write.clj
Branches > main > 67c943e > files / src / net / bowmap / network / packet / write.clj
(ns net.bowmap.network.packet.write
"Functions to write Minecraft protocol types.
When given bad data, write functions will throw.
See https://minecraft.wiki/w/Java_Edition_protocol/Packets#Data_types"
(:require
[clojure.alpha.spec :as s]
[clojure.data.json :as json]
[clojure.set :as set]
[dev.grahp.error :refer [adorn raise]]
[dev.grahp.spec :as S]
[net.bowmap.network.message :as msg]
[net.bowmap.network.packet.types :as t])
(:import
[io.netty.buffer ByteBuf CompositeByteBuf Unpooled]
[java.nio.charset Charset]
[java.util UUID]))
(S/def ::writer (s/fspec :args (s/cat :buf #(instance? ByteBuf %) :msg ::msg/message)
:ret #(instance? ByteBuf %)))
(defn varint-> [buf n]
(loop [buf buf
n n]
(let [b (bit-and n 0x7F)
nxt (unsigned-bit-shift-right n 7)]
(if (zero? nxt)
(ByteBuf/.writeByte buf b)
(recur (ByteBuf/.writeByte buf (bit-or b 0x80))
nxt)))))
(defn length-prefixed
"Returns a new ByteBuf prefixed by an encoded varint of the length of 'buf'."
[buf]
(-> (Unpooled/compositeBuffer 2)
(CompositeByteBuf/.addComponent true (varint-> (Unpooled/buffer t/max-varint-size) (ByteBuf/.writerIndex buf)))
(CompositeByteBuf/.addComponent true buf)))
(defn string-> [buf s]
(doto buf
(varint-> (count s))
(ByteBuf/.writeCharSequence s (Charset/forName "UTF-8"))))
(defn json-> [buf s]
(string-> buf (json/write-str s)))
(defn array-> [writer]
(fn [buf xs]
(reduce (fn [acc x]
(writer acc x))
buf xs)))
(defn list-> [writer]
(let [writer (array-> writer)]
(fn [buf xs]
(-> (varint-> buf (count xs))
(writer xs)))))
(defn uuid-> [buf uuid]
(-> buf
(ByteBuf/.writeLong (UUID/.getMostSignificantBits uuid))
(ByteBuf/.writeLong (UUID/.getLeastSignificantBits uuid))))
; TODO This is where you could check for optionality I think. If the fields aren't [:optional ...]
; TODO Inline
(defn ^:private write-table! [buf table m]
(reduce (fn [acc {::t/keys [field codec]}]
(adorn (codec acc (get m field))
"Error while writing message table field" {:field field :writer codec :value (get m field)}))
buf table))
(defn boolean-> [buf x]
(if x
(ByteBuf/.writeByte buf 1)
(ByteBuf/.writeByte buf 0)))
(defn context-optional-> [writer]
(fn [buf x]
(if x
(writer buf x)
buf)))
;;; NBT
(defn write-modified-utf8! [buf s]
(reduce (fn [acc code]
(cond (zero? code) (-> buf
(ByteBuf/.writeByte 0xC0)
(ByteBuf/.writeByte 0x80))
(<= 1 code 0x7F) (ByteBuf/.writeByte acc code)
(<= 0x80 code 0x7FF) (-> acc
(ByteBuf/.writeByte (bit-or 0xC0 (bit-shift-right code 6)))
(ByteBuf/.writeByte (bit-or 0x80 (bit-and code 0x3F))))
:else (-> acc
(ByteBuf/.writeByte (bit-or 0xE0 (bit-shift-right code 12)))
(ByteBuf/.writeByte (bit-or 0x80 (bit-and (bit-shift-right code 6) 0x3F)))
(ByteBuf/.writeByte (bit-or 0x80 (bit-and code 0x3F))))))
buf
(map int (String/.toCharArray s))))
(defn write-nbt-string! [buf s]
(let [s (name s)]
(-> buf
(ByteBuf/.writeShort (count s))
(write-modified-utf8! s))))
;; TODO probably get rid of these keywords and just have 2 conds?
