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net/tshttpproxy: aggressively rate-limit error logs in Transport.Proxy path

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Otherwise log upload HTTP requests generate proxy errrors which
generate logs which generate HTTP requests which generate proxy
errors which generate more logs, etc.

Fixes #879
This commit is contained in:
Brad Fitzpatrick 2020-11-03 08:53:01 -08:00
parent 07b6ffd55c
commit 1036f51a56
1 changed files with 18 additions and 3 deletions
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21
net/tshttpproxy/tshttpproxy_windows.go
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@ -19,6 +19,7 @@ import (
"github.com/alexbrainman/sspi/negotiate"
"golang.org/x/sys/windows"
"tailscale.com/types/logger"
)
var (
@ -38,6 +39,13 @@ var cachedProxy struct {
val *url.URL
}
// proxyErrorf is a rate-limited logger specifically for errors asking
// WinHTTP for the proxy information. We don't want to log about
// errors often, otherwise the log message itself will generate a new
// HTTP request which ultimately will call back into us to log again,
// forever. So for errors, we only log a bit.
var proxyErrorf = logger.RateLimitedFn(log.Printf, 10*time.Minute, 2 /* burst*/, 10 /* maxCache */)
func proxyFromWinHTTPOrCache(req *http.Request) (*url.URL, error) {
if req.URL == nil {
return nil, nil
@ -79,7 +87,14 @@ func proxyFromWinHTTPOrCache(req *http.Request) (*url.URL, error) {
setNoProxyUntil(10 * time.Second)
return nil, nil
}
log.Printf("tshttpproxy: winhttp: GetProxyForURL(%q): %v/%#v", urlStr, err, err)
if err == windows.ERROR_INVALID_PARAMETER {
// Seen on Windows 8.1. (https://github.com/tailscale/tailscale/issues/879)
// TODO(bradfitz): figure this out.
setNoProxyUntil(time.Hour)
proxyErrorf("tshttpproxy: winhttp: GetProxyForURL(%q): ERROR_INVALID_PARAMETER [unexpected]", urlStr)
return nil, nil
}
proxyErrorf("tshttpproxy: winhttp: GetProxyForURL(%q): %v/%#v", urlStr, err, err)
if err == syscall.Errno(ERROR_WINHTTP_UNABLE_TO_DOWNLOAD_SCRIPT) {
setNoProxyUntil(10 * time.Second)
return nil, nil
@ -88,7 +103,7 @@ func proxyFromWinHTTPOrCache(req *http.Request) (*url.URL, error) {
case <-ctx.Done():
cachedProxy.Lock()
defer cachedProxy.Unlock()
log.Printf("tshttpproxy: winhttp: GetProxyForURL(%q): timeout; using cached proxy %v", urlStr, cachedProxy.val)
proxyErrorf("tshttpproxy: winhttp: GetProxyForURL(%q): timeout; using cached proxy %v", urlStr, cachedProxy.val)
return cachedProxy.val, nil
}
}
@ -96,7 +111,7 @@ func proxyFromWinHTTPOrCache(req *http.Request) (*url.URL, error) {
func proxyFromWinHTTP(ctx context.Context, urlStr string) (proxy *url.URL, err error) {
whi, err := winHTTPOpen()
if err != nil {
log.Printf("winhttp: Open: %v", err)
proxyErrorf("winhttp: Open: %v", err)
return nil, err
}
defer whi.Close()