ipn/ipnlocal: simplify redactErr (#6716)

Use multierr.Range to iterate through an error tree
instead of multiple invocations of errors.As.
This scales better as we add more Go error types to the switch.

Signed-off-by: Joe Tsai <joetsai@digital-static.net>
pull/6717/head
Joe Tsai 2 years ago committed by GitHub
parent c47578b528
commit bd2995c14b
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23

@ -48,6 +48,7 @@ import (
"tailscale.com/net/netutil"
"tailscale.com/tailcfg"
"tailscale.com/util/clientmetric"
"tailscale.com/util/multierr"
"tailscale.com/util/strs"
"tailscale.com/wgengine"
"tailscale.com/wgengine/filter"
@ -365,58 +366,45 @@ func redactString(s string) string {
return string(b)
}
func redactErr(err error) error {
func redactErr(root error) error {
// redactStrings is a list of sensitive strings that were redacted.
// It is not sufficient to just snub out sensitive fields in Go errors
// since some wrapper errors like fmt.Errorf pre-cache the error string,
// which would unfortunately remain unaffected.
var redactStrings []string
var pe *os.PathError
if errors.As(err, &pe) {
// If this is the root error, then we can redact it directly.
if err == pe {
pe.Path = redactString(pe.Path)
return pe
// Redact sensitive fields in known Go error types.
var unknownErrors int
multierr.Range(root, func(err error) bool {
switch err := err.(type) {
case *os.PathError:
redactStrings = append(redactStrings, err.Path)
err.Path = redactString(err.Path)
case *os.LinkError:
redactStrings = append(redactStrings, err.New, err.Old)
err.New = redactString(err.New)
err.Old = redactString(err.Old)
default:
unknownErrors++
}
return true
})
// Otherwise, we have a *PathError somewhere in the error
// chain, and we can't redact it because something later in the
// chain may have cached the Error() return already (as
// fmt.Errorf does).
//
// Add this path to the set of paths that we will redact, below.
redactStrings = append(redactStrings, pe.Path)
// Also redact the Path value so that anything that calls
// Unwrap in the future gets the redacted value.
pe.Path = redactString(pe.Path)
}
var le *os.LinkError
if errors.As(err, &le) {
// If this is the root error, then we can redact it directly.
if err == le {
le.New = redactString(le.New)
le.Old = redactString(le.Old)
return le
}
// As above
redactStrings = append(redactStrings, le.New, le.Old)
le.New = redactString(le.New)
le.Old = redactString(le.Old)
}
if len(redactStrings) == 0 {
return err
}
s := err.Error()
for _, toRedact := range redactStrings {
s = strings.Replace(s, toRedact, redactString(toRedact), -1)
// If there are no redacted strings or no unknown error types,
// then we can return the possibly modified root error verbatim.
// Otherwise, we must replace redacted strings from any wrappers.
if len(redactStrings) == 0 || unknownErrors == 0 {
return root
}
// Stringify and and replace any paths that we found above, then return
// Stringify and replace any paths that we found above, then return
// the error wrapped in a type that uses the newly-redacted string
// while also allowing Unwrap()-ing to the inner error type(s).
return &redactedErr{msg: s, inner: err}
s := root.Error()
for _, toRedact := range redactStrings {
s = strings.ReplaceAll(s, toRedact, redactString(toRedact))
}
return &redactedErr{msg: s, inner: root}
}
func touchFile(path string) error {

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