Remove bincode (#314)

* Update authority check to use PDA

* Format

* Remove bincode from the program code

* Comments

Author: guibescos

program/rust/Cargo.toml

@@ -14,7 +14,6 @@ bytemuck = "1.11.0"
 thiserror = "1.0"
 num-derive = "0.3"
 num-traits = "0.2"
-bincode = "1.3.3"
 
 [dev-dependencies]
 solana-program-test = "=1.13.3"
@@ -23,6 +22,7 @@ tokio = "1.14.1"
 hex = "0.3.1"
 quickcheck = "1"
 quickcheck_macros = "1"
+bincode = "1.3.3"
 
 [features]
 debug = []

program/rust/src/utils.rs

@@ -17,19 +17,21 @@ use {
         },
         OracleError,
     },
+    bytemuck::{
+        Pod,
+        Zeroable,
+    },
     num_traits::FromPrimitive,
     solana_program::{
         account_info::AccountInfo,
-        bpf_loader_upgradeable::{
-            self,
-            UpgradeableLoaderState,
-        },
+        bpf_loader_upgradeable,
         program::invoke,
         program_error::ProgramError,
         pubkey::Pubkey,
         system_instruction::transfer,
         sysvar::rent::Rent,
     },
+    std::cell::Ref,
 };
 
 
@@ -210,6 +212,23 @@ pub fn is_component_update(cmd_args: &UpdPriceArgs) -> Result<bool, OracleError>
     }
 }
 
+/// This struct represents UpgradeableLoaderState from bpf-upgradable-loader.
+/// Solana uses bincode for the struct. However the bincode crate is too big the space we have onchain,
+/// therefore we will use bytemuck for deserialization
+#[repr(C)]
+#[derive(Pod, Zeroable, Copy, Clone)]
+struct ProgramdataAccount {
+    /// 3 is the variant for programdata
+    pub account_type:          u32,
+    /// Space for slot of last upgrade (we don't use this field)
+    pub slot:                  [u32; 2],
+    /// 0 if immutable, 1 if has upgrade authority
+    pub has_upgrade_authority: u8,
+    /// Upgrade authority of the program
+    pub upgrade_authority:     Pubkey,
+    /// Unused field needed for this struct to be Pod
+    pub unused:                [u8; 3],
+}
 
 /// Check that `programdata_account` is actually the buffer for `program_id`.
 /// Check that the authority in `programdata_account` matches `upgrade_authority_account`.
@@ -218,9 +237,8 @@ pub fn check_is_upgrade_authority_for_program(
     programdata_account: &AccountInfo,
     program_id: &Pubkey,
 ) -> Result<(), ProgramError> {
-    let programdata_deserialized: UpgradeableLoaderState =
-        bincode::deserialize(&programdata_account.try_borrow_data()?)
-            .map_err(|_| OracleError::DeserializationError)?;
+    let programdata_deserialized: Ref<ProgramdataAccount> =
+        load_account_as::<ProgramdataAccount>(programdata_account)?;
 
     // 1. programdata_account is actually this program's buffer
     let (programdata_address, _) =
@@ -233,18 +251,15 @@ pub fn check_is_upgrade_authority_for_program(
 
 
     // 2. upgrade_authority_account is actually the authority inside programdata_account
-    if let UpgradeableLoaderState::ProgramData {
-        slot: _,
-        upgrade_authority_address: Some(upgrade_authority_key),
-    } = programdata_deserialized
-    {
-        pyth_assert(
-            upgrade_authority_key.eq(upgrade_authority_account.key),
-            OracleError::InvalidUpgradeAuthority.into(),
-        )?;
-    } else {
-        return Err(OracleError::InvalidUpgradeAuthority.into());
-    }
+    pyth_assert(
+        programdata_deserialized
+            .upgrade_authority
+            .eq(upgrade_authority_account.key)
+            && programdata_deserialized.account_type == 3
+            && programdata_deserialized.has_upgrade_authority == 1,
+        OracleError::InvalidUpgradeAuthority.into(),
+    )?;
+
     Ok(())
 }