katbin/lib/ketbin/accounts/user_token.ex

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Elixir
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defmodule Ketbin.Accounts.UserToken do
use Ecto.Schema
import Ecto.Query
@hash_algorithm :sha256
@rand_size 32
# It is very important to keep the reset password token expiry short,
# since someone with access to the email may take over the account.
@reset_password_validity_in_days 1
@confirm_validity_in_days 7
@change_email_validity_in_days 7
@session_validity_in_days 60
schema "users_tokens" do
field :token, :binary
field :context, :string
field :sent_to, :string
belongs_to :user, Ketbin.Accounts.User
timestamps(updated_at: false)
end
@doc """
Generates a token that will be stored in a signed place,
such as session or cookie. As they are signed, those
tokens do not need to be hashed.
"""
def build_session_token(user) do
token = :crypto.strong_rand_bytes(@rand_size)
{token, %Ketbin.Accounts.UserToken{token: token, context: "session", user_id: user.id}}
end
@doc """
Checks if the token is valid and returns its underlying lookup query.
The query returns the user found by the token.
"""
def verify_session_token_query(token) do
query =
from token in token_and_context_query(token, "session"),
join: user in assoc(token, :user),
where: token.inserted_at > ago(@session_validity_in_days, "day"),
select: user
{:ok, query}
end
@doc """
Builds a token with a hashed counter part.
The non-hashed token is sent to the user email while the
hashed part is stored in the database, to avoid reconstruction.
The token is valid for a week as long as users don't change
their email.
"""
def build_email_token(user, context) do
build_hashed_token(user, context, user.email)
end
defp build_hashed_token(user, context, sent_to) do
token = :crypto.strong_rand_bytes(@rand_size)
hashed_token = :crypto.hash(@hash_algorithm, token)
{Base.url_encode64(token, padding: false),
%Ketbin.Accounts.UserToken{
token: hashed_token,
context: context,
sent_to: sent_to,
user_id: user.id
}}
end
@doc """
Checks if the token is valid and returns its underlying lookup query.
The query returns the user found by the token.
"""
def verify_email_token_query(token, context) do
case Base.url_decode64(token, padding: false) do
{:ok, decoded_token} ->
hashed_token = :crypto.hash(@hash_algorithm, decoded_token)
days = days_for_context(context)
query =
from token in token_and_context_query(hashed_token, context),
join: user in assoc(token, :user),
where: token.inserted_at > ago(^days, "day") and token.sent_to == user.email,
select: user
{:ok, query}
:error ->
:error
end
end
defp days_for_context("confirm"), do: @confirm_validity_in_days
defp days_for_context("reset_password"), do: @reset_password_validity_in_days
@doc """
Checks if the token is valid and returns its underlying lookup query.
The query returns the user token record.
"""
def verify_change_email_token_query(token, context) do
case Base.url_decode64(token, padding: false) do
{:ok, decoded_token} ->
hashed_token = :crypto.hash(@hash_algorithm, decoded_token)
query =
from token in token_and_context_query(hashed_token, context),
where: token.inserted_at > ago(@change_email_validity_in_days, "day")
{:ok, query}
:error ->
:error
end
end
@doc """
Returns the given token with the given context.
"""
def token_and_context_query(token, context) do
from Ketbin.Accounts.UserToken, where: [token: ^token, context: ^context]
end
@doc """
Gets all tokens for the given user for the given contexts.
"""
def user_and_contexts_query(user, :all) do
from t in Ketbin.Accounts.UserToken, where: t.user_id == ^user.id
end
def user_and_contexts_query(user, [_ | _] = contexts) do
from t in Ketbin.Accounts.UserToken, where: t.user_id == ^user.id and t.context in ^contexts
end
end