feedget/cache.go

65 lines
1.5 KiB
Go

package main
import (
"errors"
"io"
)
type HTTPCache struct {
}
// MaxBytesReader is similar to io.LimitReader but is intended for
// limiting the size of incoming request bodies. In contrast to
// io.LimitReader, MaxBytesReader's result is a ReadCloser, returns a
// non-EOF error for a Read beyond the limit, and closes the
// underlying reader when its Close method is called.
//
// MaxBytesReader prevents clients from accidentally or maliciously
// sending a large request and wasting server resources.
//
// Based on http.MaxBytesReader
func MaxBytesReader(r io.ReadCloser, n int64) io.ReadCloser {
if n < 0 { // Treat negative limits as equivalent to 0.
n = 0
}
return &maxBytesReader{r: r, n: n}
}
type maxBytesReader struct {
r io.ReadCloser // underlying reader
n int64 // max bytes remaining
err error // sticky error
}
func (l *maxBytesReader) Read(p []byte) (n int, err error) {
if l.err != nil {
return 0, l.err
}
if len(p) == 0 {
return 0, nil
}
// If they asked for a 32KB byte read but only 5 bytes are
// remaining, no need to read 32KB. 6 bytes will answer the
// question of the whether we hit the limit or go past it.
if int64(len(p)) > l.n+1 {
p = p[:l.n+1]
}
n, err = l.r.Read(p)
if int64(n) <= l.n {
l.n -= int64(n)
l.err = err
return n, err
}
n = int(l.n)
l.n = 0
l.err = errors.New("http: response body too large")
return n, l.err
}
func (l *maxBytesReader) Close() error {
return l.r.Close()
}