Update macaroon lib with version supporting empty strings

Use "" for delegation to the device owner.

Change-Id: Ibb4a1da07817eebcbe8b0675381f98af3fdbe947
Reviewed-on: https://weave-review.googlesource.com/2391
Reviewed-by: Vitaly Buka <vitalybuka@google.com>

src/privet/auth_manager.cc

diff --git a/src/privet/auth_manager.cc b/src/privet/auth_manager.cc
index f3d32f5..3c08071 100644
--- a/src/privet/auth_manager.cc
+++ b/src/privet/auth_manager.cc
@@ -405,7 +405,7 @@
   TimestampCaveat issued{now};
 
   ServiceCaveat client{owner == RootClientTokenOwner::kCloud ? "google.com"
-                                                             : "privet"};
+                                                             : ""};
   return CreateMacaroonToken(
       auth_secret_, now,
       {

src/privet/auth_manager_unittest.cc

diff --git a/src/privet/auth_manager_unittest.cc b/src/privet/auth_manager_unittest.cc
index 2adb1c2..d88d033 100644
--- a/src/privet/auth_manager_unittest.cc
+++ b/src/privet/auth_manager_unittest.cc
@@ -146,7 +146,7 @@
 }
 
 TEST_F(AuthManagerTest, GetRootClientAuthToken) {
-  EXPECT_EQ("WCaDQxkgAUYIGhudoQBIDEZwcml2ZXRQ5aV4jIdY2JGosyU0APnQpA==",
+  EXPECT_EQ("WCCDQxkgAUYIGhudoQBCDEBQZgRhYq78I8GtFUZHNBbfGw==",
             Base64Encode(
                 auth_.GetRootClientAuthToken(RootClientTokenOwner::kClient)));
 }
@@ -160,7 +160,7 @@
 TEST_F(AuthManagerTest, GetRootClientAuthTokenDifferentTime) {
   auto new_time = clock_.Now() + base::TimeDelta::FromDays(15);
   EXPECT_CALL(clock_, Now()).WillRepeatedly(Return(new_time));
-  EXPECT_EQ("WCaDQxkgAUYIGhuxZ4BIDEZwcml2ZXRQsDNy7gcfJT/yvRs3/q40oA==",
+  EXPECT_EQ("WCCDQxkgAUYIGhuxZ4BCDEBQjO+OTbjjTzZ/Dvk66nfQqg==",
             Base64Encode(
                 auth_.GetRootClientAuthToken(RootClientTokenOwner::kClient)));
 }
@@ -168,7 +168,7 @@
 TEST_F(AuthManagerTest, GetRootClientAuthTokenDifferentSecret) {
   AuthManager auth{kSecret2, {}, kSecret1, &clock_};
   EXPECT_EQ(
-      "WCaDQxkgAUYIGhudoQBIDEZwcml2ZXRQKw9xcidyzrelxUkgkLmv1g==",
+      "WCCDQxkgAUYIGhudoQBCDEBQ2MZF8YXv5pbtmMxwz9VtLA==",
       Base64Encode(auth.GetRootClientAuthToken(RootClientTokenOwner::kClient)));
 }
 

third_party/libuweave/src/macaroon_caveat.c

diff --git a/third_party/libuweave/src/macaroon_caveat.c b/third_party/libuweave/src/macaroon_caveat.c
index a2b26dc..3b26b29 100644
--- a/third_party/libuweave/src/macaroon_caveat.c
+++ b/third_party/libuweave/src/macaroon_caveat.c
@@ -102,7 +102,7 @@
                                       uint8_t* buffer,
                                       size_t buffer_size,
                                       UwMacaroonCaveat* new_caveat) {
-  if (str == NULL || str_len == 0 || buffer == NULL || buffer_size == 0 ||
+  if ((str == NULL && str_len != 0) || buffer == NULL || buffer_size == 0 ||
       new_caveat == NULL ||
       uw_macaroon_caveat_creation_get_buffsize_(type, str_len) > buffer_size) {
     return false;