From e8c0df004ebbcc8131521df240ff5886280af053 Mon Sep 17 00:00:00 2001
From: Bram <bram@noordstar.me>
Date: Thu, 30 May 2024 10:48:20 +0200
Subject: [PATCH] Add removePasswordOnLogin setting

---
 src/Internal/Config/Default.elm  | 16 +++++++
 src/Internal/Config/Text.elm     |  4 ++
 src/Internal/Values/Settings.elm | 19 +++++++-
 src/Matrix/Settings.elm          | 75 +++++++++++++++++++++++++-------
 4 files changed, 98 insertions(+), 16 deletions(-)

diff --git a/src/Internal/Config/Default.elm b/src/Internal/Config/Default.elm
index 737bb96..53a5db2 100644
--- a/src/Internal/Config/Default.elm
+++ b/src/Internal/Config/Default.elm
@@ -1,6 +1,7 @@
 module Internal.Config.Default exposing
     ( currentVersion, deviceName
     , syncTime
+    , removePasswordOnLogin
     )
 
 {-| This module hosts all default settings and configurations that the Vault
@@ -16,6 +17,11 @@ will assume until overriden by the user.
 
 @docs syncTime
 
+
+## Security
+
+@docs removePasswordOnLogin
+
 -}
 
 
@@ -52,3 +58,13 @@ The value is in miliseconds, so it is set at 30,000.
 syncTime : Int
 syncTime =
     30 * 1000
+
+
+{-| Once the Matrix API has logged in successfully, it does not need to remember
+the user's password. However, to keep the Vault logged in automatically, one may
+choose to remember the password in order to get a new access token when an old
+access token has expired.
+-}
+removePasswordOnLogin : Bool
+removePasswordOnLogin =
+    True
diff --git a/src/Internal/Config/Text.elm b/src/Internal/Config/Text.elm
index 256fb13..a63e936 100644
--- a/src/Internal/Config/Text.elm
+++ b/src/Internal/Config/Text.elm
@@ -321,6 +321,7 @@ fields :
     , settings :
         { currentVersion : Desc
         , deviceName : Desc
+        , removePasswordOnLogin : Desc
         , syncTime : Desc
         }
     , timeline :
@@ -501,6 +502,9 @@ fields =
         , deviceName =
             [ "Indicates the device name that is communicated to the Matrix API."
             ]
+        , removePasswordOnLogin =
+            [ "Remove the password as soon as a valid access token has been received."
+            ]
         , syncTime =
             [ "Indicates the frequency in miliseconds with which the Elm SDK should long-poll the /sync endpoint."
             ]
diff --git a/src/Internal/Values/Settings.elm b/src/Internal/Values/Settings.elm
index 4696b7a..eed039a 100644
--- a/src/Internal/Values/Settings.elm
+++ b/src/Internal/Values/Settings.elm
@@ -35,6 +35,7 @@ behave under the user's preferred settings.
 type alias Settings =
     { currentVersion : String
     , deviceName : String
+    , removePasswordOnLogin : Bool
     , syncTime : Int
     }
 
@@ -43,7 +44,7 @@ type alias Settings =
 -}
 coder : Json.Coder Settings
 coder =
-    Json.object3
+    Json.object4
         { name = Text.docs.settings.name
         , description = Text.docs.settings.description
         , init = Settings
@@ -66,6 +67,21 @@ coder =
             , defaultToString = identity
             }
         )
+        (Json.field.optional.withDefault
+            { fieldName = "removePasswordOnLogin"
+            , toField = .removePasswordOnLogin
+            , description = Text.fields.settings.removePasswordOnLogin
+            , coder = Json.bool
+            , default = Tuple.pair Default.removePasswordOnLogin []
+            , defaultToString =
+                \b ->
+                    if b then
+                        "true"
+
+                    else
+                        "false"
+            }
+        )
         (Json.field.optional.withDefault
             { fieldName = "syncTime"
             , toField = .syncTime
@@ -97,5 +113,6 @@ init : Settings
 init =
     { currentVersion = Default.currentVersion
     , deviceName = Default.deviceName
+    , removePasswordOnLogin = Default.removePasswordOnLogin
     , syncTime = Default.syncTime
     }
diff --git a/src/Matrix/Settings.elm b/src/Matrix/Settings.elm
index bd0102d..7c84e3b 100644
--- a/src/Matrix/Settings.elm
+++ b/src/Matrix/Settings.elm
@@ -2,6 +2,8 @@ module Matrix.Settings exposing
     ( setAccessToken, removeAccessToken
     , getDeviceName, setDeviceName
     , getSyncTime, setSyncTime
+    , setPassword
+    , removePassword, removePasswordOnLogin
     )
 
