add find_and_parse_declared_proof transaction introspection helper

program/src/declare_proof.rs

@@ -3,26 +3,27 @@ use solana_program::{
     entrypoint::ProgramResult,
     program_error::ProgramError,
     pubkey::Pubkey,
+    sanitize::SanitizeError,
+    serialize_utils::{read_pubkey, read_u16},
 };
 
 
 /// DeclareProof is used by other instructions in the same transaction.
 /// - Other instructions will use transaction introspection to ensure they
 /// only process the declared proof.
-/// - Other instructions that need to validate the declared proof will only 
-/// look at the first and second instructions in the transaction
+/// - Other instructions that need to get the declared proof for validation
+/// will only look at the first and second instructions in the transaction
 ///
 /// Safety requirements:
 /// - No safety requirements are required in this instruction to keep cu's as
 /// low as possible. Other instructions that use the declared proof handle
 /// validation via the loader.
+/// - Only one account should be provided.
 pub fn process_declare_proof<'a, 'info>(
     _program_id: &Pubkey,
     accounts: &'a [AccountInfo<'info>],
     _data: &[u8],
 ) -> ProgramResult {
-    // Ensure one account info is provided
-    // Validation of this proof is handled by the mine ix
     let [_proof_info] =
         accounts
     else {
@@ -32,3 +33,44 @@ pub fn process_declare_proof<'a, 'info>(
     Ok(())
 }
 
+/// Errors if:
+/// - Fails to find and parse the declared proof pubkey in the second instruction
+/// of the transaction
+pub fn find_and_parse_declared_proof(data: &[u8]) -> Result<Pubkey, SanitizeError> {
+    // start the current byte index at 0
+    let mut current = 0;
+    let num_instructions = read_u16(&mut current, data)?;
+
+    if num_instructions < 2 {
+        // Not enough instructions in this transaction.
+        // The declare_proof instruction must be included with 
+        // the other instruction in the same transaction.
+        return Err(SanitizeError::IndexOutOfBounds)
+    }
+
+    // The first ix should be a set compute budget ix
+    // The second ix should be a declare_proof ix
+    // The starting index is the second ix
+    let index = 1;
+
+    current += index * 2;
+    let start = read_u16(&mut current, data)?;
+
+    current = start as usize;
+
+    current += 2; // skip the accounts length variable
+    current += 1; // skip the meta_byte
+
+    // The only account provided should be the proof pubkey
+    let proof_pubkey = read_pubkey(&mut current, data)?;
+
+    // There shouldn't be any more accounts,
+    // this should be the Ore program ID
+    let program_pubkey = read_pubkey(&mut current, data)?;
+    if program_pubkey.eq(&ore_api::ID) {
+        return Ok(proof_pubkey);
+    } else {
+        return Err(SanitizeError::InvalidValue);
+    }
+}
+