network: fix room socket races and share the room network check

bsd:s, bsd:u and bsd:a share one file descriptor table, but each
service bound its own proxy packet callback, so every room packet was
queued three times on each socket. Bind the callback once.

The room thread walked the descriptor table without a lock while bsd
created and closed sockets, so it could reach a destroyed or not yet
created socket. Guard the table with a mutex, and publish a socket only
after it is created and initialized. Check airplane mode before an fd
is taken, so a refused socket no longer leaks its slot.

ProxySocket now initializes protocol, decompresses packets outside the
packet lock without copying the compressed data first, and keeps a read
offset for partial TCP reads instead of erasing from the front.

Add Network::GetRoomIPv4Address(), set only in the Joined and Moderator
states. NIFM uses it for network availability and for every reported
address, including EnumerateNetworkInterfaces and GetCurrentIpAddress,
so no call reports the room address while another rejects the network.

Assisted-by: Claude Opus 5.5 (investigation and implementation)

1 files changed, 2 insertions, 1 deletions

diff --git a/src/core/internal_network/socket_proxy.h b/src/core/internal_network/socket_proxy.h
index 8343fcbae1..d2bd7aae77 100644
--- a/src/core/internal_network/socket_proxy.h
+++ b/src/core/internal_network/socket_proxy.h
@@ -90,7 +90,8 @@ private:
     SockAddrIn local_endpoint{};
     bool blocking = true;
     std::queue<ProxyPacket> received_packets;
-    Protocol protocol;
+    std::size_t front_read_offset = 0; ///< Bytes of the front TCP packet that were already read
+    Protocol protocol{};
 
     std::mutex packets_mutex;
     std::condition_variable packets_cv;