 {-| The Matrix Vault has lots of configurable variables that you rarely want to
@@ -50,20 +52,39 @@ The value is in miliseconds, so it is set at 30,000.
 
 @docs getSyncTime, setSyncTime
 
+
+## Password
+
+When a Vault wants to access the Matrix API, it needs an access token. This can
+either be provided directly, or the Vault can get one itself by using a password
+to log in.
+
+@docs setPassword
+
+For security reasons, it is not possible to read whatever password is stored in
+the Vault. An attacker with access to the memory might be able to find it,
+however, so the Vault offers ways to remove the password from memory.
+
+@docs removePassword, removePasswordOnLogin
+
 -}
 
 import Internal.Values.Envelope as Envelope
 import Types exposing (Vault(..))
 
 
-{-| Insert a suggested access token.
+{-| Determine the device name.
 -}
-setAccessToken : String -> Vault -> Vault
-setAccessToken token (Vault vault) =
-    vault
-        |> Envelope.mapContext
-            (\c -> { c | suggestedAccessToken = Just token })
-        |> Vault
+getDeviceName : Vault -> String
+getDeviceName (Vault vault) =
+    Envelope.extractSettings .deviceName vault
+
+
+{-| Determine the sync timeout value.
+-}
+getSyncTime : Vault -> Int
+getSyncTime (Vault vault) =
+    Envelope.extractSettings .syncTime vault
 
 
 {-| Remove an access token that has been inserted using the
@@ -80,11 +101,32 @@ removeAccessToken (Vault vault) =
         |> Vault
 
 
-{-| Determine the device name.
+{-| Remove a password that is stored in the Matrix Vault.
 -}
-getDeviceName : Vault -> String
-getDeviceName (Vault vault) =
-    Envelope.extractSettings .deviceName vault
+removePassword : Vault -> Vault
+removePassword (Vault vault) =
+    vault
+        |> Envelope.mapContext
+            (\c -> { c | password = Nothing })
+        |> Vault
+
+
+{-| Remove password from the Vault as soon as a valid access token has been
+received from the Matrix API.
+-}
+removePasswordOnLogin : Bool -> Vault -> Vault
+removePasswordOnLogin b (Vault vault) =
+    Vault <| Envelope.mapSettings (\s -> { s | removePasswordOnLogin = b }) vault
+
+
+{-| Insert a suggested access token.
+-}
+setAccessToken : String -> Vault -> Vault
+setAccessToken token (Vault vault) =
+    vault
+        |> Envelope.mapContext
+            (\c -> { c | suggestedAccessToken = Just token })
+        |> Vault
 
 
 {-| Override the device name.
@@ -94,11 +136,14 @@ setDeviceName name (Vault vault) =
     Vault <| Envelope.mapSettings (\s -> { s | deviceName = name }) vault
 
 
-{-| Determine the sync timeout value.
+{-| Set a password for the given user.
 -}
-getSyncTime : Vault -> Int
-getSyncTime (Vault vault) =
-    Envelope.extractSettings .syncTime vault
+setPassword : String -> Vault -> Vault
+setPassword password (Vault vault) =
+    vault
+        |> Envelope.mapContext
+            (\c -> { c | password = Just password })
+        |> Vault
 
 
 {-| Override the sync timeout value.