Encode mint in token ID on Solana

Change-Id: Ice9c2b64992e60bb8a0eb5d0a109043eda2d44ac

solana/modules/nft_bridge/program/src/api/complete_transfer.rs

@@ -101,7 +101,13 @@ pub fn complete_native(
     }
 
     // Verify VAA
-    if accs.vaa.token_address != accs.mint.info().key.to_bytes() {
+    // Please refer to transfer.rs for why the token id is used to store the mint
+    if accs.vaa.token_address != [1u8; 32] {
+        return Err(InvalidMint.into());
+    }
+    let mut token_id_bytes = [0u8; 32];
+    accs.vaa.token_id.to_big_endian(&mut token_id_bytes);
+    if token_id_bytes != accs.mint.info().key.to_bytes() {
         return Err(InvalidMint.into());
     }
     if accs.vaa.token_chain != CHAIN_ID_SOLANA {

solana/modules/nft_bridge/program/src/api/transfer.rs

@@ -187,15 +187,18 @@ pub fn transfer_native(
         Metadata::from_account_info(accs.spl_metadata.info()).ok_or(InvalidMetadata)?;
 
     // Post message
+    // Given there is no tokenID equivalent on Solana and each distinct token address is translated
+    // into a new contract on EVM based chains (which is costly), we use a static token_address
+    // and encode the mint in the token_id.
     let payload = PayloadTransfer {
-        token_address: accs.mint.info().key.to_bytes(),
+        token_address: [1u8; 32],
         token_chain: 1,
         to: data.target_address,
         to_chain: data.target_chain,
         symbol: metadata.data.symbol,
         name: metadata.data.name,
         uri: metadata.data.uri,
-        token_id: U256::from(0), // TODO
+        token_id: U256::from_big_endian(&accs.mint.info().key.to_bytes()),
     };
     let params = (
         bridge::instruction::Instruction::PostMessage,

solana/modules/nft_bridge/program/src/wasm.rs

@@ -168,6 +168,8 @@ pub fn complete_transfer_native_ix(
         payload: vaa.payload,
     };
 
+    let mut mint_bytes = [0u8; 32];
+    payload.token_id.to_big_endian(&mut mint_bytes);
     let ix = complete_native(
         program_id,
         bridge_id,
@@ -175,7 +177,7 @@ pub fn complete_transfer_native_ix(
         message_key,
         post_vaa_data,
         to_authority,
-        Pubkey::new(&payload.token_address),
+        Pubkey::new(&mint_bytes),
         CompleteNativeData {},
     )
     .unwrap();