refactor: generalize IPC ParseAddress to use sockaddr_storage #34845

This is a pure structural refactor with zero behavior change.

Motivation

Currently, ParseAddress and the underlying connect/bind functions in src/ipc/process.cpp are hardwired to use struct sockaddr_un. This tightly couples the IPC implementation to Unix domain sockets and makes it difficult to introduce other socket types.

This PR abstracts the address parsing to use the protocol-agnostic sockaddr_storage and socklen_t.

• The existing Unix socket logic is extracted into a ParseUnixAddress helper.
• The main ParseAddress function is turned into a clean dispatcher.
• connect and bind are updated to use the generic ss_family and dynamic address lengths.

This structural change paves the way for introducing authenticated TCP socket support to multiprocess IPC (addressing #32802). By separating this refactor from the TCP implementation, it keeps the diff footprint small and makes the follow-on feature PR much easier to review.

(Note: The follow-on TCP work will rely on reusing the existing RPC cookie auth and explicit SSH tunneling for untrusted networks, mirroring our existing RPC threat model without introducing new dependencies).

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LLM Linter (✨ experimental)

Possible places where named args for integral literals may be used (e.g. func(x, /*named_arg=*/0) in C++, and func(x, named_arg=0) in Python):

• ::socket(addr.ss_family, SOCK_STREAM, 0) in src/ipc/process.cpp
• ::socket(addr.ss_family, SOCK_STREAM, 0) in src/ipc/process.cpp
• strncpy(addr.sun_path, path_str.c_str(), sizeof(addr.sun_path)-1) in src/ipc/process.cpp

^{2026-03-17 19:43:56}