Add switching vote instruction (#10197)

* Add switching vote

* Make sure vote size stays under gossip limit

Co-authored-by: Carl <carl@solana.com>

core/src/cluster_info.rs

@@ -2052,10 +2052,11 @@ pub fn stake_weight_peers<S: std::hash::BuildHasher>(
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::crds_value::CrdsValueLabel;
+    use crate::crds_value::{CrdsValue, CrdsValueLabel, Vote as CrdsVote};
     use rayon::prelude::*;
     use solana_perf::test_tx::test_tx;
     use solana_sdk::signature::{Keypair, Signer};
+    use solana_vote_program::{vote_instruction, vote_state::Vote};
     use std::collections::HashSet;
     use std::net::{IpAddr, Ipv4Addr};
     use std::sync::Arc;
@@ -2763,4 +2764,31 @@ mod tests {
         assert_eq!(slots, range);
         assert!(since.is_some());
     }
+
+    #[test]
+    fn test_vote_size() {
+        let slots = vec![1; 32];
+        let vote = Vote::new(slots, Hash::default());
+        let keypair = Arc::new(Keypair::new());
+
+        // Create the biggest possible vote transaction
+        let vote_ix = vote_instruction::vote_switch(
+            &keypair.pubkey(),
+            &keypair.pubkey(),
+            vote,
+            Hash::default(),
+        );
+        let mut vote_tx = Transaction::new_with_payer(&[vote_ix], Some(&keypair.pubkey()));
+
+        vote_tx.partial_sign(&[keypair.as_ref()], Hash::default());
+        vote_tx.partial_sign(&[keypair.as_ref()], Hash::default());
+
+        let vote = CrdsVote {
+            from: keypair.pubkey(),
+            transaction: vote_tx,
+            wallclock: 0,
+        };
+        let vote = CrdsValue::new_signed(CrdsData::Vote(1, vote), &Keypair::new());
+        assert!(bincode::serialized_size(&vote).unwrap() <= MAX_PROTOCOL_PAYLOAD_SIZE);
+    }
 }

programs/vote/src/vote_instruction.rs

@@ -11,6 +11,7 @@ use serde_derive::{Deserialize, Serialize};
 use solana_metrics::inc_new_counter_info;
 use solana_sdk::{
     account::{get_signers, KeyedAccount},
+    hash::Hash,
     instruction::{AccountMeta, Instruction, InstructionError, WithSigner},
     program_utils::{limited_deserialize, next_keyed_account, DecodeError},
     pubkey::Pubkey,
@@ -95,6 +96,15 @@ pub enum VoteInstruction {
     ///    1 - New validator identity (node_pubkey)
     ///
     UpdateValidatorIdentity,
+
+    /// A Vote instruction with recent votes
+    ///    requires authorized voter signature
+    ///
+    /// Expects 3 Accounts:
+    ///    0 - Vote account to vote with
+    ///    1 - Slot hashes sysvar
+    ///    2 - Clock sysvar
+    VoteSwitch(Vote, Hash),
 }
 
 fn initialize_account(vote_pubkey: &Pubkey, vote_init: &VoteInit) -> Instruction {
@@ -195,6 +205,26 @@ pub fn vote(vote_pubkey: &Pubkey, authorized_voter_pubkey: &Pubkey, vote: Vote)
     Instruction::new(id(), &VoteInstruction::Vote(vote), account_metas)
 }
 
+pub fn vote_switch(
+    vote_pubkey: &Pubkey,
+    authorized_voter_pubkey: &Pubkey,
+    vote: Vote,
+    proof_hash: Hash,
+) -> Instruction {
+    let account_metas = vec![
+        AccountMeta::new(*vote_pubkey, false),
+        AccountMeta::new_readonly(sysvar::slot_hashes::id(), false),
+        AccountMeta::new_readonly(sysvar::clock::id(), false),
+    ]
+    .with_signer(authorized_voter_pubkey);
+
+    Instruction::new(
+        id(),
+        &VoteInstruction::VoteSwitch(vote, proof_hash),
+        account_metas,
+    )
+}
+
 pub fn withdraw(
     vote_pubkey: &Pubkey,
     authorized_withdrawer_pubkey: &Pubkey,
@@ -245,7 +275,7 @@ pub fn process_instruction(
             next_keyed_account(keyed_accounts)?.unsigned_key(),
             &signers,
         ),
-        VoteInstruction::Vote(vote) => {
+        VoteInstruction::Vote(vote) | VoteInstruction::VoteSwitch(vote, _) => {
             inc_new_counter_info!("vote-native", 1);
             vote_state::process_vote(
                 me,
@@ -328,6 +358,15 @@ mod tests {
             )),
             Err(InstructionError::InvalidAccountData),
         );
+        assert_eq!(
+            process_instruction(&vote_switch(
+                &Pubkey::default(),
+                &Pubkey::default(),
+                Vote::default(),
+                Hash::default(),
+            )),
+            Err(InstructionError::InvalidAccountData),
+        );
         assert_eq!(
             process_instruction(&authorize(
                 &Pubkey::default(),