net/http: handle "close" amongst multiple Connection tokens

Fixes #8840

Change-Id: I194d0248734c15336f91a6bcf57ffcc9c0a3a435
Reviewed-on: https://go-review.googlesource.com/9434
Reviewed-by: David Crawshaw <crawshaw@golang.org>

4 files changed, 197 insertions, 4 deletions

diff --git a/src/net/http/lex.go b/src/net/http/lex.go
index cb33318f49..50b14f8b32 100644
--- a/src/net/http/lex.go
+++ b/src/net/http/lex.go
@@ -4,6 +4,11 @@
 
 package http
 
+import (
+	"strings"
+	"unicode/utf8"
+)
+
 // This file deals with lexical matters of HTTP
 
 var isTokenTable = [127]bool{
@@ -94,3 +99,71 @@ func isToken(r rune) bool {
 func isNotToken(r rune) bool {
 	return !isToken(r)
 }
+
+// headerValuesContainsToken reports whether any string in values
+// contains the provided token, ASCII case-insensitively.
+func headerValuesContainsToken(values []string, token string) bool {
+	for _, v := range values {
+		if headerValueContainsToken(v, token) {
+			return true
+		}
+	}
+	return false
+}
+
+// isOWS reports whether b is an optional whitespace byte, as defined
+// by RFC 7230 section 3.2.3.
+func isOWS(b byte) bool { return b == ' ' || b == '\t' }
+
+// trimOWS returns x with all optional whitespace removes from the
+// beginning and end.
+func trimOWS(x string) string {
+	// TODO: consider using strings.Trim(x, " \t") instead,
+	// if and when it's fast enough. See issue 10292.
+	// But this ASCII-only code will probably always beat UTF-8
+	// aware code.
+	for len(x) > 0 && isOWS(x[0]) {
+		x = x[1:]
+	}
+	for len(x) > 0 && isOWS(x[len(x)-1]) {
+		x = x[:len(x)-1]
+	}
+	return x
+}
+
+// headerValueContainsToken reports whether v (assumed to be a
+// 0#element, in the ABNF extension described in RFC 7230 section 7)
+// contains token amongst its comma-separated tokens, ASCII
+// case-insensitively.
+func headerValueContainsToken(v string, token string) bool {
+	v = trimOWS(v)
+	if comma := strings.IndexByte(v, ','); comma != -1 {
+		return tokenEqual(trimOWS(v[:comma]), token) || headerValueContainsToken(v[comma+1:], token)
+	}
+	return tokenEqual(v, token)
+}
+
+// lowerASCII returns the ASCII lowercase version of b.
+func lowerASCII(b byte) byte {
+	if 'A' <= b && b <= 'Z' {
+		return b + ('a' - 'A')
+	}
+	return b
+}
+
+// tokenEqual reports whether t1 and t2 are equal, ASCII case-insensitively.
+func tokenEqual(t1, t2 string) bool {
+	if len(t1) != len(t2) {
+		return false
+	}
+	for i, b := range t1 {
+		if b >= utf8.RuneSelf {
+			// No UTF-8 or non-ASCII allowed in tokens.
+			return false
+		}
+		if lowerASCII(byte(b)) != lowerASCII(t2[i]) {
+			return false
+		}
+	}
+	return true
+}
diff --git a/src/net/http/lex_test.go b/src/net/http/lex_test.go
index 6d9d294f70..986fda17dc 100644
--- a/src/net/http/lex_test.go
+++ b/src/net/http/lex_test.go
@@ -29,3 +29,73 @@ func TestIsToken(t *testing.T) {
 		}
 	}
 }
+
+func TestHeaderValuesContainsToken(t *testing.T) {
+	tests := []struct {
+		vals  []string
+		token string
+		want  bool
+	}{
+		{
+			vals:  []string{"foo"},
+			token: "foo",
+			want:  true,
+		},
+		{
+			vals:  []string{"bar", "foo"},
+			token: "foo",
+			want:  true,
+		},
+		{
+			vals:  []string{"foo"},
+			token: "FOO",
+			want:  true,
+		},
+		{
+			vals:  []string{"foo"},
+			token: "bar",
+			want:  false,
+		},
+		{
+			vals:  []string{" foo "},
+			token: "FOO",
+			want:  true,
+		},
+		{
+			vals:  []string{"foo,bar"},
+			token: "FOO",
+			want:  true,
+		},
+		{
+			vals:  []string{"bar,foo,bar"},
+			token: "FOO",
+			want:  true,
+		},
+		{
+			vals:  []string{"bar , foo"},
+			token: "FOO",
+			want:  true,
+		},
+		{
+			vals:  []string{"foo ,bar "},
+			token: "FOO",
+			want:  true,
+		},
+		{
+			vals:  []string{"bar, foo ,bar"},
+			token: "FOO",
+			want:  true,
+		},
+		{
+			vals:  []string{"bar , foo"},
+			token: "FOO",
+			want:  true,
+		},
+	}
+	for _, tt := range tests {
+		got := headerValuesContainsToken(tt.vals, tt.token)
+		if got != tt.want {
+			t.Errorf("headerValuesContainsToken(%q, %q) = %v; want %v", tt.vals, tt.token, got, tt.want)
+		}
+	}
+}
diff --git a/src/net/http/response_test.go b/src/net/http/response_test.go
index 06e940d9ab..421cf55f49 100644
--- a/src/net/http/response_test.go
+++ b/src/net/http/response_test.go
@@ -405,6 +405,57 @@ some body`,
 
