Remove INET_ADDRSTRLEN limit for symbolic hostnames and optimize socket connections.

[Jakio815]

Summary

• Remove server_hostname from socket_priv_t, which was actually not necessary to save in the struct.
• Fix bug setting pointers of net_abs in stack to NULL after shutdown_net().
• Support connect_to_socket() use in_addr instead of char* hostname when available.

1. Remove server_hostname from socket_priv_t

There was a bug found in #576, which happened after merging #508, not allowing symbolic hostnames longer than 16 bytes (INET_ADDRSTRLEN) from being connected.
This happened because there was a memcpy() to save the host_name in char server_hostname[INET_ADDRSTRLEN];.

While investigating this, the code only used this for printing debug messages on the hostname, and it was never used again.
I removed the server_hostname field from socket_priv_t.

2. Bug Fix: Remove unnecessary NULL setting to pointers.

After shutdown_net(net_abs), I set all net_abs to NULL, however some were just pointers from the stack, so had no effect. Removed all of these. Thanks for reporting this @edwardalee.

3. Support connect_to_socket() use in_addr instead of char* hostname when available.

When a federate tries to connect another federate, the RTI sends the target federate's IP address in a network format (uint32_t), not the presentation format (192.168.0.1 or localhost).
However, connect_to_socket() only supported the presentation format as the input parameter.
So there was some inefficiency where federate.c does inet_ntop() to convert the recieved network format into the presentation format, and inside connect_to_socket, does getaddrinfo to convert that presentation format backward into the network format (struct sockaddr_in) to make the actual system call connect().

So, by updating connect_to_socket() to accept an optional struct in_addr*, this PR removes this redundant Network -> Presentation -> Network conversion, which removes unnecessary DNS resolution overhead.

Why we couldn't remove getaddrinfo() entirely?

The redundancy above was from lf_connect_to_federate, however, connect_to_net is used once again in lf_connect_to_rti.

However, when used in lf_connect_to_rti, this always uses the char* hostname, because the RTI's address is provided strictly as a human-readable string (e.g., "localhost", "192.168.0.1" or "rti-server.domain.com"), performing DNS resolution via getaddrinfo() is mandatory to discover its actual network routing address. Therefore, connect_to_socket() was updated to selectively bypass DNS only when a raw IP is available.

This suggestion was also made by @edwardalee, thanks for your insight!

[Copilot]

Pull request overview

This PR updates the socket-based network abstraction used by the federated runtime to (1) avoid truncating symbolic hostnames, and (2) optimize certain federate-to-federate connections by using an already-available IPv4 address directly instead of round-tripping through presentation format + DNS resolution.

Changes:

• Removed persisted server_hostname storage from socket_priv_t (fixes hostname truncation caused by INET_ADDRSTRLEN-sized buffers).
• Extended socket connection parameters to optionally pass a raw struct in_addr* and bypass getaddrinfo() when available.
• Cleaned up ineffective “set local pointer to NULL after shutdown” code paths.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
network/impl/src/socket_common.c	Removes debug hostname storage; adds connect_to_socket() fast-path using struct in_addr.
network/impl/src/lf_socket_support.c	Stops copying hostname into a fixed-size buffer; passes hostname/IP through to connect_to_socket().
network/api/socket_common.h	Adds optional server_ip_addr to connection params; removes server_hostname from socket_priv_t; updates API docs/signature.
core/federated/RTI/rti_remote.h	Updates comments to reflect removal of server_hostname tracking.
core/federated/RTI/rti_remote.c	Removes hostname-based debug log and ineffective NULL assignments after shutdown.
core/federated/federate.c	Uses server_ip_addr when connecting to federates; avoids terminating accept loop on transient accept failure.

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[Copilot]

connect_to_socket() logs "Connected to ..." unconditionally, even when ret remains < 0 due to timeout or repeated failures. This can mislead operators and test logs. Consider only printing the success message when ret == 0, and print a failure/timeout message (or nothing) otherwise; also handle inet_ntop() failure before using host_str.

Suggested change

	if (ip_addr != NULL) {
	char host_str[INET_ADDRSTRLEN];
	inet_ntop(AF_INET, ip_addr, host_str, INET_ADDRSTRLEN);
	lf_print_info("Connected to %s:%d.", host_str, used_port);
	} else {
	lf_print_info("Connected to %s:%d.", hostname, used_port);
	if (ret == 0) {
	if (ip_addr != NULL) {
	char host_str[INET_ADDRSTRLEN];
	if (inet_ntop(AF_INET, ip_addr, host_str, INET_ADDRSTRLEN) != NULL) {
	lf_print_info("Connected to %s:%d.", host_str, used_port);
	} else {
	lf_print_info("Connected to port %d.", used_port);
	}
	} else {
	lf_print_info("Connected to %s:%d.", hostname, used_port);
	}

[Jakio815]

I don't think we need this? On line 267, which is not shown here,

    if (ret < 0) {
      lf_sleep(CONNECT_RETRY_INTERVAL);
      lf_print_warning("Could not connect. Will try again every " PRINTF_TIME " nanoseconds. Connecting to port %d.\n",
                       CONNECT_RETRY_INTERVAL, used_port);
      continue;
    } else {
      break;
    }
  }

If ret<0, it continues, so it wouldn't get to this part if ret<0.

[Copilot]

In the getaddrinfo() call, (const char*)&str is a confusing cast of an array address to char* (and can hide type issues). Passing str directly is clearer and avoids relying on an unnecessary cast.

Suggested change

	if (getaddrinfo(hostname, (const char*)&str, &hints, &result)) {
	if (getaddrinfo(hostname, str, &hints, &result)) {

[Jakio815]

Fixed.

[Copilot]

If accept_net() returns NULL (e.g., because the server socket was closed and accept() starts failing with EBADF), continue will immediately retry in a tight loop, potentially spamming logs and burning CPU until _lf_termination_executed flips. Consider breaking/returning on NULL (as before), or adding an explicit backoff + exit condition based on errno/termination state.

Suggested change

	continue;
	break;

[Jakio815]

void* lf_handle_p2p_connections_from_federates(void* env_arg) {
...
  while (received_federates < _fed.number_of_inbound_p2p_connections && !_lf_termination_executed) {
    if (rti_failed()) {
      break;
    }
    // Wait for an incoming connection request.
    net_abstraction_t net = accept_net(_fed.server_net);
    if (net == NULL) {
      lf_print_warning("Federate failed to accept the network abstraction.");
      continue;
    }
...
  }

  LF_PRINT_LOG("All %zu remote federates are connected.", _fed.number_of_inbound_p2p_connections);
  return NULL;
}

I think it should still be continue, however, as it says it will keep looping when there are spamming connect() attempts.

How about adding a short sleep like 100 ms? @edwardalee

Also besides of that after rti_failed(), I think it should be return NULL;, because it shouldn't print the log that all remote federates are connected.

[Copilot]

server_ip_addr is treated as an input-only value (and connect_to_socket() does not modify it). Declaring this as const struct in_addr* (in both socket_connection_params_t and connect_to_socket() signature) would better communicate intent and allow callers to pass pointers to const data without casts.

[Jakio815]

Fixed.