qt: Add option for sending Tx to specific peer in UI

[1440000bytes]

Closes #50

[1440000bytes]

[luke-jr]

Seems strange to have this before the normal sendrawtransaction, but ok :)

[1440000bytes]

Thanks for the review. I will address these comments during the weekend.

[1440000bytes]

I have made the changes in last commit based on the review comments. Tested it with single and multiple peers. It works as expected.

Sending to a single peer

Sending to multiple peers

[kwsantiago]

This needs proper transaction validation and error handling.

Also from a security perspective there is no permission check (should verify peer accepts the transaction relay) and there is no rate limiting against spamming peers with transactions.

[1440000bytes]

[1440000bytes]

This needs proper transaction validation and error handling.

Also from a security perspective there is no permission check (should verify peer accepts the transaction relay) and there is no rate limiting against spamming peers with transactions.

Thanks for the review. Added tx validation and error handling in the last commit. I don't think this feature needs rate limiting.

[1440000bytes]

I have fixed the error handling and tested it with incorrect peer id. Also addressed other review comments.

[kwsantiago]

The errorMessage and peerIds are accessed from multiple threads without proper synchronization. While there's a mutex for errorMessage, peerIds has no protection.

[kwsantiago]

The lambda captures this (1710-1744) and creates a shared connection that may outlive the RPCConsole object if the window is closed before all async operations complete.

[kwsantiago]

There is no validation that sendmsgtopeer RPC command exists or is available before attempting to use it.

[kwsantiago]

The MAX_TX_SIZE check (4MB) is arbitrary and doesn't match protocol limits. Ideally we should use actual protocol constants.