Graham McIntire
c6d2c48264
Adds bearer-token authenticated REST API at /api/v1 covering every action a non-admin user can perform on the website: contact + beacon submission, beacon-monitor management, propagation queries, profile read/update, and self-service API token issuance/revocation. Security: SHA-256-hashed bearer tokens (mwp_ prefix, plaintext shown once at creation), RFC 9457 problem+json error responses, RFC 9651 RateLimit-* headers backed by an ETS bucket (600/min per token, 60/min per anonymous IP, 30/min on /auth/tokens), private-contact filtering by viewer. Docs at docs/api/README.md (prose reference) and docs/api/openapi.yaml (OpenAPI 3.1 spec covering every endpoint, response, and schema). Tests: 124 new tests across schema, plug, error renderer, rate limiter, fallback, and every controller. 16/17 API modules at 100% line coverage; FallbackController at 87.5% (one defmodule line, an Erlang-cover artifact for action_fallback-only modules).
91 lines
2.7 KiB
Elixir
91 lines
2.7 KiB
Elixir
defmodule MicrowavepropWeb.Api.RateLimiter do
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@moduledoc """
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Tiny ETS-backed fixed-window rate limiter for `/api/v1`.
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No external dependency, no supervisor entry — the named ETS table
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is created lazily on the first request and survives for the
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lifetime of the BEAM. Each (bucket, window) pair holds a counter
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incremented atomically via `:ets.update_counter/4`.
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Default limits (overridable per plug invocation):
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* authenticated requests: 600 / minute, keyed by API token id
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* anonymous requests: 60 / minute, keyed by client IP
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The plug emits the RFC 9651 `RateLimit` headers and a 429
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problem+json response when the bucket is exhausted.
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"""
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@behaviour Plug
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import Plug.Conn
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alias MicrowavepropWeb.Api.ErrorJSON
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@table :microwaveprop_api_rate_limiter
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@default_window_ms 60_000
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@default_anon_limit 60
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@default_auth_limit 600
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@doc """
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Initializes the named ETS table. Idempotent — safe to call from
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application boot and from tests. Returns `:ok` whether the table
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existed already or was created by this call.
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"""
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@spec init_table() :: :ok
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def init_table do
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if :ets.whereis(@table) == :undefined do
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:ets.new(@table, [:set, :public, :named_table, write_concurrency: true])
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end
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:ok
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end
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@doc "Resets the ETS table. Test helper."
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@spec reset() :: :ok
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def reset do
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init_table()
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:ets.delete_all_objects(@table)
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:ok
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end
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@impl true
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def init(opts), do: opts
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@impl true
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def call(conn, opts) do
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init_table()
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now = System.system_time(:millisecond)
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window_ms = Keyword.get(opts, :window_ms, @default_window_ms)
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{bucket, limit} = bucket_for(conn, opts)
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window = div(now, window_ms)
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key = {bucket, window}
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count = :ets.update_counter(@table, key, {2, 1}, {key, 0})
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remaining = max(limit - count, 0)
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reset_in = div((window + 1) * window_ms - now + 999, 1000)
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conn =
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conn
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|> put_resp_header("ratelimit-limit", Integer.to_string(limit))
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|> put_resp_header("ratelimit-remaining", Integer.to_string(remaining))
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|> put_resp_header("ratelimit-reset", Integer.to_string(reset_in))
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if count > limit do
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conn
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|> put_resp_header("retry-after", Integer.to_string(reset_in))
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|> ErrorJSON.send_problem(429, "too_many_requests", "Rate limit exceeded; retry after #{reset_in}s.")
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else
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conn
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end
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end
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defp bucket_for(conn, opts) do
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case conn.assigns[:current_api_token] do
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%{id: id} ->
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{{:token, id}, Keyword.get(opts, :auth_limit, @default_auth_limit)}
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_ ->
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ip = conn.remote_ip |> :inet.ntoa() |> to_string()
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{{:ip, ip}, Keyword.get(opts, :anon_limit, @default_anon_limit)}
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end
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end
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end
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