Fix rostopic echo not working because it doesn't provide md5sum

roslibrust/examples/ros1_talker.rs

@@ -16,7 +16,7 @@ async fn main() -> Result<(), anyhow::Error> {
         .map_err(|err| err)?;
     let publisher = nh.advertise::<std_msgs::String>("/chatter", 1).await?;
 
-    for count in 0..10 {
+    for count in 0..50 {
         publisher
             .publish(&std_msgs::String {
                 data: format!("hello world from rust {count}"),

roslibrust/src/ros1/publisher.rs

@@ -76,7 +76,7 @@ impl Publication {
             caller_id: node_name.to_string(),
             latching,
             msg_definition: msg_definition.to_owned(),
-            md5sum: md5sum.to_owned(),
+            md5sum: Some(md5sum.to_owned()),
             topic: Some(topic_name.to_owned()),
             topic_type: topic_type.to_owned(),
             tcp_nodelay: false,
@@ -100,27 +100,32 @@ impl Publication {
                             ConnectionHeader::from_bytes(&connection_header[..bytes])
                         {
                             log::debug!(
-                                "Received subscribe request for {:?} with md5sum {}",
+                                "Received subscribe request for {:?} with md5sum {:?}",
                                 connection_header.topic,
                                 connection_header.md5sum
                             );
                             // I can't find documentation for this anywhere, but when using
                             // `rostopic hz` with one of our publishers I discovered that the rospy code sent "*" as the md5sum
                             // To indicate a "generic subscription"...
-                            if connection_header.md5sum != "*" {
-                                if connection_header.md5sum != responding_conn_header.md5sum {
-                                    log::warn!(
-                                    "Got subscribe request for {}, but md5sums do not match. Expected {}, received {}",
+                            // I also discovered that `rostopic echo` does not send a md5sum (even thou ros documentation says its required)
+                            if let Some(connection_md5sum) = connection_header.md5sum {
+                                if connection_md5sum != "*" {
+                                    if let Some(local_md5sum) = &responding_conn_header.md5sum {
+                                        if connection_md5sum != *local_md5sum {
+                                            log::warn!(
+                                    "Got subscribe request for {}, but md5sums do not match. Expected {:?}, received {:?}",
                                     topic_name,
-                                    responding_conn_header.md5sum,
-                                    connection_header.md5sum,
+                                    local_md5sum,
+                                    connection_md5sum,
                                     );
-                                    // Close the TCP connection
-                                    stream
-                                        .shutdown()
-                                        .await
-                                        .expect("Unable to shutdown tcpstream");
-                                    continue;
+                                            // Close the TCP connection
+                                            stream
+                                                .shutdown()
+                                                .await
+                                                .expect("Unable to shutdown tcpstream");
+                                            continue;
+                                        }
+                                    }
                                 }
                             }
                             // Write our own connection header in response

roslibrust/src/ros1/service_client.rs

@@ -97,7 +97,7 @@ impl ServiceClientLink {
             caller_id: node_name.to_string(),
             latching: false,
             msg_definition: srv_definition.to_owned(),
-            md5sum: md5sum.to_owned(),
+            md5sum: Some(md5sum.to_owned()),
             // Note: using "topic" indicates a subscription
             // using "service" indicates a service client
             topic: None,

roslibrust/src/ros1/service_server.rs

@@ -169,7 +169,7 @@ impl ServiceServerLink {
             caller_id: node_name.to_string(),
             latching: false,
             msg_definition: "".to_string(),
-            md5sum: "".to_string(),
+            md5sum: None,
             service: None,
             topic: None,
             topic_type: "".to_string(),

roslibrust/src/ros1/subscriber.rs

@@ -59,7 +59,7 @@ impl Subscription {
             caller_id: node_name.to_string(),
             latching: false,
             msg_definition,
-            md5sum,
+            md5sum: Some(md5sum),
             topic: Some(topic_name.to_owned()),
             topic_type: topic_type.to_owned(),
             tcp_nodelay: false,
@@ -168,7 +168,7 @@ async fn establish_publisher_connection(
             Ok(stream)
         } else {
             log::error!(
-                "Tried to subscribe to {}, but md5sums do not match. Expected {}, received {}",
+                "Tried to subscribe to {}, but md5sums do not match. Expected {:?}, received {:?}",
                 topic_name,
                 conn_header.md5sum,
                 responded_header.md5sum

roslibrust/src/ros1/tcpros.rs

@@ -15,7 +15,7 @@ pub struct ConnectionHeader {
     pub caller_id: String,
     pub latching: bool, // TODO this field should be optional and None for service clients and servers
     pub msg_definition: String, // TODO this should be optional and None for service clients and servers
-    pub md5sum: String,
+    pub md5sum: Option<String>,
     // TODO we may want to distinguish between service and topic headers with different types?
     pub service: Option<String>,
     pub topic: Option<String>,
@@ -35,7 +35,7 @@ impl ConnectionHeader {
         let mut msg_definition = String::new();
         let mut caller_id = String::new();
         let mut latching = false;
-        let mut md5sum = String::new();
+        let mut md5sum = None;
         let mut topic = None;
         let mut service = None;
         let mut topic_type = String::new();
@@ -63,7 +63,9 @@ impl ConnectionHeader {
                 field[equals_pos + 1..].clone_into(&mut latching_str);
                 latching = &latching_str != "0";
             } else if field.starts_with("md5sum=") {
-                field[equals_pos + 1..].clone_into(&mut md5sum);
+                let mut md5sum_str = String::new();
+                field[equals_pos + 1..].clone_into(&mut md5sum_str);
+                md5sum = Some(md5sum_str);
             } else if field.starts_with("topic=") {
                 let mut topic_str = String::new();
                 field[equals_pos + 1..].clone_into(&mut topic_str);
@@ -113,9 +115,11 @@ impl ConnectionHeader {
         header_data.write_u32::<LittleEndian>(latching_str.len() as u32)?;
         header_data.write(latching_str.as_bytes())?;
 
-        let md5sum = format!("md5sum={}", self.md5sum);
-        header_data.write_u32::<LittleEndian>(md5sum.len() as u32)?;
-        header_data.write(md5sum.as_bytes())?;
+        if let Some(md5sum) = self.md5sum.as_ref() {
+            let md5sum = format!("md5sum={}", md5sum);
+            header_data.write_u32::<LittleEndian>(md5sum.len() as u32)?;
+            header_data.write(md5sum.as_bytes())?;
+        }
 
         let msg_definition = format!("message_definition={}", self.msg_definition);
         header_data.write_u32::<LittleEndian>(msg_definition.len() as u32)?;