streams.clj

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Branches > main > e860102 > files / src / net / bowmap / server / network / streams.clj

(ns net.bowmap.server.network.streams
  (:require
   [net.bowmap.server.protocol.types :refer [max-varint-size]])
  (:import
   [io.netty.buffer ByteBuf Unpooled]
   [java.io
    EOFException
    IOException
    InputStream
    OutputStream]))

(defn read-byte!!
  "Blocks and reads an unsigned byte (int) from an InputStream.
   Throws if EOF is reached."
  [input-stream]
  (let [x (InputStream/.read input-stream)]
    (if (= x -1)
      (throw (EOFException. "EOF while reading from InputStream"))
      x)))

(defn read-varint!!
  "Blocks and reads a varint from an InputStream.
   Throws if EOF is reached, or if the encoded varint is invalid."
  [input-stream]
  (loop [num-read 0
         result 0]
    (if (>= num-read max-varint-size)
      (throw (IOException. "VarInt too long"))
      (let [b (read-byte!! input-stream)
            result' (bit-or result (bit-shift-left (bit-and b 0x7F) (* 7 num-read)))]
        (if (zero? (bit-and b 0x80))
          result'
          (recur (inc num-read) result'))))))

(defn read-frame!!
  "Blocks and reads a frame from an InputStream.
   Throws if EOF is reached, or if the encoded frame is invalid."
  [input-stream]
  (let [len (read-varint!! input-stream)
        arr (byte-array len)]
    (loop [offset 0]
      (when (< offset len)
        (let [r (InputStream/.read input-stream arr offset (- len offset))]
          (if (= r -1)
            (throw (EOFException. "EOF while reading frame"))
            (recur (+ offset r))))))
    (Unpooled/wrappedBuffer arr)))

(defn write-frame!!
  "Blocks and writes a frame to an OutputStream.
   Throws if the frame cannot be written."
  [frame output-stream]
  (let [len (ByteBuf/.readableBytes frame)
        arr (byte-array len)]
    (ByteBuf/.readBytes frame arr)
    (OutputStream/.write output-stream arr)
    (OutputStream/.flush output-stream)))