103 lines
2.6 KiB
Elixir
103 lines
2.6 KiB
Elixir
defmodule ToweropsWeb.Api.V1.StripeWebhookController do
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use ToweropsWeb, :controller
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alias Towerops.Billing.WebhookProcessor
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require Logger
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@doc """
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Stripe webhook endpoint.
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Receives events like payment_intent.succeeded, customer.subscription.updated.
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Verifies signature before processing.
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"""
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def create(conn, _params) do
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signature = conn |> get_req_header("stripe-signature") |> List.first()
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raw_body = conn.private[:raw_body] || ""
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case verify_signature(raw_body, signature) do
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:ok ->
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event = Jason.decode!(raw_body)
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case WebhookProcessor.process(event) do
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:ok ->
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json(conn, %{received: true})
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{:error, reason} ->
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Logger.error("Webhook processing failed: #{inspect(reason)}")
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json(conn, %{received: true})
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end
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{:error, :invalid_signature} ->
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Logger.warning("Invalid webhook signature")
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conn
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|> put_status(401)
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|> json(%{error: "Invalid signature"})
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{:error, reason} ->
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Logger.error("Webhook verification failed: #{inspect(reason)}")
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conn
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|> put_status(400)
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|> json(%{error: "Verification failed"})
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end
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end
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defp verify_signature(payload, signature_header) do
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webhook_secret = Application.fetch_env!(:towerops, :stripe_webhook_secret)
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with {:ok, timestamp, signature} <- parse_signature_header(signature_header),
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:ok <- check_timestamp_tolerance(timestamp, 300) do
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signed_payload = "#{timestamp}.#{payload}"
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expected_signature =
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:hmac
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|> :crypto.mac(:sha256, webhook_secret, signed_payload)
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|> Base.encode16(case: :lower)
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if Plug.Crypto.secure_compare(signature, expected_signature) do
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:ok
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else
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{:error, :invalid_signature}
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end
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end
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end
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defp parse_signature_header(header) do
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parts = String.split(header, ",")
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timestamp =
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Enum.find_value(parts, fn part ->
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case String.split(part, "=") do
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["t", t] -> t
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_ -> nil
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end
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end)
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signature =
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Enum.find_value(parts, fn part ->
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case String.split(part, "=") do
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["v1", sig] -> sig
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_ -> nil
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end
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end)
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if timestamp && signature do
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{:ok, timestamp, signature}
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else
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{:error, :malformed_header}
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end
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end
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defp check_timestamp_tolerance(timestamp_str, max_age_seconds) do
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timestamp = String.to_integer(timestamp_str)
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now = System.system_time(:second)
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if abs(now - timestamp) <= max_age_seconds do
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:ok
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else
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{:error, :timestamp_too_old}
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end
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end
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end
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