streams.clj
Branches > main > 0afd85a > files / src / net / bowmap / server / network / streams.clj
(ns net.bowmap.server.network.streams
"Functions for reading and writing frames to Input and OutputStreams"
(:require
[net.bowmap.server.packet.frame :as frame]
[net.bowmap.server.packet.readers :refer [max-varint-size]])
(:import
[java.io 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 (IOException. "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 (IOException. "EOF while reading frame"))
(recur (+ offset r))))))
(frame/frame arr)))
(defn write-varint!!
"Blocks and writes a varint to an OutputStream."
[output-stream n]
(loop [n n]
(let [b (bit-and n 0x7F)
nxt (unsigned-bit-shift-right n 7)]
(if (zero? nxt)
(OutputStream/.write output-stream b)
(do (OutputStream/.write output-stream (bit-or b 0x80))
(recur nxt))))))
(defn write-frame!!
"Blocks and writes a frame to an OutputStream.
Throws if the frame cannot be written."
[frame output-stream]
(let [array (frame/array frame)]
(doto output-stream
(write-varint!! (alength array))
(OutputStream/.write array)
(OutputStream/.flush))))