 		"foobar",
 	},
+
+	// Both keep-alive and close, on the same Connection line. (Issue 8840)
+	{
+		"HTTP/1.1 200 OK\r\n" +
+			"Content-Length: 256\r\n" +
+			"Connection: keep-alive, close\r\n" +
+			"\r\n",
+
+		Response{
+			Status:     "200 OK",
+			StatusCode: 200,
+			Proto:      "HTTP/1.1",
+			ProtoMajor: 1,
+			ProtoMinor: 1,
+			Request:    dummyReq("HEAD"),
+			Header: Header{
+				"Content-Length": {"256"},
+			},
+			TransferEncoding: nil,
+			Close:            true,
+			ContentLength:    256,
+		},
+
+		"",
+	},
+
+	// Both keep-alive and close, on different Connection lines. (Issue 8840)
+	{
+		"HTTP/1.1 200 OK\r\n" +
+			"Content-Length: 256\r\n" +
+			"Connection: keep-alive\r\n" +
+			"Connection: close\r\n" +
+			"\r\n",
+
+		Response{
+			Status:     "200 OK",
+			StatusCode: 200,
+			Proto:      "HTTP/1.1",
+			ProtoMajor: 1,
+			ProtoMinor: 1,
+			Request:    dummyReq("HEAD"),
+			Header: Header{
+				"Content-Length": {"256"},
+			},
+			TransferEncoding: nil,
+			Close:            true,
+			ContentLength:    256,
+		},
+
+		"",
+	},
 }
 
 func TestReadResponse(t *testing.T) {
diff --git a/src/net/http/transfer.go b/src/net/http/transfer.go
index 7372d7537e..5640344345 100644
--- a/src/net/http/transfer.go
+++ b/src/net/http/transfer.go
@@ -508,14 +508,13 @@ func shouldClose(major, minor int, header Header, removeCloseHeader bool) bool {
 	if major < 1 {
 		return true
 	} else if major == 1 && minor == 0 {
-		if !strings.Contains(strings.ToLower(header.get("Connection")), "keep-alive") {
+		vv := header["Connection"]
+		if headerValuesContainsToken(vv, "close") || !headerValuesContainsToken(vv, "keep-alive") {
 			return true
 		}
 		return false
 	} else {
-		// TODO: Should split on commas, toss surrounding white space,
-		// and check each field.
-		if strings.ToLower(header.get("Connection")) == "close" {
+		if headerValuesContainsToken(header["Connection"], "close") {
 			if removeCloseHeader {
 				header.Del("Connection")
 			}