Add windows support to normalizePath

This is probably still not 100% sure and there are still many bugs with
FS on windows. But it's a slight improvement.

Fixes valyala#1226

strings.go

@@ -7,21 +7,25 @@ var (
 )
 
 var (
-	strSlash            = []byte("/")
-	strSlashSlash       = []byte("//")
-	strSlashDotDot      = []byte("/..")
-	strSlashDotSlash    = []byte("/./")
-	strSlashDotDotSlash = []byte("/../")
-	strCRLF             = []byte("\r\n")
-	strHTTP             = []byte("http")
-	strHTTPS            = []byte("https")
-	strHTTP10           = []byte("HTTP/1.0")
-	strHTTP11           = []byte("HTTP/1.1")
-	strColon            = []byte(":")
-	strColonSlashSlash  = []byte("://")
-	strColonSpace       = []byte(": ")
-	strCommaSpace       = []byte(", ")
-	strGMT              = []byte("GMT")
+	strSlash                    = []byte("/")
+	strSlashSlash               = []byte("//")
+	strSlashDotDot              = []byte("/..")
+	strSlashDotSlash            = []byte("/./")
+	strSlashDotDotSlash         = []byte("/../")
+	strBackSlashDotDot          = []byte(`\..`)
+	strBackSlashDotBackSlash    = []byte(`\.\`)
+	strSlashDotDotBackSlash     = []byte(`/..\`)
+	strBackSlashDotDotBackSlash = []byte(`\..\`)
+	strCRLF                     = []byte("\r\n")
+	strHTTP                     = []byte("http")
+	strHTTPS                    = []byte("https")
+	strHTTP10                   = []byte("HTTP/1.0")
+	strHTTP11                   = []byte("HTTP/1.1")
+	strColon                    = []byte(":")
+	strColonSlashSlash          = []byte("://")
+	strColonSpace               = []byte(": ")
+	strCommaSpace               = []byte(", ")
+	strGMT                      = []byte("GMT")
 
 	strResponseContinue = []byte("HTTP/1.1 100 Continue\r\n\r\n")
 

uri.go

@@ -5,6 +5,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"path/filepath"
 	"strconv"
 	"sync"
 )
@@ -634,6 +635,60 @@ func normalizePath(dst, src []byte) []byte {
 		b = b[:nn+1]
 	}
 
+	if filepath.Separator == '\\' {
+		// remove \.\ parts
+		b = dst
+		for {
+			n := bytes.Index(b, strBackSlashDotBackSlash)
+			if n < 0 {
+				break
+			}
+			nn := n + len(strSlashDotSlash) - 1
+			copy(b[n:], b[nn:])
+			b = b[:len(b)-nn+n]
+		}
+
+		// remove /foo/..\ parts
+		for {
+			n := bytes.Index(b, strSlashDotDotBackSlash)
+			if n < 0 {
+				break
+			}
+			nn := bytes.LastIndexByte(b[:n], '/')
+			if nn < 0 {
+				nn = 0
+			}
+			n += len(strSlashDotDotBackSlash) - 1
+			copy(b[nn:], b[n:])
+			b = b[:len(b)-n+nn]
+		}
+
+		// remove /foo\..\ parts
+		for {
+			n := bytes.Index(b, strBackSlashDotDotBackSlash)
+			if n < 0 {
+				break
+			}
+			nn := bytes.LastIndexByte(b[:n], '/')
+			if nn < 0 {
+				nn = 0
+			}
+			n += len(strBackSlashDotDotBackSlash) - 1
+			copy(b[nn:], b[n:])
+			b = b[:len(b)-n+nn]
+		}
+
+		// remove trailing \foo\..
+		n := bytes.LastIndex(b, strBackSlashDotDot)
+		if n >= 0 && n+len(strSlashDotDot) == len(b) {
+			nn := bytes.LastIndexByte(b[:n], '/')
+			if nn < 0 {
+				return append(dst[:0], strSlash...)
+			}
+			b = b[:nn+1]
+		}
+	}
+
 	return b
 }