Merge pull request #419 from owncloud/improvement/oauth2_pkce

Add PKCE support

Author: abelgardep

owncloudComLibrary/src/main/java/com/owncloud/android/lib/common/http/HttpConstants.java

@@ -56,6 +56,7 @@ public class HttpConstants {
     public static final String OAUTH_HEADER_GRANT_TYPE = "grant_type";
     public static final String OAUTH_HEADER_REDIRECT_URI = "redirect_uri";
     public static final String OAUTH_HEADER_REFRESH_TOKEN = "refresh_token";
+    public static final String OAUTH_HEADER_CODE_VERIFIER = "code_verifier";
 
     /***********************************************************************************************************
      ************************************************ CONTENT TYPES ********************************************

owncloudComLibrary/src/main/java/com/owncloud/android/lib/resources/oauth/params/TokenRequestParams.kt

@@ -39,14 +39,16 @@ sealed class TokenRequestParams(
         clientAuth: String,
         grantType: String,
         val authorizationCode: String,
-        val redirectUri: String
+        val redirectUri: String,
+        val codeVerifier: String,
     ) : TokenRequestParams(tokenEndpoint, clientAuth, grantType) {
 
         override fun toRequestBody(): RequestBody =
             FormBody.Builder()
                 .add(HttpConstants.OAUTH_HEADER_AUTHORIZATION_CODE, authorizationCode)
                 .add(HttpConstants.OAUTH_HEADER_GRANT_TYPE, grantType)
                 .add(HttpConstants.OAUTH_HEADER_REDIRECT_URI, redirectUri)
+                .add(HttpConstants.OAUTH_HEADER_CODE_VERIFIER, codeVerifier)
                 .build()
     }