distribution/registry/handlers/helpers.go
Sebastiaan van Stijn 3b391d3290
replace strings.Split(N) for strings.Cut() or alternatives
Go 1.18 and up now provides a strings.Cut() which is better suited for
splitting key/value pairs (and similar constructs), and performs better:

```go
func BenchmarkSplit(b *testing.B) {
	b.ReportAllocs()
	data := []string{"12hello=world", "12hello=", "12=hello", "12hello"}
	for i := 0; i < b.N; i++ {
		for _, s := range data {
			_ = strings.SplitN(s, "=", 2)[0]
		}
	}
}

func BenchmarkCut(b *testing.B) {
	b.ReportAllocs()
	data := []string{"12hello=world", "12hello=", "12=hello", "12hello"}
	for i := 0; i < b.N; i++ {
		for _, s := range data {
			_, _, _ = strings.Cut(s, "=")
		}
	}
}
```

    BenchmarkSplit
    BenchmarkSplit-10    	 8244206	       128.0 ns/op	     128 B/op	       4 allocs/op
    BenchmarkCut
    BenchmarkCut-10      	54411998	        21.80 ns/op	       0 B/op	       0 allocs/op

While looking at occurrences of `strings.Split()`, I also updated some for alternatives,
or added some constraints;

- for cases where an specific number of items is expected, I used `strings.SplitN()`
  with a suitable limit. This prevents (theoretical) unlimited splits.
- in some cases it we were using `strings.Split()`, but _actually_ were trying to match
  a prefix; for those I replaced the code to just match (and/or strip) the prefix.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
2022-11-10 22:38:12 +01:00

85 lines
2.5 KiB
Go

package handlers
import (
"context"
"errors"
"fmt"
"io"
"net/http"
"strconv"
"strings"
dcontext "github.com/distribution/distribution/v3/context"
)
// closeResources closes all the provided resources after running the target
// handler.
func closeResources(handler http.Handler, closers ...io.Closer) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
for _, closer := range closers {
defer closer.Close()
}
handler.ServeHTTP(w, r)
})
}
// copyFullPayload copies the payload of an HTTP request to destWriter. If it
// receives less content than expected, and the client disconnected during the
// upload, it avoids sending a 400 error to keep the logs cleaner.
//
// The copy will be limited to `limit` bytes, if limit is greater than zero.
func copyFullPayload(ctx context.Context, responseWriter http.ResponseWriter, r *http.Request, destWriter io.Writer, limit int64, action string) error {
// Get a channel that tells us if the client disconnects
clientClosed := r.Context().Done()
body := r.Body
if limit > 0 {
body = http.MaxBytesReader(responseWriter, body, limit)
}
// Read in the data, if any.
copied, err := io.Copy(destWriter, body)
if clientClosed != nil && (err != nil || (r.ContentLength > 0 && copied < r.ContentLength)) {
// Didn't receive as much content as expected. Did the client
// disconnect during the request? If so, avoid returning a 400
// error to keep the logs cleaner.
select {
case <-clientClosed:
// Set the response code to "499 Client Closed Request"
// Even though the connection has already been closed,
// this causes the logger to pick up a 499 error
// instead of showing 0 for the HTTP status.
responseWriter.WriteHeader(499)
dcontext.GetLoggerWithFields(ctx, map[interface{}]interface{}{
"error": err,
"copied": copied,
"contentLength": r.ContentLength,
}, "error", "copied", "contentLength").Error("client disconnected during " + action)
return errors.New("client disconnected")
default:
}
}
if err != nil {
dcontext.GetLogger(ctx).Errorf("unknown error reading request payload: %v", err)
return err
}
return nil
}
func parseContentRange(cr string) (start int64, end int64, err error) {
rStart, rEnd, ok := strings.Cut(cr, "-")
if !ok {
return -1, -1, fmt.Errorf("invalid content range format, %s", cr)
}
start, err = strconv.ParseInt(rStart, 10, 64)
if err != nil {
return -1, -1, err
}
end, err = strconv.ParseInt(rEnd, 10, 64)
if err != nil {
return -1, -1, err
}
return start, end, nil
}