feat(gossipsub): apply max_transmit_size to the published message

Cargo.toml

@@ -83,7 +83,7 @@ libp2p-core = { version = "0.42.0", path = "core" }
 libp2p-dcutr = { version = "0.12.0", path = "protocols/dcutr" }
 libp2p-dns = { version = "0.42.0", path = "transports/dns" }
 libp2p-floodsub = { version = "0.45.0", path = "protocols/floodsub" }
-libp2p-gossipsub = { version = "0.47.1", path = "protocols/gossipsub" }
+libp2p-gossipsub = { version = "0.48.0", path = "protocols/gossipsub" }
 libp2p-identify = { version = "0.45.1", path = "protocols/identify" }
 libp2p-identity = { version = "0.2.9" }
 libp2p-kad = { version = "0.47.0", path = "protocols/kad" }

protocols/gossipsub/CHANGELOG.md

@@ -1,3 +1,8 @@
+## 0.48.0
+
+- Apply `max_transmit_size` to the inner message instead of the final payload.
+  See [PR 5642](https://github.com/libp2p/rust-libp2p/pull/5642).
+
 ## 0.47.1
 
 - Attempt to publish to at least mesh_n peers when flood publish is disabled.

protocols/gossipsub/Cargo.toml

@@ -3,7 +3,7 @@ name = "libp2p-gossipsub"
 edition = "2021"
 rust-version = { workspace = true }
 description = "Gossipsub protocol for libp2p"
-version = "0.47.1"
+version = "0.48.0"
 authors = ["Age Manning <Age@AgeManning.com>"]
 license = "MIT"
 repository = "https://github.com/libp2p/rust-libp2p"

protocols/gossipsub/src/behaviour.rs

@@ -583,6 +583,11 @@ where
             .data_transform
             .outbound_transform(&topic, data.clone())?;
 
+        // check that the size doesn't exceed the max transmission size.
+        if transformed_data.len() > self.config.max_transmit_size() {
+            return Err(PublishError::MessageTooLarge);
+        }
+
         let raw_message = self.build_raw_message(topic, transformed_data)?;
 
         // calculate the message id from the un-transformed data
@@ -593,11 +598,6 @@ where
             topic: raw_message.topic.clone(),
         });
 
-        // check that the size doesn't exceed the max transmission size
-        if raw_message.raw_protobuf_len() > self.config.max_transmit_size() {
-            return Err(PublishError::MessageTooLarge);
-        }
-
         // Check the if the message has been published before
         if self.duplicate_cache.contains(&msg_id) {
             // This message has already been seen. We don't re-publish messages that have already

protocols/gossipsub/src/config.rs

@@ -174,7 +174,8 @@ impl Config {
 
     /// The maximum byte size for each gossipsub RPC (default is 65536 bytes).
     ///
-    /// This represents the maximum size of the entire protobuf payload. It must be at least
+    /// This represents the maximum size of the published message. It is additionally wrapped
+    /// in a protobuf struct, so the actual wire size may be a bit larger. It must be at least
     /// large enough to support basic control messages. If Peer eXchange is enabled, this
     /// must be large enough to transmit the desired peer information on pruning. It must be at
     /// least 100 bytes. Default is 65536 bytes.