tProxy: aggregated-mode `channel_id` collision can overwrite the `AGGREGATED_CHANNEL_ID` upstream channel

[GitGab19]

Suggested Fix

diff --git a/miner-apps/translator/src/lib/sv2/channel_manager/mod.rs b/miner-apps/translator/src/lib/sv2/channel_manager/mod.rs
--- a/miner-apps/translator/src/lib/sv2/channel_manager/mod.rs
+++ b/miner-apps/translator/src/lib/sv2/channel_manager/mod.rs
@@ -879,10 +879,17 @@ impl ChannelManager {
                 // Find max channel ID, excluding AGGREGATED_CHANNEL_ID
                 // (u32::MAX) which would cause overflow when adding 1
                 let channel_id = self
                     .extended_channels
                     .iter()
                     .filter(|x| *x.key() != AGGREGATED_CHANNEL_ID)
                     .fold(0, |acc, x| std::cmp::max(acc, *x.key()));
                 let next_channel_id = channel_id + 1;
+                if next_channel_id == AGGREGATED_CHANNEL_ID {
+                    error!("Refusing to allocate reserved aggregated channel ID to downstream");
+                    return Err(TproxyError::fallback(
+                        TproxyErrorKind::OpenMiningChannelError,
+                    ));
+                }
+
                 let success_extranonce_prefix: Vec<u8> = new_extranonce_prefix.as_bytes().to_vec();
                 let new_downstream_extended_channel = ExtendedChannel::new(
                     next_channel_id,

Note

I'm not sure we should trigger fallback in this case, probably it's better to just disconnect the client which is asking for this new channel.