lib: optional binding IP support for gRPC server

[PalSubham]

Usage

Binding IP can be configured in daemons file for individual daemon options using -M grpc:<IP>:<port>.
This is fully backward compatible with port-only config.

Changes

Instead of directly using std::stoul on the argument, it is divided into two parts at last occuring ":" character, given it is present. Default IP is same as 0.0.0.0.
Inside frr_grpc_init, the combined data is stored as fields of a struct whose pointer is placed in fpt->data.
This is used in AddListeningPort method of grpc::ServerBuilder inside grpc_pthread_start while building grpc::Server.

Resolves

Resolves #23294

[greptile-apps]

Greptile Summary

This PR adds an optional host component to the gRPC module argument and passes the parsed host and port to the server thread.

• Introduces a grpc_args structure for thread startup data.
• Parses both legacy port-only and new host-and-port configurations.
• Builds the gRPC listening endpoint from the configured host and port.
• The startup routine currently reads the port from the structure pointer rather than its port field, and IPv6 endpoint formatting is incomplete.

Confidence Score: 3/5

This PR is not safe to merge because the configured gRPC port is discarded at runtime and IPv6 binding input cannot be emitted as a valid endpoint.

The new thread-data representation is incompatible with the retained pointer-to-integer port read, so both default and explicitly configured servers generally bind incorrectly or fail to start; IPv6 host formatting introduces another startup failure path.

Files Needing Attention: lib/northbound_grpc.cpp

Important Files Changed

Filename	Overview
lib/northbound_grpc.cpp	Adds configurable gRPC binding hosts, but currently derives the listening port from a pointer, mishandles ordinary IPv6 input, and leaves new startup data unowned.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart LR
  A["-M grpc:[host:]port"] --> B["Parse host and port"]
  B --> C["Allocate grpc_args"]
  C --> D["Store pointer in fpt->data"]
  D --> E["grpc_pthread_start"]
  E --> F["Build host:port endpoint"]
  F --> G["ServerBuilder::AddListeningPort"]
  G --> H["gRPC server"]

Loading

Comments Outside Diff (1)

1. lib/northbound_grpc.cpp, line 1276-1288 (link)

   Thread Arguments Are Leaked

   The new grpc_args object remains caller-owned, but neither normal shutdown nor the frr_pthread_run failure path deletes it. Each init/finish cycle leaks this object, and a startup failure also leaves the newly registered frr_pthread undisposed, causing stale allocations to accumulate.

   Prompt To Fix With AI

   This is a comment left during a code review.
   Path: lib/northbound_grpc.cpp
   Line: 1276-1288
   
   Comment:
   **Thread Arguments Are Leaked**
   
   The new `grpc_args` object remains caller-owned, but neither normal shutdown nor the `frr_pthread_run` failure path deletes it. Each init/finish cycle leaks this object, and a startup failure also leaves the newly registered `frr_pthread` undisposed, causing stale allocations to accumulate.
   
   ---
   
   For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.

Prompt To Fix All With AI

### Issue 1
lib/northbound_grpc.cpp:1147
**Port Read From Pointer**

`fpt->data` now points to a `grpc_args`, but this line still converts the pointer itself into the port number instead of reading `args->port`. As a result, every configuration discards the validated or default port and attempts to bind using a truncated heap address, leaving gRPC unavailable on the configured endpoint or potentially listening on an unintended port.

```suggestion
	uint port = args->port;
```

### Issue 2
lib/northbound_grpc.cpp:1156
**IPv6 Endpoint Lacks Brackets**

For an IPv6 configuration such as `2001:db8::1:50051`, parsing yields the host `2001:db8::1`, but this code reconstructs the endpoint without the brackets required around an IPv6 address. gRPC therefore receives an invalid endpoint and the server cannot start for ordinary IPv6 binding input.

### Issue 3
lib/northbound_grpc.cpp:1276-1288
**Thread Arguments Are Leaked**

The new `grpc_args` object remains caller-owned, but neither normal shutdown nor the `frr_pthread_run` failure path deletes it. Each init/finish cycle leaks this object, and a startup failure also leaves the newly registered `frr_pthread` undisposed, causing stale allocations to accumulate.

### Issue 4
lib/northbound_grpc.cpp:1366
**Malformed Ports Pass Validation**

This parser narrows the result of `std::stoul` directly to `uint` and does not check whether the full suffix was consumed. Inputs such as `127.0.0.1:50051junk` are silently accepted, while sufficiently large values can wrap into the valid range before the bounds check, making invalid configurations appear valid.

---

For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.

_{Reviews (1): Last reviewed commit: "added optional binding IP support for gr..." | Re-trigger Greptile}

[donaldsharp]

please take a few minutes and familiarize yourself with the workflow.rst documentation and follow it for your submissions. This is a no go until this is fixed

[PalSubham]

I read it. I'll fix the issues.