Benchmarking, packaging, and fix issues, tests and perfomance (#797)

### performance
- handling of the very big packet(any size that can be buffered)
- speeding up TCP sessions by using message hints: Added **proto.HasFullPayload** that helps to validate the entire HTTP request, it supports `Chunked` encoding too! Added **proto.HasRequestTitle** and **proto.HasResponseTitle** for validating the beginning of HTTP request. Those methods are used `input_raw.go` with `TCP`.
- supports Keep-Alive: the above functions helps to support keep-alive

### Packaging
- **capture:** engines(capture/doc.go)
- **tcp:** tcp message parser (tcp/doc.go)

### benchmarking
- **capture.BenchmarkPcapDump:** the benchmarks regarding dumping packets in a pcap file
- **capture.BenchmarkPcapFile:** the benchmarks of reading packets from a pcap file
- **capture.BenchmarkPcap:** the benchmarks of parsing packets from the loopback interface with pcap handles
- **proto.BenchmarkHasFullPayload:**: benchmarking this function which validates the HTTP payload
- **tcp.BenchmarkPacketParseAndSort:** benchmarks of parsing and sorting packets
- **tcp.BenchmarkMessageParserWithoutHint:** benchmarks of message reasembling by using `SYN` and `FIN` flag
- **tcp.BenchmarkMessageParserWithHint:** benchmarks of message reasembling by using `proto.HasRequestTitle` and `proto.HasFullPayload` flag

### issues
see linked issues

###  tests
- fixed input raw and engine tests

**Most of the changed of the files, was about using functionalities of** `tcp` **and** `capture` **in existing functionalities**

.travis.yml

@@ -1,6 +1,6 @@
 language: go
 go: 1.14
-script: sudo -E bash -c "source /etc/profile && eval '$(gimme 1.14)' && export GOPATH=$HOME/gopath:$GOPATH && go get && GORACE='halt_on_error=1' go test ./... -v -timeout 120s -race"
+script: sudo -E bash -c "source /etc/profile && eval '$(gimme 1.14)' && export GOPATH=$HOME/gopath:$GOPATH && go test ./... -v -timeout 120s"
 
 before_install:
   - sudo apt-get install libpcap-dev -y

byteutils/byteutils.go

@@ -1,6 +1,11 @@
-// Package byteutils probvides helpers for working with byte slices
+// Package byteutils provides helpers for working with byte slices
 package byteutils
 
+import (
+	"reflect"
+	"unsafe"
+)
+
 // Cut elements from slice for a given range
 func Cut(a []byte, from, to int) []byte {
 	copy(a[from:], a[to:])
@@ -41,3 +46,11 @@ func Replace(a []byte, from, to int, new []byte) []byte {
 	copy(a[from:], new)
 	return a
 }
+
+// SliceToString preferred for large body payload (zero allocation and faster)
+func SliceToString(buf *[]byte, s *string) {
+	bHeader := (*reflect.SliceHeader)(unsafe.Pointer(buf))
+	sHeader := (*reflect.StringHeader)(unsafe.Pointer(s))
+	sHeader.Data = bHeader.Data
+	sHeader.Len = bHeader.Len
+}

byteutils/byteutils_test.go

@@ -30,3 +30,11 @@ func TestReplace(t *testing.T) {
 		t.Error("Should replace when replacement length bigger")
 	}
 }
+
+func BenchmarkStringtoSlice(b *testing.B) {
+	b.StopTimer()
+	buf := make([]byte, b.N)
+	b.StartTimer()
+	s := new(string)
+	SliceToString(&buf, s)
+}