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-rw-r--r--modules/caddyhttp/reverseproxy/reverseproxy.go27
1 files changed, 24 insertions, 3 deletions
diff --git a/modules/caddyhttp/reverseproxy/reverseproxy.go b/modules/caddyhttp/reverseproxy/reverseproxy.go
index bed5289..3a2457f 100644
--- a/modules/caddyhttp/reverseproxy/reverseproxy.go
+++ b/modules/caddyhttp/reverseproxy/reverseproxy.go
@@ -18,6 +18,7 @@ import (
"bytes"
"context"
"encoding/json"
+ "errors"
"fmt"
"io"
"io/ioutil"
@@ -384,8 +385,7 @@ func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request, next caddyht
// DialInfo struct should have valid network address syntax
dialInfo, err := upstream.fillDialInfo(r)
if err != nil {
- err = fmt.Errorf("making dial info: %v", err)
- return caddyhttp.Error(http.StatusBadGateway, err)
+ return statusError(fmt.Errorf("making dial info: %v", err))
}
// attach to the request information about how to dial the upstream;
@@ -438,7 +438,7 @@ func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request, next caddyht
}
}
- return caddyhttp.Error(http.StatusBadGateway, proxyErr)
+ return statusError(proxyErr)
}
// prepareRequest modifies req so that it is ready to be proxied,
@@ -762,6 +762,27 @@ func removeConnectionHeaders(h http.Header) {
}
}
+// statusError returns an error value that has a status code.
+func statusError(err error) error {
+ // errors proxying usually mean there is a problem with the upstream(s)
+ statusCode := http.StatusBadGateway
+
+ // if the client canceled the request (usually this means they closed
+ // the connection, so they won't see any response), we can report it
+ // as a client error (4xx) and not a server error (5xx); unfortunately
+ // the Go standard library, at least at time of writing in late 2020,
+ // obnoxiously wraps the exported, standard context.Canceled error with
+ // an unexported garbage value that we have to do a substring check for:
+ // https://github.com/golang/go/blob/6965b01ea248cabb70c3749fd218b36089a21efb/src/net/net.go#L416-L430
+ if errors.Is(err, context.Canceled) || strings.Contains(err.Error(), "operation was canceled") {
+ // regrettably, there is no standard error code for "client closed connection", but
+ // for historical reasons we can use a code that a lot of people are already using;
+ // using 5xx is problematic for users; see #3748
+ statusCode = 499
+ }
+ return caddyhttp.Error(statusCode, err)
+}
+
// LoadBalancing has parameters related to load balancing.
type LoadBalancing struct {
// A selection policy is how to choose an available backend.