net/http: add more IDNA2008 tests and fix some omissions

It wasn't lowercasing the string, folding widths, and putting strings
into NFC form. Do those.

Fixes #13835

Change-Id: Ia3de6159417cacec203b48e206e51d79f945df58
Reviewed-on: https://go-review.googlesource.com/29860
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Marcel van Lohuizen <mpvl@golang.org>

1 files changed, 10 insertions, 0 deletions

diff --git a/src/net/http/http.go b/src/net/http/http.go
index b34ae41ec5..258efbb152 100644
--- a/src/net/http/http.go
+++ b/src/net/http/http.go
@@ -6,6 +6,7 @@ package http
 
 import (
 	"strings"
+	"unicode/utf8"
 
 	"golang_org/x/net/lex/httplex"
 )
@@ -41,3 +42,12 @@ func removeEmptyPort(host string) string {
 func isNotToken(r rune) bool {
 	return !httplex.IsTokenRune(r)
 }
+
+func isASCII(s string) bool {
+	for i := 0; i < len(s); i++ {
+		if s[i] >= utf8.RuneSelf {
+			return false
+		}
+	}
+	return true
+}