oss-fuzz/projects/golang/multipart_fuzzer.go

125 lines
2.5 KiB
Go

// Copyright 2015 go-fuzz project authors. All rights reserved.
// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
package multipart
import (
"bytes"
"fmt"
"io"
"io/ioutil"
"mime/multipart"
"net/textproto"
"runtime"
"github.com/dvyukov/go-fuzz-corpus/fuzz"
)
type Part struct {
hdr textproto.MIMEHeader
data []byte
}
func Fuzz(data []byte) int {
defer func() {
if r := recover(); r != nil {
}
runtime.GC()
}()
const boundary = "dfhjksd23f43242f43fv4b4g2g2g23vf2"
{
r := multipart.NewReader(bytes.NewReader(data), boundary)
f, err := r.ReadForm(1 << 20)
if err == nil {
f.RemoveAll()
}
}
fmt.Println("Creating multipart reader")
r := multipart.NewReader(bytes.NewReader(data), boundary)
fmt.Println("Reading")
var parts []Part
for {
p, err := r.NextPart()
if err == io.EOF {
break
}
if err != nil {
return 0
}
p.FileName()
p.FormName()
pdata, err := ioutil.ReadAll(p)
if err != nil {
return 0
}
p.Close()
// The parser is loose here.
// If data contains \n followed by boundary (but without \r),
// it parses it as part body. However, when it serializes it back,
// it writes \r\n followed by boundary, which becomes new part separator.
if bytes.Contains(pdata, []byte(boundary)) {
continue
}
parts = append(parts, Part{p.Header, pdata})
}
if len(parts) == 0 {
return 0
}
fmt.Println("Creating new writer")
buf := new(bytes.Buffer)
w := multipart.NewWriter(buf)
w.SetBoundary(boundary)
fmt.Println("Writing data")
for _, p := range parts {
pw, err := w.CreatePart(p.hdr)
if err != nil {
panic(err)
}
n, err := pw.Write(p.data)
if err != nil {
panic(err)
}
if n != len(p.data) {
panic("partial write")
}
}
w.Close()
fmt.Println("Time to compare")
data1 := buf.Bytes()
r1 := multipart.NewReader(buf, boundary)
var parts1 []Part
for {
p, err := r1.NextPart()
if err == io.EOF {
break
}
if err != nil {
fmt.Printf("parts0: %+v\n", parts)
fmt.Printf("data0: %q\n", data)
fmt.Printf("data1: %q\n", data1)
panic(err)
}
p.FileName()
p.FormName()
pdata, err := ioutil.ReadAll(p)
if err != nil {
panic(err)
}
p.Close()
parts1 = append(parts1, Part{p.Header, pdata})
}
fmt.Println("Performing deep equal")
if !fuzz.DeepEqual(parts, parts1) {
fmt.Printf("parts0: %+v\n", parts)
fmt.Printf("parts1: %+v\n", parts1)
fmt.Printf("data0: %q\n", data)
fmt.Printf("data1: %q\n", data1)
panic("data has changed")
}
return 1
}