(defn nbt-type [x]
(cond (string? x) :string
(ident? x) :string
(boolean? x) :boolean
;; Right now all numbers are encoded as longs since the client allows it, but that's obviously quite wasteful
(int? x) :long
(float? x) (if (= (float x) x)
:float
:double)
(map? x) :compound
;; I believe you can also typed arrays for efficiency as well? I think they might store differently on the client.
(seqable? x) :list
:else (raise "Failed to encode NBT value!" {:val x})))
(declare nbt-ids nbt-writers)
(defn write-nbt-list! [buf xs]
;; Lists are homogenous, so it just looks at the first element and tries to encode all elements with that type
;; Should probably check that all the elements actually have the same nbt type lol
(let [t (nbt-type (first xs))
id (nbt-ids t)
writer (array-> (nbt-writers t))]
(-> buf
(ByteBuf/.writeByte id)
(ByteBuf/.writeInt (count xs))
(writer xs))))
(defn write-nbt-compound! [buf m]
(-> (reduce (fn [acc [k v]]
(let [t (nbt-type v)]
(-> acc
(ByteBuf/.writeByte (nbt-ids t))
(write-nbt-string! (name k))
((nbt-writers t) v))))
buf m)
(ByteBuf/.writeByte 0x00)))
(defn nbt-writer
"Returns the NBT writer function for value 'x'.
Throws if 'x' cannot be encoded into NBT."
[x]
(nbt-writers (nbt-type x)))
(defn nbt->
"Writes NBT value 'x' into buf, throws if the value cannot be encoded (this will muck the buffer so don't try to recover)"
[buf x]
(-> buf
(ByteBuf/.writeByte 0x0a)
((nbt-writer x) x)))
(def nbt-writers {:byte ByteBuf/.writeByte
:boolean boolean->
:short ByteBuf/.writeShort
:int ByteBuf/.writeInt
:long ByteBuf/.writeLong
:float ByteBuf/.writeFloat
:double ByteBuf/.writeDouble
:string write-nbt-string!
:list write-nbt-list!
:compound write-nbt-compound!})
(def nbt-ids {:byte 1
:boolean 1 ; Booleans are just bytes 0/1
:short 2
:int 3
:long 4
:float 5
:double 6
:string 8
:list 9
:compound 10})
;; End NBT lol
(def byte-> ByteBuf/.writeByte)
(def ubyte-> ByteBuf/.writeByte)
(def short-> ByteBuf/.writeShort)
(def ushort-> ByteBuf/.writeShort)
(def int-> ByteBuf/.writeInt)
(def long-> ByteBuf/.writeLong)
(def float-> ByteBuf/.writeFloat)
(def double-> ByteBuf/.writeDouble)
(def identifier-> string->)
(defn position-> [pos]
(raise "YOU NEVER ACTUALLY IMPLEMENTED THE POSITION TYPE REMEMBER?"))
; TODO is this right?
(defn or-> [writer default]
(fn [buf x]
(let [x (if (nil? x) default x)]
(writer buf x))))
;; TODO what actually happens when the value is nil?
(defn enum->
"Writes an enum with writer 't', and a map 'm', which maps encoded values to values, so it is 'backwards'.
For instance, the map {1 :foo} will write :foo as 1."
[writer m]
(let [m (set/map-invert m)]
(fn [buf x]
(writer buf (m x)))))
(defn optional-> [writer]
(let [writer (context-optional-> writer)]
(fn [buf x]
(boolean-> buf x)
(writer buf x))))
; Want to conform the given map to the table, and error if any non-optional keys are missing?
(defn table-> [t]
(let [table (S/ensure-conform ::t/table t)]
(fn [buf m]
(write-table! buf table m))))