feat : Check config hash and ProgramInfoChanged event

src/appchain.cairo

@@ -5,6 +5,7 @@
 mod errors {
     const INVALID_ADDRESS: felt252 = 'Config: invalid address';
     const SNOS_INVALID_PROGRAM_OUTPUT_SIZE: felt252 = 'snos: invalid output size';
+    const SNOS_INVALID_CONFIG_HASH: felt252 = 'snos: invalid config hash';
     const SNOS_INVALID_MESSAGES_SEGMENTS: felt252 = 'snos: invalid messages segments';
 }
 
@@ -25,6 +26,7 @@ mod appchain {
         messaging_cpt, messaging_cpt::InternalTrait as MessagingInternal, IMessaging,
         output_process, output_process::{MessageToStarknet, MessageToAppchain},
     };
+    use piltover::snos_output::ProgramOutput;
     use piltover::snos_output;
     use starknet::ContractAddress;
     use super::errors;
@@ -94,6 +96,15 @@ mod appchain {
                 errors::SNOS_INVALID_PROGRAM_OUTPUT_SIZE
             );
 
+            let mut program_output_mut = program_output;
+            let program_output_struct: ProgramOutput = Serde::deserialize(ref program_output_mut)
+                .unwrap();
+            let (_, current_config_hash): (felt252, felt252) = self.config.program_info.read();
+            assert(
+                program_output_struct.config_hash == current_config_hash,
+                errors::SNOS_INVALID_CONFIG_HASH
+            );
+
             let mut offset = snos_output::HEADER_SIZE;
 
             // TODO(#7): We should update SNOS output to have the messages count

src/config/component.cairo

@@ -20,7 +20,7 @@ mod config_cpt {
         interface::IOwnable,
     };
     use piltover::config::interface::IConfig;
-    use starknet::{ContractAddress, get_caller_address};
+    use starknet::ContractAddress;
     use super::errors;
 
     #[storage]
@@ -79,7 +79,7 @@ mod config_cpt {
             self
                 .emit(
                     ProgramInfoChanged {
-                        changed_by: get_caller_address(),
+                        changed_by: starknet::get_caller_address(),
                         old_program_hash: old_program_hash,
                         new_program_hash: program_hash,
                         old_config_hash: old_config_hash,

src/snos_output.cairo

@@ -15,7 +15,7 @@ const MESSAGE_TO_APPCHAIN_HEADER_SIZE: usize = 5;
 /// <https://github.com/starkware-libs/cairo-lang/blob/caba294d82eeeccc3d86a158adb8ba209bf2d8fc/src/starkware/starknet/core/os/output.cairo#L52>.
 /// The names are taken from SNOS repository:
 /// <https://github.com/keep-starknet-strange/snos/blob/ad9a7df5fdbb63c813db285346eb667e032762e0/src/io/output.rs#L17>.
-#[derive(Serde)]
+#[derive(Drop, Serde)]
 struct ProgramOutput {
     /// The state commitment before this block.
     prev_state_root: felt252,

tests/test_appchain.cairo

@@ -117,6 +117,7 @@ fn update_state_ok() {
     let (appchain, _spy) = deploy_with_owner(c::OWNER().into());
 
     let imsg = IMessagingDispatcher { contract_address: appchain.contract_address };
+    let iconfig = IConfigDispatcher { contract_address: appchain.contract_address };
 
     let contract_sn = starknet::contract_address_const::<
         993696174272377493693496825928908586134624850969
@@ -137,6 +138,13 @@ fn update_state_ok() {
     ]
         .span();
 
+    snf::start_prank(CheatTarget::One(appchain.contract_address), c::OWNER());
+    iconfig
+        .set_program_info(
+            program_hash: 0x11,
+            config_hash: 2590421891839256512113614983194993186457498815986333310670788206383913888162
+        );
+
     // The state update contains a message to appchain, therefore, before
     // being sealed, it must be sent first.
     // The nonce must be adjusted to ensure the correct message to be sent.