From 4eb3bdaa13d77ab7f828503689a020efd41438e6 Mon Sep 17 00:00:00 2001
From: Alexandre Tuleu <alexandre.tuleu.2005@polytechnique.org>
Date: Mon, 17 Aug 2015 13:50:16 +0200
Subject: [PATCH] Adds an internal library for JWS  / JWT encoding

---
 jwt/.gitignore     |  1 +
 jwt/Makefile       |  9 +++++++
 jwt/base64.go      | 32 +++++++++++++++++++++++
 jwt/base64_test.go | 63 ++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 105 insertions(+)
 create mode 100644 jwt/.gitignore
 create mode 100644 jwt/Makefile
 create mode 100644 jwt/base64.go
 create mode 100644 jwt/base64_test.go

diff --git a/jwt/.gitignore b/jwt/.gitignore
new file mode 100644
index 0000000..b51c70b
--- /dev/null
+++ b/jwt/.gitignore
@@ -0,0 +1 @@
+cover.out
diff --git a/jwt/Makefile b/jwt/Makefile
new file mode 100644
index 0000000..478df7c
--- /dev/null
+++ b/jwt/Makefile
@@ -0,0 +1,9 @@
+all: build check
+
+build:
+	go build
+
+check:
+	go test -coverprofile=cover.out -covermode=count
+	go vet
+	golint
diff --git a/jwt/base64.go b/jwt/base64.go
new file mode 100644
index 0000000..43c7e6e
--- /dev/null
+++ b/jwt/base64.go
@@ -0,0 +1,32 @@
+package jwt
+
+import (
+	"encoding/base64"
+	"fmt"
+	"strings"
+)
+
+// Base64Encode encodes a payload of data as a string, like specified
+// in RFC 7515 (no trailing '='
+func Base64Encode(b []byte) string {
+	return strings.TrimRight(base64.URLEncoding.EncodeToString(b), "=")
+}
+
+// Base64Decode decodes a payload of data as a []byte, like specified
+// in RFC 7515 (no trailing '=')
+func Base64Decode(s string) ([]byte, error) {
+	switch len(s) % 4 {
+	case 2:
+		s += "=="
+	case 3:
+		s += "="
+	case 1:
+		return nil, fmt.Errorf("jwt: Invalid base64 string (length:%d %% 4 == 1): '%s'", len(s), s)
+	}
+	d, err := base64.URLEncoding.DecodeString(s)
+	if err != nil {
+		return nil, fmt.Errorf("jwt: %s", err)
+	}
+	return d, nil
+
+}
diff --git a/jwt/base64_test.go b/jwt/base64_test.go
new file mode 100644
index 0000000..5bb17d1
--- /dev/null
+++ b/jwt/base64_test.go
@@ -0,0 +1,63 @@
+package jwt
+
+import (
+	"testing"
+
+	. "gopkg.in/check.v1"
+)
+
+func Test(t *testing.T) {
+	TestingT(t)
+}
+
+type Base64Suite struct{}
+
+var _ = Suite(&Base64Suite{})
+
+type dataAndEncode struct {
+	data    []byte
+	encoded string
+}
+
+func (s *Base64Suite) TestEncodeWithNoTrailing(c *C) {
+	data := []dataAndEncode{
+		{[]byte{0, 0, 0}, "AAAA"}, //With trailing Should be AAAA
+		{[]byte{0, 0}, "AAA"},     //With trailing Should be AAA=
+		{[]byte{0}, "AA"},         //With trailing Should be AA==
+	}
+
+	for _, d := range data {
+		res := Base64Encode(d.data)
+		c.Check(res, Equals, d.encoded)
+	}
+
+}
+
+func (s *Base64Suite) TestDecodeWithNoTrailing(c *C) {
+	data := map[string][]byte{
+		"AAAA": []byte{0, 0, 0},
+		"AAA":  []byte{0, 0},
+		"AA":   []byte{0},
+	}
+
+	for encoded, expected := range data {
+		res, err := Base64Decode(encoded)
+		if c.Check(err, IsNil) == false {
+			continue
+		}
+		c.Check(res, DeepEquals, expected)
+	}
+}
+
+func (s *Base64Suite) TestDetectBadFormat(c *C) {
+	data := map[string]string{
+		"A":        `jwt: Invalid base64 string \(length:[0-9]+ % 4 == 1\): 'A'`,
+		"ABCD%===": `jwt: illegal base64 data at input byte [0-9]+`,
+	}
+
+	for encoded, errorMatches := range data {
+		res, err := Base64Decode(encoded)
+		c.Check(err, ErrorMatches, errorMatches)
+		c.Check(res, IsNil)
+	}
+}