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caddy/middleware/middleware.go
Matthew Holt 2a46f2a14e Revert recent Content-Length-related changes and fix fastcgi return
fastcgi's ServeHTTP method originally returned the correct value (0) in
b51e8bc191. Later, I mistakenly suggested
we change that to return the status code because I forgot that status
codes aren't logged by the return value. So fastcgi broke due in
3966936bd6 due to my error.

We later had to try to make up for this with ugly Content-Length checks
like in c37ad7f677. Turns out that all we
had to do was fix the returned status here back to 0. The proxy
middleware behaves the same way, and returning 0 is correct. We should
only return a status code if the response has not been written, but with
upstream servers, we do write a response; they do not know about our
error handler.

Also clarifed this in the middleware.Handler documentation.
2016-03-02 11:33:40 -07:00

103 lines
3.8 KiB
Go

// Package middleware provides some types and functions common among middleware.
package middleware
import (
"net/http"
"path"
"time"
)
type (
// Middleware is the middle layer which represents the traditional
// idea of middleware: it chains one Handler to the next by being
// passed the next Handler in the chain.
Middleware func(Handler) Handler
// Handler is like http.Handler except ServeHTTP may return a status
// code and/or error.
//
// If ServeHTTP writes to the response body, it should return a status
// code of 0. This signals to other handlers above it that the response
// body is already written, and that they should not write to it also.
//
// If ServeHTTP encounters an error, it should return the error value
// so it can be logged by designated error-handling middleware.
//
// If writing a response after calling another ServeHTTP method, the
// returned status code SHOULD be used when writing the response.
//
// If handling errors after calling another ServeHTTP method, the
// returned error value SHOULD be logged or handled accordingly.
//
// Otherwise, return values should be propagated down the middleware
// chain by returning them unchanged.
Handler interface {
ServeHTTP(http.ResponseWriter, *http.Request) (int, error)
}
// HandlerFunc is a convenience type like http.HandlerFunc, except
// ServeHTTP returns a status code and an error. See Handler
// documentation for more information.
HandlerFunc func(http.ResponseWriter, *http.Request) (int, error)
)
// ServeHTTP implements the Handler interface.
func (f HandlerFunc) ServeHTTP(w http.ResponseWriter, r *http.Request) (int, error) {
return f(w, r)
}
// IndexFile looks for a file in /root/fpath/indexFile for each string
// in indexFiles. If an index file is found, it returns the root-relative
// path to the file and true. If no index file is found, empty string
// and false is returned. fpath must end in a forward slash '/'
// otherwise no index files will be tried (directory paths must end
// in a forward slash according to HTTP).
//
// All paths passed into and returned from this function use '/' as the
// path separator, just like URLs. IndexFle handles path manipulation
// internally for systems that use different path separators.
func IndexFile(root http.FileSystem, fpath string, indexFiles []string) (string, bool) {
if fpath[len(fpath)-1] != '/' || root == nil {
return "", false
}
for _, indexFile := range indexFiles {
// func (http.FileSystem).Open wants all paths separated by "/",
// regardless of operating system convention, so use
// path.Join instead of filepath.Join
fp := path.Join(fpath, indexFile)
f, err := root.Open(fp)
if err == nil {
f.Close()
return fp, true
}
}
return "", false
}
// SetLastModifiedHeader checks if the provided modTime is valid and if it is sets it
// as a Last-Modified header to the ResponseWriter. If the modTime is in the future
// the current time is used instead.
func SetLastModifiedHeader(w http.ResponseWriter, modTime time.Time) {
if modTime.IsZero() || modTime.Equal(time.Unix(0, 0)) {
// the time does not appear to be valid. Don't put it in the response
return
}
// RFC 2616 - Section 14.29 - Last-Modified:
// An origin server MUST NOT send a Last-Modified date which is later than the
// server's time of message origination. In such cases, where the resource's last
// modification would indicate some time in the future, the server MUST replace
// that date with the message origination date.
now := currentTime()
if modTime.After(now) {
modTime = now
}
w.Header().Set("Last-Modified", modTime.UTC().Format(http.TimeFormat))
}
// currentTime, as it is defined here, returns time.Now().
// It's defined as a variable for mocking time in tests.
var currentTime = func() time.Time {
return time.Now()
}