From c1f354a01ce0384149bebc1874e483c25881ed79 Mon Sep 17 00:00:00 2001
From: Leonid Bugaev <leonsbox@gmail.com>
Date: Fri, 27 May 2016 16:36:28 +0500
Subject: [PATCH] Support lower case headers

---
 proto/proto.go      | 82 ++++++++++++++++++++++++++++++++++++++++++++-
 proto/proto_test.go | 13 +++++++
 2 files changed, 94 insertions(+), 1 deletion(-)

diff --git a/proto/proto.go b/proto/proto.go
index ad7fe74..314e190 100644
--- a/proto/proto.go
+++ b/proto/proto.go
@@ -41,11 +41,91 @@ func MIMEHeadersStartPos(payload []byte) int {
 	return bytes.Index(payload, CLRF) + 2 // Find first line end
 }
 
+
+func isLower(b byte) bool {
+	if 'a' <= b && b <= 'z' {
+		return true
+	}
+
+	return false
+}
+
+func toUpper(b byte) byte {
+	if 'a' <= b && b <= 'z' {
+		b -= 'a' - 'A'
+	}
+	return b
+}
+
+func toLower(b byte) byte {
+	if 'A' <= b && b <= 'Z' {
+		b += 'a' - 'A'
+	}
+	return b
+}
+
+func headerIndex(payload []byte, name []byte) int {
+	isLower := isLower(name[0])
+	i := 0
+
+	for {
+		if i >= len(payload) {
+			return -1
+		}
+
+		if payload[i] == '\n' {
+			i++
+
+			// We are at the end
+			if i == len(payload) {
+				return -1
+			}
+
+			if payload[i] == name[0] ||
+			   (!isLower && payload[i] == toLower(name[0])) ||
+			   ( isLower && payload[i] == toUpper(name[0])) {
+
+			   	i++
+				j := 1
+				for {
+					if j == len(name) {
+						// Matched, and return start of the header
+						return i - len(name)
+					}
+
+					if payload[i] != name[j] {
+						break
+					}
+
+					// If compound header name do one more case check: Content-Length or Transfer-Encoding
+					if name[j] == '-' {
+						i++
+						j++
+
+						if !(payload[i] == name[j] ||
+			   			   (!isLower && payload[i] == toLower(name[j])) ||
+			   			   ( isLower && payload[i] == toUpper(name[j]))) {
+							break
+			   			}
+					}
+
+					j++
+					i++
+				}
+			}
+		}
+
+		i++
+	}
+
+	return -1
+}
+
 // header return value and positions of header/value start/end.
 // If not found, value will be blank, and headerStart will be -1
 // Do not support multi-line headers.
 func header(payload []byte, name []byte) (value []byte, headerStart, valueStart, headerEnd int) {
-	headerStart = bytes.Index(payload, name)
+	headerStart = headerIndex(payload, name)
 
 	if headerStart == -1 {
 		return
diff --git a/proto/proto_test.go b/proto/proto_test.go
index c489a4e..a8d9179 100644
--- a/proto/proto_test.go
+++ b/proto/proto_test.go
@@ -41,6 +41,19 @@ func TestHeader(t *testing.T) {
 	if _, headerStart, _, _ = header(payload, []byte("Not-Found")); headerStart != -1 {
 		t.Error("Should not found header")
 	}
+
+	// Lower case headers
+	payload = []byte("POST /post HTTP/1.1\r\ncontent-length: 7\r\nHost: www.w3.org\r\n\r\na=1&b=2")
+
+	if val = Header(payload, []byte("Content-Length")); !bytes.Equal(val, []byte("7")) {
+		t.Error("Should find lower case 2 word header")
+	}
+
+	payload = []byte("POST /post HTTP/1.1\r\ncontent-length: 7\r\nhost: www.w3.org\r\n\r\na=1&b=2")
+
+	if val = Header(payload, []byte("host")); !bytes.Equal(val, []byte("www.w3.org")) {
+		t.Error("Should find lower case 1 word header")
+	}
 }
 
 func TestMIMEHeadersEndPos(t *testing.T) {