182 lines
6.8 KiB
Elixir
182 lines
6.8 KiB
Elixir
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defmodule <%= inspect schema.module %>Token do
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use Ecto.Schema
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import Ecto.Query
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alias <%= inspect schema.module %>Token
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@hash_algorithm :sha256
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@rand_size 32
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# It is very important to keep the reset password token expiry short,
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# since someone with access to the email may take over the account.
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@reset_password_validity_in_days 1
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@confirm_validity_in_days 7
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@change_email_validity_in_days 7
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@session_validity_in_days 60
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<%= if schema.binary_id do %>
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@primary_key {:id, :binary_id, autogenerate: true}
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@foreign_key_type :binary_id<% end %>
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schema "<%= schema.table %>_tokens" do
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field :token, :binary
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field :context, :string
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field :sent_to, :string
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belongs_to :<%= schema.singular %>, <%= inspect schema.module %>
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timestamps(updated_at: false)
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end
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@doc """
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Generates a token that will be stored in a signed place,
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such as session or cookie. As they are signed, those
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tokens do not need to be hashed.
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The reason why we store session tokens in the database, even
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though Phoenix already provides a session cookie, is because
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Phoenix' default session cookies are not persisted, they are
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simply signed and potentially encrypted. This means they are
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valid indefinitely, unless you change the signing/encryption
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salt.
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Therefore, storing them allows individual <%= schema.singular %>
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sessions to be expired. The token system can also be extended
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to store additional data, such as the device used for logging in.
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You could then use this information to display all valid sessions
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and devices in the UI and allow users to explicitly expire any
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session they deem invalid.
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"""
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def build_session_token(<%= schema.singular %>) do
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token = :crypto.strong_rand_bytes(@rand_size)
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{token, %<%= inspect schema.alias %>Token{token: token, context: "session", <%= schema.singular %>_id: <%= schema.singular %>.id}}
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end
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@doc """
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Checks if the token is valid and returns its underlying lookup query.
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The query returns the <%= schema.singular %> found by the token, if any.
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The token is valid if it matches the value in the database and it has
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not expired (after @session_validity_in_days).
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"""
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def verify_session_token_query(token) do
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query =
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from token in token_and_context_query(token, "session"),
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join: <%= schema.singular %> in assoc(token, :<%= schema.singular %>),
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where: token.inserted_at > ago(@session_validity_in_days, "day"),
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select: <%= schema.singular %>
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{:ok, query}
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end
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@doc """
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Builds a token and its hash to be delivered to the <%= schema.singular %>'s email.
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The non-hashed token is sent to the <%= schema.singular %> email while the
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hashed part is stored in the database. The original token cannot be reconstructed,
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which means anyone with read-only access to the database cannot directly use
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the token in the application to gain access. Furthermore, if the user changes
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their email in the system, the tokens sent to the previous email are no longer
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valid.
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Users can easily adapt the existing code to provide other types of delivery methods,
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for example, by phone numbers.
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"""
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def build_email_token(<%= schema.singular %>, context) do
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build_hashed_token(<%= schema.singular %>, context, <%= schema.singular %>.email)
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end
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defp build_hashed_token(<%= schema.singular %>, context, sent_to) do
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token = :crypto.strong_rand_bytes(@rand_size)
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hashed_token = :crypto.hash(@hash_algorithm, token)
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{Base.url_encode64(token, padding: false),
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%<%= inspect schema.alias %>Token{
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token: hashed_token,
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context: context,
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sent_to: sent_to,
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<%= schema.singular %>_id: <%= schema.singular %>.id
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}}
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end
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@doc """
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Checks if the token is valid and returns its underlying lookup query.
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The query returns the <%= schema.singular %> found by the token, if any.
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The given token is valid if it matches its hashed counterpart in the
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database and the user email has not changed. This function also checks
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if the token is being used within a certain period, depending on the
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context. The default contexts supported by this function are either
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"confirm", for account confirmation emails, and "reset_password",
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for resetting the password. For verifying requests to change the email,
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see `verify_change_email_token_query/2`.
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"""
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def verify_email_token_query(token, context) do
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case Base.url_decode64(token, padding: false) do
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{:ok, decoded_token} ->
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hashed_token = :crypto.hash(@hash_algorithm, decoded_token)
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days = days_for_context(context)
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query =
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from token in token_and_context_query(hashed_token, context),
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join: <%= schema.singular %> in assoc(token, :<%= schema.singular %>),
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where: token.inserted_at > ago(^days, "day") and token.sent_to == <%= schema.singular %>.email,
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select: <%= schema.singular %>
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{:ok, query}
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:error ->
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:error
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end
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end
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defp days_for_context("confirm"), do: @confirm_validity_in_days
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defp days_for_context("reset_password"), do: @reset_password_validity_in_days
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@doc """
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Checks if the token is valid and returns its underlying lookup query.
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The query returns the <%= schema.singular %> found by the token, if any.
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This is used to validate requests to change the <%= schema.singular %>
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email. It is different from `verify_email_token_query/2` precisely because
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`verify_email_token_query/2` validates the email has not changed, which is
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the starting point by this function.
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The given token is valid if it matches its hashed counterpart in the
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database and if it has not expired (after @change_email_validity_in_days).
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The context must always start with "change:".
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"""
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def verify_change_email_token_query(token, "change:" <> _ = context) do
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case Base.url_decode64(token, padding: false) do
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{:ok, decoded_token} ->
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hashed_token = :crypto.hash(@hash_algorithm, decoded_token)
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query =
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from token in token_and_context_query(hashed_token, context),
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where: token.inserted_at > ago(@change_email_validity_in_days, "day")
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{:ok, query}
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:error ->
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:error
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end
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end
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@doc """
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Returns the token struct for the given token value and context.
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"""
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def token_and_context_query(token, context) do
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from <%= inspect schema.alias %>Token, where: [token: ^token, context: ^context]
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end
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@doc """
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Gets all tokens for the given <%= schema.singular %> for the given contexts.
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"""
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def <%= schema.singular %>_and_contexts_query(<%= schema.singular %>, :all) do
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from t in <%= inspect schema.alias %>Token, where: t.<%= schema.singular %>_id == ^<%= schema.singular %>.id
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end
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def <%= schema.singular %>_and_contexts_query(<%= schema.singular %>, [_ | _] = contexts) do
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from t in <%= inspect schema.alias %>Token, where: t.<%= schema.singular %>_id == ^<%= schema.singular %>.id and t.context in ^contexts
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end
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end
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