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fix: UDPSClient uses two-arg Join so multicast receiver lands on the right interface

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UDPSClient::ConnectMulticast was calling the single-arg BasicUDPSocket::Join,
which forwards NULL as the local interface and lets the kernel bind to
INADDR_ANY.  On a multi-homed host (or when the server sends on loopback via
Interface = "127.0.0.1") the client joins the wrong interface and silently
receives nothing.

Fix: read the optional Interface key inside the useMulticast block in
UDPSClient::Initialise; in ConnectMulticast call the two-arg
Join(group, interface) when Interface is set, and fall back to the one-arg
call otherwise to preserve the existing INADDR_ANY behaviour for configs that
omit it.

Forward the new optional Interface key through UDPStreamerClient (read from
DataSource config, written into the UDPSClient ConfigurationDatabase only
when non-empty).  Extend the "Joined multicast group" log to report the
interface name or "default".

Regression test TestExecute_MulticastReceivesDataOnInterface: mock TCP
control listener + multicast UDP DATA socket with IP_MULTICAST_IF set to
127.0.0.1, verifying a uint32 value of 424242 reaches DataSource signal
memory.  Confirmed FAILED without the Join fix and PASSED with it.

Suite: 133/133 (was 132/132 before this commit).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
This commit is contained in:
Martino Ferrari
2026-08-17 08:23:41 +02:00
co-authored by Claude Sonnet 4.6
parent 61a2aa3988
commit 14d5351a81
8 changed files with 270 additions and 9 deletions
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Docs/UDPStreamer.md
+44
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@@ -298,6 +298,50 @@ PrepareNextState() ← opens UDP server socket, starts background threa
}
```
---
## UDPStreamerClient DataSource
`UDPStreamerClient` is a MARTe2 **input** DataSource that receives signals from a `UDPStreamer`
server. Transport, fragment reassembly, and auto-reconnect are delegated to `UDPSClient`; the
DataSource only decodes CONFIG/DATA payloads into real-time signal memory.
### Configuration
```
+ClientDS = {
Class = UDPStreamerClient
ServerAddress = "192.168.1.10" // UDPStreamer server IP
Port = 44500 // Server port
// Multicast (optional — omit for unicast)
MulticastGroup = "239.0.0.1"
DataPort = 44501 // UDP data port (default: Port+1)
Interface = "192.168.1.10" // See table below
MaxPayloadSize = 1400
Signals = {
Counter = { Type = uint32 }
}
}
```
### Parameters
| Parameter | Type | Default | Description |
| --------------- | ------- | ---------- | ----------- |
| `ServerAddress` | string | 127.0.0.1 | IPv4 address of the `UDPStreamer` server. |
| `Port` | uint16 | 44500 | Server UDP port (unicast) or TCP control port (multicast). |
| `MulticastGroup`| string | *(absent)* | IPv4 multicast address. Presence enables multicast mode. |
| `DataPort` | uint16 | Port+1 | UDP port for multicast DATA datagrams. |
| `Interface` | string | *(absent)* | Local IPv4 dotted-quad address (e.g. `"127.0.0.1"`) of the interface to join the multicast group on. **Optional**: omitting it uses the default-route interface (INADDR_ANY), which silently receives nothing if the server sends on a different interface. Not an interface name — `"eth0"` is invalid. |
| `MaxPayloadSize`| uint32 | 1400 | Max payload bytes per datagram (must match the server). |
| `SilenceTimeout`| float32 | 1.0 | Seconds of no data before auto-reconnect. 0 disables. |
| `KeepAliveInterval` | uint32 | 15 | Seconds between unicast keepalive ACKs. 0 disables. |
| `CPUMask` | uint32 | 0xFFFFFFFF | CPU affinity for the background receiver thread. |
| `StackSize` | uint32 | default | Stack size in bytes for the receiver thread. |
With `MaxPayloadSize = 1400`, a single 1000-element float32 signal produces:
```