v1.18: RPC sendTransaction: be more liberal in determining and settin…

…g last_valid_block_height for skip_preflight case (backport of #483) (#873)

RPC sendTransaction: be more liberal in determining and setting last_valid_block_height for skip_preflight case (#483)

* RPC sendTransaction: if skip_preflight, use processed-commitment Bank for last_valid_block_height and sanitization

* Use nonce retry logic for skip_preflight transactions if blockhash was not found

(cherry picked from commit 65a24d5)

Co-authored-by: Tyera <tyera@anza.xyz>

rpc/src/rpc.rs

@@ -3602,8 +3602,11 @@ pub mod rpc_full {
             let (wire_transaction, unsanitized_tx) =
                 decode_and_deserialize::<VersionedTransaction>(data, binary_encoding)?;
 
-            let preflight_commitment =
-                preflight_commitment.map(|commitment| CommitmentConfig { commitment });
+            let preflight_commitment = if skip_preflight {
+                Some(CommitmentConfig::processed())
+            } else {
+                preflight_commitment.map(|commitment| CommitmentConfig { commitment })
+            };
             let preflight_bank = &*meta.get_bank_with_config(RpcContextConfig {
                 commitment: preflight_commitment,
                 min_context_slot,
@@ -3619,7 +3622,7 @@ pub mod rpc_full {
             let durable_nonce_info = transaction
                 .get_durable_nonce()
                 .map(|&pubkey| (pubkey, *transaction.message().recent_blockhash()));
-            if durable_nonce_info.is_some() {
+            if durable_nonce_info.is_some() || (skip_preflight && last_valid_block_height == 0) {
                 // While it uses a defined constant, this last_valid_block_height value is chosen arbitrarily.
                 // It provides a fallback timeout for durable-nonce transaction retries in case of
                 // malicious packing of the retry queue. Durable-nonce transactions are otherwise