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			105 lines
		
	
	
		
			2.8 KiB
		
	
	
	
		
			Go
		
	
	
	
	
	
			
		
		
	
	
			105 lines
		
	
	
		
			2.8 KiB
		
	
	
	
		
			Go
		
	
	
	
	
	
// Copyright 2015 Light Code Labs, LLC
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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//     http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package limits
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import (
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	"io"
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	"net/http"
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	"github.com/mholt/caddy/caddyhttp/httpserver"
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)
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// Limit is a middleware to control request body size
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type Limit struct {
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	Next       httpserver.Handler
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	BodyLimits []httpserver.PathLimit
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}
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func (l Limit) ServeHTTP(w http.ResponseWriter, r *http.Request) (int, error) {
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	if r.Body == nil {
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		return l.Next.ServeHTTP(w, r)
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	}
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	// apply the path-based request body size limit.
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	for _, bl := range l.BodyLimits {
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		if httpserver.Path(r.URL.Path).Matches(bl.Path) {
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			r.Body = MaxBytesReader(w, r.Body, bl.Limit)
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			break
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		}
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	}
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	return l.Next.ServeHTTP(w, r)
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}
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// MaxBytesReader and its associated methods are borrowed from the
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// Go Standard library (comments intact). The only difference is that
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// it returns a ErrMaxBytesExceeded error instead of a generic error message
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// when the request body has exceeded the requested limit
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func MaxBytesReader(w http.ResponseWriter, r io.ReadCloser, n int64) io.ReadCloser {
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	return &maxBytesReader{w: w, r: r, n: n}
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}
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type maxBytesReader struct {
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	w   http.ResponseWriter
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	r   io.ReadCloser // underlying reader
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	n   int64         // max bytes remaining
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	err error         // sticky error
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}
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func (l *maxBytesReader) Read(p []byte) (n int, err error) {
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	if l.err != nil {
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		return 0, l.err
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	}
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	if len(p) == 0 {
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		return 0, nil
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	}
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	// If they asked for a 32KB byte read but only 5 bytes are
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	// remaining, no need to read 32KB. 6 bytes will answer the
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	// question of the whether we hit the limit or go past it.
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	if int64(len(p)) > l.n+1 {
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		p = p[:l.n+1]
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	}
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	n, err = l.r.Read(p)
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	if int64(n) <= l.n {
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		l.n -= int64(n)
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		l.err = err
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		return n, err
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	}
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	n = int(l.n)
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	l.n = 0
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	// The server code and client code both use
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	// maxBytesReader. This "requestTooLarge" check is
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	// only used by the server code. To prevent binaries
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	// which only using the HTTP Client code (such as
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	// cmd/go) from also linking in the HTTP server, don't
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	// use a static type assertion to the server
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	// "*response" type. Check this interface instead:
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	type requestTooLarger interface {
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		requestTooLarge()
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	}
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	if res, ok := l.w.(requestTooLarger); ok {
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		res.requestTooLarge()
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	}
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	l.err = httpserver.ErrMaxBytesExceeded
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	return n, l.err
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}
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func (l *maxBytesReader) Close() error {
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	return l.r.Close()
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}
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