Tahr.RPC.Dispatcher (tahr v0.1.0)

Map an incoming Tahr.RPC.Message.Call to the registered handler for its {program, version} pair, then wrap the result in the appropriate Tahr.RPC.Message.AcceptedReply / DeniedReply.

The dispatcher is stateless — handlers are passed in via the programs map. The TCP server holds the registry; this module is pure-function so it's trivial to unit-test.

RPC error mapping

RPC version != 2 → RPC_MISMATCH (denied)
Unknown program → PROG_UNAVAIL
Wrong version of a known program → PROG_MISMATCH
Handler returns :proc_unavail → PROC_UNAVAIL
Handler returns :garbage_args → GARBAGE_ARGS
Handler returns :system_err or raises → SYSTEM_ERR
Handler returns {:ok, body} → SUCCESS with body

Summary

Types

programs()

Registry of installed handlers

Functions

dispatch(call, programs, extras \\ %{})

Dispatch a single call. Returns a Message.reply() ready to be encoded with Message.encode_reply/1.

Types

programs()

@type programs() :: %{
  required(non_neg_integer()) => %{required(non_neg_integer()) => module()}
}

Registry of installed handlers:

%{
  100000 => %{2 => SomeModule},  # portmapper
  100003 => %{3 => Nfs3Handler}  # NFSv3
}

Functions

dispatch(call, programs, extras \\ %{})

@spec dispatch(Tahr.RPC.Message.Call.t(), programs(), map()) ::
  Tahr.RPC.Message.reply()

Dispatch a single call. Returns a Message.reply() ready to be encoded with Message.encode_reply/1.

extras is merged into the handler ctx map — the TCP server uses it to surface the connection's client address as ctx.peer so handlers can apply per-export host filtering.