initial FriendsResponse packet and tests; though the packet works, it displays odd behavior when decoded by client; might be intentional

common/src/main/scala/net/psforever/packet/GamePacketOpcode.scala

@@ -455,7 +455,7 @@ object GamePacketOpcode extends Enumeration {
     case 0x70 => noDecoder(SquadMemberEvent)
     case 0x71 => noDecoder(PlatoonEvent)
     case 0x72 => noDecoder(FriendsRequest)
-    case 0x73 => noDecoder(FriendsResponse)
+    case 0x73 => game.FriendsReponse.decode
     case 0x74 => noDecoder(TriggerEnvironmentalDamageMessage)
     case 0x75 => noDecoder(TrainingZoneMessage)
     case 0x76 => noDecoder(DeployableObjectsInfoMessage)

common/src/main/scala/net/psforever/packet/PSPacket.scala

@@ -203,4 +203,17 @@ object PacketHelpers {
 
   def encodedStringWithLimit(limit : Int) : Codec[String] = variableSizeBytes(encodedStringSizeWithLimit(limit), ascii)
   */
+
+  /**
+    * Construct a `Codec` for reading `wchar_t` (wide character) `Strings` whose length field are constrained to specific bit size proportions.
+    * Padding may also exist between the length field and the beginning of the contents.
+    * @param lenSize a codec that defines the bit size that encodes the length
+    * @param adjustment the optional alignment for padding; defaults to 0
+    * @return the `String` `Codec`
+    */
+  def specSizeWideStringAligned(lenSize : Codec[Int], adjustment : Int = 0) : Codec[String] =
+    variableSizeBytes((lenSize <~ ignore(adjustment)).xmap(
+      insize => insize*2, // number of symbols -> number of bytes (decode)
+      outSize => outSize/2 // number of bytes -> number of symbols (encode)
+    ), utf16)
 }

common/src/main/scala/net/psforever/packet/game/FriendsResponse.scala

@@ -0,0 +1,29 @@
+// Copyright (c) 2016 PSForever.net to present
+package net.psforever.packet.game
+
+import net.psforever.packet.{GamePacketOpcode, Marshallable, PacketHelpers, PlanetSideGamePacket}
+import scodec.Codec
+import scodec.codecs._
+
+/**
+  * na
+  * @param player_guid the player
+  * @param friend the name of the friend
+  * @param unk na
+  */
+final case class FriendsResponse(player_guid : PlanetSideGUID,
+                                 friend : String,
+                                 unk : Int)
+  extends PlanetSideGamePacket {
+  type Packet = FriendsResponse
+  def opcode = GamePacketOpcode.FriendsResponse
+  def encode = FriendsReponse.encode(this)
+}
+
+object FriendsReponse extends Marshallable[FriendsResponse] {
+  implicit val codec : Codec[FriendsResponse] = (
+    ("player_guid" | PlanetSideGUID.codec) ::
+      ("friend" | PacketHelpers.specSizeWideStringAligned(uint(5), 3)) ::
+      ("unk" | uint8L)
+    ).as[FriendsResponse]
+}

common/src/test/scala/GamePacketTest.scala

@@ -830,6 +830,29 @@ class GamePacketTest extends Specification {
       }
     }
 
+    "FriendsResponse" should {
+      val string = hex"73 618C 60 4B007500720074004800650063007400690063002D004700 00"
+
+      "decode" in {
+        PacketCoding.DecodePacket(string).require match {
+          case FriendsResponse(player_guid, friend, unk) =>
+            player_guid mustEqual PlanetSideGUID(35937)
+            friend.length mustEqual 12
+            friend mustEqual "KurtHectic-G"
+            unk mustEqual 0
+          case default =>
+            ko
+        }
+      }
+
+      "encode" in {
+        val msg = FriendsResponse(PlanetSideGUID(35937), "KurtHectic-G", 0)
+        val pkt = PacketCoding.EncodePacket(msg).require.toByteVector
+
+        pkt mustEqual string
+      }
+    }
+
     "WeaponDryFireMessage" should {
       val string = hex"52 4C00"