Use base64.RawURLEncoding to decode signed request data.

app.go

@@ -11,6 +11,7 @@ import (
 	"bytes"
 	"crypto/hmac"
 	"crypto/sha256"
+	"encoding/base64"
 	"encoding/json"
 	"fmt"
 	"strings"
@@ -38,14 +39,14 @@ func (app *App) ParseSignedRequest(signedRequest string) (res Result, err error)
 		return
 	}
 
-	sig, e1 := decodeBase64URLEncodingString(strs[0])
+	sig, e1 := base64.RawURLEncoding.DecodeString(strs[0])
 
 	if e1 != nil {
 		err = fmt.Errorf("cannot decode signed request sig. error is %v.", e1)
 		return
 	}
 
-	payload, e2 := decodeBase64URLEncodingString(strs[1])
+	payload, e2 := base64.RawURLEncoding.DecodeString(strs[1])
 
 	if e2 != nil {
 		err = fmt.Errorf("cannot decode signed request payload. error is %v.", e2)

session.go

@@ -11,14 +11,12 @@ import (
 	"bytes"
 	"crypto/hmac"
 	"crypto/sha256"
-	"encoding/base64"
 	"encoding/hex"
 	"encoding/json"
 	"fmt"
 	"io"
 	"net/http"
 	"net/url"
-	"strings"
 )
 
 // Makes a facebook graph api call.
@@ -649,22 +647,3 @@ func (session *Session) addDebugInfo(res Result, response *http.Response) Result
 	res["__debug__"] = debugInfo
 	return res
 }
-
-func decodeBase64URLEncodingString(data string) ([]byte, error) {
-	buf := bytes.NewBufferString(data)
-
-	// go's URLEncoding implementation requires base64 padding.
-	if m := len(data) % 4; m != 0 {
-		buf.WriteString(strings.Repeat("=", 4-m))
-	}
-
-	reader := base64.NewDecoder(base64.URLEncoding, buf)
-	output := &bytes.Buffer{}
-	_, err := io.Copy(output, reader)
-
-	if err != nil {
-		return nil, err
-	}
-
-	return output.Bytes(), nil
-}