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Sanitize IP addresses from server log output

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Added a scrubber that takes all logging output to the standard logger
and passes through a series of regular expressions to replace IP
addresses with safe strings (e.g., X.X.X.X:443).

Ensure server logs to stdout are also scrubbed
This commit is contained in:
Cecylia Bocovich 2019-03-20 15:50:55 -04:00
parent 88f282c733
commit f586a4bab8
2 changed files with 51 additions and 2 deletions
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26
server/server.go
View file

@ -15,6 +15,7 @@ import (
"os"
"os/signal"
"path/filepath"
"regexp"
"strings"
"sync"
"syscall"
@ -54,6 +55,22 @@ additional HTTP listener on port 80 to work with ACME.
flag.PrintDefaults()
}
// An io.Writer that can be used as the output for a logger that first
// sanitizes logs and then writes to the provided io.Writer
type logScrubber struct {
output io.Writer
}
func (ls *logScrubber) Write(b []byte) (n int, err error) {
//First scrub the input of IP addresses
reIPv4 := regexp.MustCompile(`\b\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}\b`)
reIPv6 := regexp.MustCompile(`(([0-9a-fA-F]{1,4}:){7,7}[0-9a-fA-F]{1,4}|([0-9a-fA-F]{1,4}:){1,7}:|([0-9a-fA-F]{1,4}:){1,6}:[0-9a-fA-F]{1,4}|([0-9a-fA-F]{1,4}:){1,5}(:[0-9a-fA-F]{1,4}){1,2}|([0-9a-fA-F]{1,4}:){1,4}(:[0-9a-fA-F]{1,4}){1,3}|([0-9a-fA-F]{1,4}:){1,3}(:[0-9a-fA-F]{1,4}){1,4}|([0-9a-fA-F]{1,4}:){1,2}(:[0-9a-fA-F]{1,4}){1,5}|[0-9a-fA-F]{1,4}:((:[0-9a-fA-F]{1,4}){1,6})|:((:[0-9a-fA-F]{1,4}){1,7}|:)|fe80:(:[0-9a-fA-F]{0,4}){0,4}%[0-9a-zA-Z]{1,}|::(ffff(:0{1,4}){0,1}:){0,1}((25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])\.){3,3}(25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])|([0-9a-fA-F]{1,4}:){1,4}:((25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])\.){3,3}(25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9]))`)
scrubbedBytes := reIPv4.ReplaceAll(b, []byte("X.X.X.X"))
scrubbedBytes = reIPv6.ReplaceAll(scrubbedBytes,
[]byte("X:X:X:X:X:X:X:X"))
return ls.output.Write(scrubbedBytes)
}
// An abstraction that makes an underlying WebSocket connection look like an
// io.ReadWriteCloser.
type webSocketConn struct {
@ -280,7 +297,14 @@ func main() {
log.Fatalf("can't open log file: %s", err)
}
defer f.Close()
log.SetOutput(f)
//We want to send the log output through our scrubber first
scrubber := &logScrubber{f}
log.SetOutput(scrubber)
} else {
// we still want to send log output through our scrubber, even
// if no log file was specified
scrubber := &logScrubber{os.Stdout}
log.SetOutput(scrubber)
}
if !disableTLS && acmeHostnamesCommas == "" {

25
server/server_test.go
View file

@ -1,6 +1,8 @@
package main
import (
"bytes"
"log"
"net"
"strconv"
"testing"
@ -47,3 +49,26 @@ func TestClientAddr(t *testing.T) {
}
}
}
func TestLogScrubber(t *testing.T) {
var buff bytes.Buffer
scrubber := &logScrubber{&buff}
log.SetFlags(0) //remove all extra log output for test comparisons
log.SetOutput(scrubber)
log.Printf("%s", "http: TLS handshake error from 129.97.208.23:38310:")
if bytes.Compare(buff.Bytes(), []byte("http: TLS handshake error from X.X.X.X:38310:\n")) != 0 {
t.Errorf("log scrubber didn't scrub IPv4 address. Output: %s", string(buff.Bytes()))
}
buff.Reset()
log.Printf("%s", "http2: panic serving [2620:101:f000:780:9097:75b1:519f:dbb8]:58344: interface conversion: *http2.responseWriter is not http.Hijacker: missing method Hijack")
if bytes.Compare(buff.Bytes(), []byte("http2: panic serving [X:X:X:X:X:X:X:X]:58344: interface conversion: *http2.responseWriter is not http.Hijacker: missing method Hijack\n")) != 0 {
t.Errorf("log scrubber didn't scrub IPv6 address. Output: %s", string(buff.Bytes()))
}
buff.Reset()
}