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lib/plug/conn/cookies.ex

defmodule Plug.Conn.Cookies do
@moduledoc """
Conveniences for encoding and decoding cookies.
"""
@doc """
Decodes the given cookies as given in either a request or response header.
If a cookie is invalid, it is automatically discarded from the result.
## Examples
iex> decode("key1=value1;key2=value2")
%{"key1" => "value1", "key2" => "value2"}
"""
def decode(cookie) when is_binary(cookie) do
Map.new(decode_kv(cookie, []))
end
defp decode_kv("", acc), do: acc
defp decode_kv(<<h, t::binary>>, acc) when h in [?\s, ?\t], do: decode_kv(t, acc)
defp decode_kv(kv, acc) when is_binary(kv), do: decode_key(kv, "", acc)
defp decode_key(<<h, t::binary>>, _key, acc) when h in [?\s, ?\t, ?\r, ?\n, ?\v, ?\f],
do: skip_until_cc(t, acc)
defp decode_key(<<?;, t::binary>>, _key, acc), do: decode_kv(t, acc)
defp decode_key(<<?=, t::binary>>, "", acc), do: skip_until_cc(t, acc)
defp decode_key(<<?=, t::binary>>, key, acc), do: decode_value(t, "", 0, key, acc)
defp decode_key(<<h, t::binary>>, key, acc), do: decode_key(t, <<key::binary, h>>, acc)
defp decode_key(<<>>, _key, acc), do: acc
defp decode_value(<<?;, t::binary>>, value, spaces, key, acc),
do: decode_kv(t, [{key, trim_spaces(value, spaces)} | acc])
defp decode_value(<<?\s, t::binary>>, value, spaces, key, acc),
do: decode_value(t, <<value::binary, ?\s>>, spaces + 1, key, acc)
defp decode_value(<<h, t::binary>>, _value, _spaces, _key, acc)
when h in [?\t, ?\r, ?\n, ?\v, ?\f],
do: skip_until_cc(t, acc)
defp decode_value(<<h, t::binary>>, value, _spaces, key, acc),
do: decode_value(t, <<value::binary, h>>, 0, key, acc)
defp decode_value(<<>>, value, spaces, key, acc),
do: [{key, trim_spaces(value, spaces)} | acc]
defp skip_until_cc(<<?;, t::binary>>, acc), do: decode_kv(t, acc)
defp skip_until_cc(<<_, t::binary>>, acc), do: skip_until_cc(t, acc)
defp skip_until_cc(<<>>, acc), do: acc
defp trim_spaces(value, 0), do: value
defp trim_spaces(value, spaces), do: binary_part(value, 0, byte_size(value) - spaces)
@doc """
Encodes the given cookies as expected in a response header.
## Examples
iex> encode("key1", %{value: "value1"})
"key1=value1; path=/; HttpOnly"
iex> encode("key1", %{value: "value1", secure: true, path: "/example", http_only: false})
"key1=value1; path=/example; secure"
"""
def encode(key, opts \\ %{}) when is_map(opts) do
value = Map.get(opts, :value)
path = Map.get(opts, :path, "/")
IO.iodata_to_binary([
"#{key}=#{value}; path=#{path}",
emit_if(opts[:domain], &["; domain=", &1]),
emit_if(opts[:max_age], &encode_max_age(&1, opts)),
emit_if(Map.get(opts, :secure, false), "; secure"),
emit_if(Map.get(opts, :http_only, true), "; HttpOnly"),
emit_if(Map.get(opts, :same_site, nil), &encode_same_site/1),
emit_if(opts[:extra], &["; ", &1])
])
end
defp encode_max_age(max_age, opts) do
time = Map.get(opts, :universal_time) || :calendar.universal_time()
time = add_seconds(time, max_age)
["; expires=", rfc2822(time), "; max-age=", Integer.to_string(max_age)]
end
defp encode_same_site(value) when is_binary(value), do: "; SameSite=#{value}"
defp emit_if(value, fun_or_string) do
cond do
!value ->
[]
is_function(fun_or_string) ->
fun_or_string.(value)
is_binary(fun_or_string) ->
fun_or_string
end
end
defp pad(number) when number in 0..9, do: <<?0, ?0 + number>>
defp pad(number), do: Integer.to_string(number)
defp rfc2822({{year, month, day} = date, {hour, minute, second}}) do
# Sat, 17 Apr 2010 14:00:00 GMT
[
weekday_name(:calendar.day_of_the_week(date)),
?,,
?\s,
pad(day),
?\s,
month_name(month),
?\s,
Integer.to_string(year),
?\s,
pad(hour),
?:,
pad(minute),
?:,
pad(second),
" GMT"
]
end
defp weekday_name(1), do: "Mon"
defp weekday_name(2), do: "Tue"
defp weekday_name(3), do: "Wed"
defp weekday_name(4), do: "Thu"
defp weekday_name(5), do: "Fri"
defp weekday_name(6), do: "Sat"
defp weekday_name(7), do: "Sun"
defp month_name(1), do: "Jan"
defp month_name(2), do: "Feb"
defp month_name(3), do: "Mar"
defp month_name(4), do: "Apr"
defp month_name(5), do: "May"
defp month_name(6), do: "Jun"
defp month_name(7), do: "Jul"
defp month_name(8), do: "Aug"
defp month_name(9), do: "Sep"
defp month_name(10), do: "Oct"
defp month_name(11), do: "Nov"
defp month_name(12), do: "Dec"
defp add_seconds(time, seconds_to_add) do
time_seconds = :calendar.datetime_to_gregorian_seconds(time)
:calendar.gregorian_seconds_to_datetime(time_seconds + seconds_to_add)
end
end