Add friend-request backend service (rsFriendRequest)

[64johnlee]

Summary

Adds the libretroshare backend service for the Friend Requests feature:

• retroshare/rsfriendrequest.h — public RsFriendRequest interface
• rsserver/p3friendrequest.{h,cc} — p3FriendRequest service implementation
• Registers the new sources in both build systems (src/CMakeLists.txt and src/libretroshare.pro) so the service is compiled and linked.

Why

This is the backend companion to the GUI pull request RetroShare/RetroShare#3216 (gui: add Friend Requests page, closes RetroShare/RetroShare#1794). The GUI page links against rsFriendRequest, so this service must land for that PR to build.

The two PRs are intended to be merged together — the superproject PR's libretroshare submodule pointer references the head of this branch.

Notes

• Rebased cleanly onto current master; backend sources are additive (no changes to existing files beyond the two build-list entries).

🤖 Generated with Claude Code

[64johnlee]

Heads-up on a few follow-up commits that make this build and function end-to-end (the backend was previously additive-only):

• Link fix: define the global RsFriendRequest* rsFriendRequest (was declared extern but defined nowhere → undefined reference in consumers).
• Compile fix: p3FriendRequest now calls the no-arg p3Config() ctor — p3Config has no type-arg constructor, so the previous p3Config(CONFIG_TYPE_FRIEND_REQUESTS) didn't compile; dropped the unused macro too.
• Startup wiring: instantiate p3FriendRequest in rsinit.cc, assign the global, and register friend_requests.cfg with p3ConfigMgr.
• Detection: call onUnknownPeerConnectionAttempt() from AuthSSL::VerifyX509Callback on the ISSUER_UNKNOWN (not-a-friend) path — guarded and thread-safe.
• Build system: registered the new sources in both CMakeLists.txt and libretroshare.pro.

This is the backend companion to the GUI PR RetroShare/RetroShare#3216 (closes RetroShare/RetroShare#1794); the two are meant to merge together. One thing worth a maintainer's eye: RsFriendRequestItem uses manual serialise/deserialise (p3BanList style) — I couldn't run a full save/load cycle locally, so a check there would be appreciated.

[csoler]

Thx for contributing.

• Here the serialization system has entirely been re-written instead of using serial_process() and the macro RS_SERIAL_PROCESS which does it all for you. This will remove 50% of your code.
• p3peermgr already deals with friends, so that would be the place to add a list of pending requests. You'd benefit from the existing serializer there and so on:
  1 - add a new item type to hold the list of friend requests (just like you did)
  2 - update RsPeerConfigSerialiser to deal with it. See for instance how other items serialize automatically using serial_process().
  3 - add the API to rsPeers instead of a new RsFriendRequests

Overall this will be much less code.

(And just in case, don't simply copy-paste these suggestions into an AI without thinking 8-) )

[defnax]

@64johnlee rebase? branch is broken with master

[defnax]

flowchart TD
    A["Unknown peer attempts<br/>a secure connection"] --> B{"TLS certificate<br/>verification result"}

    B -->|"Known friend"| C["Continue through the normal<br/>RetroShare connection flow"]
    B -->|"Issuer unknown"| D["AuthSSL extracts identity data<br/>SSL ID · PGP ID · name · fingerprint"]

    D --> E["rsFriendRequest records the request"]

    E --> F{"Existing request?"}
    F -->|"No"| G["Create pending entry<br/>first seen · last seen · attempts = 1"]
    F -->|"Yes"| H["Update last seen<br/>increment attempt count<br/>preserve rejection decision"]

    G --> I["Friend Requests GUI / JSON API"]
    H --> I

    I --> J{"User decision"}

    J -->|"Accept"| K["Remove request<br/>add peer as SSL-only friend"]
    J -->|"Reject"| L["Keep entry marked rejected"]
    J -->|"Delete"| M["Remove the entry"]
    L --> N["Repeated attempts remain rejected"]
    L -->|"Clear rejected"| M

    K --> O["Controlled friendship<br/>establishment"]
    N --> P["Less repeated prompting"]
    M --> Q["Simple request-list cleanup"]

    E -.-> R["Thread-safe request storage"]
    R -.-> S["Safe use from the TLS<br/>verification callback"]

Loading

[defnax]

Main advantages:

• Converts otherwise invisible unknown-peer connection attempts into manageable friend requests.
• Gives users explicit accept, reject, delete, and cleanup controls.
• Records identity information and attempt history for better decisions.
• Deduplicates repeated attempts by SSL ID and preserves rejection choices.
• Provides one backend interface usable by the Qt GUI, JSON API, and authentication layer.
• Supports both CMake and qmake builds.
• Adds the feature mostly as a separate service, reducing changes to existing components.
• Acceptance uses RetroShare’s existing addSslOnlyFriend mechanism.

One current limitation: although the code contains save/load structures, its own TODO states that serialization is not fully registered yet, so requests currently remain in memory and are not reliably retained across restarts.