty": {},
+		"single_attempt": {
+			failedAttempts: []string{"test"},
+			expected:       "test (try 1)",
+		},
+		"multiple_same_attempts": {
+			failedAttempts: []string{"test", "test", "test"},
+			expected:       "test (tries 1, 2, 3)",
+		},
+		"multiple_different_attempts": {
+			failedAttempts: []string{"test1", "test2", "test3"},
+			expected:       "test1 (try 1); test2 (try 2); test3 (try 3)",
+		},
+		"soup_mix": {
+			failedAttempts: []string{"test1", "test2", "test1", "test3", "test2"},
+			expected:       "test1 (tries 1, 3); test2 (tries 2, 5); test3 (try 4)",
+		},
+	}
+
+	for name, testCase := range testCases {
+		testCase := testCase
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+
+			actual := dedupFailedAttempts(testCase.failedAttempts)
+			assert.Equal(t, testCase.expected, actual)
+		})
+	}
+}