Netstrings are simpler than bencode

[paster.git] / main.go

diff --git a/main.go b/main.go
index 912408b035f2b885f3d4998750d00d27d9849737..25e93d4f45ad03d34809e6b1f153b6673b3e6124 100644 (file)
--- a/main.go
+++ b/main.go
@@ -30,9 +30,12 @@ import (
        "html/template"
        "io"
        "os"
-       "strconv"
+
+       "go.cypherpunks.ru/netstring/v2"
 )
 
+const MaxExtLen = 9
+
 var (
        //go:embed asciicast.tmpl
        ASCIICastHTMLTmplRaw string
@@ -74,7 +77,7 @@ func main() {
        maxSize := flag.Uint64("max-size", 1<<20, "Maximal upload size")
        asciicastPath := flag.String("asciicast-path", "", "Generate HTMLs for .cast asciicasts, specify \"asciinema-player-v2.6.1\"")
        flag.Usage = func() {
-               fmt.Fprintf(os.Stderr, "Usage: paster [options] URL [...]\n")
+               fmt.Fprintf(os.Stderr, "Usage: paster [options] URL [URL ...]\n")
                flag.PrintDefaults()
        }
        flag.Parse()
@@ -82,114 +85,81 @@ func main() {
                flag.Usage()
                os.Exit(1)
        }
-       var fn string
-       r := bufio.NewReader(os.Stdin)
-       b, err := r.ReadByte()
+       r := netstring.NewReader(os.Stdin)
+       size, err := r.Next()
        if err != nil {
                fatal(err.Error())
        }
-       if b != 'd' {
-               fatal("bad bencode: no dictionary start")
+       if size > MaxExtLen {
+               fatal("too long extension length")
        }
-       buf := make([]byte, 21)
-       ext := ".txt"
-       var size uint64
-AnotherKey:
-       if _, err = io.ReadFull(r, buf[:3]); err != nil {
+       data, err := io.ReadAll(r)
+       if err != nil {
                fatal(err.Error())
        }
-       switch s := string(buf[:3]); s {
-       case "1:e":
-               if _, err = io.ReadFull(r, buf[:2]); err != nil {
-                       fatal(err.Error())
-               }
-               if buf[1] != ':' {
-                       fatal(`bad bencode: invalid "e" format`)
-               }
-               extLen, err := strconv.Atoi(string(buf[:1]))
-               if err != nil {
-                       fatal(err.Error())
-               }
-               if _, err = io.ReadFull(r, buf[:extLen]); err != nil {
-                       fatal(err.Error())
-               }
-               ext = "." + string(buf[:extLen])
-               goto AnotherKey
-       case "1:v":
-               n, err := r.Read(buf)
-               if err != nil {
-                       fatal(err.Error())
-               }
-               i := bytes.IndexByte(buf[:n], ':')
-               if i == -1 {
-                       fatal(`bad bencode: invalid "v" length`)
-               }
-               size, err = strconv.ParseUint(string(buf[:i]), 10, 64)
-               if err != nil {
-                       fatal(err.Error())
-               }
-               if size == 0 {
-                       fatal("empty paste")
-               }
-               if size > *maxSize {
-                       fatal("too big")
-               }
-               buf = buf[i+1 : n]
-       default:
-               fatal("bad bencode: invalid key")
+       var ext string
+       if len(data) == 0 {
+               ext = ".txt"
+       } else {
+               ext = "." + string(data)
+       }
+       size, err = r.Next()
+       if err != nil {
+               fatal(err.Error())
+       }
+       if size == 0 {
+               fatal("empty paste")
+       }
+       if size > *maxSize {
+               fatal("too big")
        }
        rnd := make([]byte, 12)
        if _, err = io.ReadFull(rand.Reader, rnd); err != nil {
                fatal(err.Error())
        }
-       fn = "." + base32.StdEncoding.WithPadding(base32.NoPadding).EncodeToString(rnd) + ext
+       fn := "." + base32.StdEncoding.WithPadding(base32.NoPadding).EncodeToString(rnd) + ext
        fd, err := os.OpenFile(fn, os.O_RDWR|os.O_CREATE|os.O_EXCL, os.FileMode(0666))
        if err != nil {
                fatal(err.Error())
        }
        h := sha512.New()
        bfd := bufio.NewWriter(fd)
-       mr := io.MultiReader(bytes.NewReader(buf), r)
        mw := io.MultiWriter(bfd, h)
-       if _, err = io.CopyN(mw, mr, int64(size-1)); err != nil {
+       buf := make([]byte, 1)
+       _, err = io.CopyN(mw, r, int64(size-1))
+       if err != nil {
                goto Failed
        }
-       if len(buf) == 0 {
-               buf = append(buf, 0)
-       } else {
-               buf = buf[:1]
-       }
-       if _, err = mr.Read(buf); err != nil {
+       _, err = r.Read(buf)
+       if err != nil {
                goto Failed
        }
-       if _, err = mw.Write(buf); err != nil {
+       _, err = mw.Write(buf)
+       if err != nil {
                goto Failed
        }
        if (ext == ".txt" || ext == ".url") && buf[0] != '\n' {
-               if err = bfd.WriteByte('\n'); err != nil {
+               err = bfd.WriteByte('\n')
+               if err != nil {
                        goto Failed
                }
        }
-       if _, err = mr.Read(buf); err != nil {
-               goto Failed
-       }
-       if buf[0] != 'e' {
-               os.Remove(fn)
-               fatal("bad bencode: no dictionary end")
-       }
-       if err = bfd.Flush(); err != nil {
+       err = bfd.Flush()
+       if err != nil {
                goto Failed
        }
-       if err = fd.Close(); err != nil {
+       err = fd.Close()
+       if err != nil {
                goto Failed
        }
-       if err = os.Rename(fn, fn[1:]); err != nil {
+       err = os.Rename(fn, fn[1:])
+       if err != nil {
                goto Failed
        }
        for _, u := range flag.Args() {
                fmt.Println(u + fn[1:])
        }
-       fmt.Println("SHA512/2:", hex.EncodeToString(h.Sum(nil)[:512/2/8]))
+       fmt.Println("SHA512/2:", hex.EncodeToString(h.Sum(nil)[:sha512.Size/2]))
        if ext == ".cast" && *asciicastPath != "" {
                if err = asciicastHTML(*asciicastPath, fn[1:]); err != nil {
                        goto Failed