Sniffer: fix infinite loop stuck

Author: patterniha

app/dispatcher/default.go

@@ -2,6 +2,7 @@ package dispatcher
 
 import (
 	"context"
+	"io"
 	"regexp"
 	"strings"
 	"sync"
@@ -373,7 +374,14 @@ func sniffer(ctx context.Context, cReader *cachedReader, metadataOnly bool, netw
 				return nil, ctx.Err()
 			default:
 				cachingStartingTimeStamp := time.Now()
+				payloadLen := payload.Len()
 				cacheErr := cReader.Cache(payload, cacheDeadline)
+				if cacheErr != nil {
+					return nil, cacheErr
+				}
+				if payload.Len() == payloadLen {
+					return nil, io.EOF
+				}
 				cachingTimeElapsed := time.Since(cachingStartingTimeStamp)
 				cacheDeadline -= cachingTimeElapsed
 
@@ -383,14 +391,14 @@ func sniffer(ctx context.Context, cReader *cachedReader, metadataOnly bool, netw
 					case common.ErrNoClue: // No Clue: protocol not matches, and sniffer cannot determine whether there will be a match or not
 						totalAttempt++
 					case protocol.ErrProtoNeedMoreData: // Protocol Need More Data: protocol matches, but need more data to complete sniffing
-						if cacheErr != nil { // Cache error (e.g. timeout) counts for failed attempt
-							totalAttempt++
-						}
+						totalAttempt++
 					default:
 						return result, err
 					}
+				} else {
+					return nil, io.EOF
 				}
-				if totalAttempt >= 2 || cacheDeadline <= 0 {
+				if totalAttempt >= 32 || cacheDeadline <= 0 {
 					return nil, errSniffingTimeout
 				}
 			}