Set the new dont_forward bit in channel_update messages

See lightning/bolts#999 should be super trivial to set.

I am looking at this as my potential first contribution and would like to clarify when the dont_forward flag should be set to 1. To my understanding, the flag should be set to 1 only in get_channel_update_for_unicast when short_channel_id does not exist but latest_inbound_scid_alias exists. In all other cases, it should be 0. Is that correct?

rust-lightning/lightning/src/ln/channelmanager.rs

Lines 2333 to 2346 in 41a6c67

    
           	/// Gets the current channel_update for the given channel. This does not check if the channel 
        
           	/// is public (only returning an Err if the channel does not yet have an assigned short_id), 
        
           	/// and thus MUST NOT be called unless the recipient of the resulting message has already 
        
           	/// provided evidence that they know about the existence of the channel. 
        
           	/// May be called with peer_state already locked! 
        
           	fn get_channel_update_for_unicast(&self, chan: &Channel<<SP::Target as SignerProvider>::Signer>) -> Result<msgs::ChannelUpdate, LightningError> { 
        
           		log_trace!(self.logger, "Attempting to generate channel update for channel {}", log_bytes!(chan.channel_id())); 
        
           		let short_channel_id = match chan.get_short_channel_id().or(chan.latest_inbound_scid_alias()) { 
        
           			None => return Err(LightningError{err: "Channel not yet established".to_owned(), action: msgs::ErrorAction::IgnoreError}), 
        
           			Some(id) => id, 
        
           		}; 
        
           		self.get_channel_update_for_onion(short_channel_id, chan) 
        
           	}

No, its unrelated to the SCID, but rather should be set based on the channel is_public

Once we do this, we should print a big fat WARNING log in ChannelManager if we receive a channel_update with the dont_forward bit set but for a channel we don't have - telling the user they may want to look at whether they are passing the correct tx index to chain::Confirm::transactions_confirmed.

Hi! Is this issue still open and available to work on?

It's been a while since the last update, so I wanted to check before diving in.

Yea, I believe so!

I wold like to contribute ? is it open.

@Thrishalmadasu

@Thrishalmadasu is it still open

@malsomesh9

@malsomesh9 I’ve already created a PR for this issue and am actively working on it.

Is there any issue I can work on beginner stage

…

On Sun, Feb 1, 2026, 12:11 Thrishalmadasu ***@***.***> wrote: *Thrishalmadasu* left a comment (lightningdevkit/rust-lightning#1672) <#1672 (comment)> @malsomesh9 <https://github.com/malsomesh9> I’ve already created a PR for this issue and am actively working on it. — Reply to this email directly, view it on GitHub <#1672 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/BWRDQE33KFZZPR4XYJLJT2D4JWNYTAVCNFSM6AAAAACSQUDDKCVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTQMZQGQ3TQNZYHA> . You are receiving this because you were mentioned.Message ID: ***@***.***>

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Set the new `dont_forward` bit in channel_update messages #1672

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	/// Gets the current channel_update for the given channel. This does not check if the channel
	/// is public (only returning an Err if the channel does not yet have an assigned short_id),
	/// and thus MUST NOT be called unless the recipient of the resulting message has already
	/// provided evidence that they know about the existence of the channel.
	/// May be called with peer_state already locked!
	fn get_channel_update_for_unicast(&self, chan: &Channel<<SP::Target as SignerProvider>::Signer>) -> Result<msgs::ChannelUpdate, LightningError> {
	log_trace!(self.logger, "Attempting to generate channel update for channel {}", log_bytes!(chan.channel_id()));
	let short_channel_id = match chan.get_short_channel_id().or(chan.latest_inbound_scid_alias()) {
	None => return Err(LightningError{err: "Channel not yet established".to_owned(), action: msgs::ErrorAction::IgnoreError}),
	Some(id) => id,
	};

	self.get_channel_update_for_onion(short_channel_id, chan)
	}

Set the new dont_forward bit in channel_update messages #1672

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jirijakes commented on Feb 10, 2023

TheBlueMatt commented on Feb 10, 2023

TheBlueMatt commented on Feb 16, 2023

Thrishalmadasu commented on Jan 22, 2026

TheBlueMatt commented on Jan 22, 2026

malsomesh9 commented on Feb 1, 2026

malsomesh9 commented on Feb 1, 2026

Thrishalmadasu commented on Feb 1, 2026

malsomesh9 commented on Feb 1, 2026

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Set the new `dont_forward` bit in channel_update messages #1672