BIT-765: Parse user information from JWT token (#127)

app/src/main/java/com/x8bit/bitwarden/data/auth/repository/model/JwtTokenDataJson.kt

@@ -0,0 +1,34 @@
+package com.x8bit.bitwarden.data.auth.repository.model
+
+import kotlinx.serialization.SerialName
+import kotlinx.serialization.Serializable
+
+/**
+ * Contains data that can be parsed from a valid JWT token.
+ *
+ * @property userId The ID of the user.
+ * @property email The user's email address.
+ * @property isEmailVerified Whether or not the user's email is verified.
+ * @property name The user's name.
+ * @property expirationAsEpochTime The expiration time measured as an epoch time in seconds.
+ * @property hasPremium True if the user has a premium account.
+ * @property authenticationMethodsReference A list of the authentication methods used during
+ * authentication.
+ */
+@Serializable
+data class JwtTokenDataJson(
+    @SerialName("sub")
+    val userId: String,
+    @SerialName("email")
+    val email: String,
+    @SerialName("email_verified")
+    val isEmailVerified: Boolean,
+    @SerialName("name")
+    val name: String?,
+    @SerialName("exp")
+    val expirationAsEpochTime: Int,
+    @SerialName("premium")
+    val hasPremium: Boolean,
+    @SerialName("amr")
+    val authenticationMethodsReference: List<String>,
+)

app/src/main/java/com/x8bit/bitwarden/data/auth/repository/util/JwtTokenUtils.kt

@@ -0,0 +1,28 @@
+package com.x8bit.bitwarden.data.auth.repository.util
+
+import com.x8bit.bitwarden.data.auth.repository.model.JwtTokenDataJson
+import com.x8bit.bitwarden.data.platform.datasource.network.util.base64UrlDecodeOrNull
+import kotlinx.serialization.json.Json
+
+/**
+ * Internal, generally basic [Json] instance for JWT parsing purposes.
+ */
+private val json by lazy { Json { ignoreUnknownKeys = true } }
+
+/**
+ * Parses a [JwtTokenDataJson] from the given [jwtToken], or `null` if this parsing is not possible.
+ */
+@Suppress("MagicNumber", "ReturnCount")
+fun parseJwtTokenDataOrNull(jwtToken: String): JwtTokenDataJson? {
+    val parts = jwtToken.split(".")
+    if (parts.size != 3) return null
+
+    val dataJson = parts[1]
+    val decodedDataJson = dataJson.base64UrlDecodeOrNull() ?: return null
+
+    return try {
+        json.decodeFromString<JwtTokenDataJson>(decodedDataJson)
+    } catch (_: Throwable) {
+        null
+    }
+}

app/src/main/java/com/x8bit/bitwarden/data/platform/datasource/network/util/NetworkUtils.kt

@@ -1,5 +1,7 @@
 package com.x8bit.bitwarden.data.platform.datasource.network.util
 
+import okio.ByteString.Companion.decodeBase64
+import java.nio.charset.Charset
 import java.util.Base64
 
 /**
@@ -15,3 +17,18 @@ fun String.base64UrlEncode(): String =
         .replace("+", "-")
         .replace("/", "_")
         .replace("=", "")
+
+/**
+ * Base 64 decode the given string after making the following replacements:
+ *
+ * - replace all "-" with "+"
+ * - replace all "_" with "/"
+ *
+ * A value of `null` will be returned if the decoding fails.
+ */
+fun String.base64UrlDecodeOrNull(): String? =
+    this
+        .replace("-", "+")
+        .replace("_", "/")
+        .decodeBase64()
+        ?.string(Charset.defaultCharset())