From d9bab6b3bdb6e9438c9e7c5bc382fb1d3d24ee4d Mon Sep 17 00:00:00 2001
From: Anis Elleuch <vadmeste@gmail.com>
Date: Fri, 4 Nov 2016 00:41:25 +0100
Subject: [PATCH] sigv4: Trim and shrink spaces in headers values (#3162)

---
 cmd/signature-v4-utils.go      | 16 ++++++++++++++++
 cmd/signature-v4-utils_test.go | 28 ++++++++++++++++++++++++++++
 cmd/signature-v4.go            |  2 +-
 3 files changed, 45 insertions(+), 1 deletion(-)

diff --git a/cmd/signature-v4-utils.go b/cmd/signature-v4-utils.go
index b0e5bc6ea..675c9b9b6 100644
--- a/cmd/signature-v4-utils.go
+++ b/cmd/signature-v4-utils.go
@@ -157,3 +157,19 @@ func extractSignedHeaders(signedHeaders []string, reqHeaders http.Header) (http.
 
 	return extractedSignedHeaders, ErrNone
 }
+
+// Trim leading and trailing spaces and replace sequential spaces with one space, following Trimall()
+// in http://docs.aws.amazon.com/general/latest/gr/sigv4-create-canonical-request.html
+func signV4TrimAll(input string) string {
+	// Remove all whitespaces first
+	cleanWhiteSpaces := func(r rune) rune {
+		switch r {
+		case '\t', '\n', '\u000b', '\r', '\f':
+			return ' '
+		}
+		return r
+	}
+	input = strings.Map(cleanWhiteSpaces, input)
+	// Compress adjacent spaces to one space and return
+	return strings.Join(strings.Fields(input), " ")
+}
diff --git a/cmd/signature-v4-utils_test.go b/cmd/signature-v4-utils_test.go
index 03418a08d..71995bd94 100644
--- a/cmd/signature-v4-utils_test.go
+++ b/cmd/signature-v4-utils_test.go
@@ -211,3 +211,31 @@ func TestFindHost(t *testing.T) {
 		t.Fatalf("Expected the APIErrorCode to be %d, but got %d", ErrNone, errCode)
 	}
 }
+
+// TestSigV4TrimAll - tests the logic of TrimAll() function
+func TestSigV4TrimAll(t *testing.T) {
+	testCases := []struct {
+		// Input.
+		inputStr string
+		// Expected result.
+		result string
+	}{
+		{"本語", "本語"},
+		{" abc ", "abc"},
+		{" a b ", "a b"},
+		{"a b ", "a b"},
+		{"a  b", "a b"},
+		{"a   b", "a b"},
+		{"   a   b  c   ", "a b c"},
+		{"a \t b  c   ", "a b c"},
+		{"\"a \t b  c   ", "\"a b c"},
+	}
+
+	// Tests generated values from url encoded name.
+	for i, testCase := range testCases {
+		result := signV4TrimAll(testCase.inputStr)
+		if testCase.result != result {
+			t.Errorf("Test %d: Expected sigV4TrimAll result to be \"%s\", but found it to be \"%s\" instead", i+1, testCase.result, result)
+		}
+	}
+}
diff --git a/cmd/signature-v4.go b/cmd/signature-v4.go
index 15952e8ac..333d4ecf3 100644
--- a/cmd/signature-v4.go
+++ b/cmd/signature-v4.go
@@ -68,7 +68,7 @@ func getCanonicalHeaders(signedHeaders http.Header, host string) string {
 				if idx > 0 {
 					buf.WriteByte(',')
 				}
-				buf.WriteString(v)
+				buf.WriteString(signV4TrimAll(v))
 			}
 			buf.WriteByte('\n')
 		}