commit adf41cd3adf6e3884626b6b7e4c7f131660343dd
Author: David Fifield <[email protected]>
Date: Sat Feb 23 02:23:05 2019 -0700
Be more careful about terminating meek-client.
First close its stdin and send SIGTERM; and then kill it if that doesn't
work. Set TOR_PT_EXIT_ON_STDIN_EOF=1 unconditionally in the subprocess.
On Windows it's the same, except don't send SIGTERM.
https://bugs.torproject.org/15125
https://bugs.torproject.org/25613
---
meek-client-torbrowser/meek-client-torbrowser.go | 27 ++++++++++++++-----
meek-client-torbrowser/terminate_other.go | 33 ++++++++++++++++++++++++
meek-client-torbrowser/terminate_windows.go | 30 +++++++++++++++++++++
3 files changed, 84 insertions(+), 6 deletions(-)
diff --git a/meek-client-torbrowser/meek-client-torbrowser.go
b/meek-client-torbrowser/meek-client-torbrowser.go
index ce79193..0f295ff 100644
--- a/meek-client-torbrowser/meek-client-torbrowser.go
+++ b/meek-client-torbrowser/meek-client-torbrowser.go
@@ -35,16 +35,27 @@ import (
"regexp"
"strings"
"syscall"
+ "time"
)
// This magic string is emitted by meek-http-helper.
var helperAddrPattern = regexp.MustCompile(`^meek-http-helper: listen
(127\.0\.0\.1:\d+)$`)
+// How long to wait for child processes to exit gracefully before killing them.
+const terminateTimeout = 2 * time.Second
+
func usage() {
fmt.Fprintf(os.Stderr, "Usage: %s [meek-client-torbrowser args] --
meek-client [meek-client args]\n", os.Args[0])
flag.PrintDefaults()
}
+// ptCmd is a *exec.Cmd augmented with an io.WriteCloser for its stdin, which
we
+// can close to instruct the PT subprocess to terminate.
+type ptCmd struct {
+ *exec.Cmd
+ StdinCloser io.WriteCloser
+}
+
// Log a call to os.Process.Kill.
func logKill(p *os.Process) error {
log.Printf("killing PID %d", p.Pid)
@@ -293,14 +304,16 @@ func grepHelperAddr(r io.Reader) (string, error) {
}
// Run meek-client and return its exec.Cmd.
-func runMeekClient(helperAddr string, meekClientCommandLine []string) (cmd
*exec.Cmd, err error) {
+func runMeekClient(helperAddr string, meekClientCommandLine []string) (cmd
*ptCmd, err error) {
meekClientPath := meekClientCommandLine[0]
args := meekClientCommandLine[1:]
args = append(args, []string{"--helper", helperAddr}...)
- cmd = exec.Command(meekClientPath, args...)
+ cmd = new(ptCmd)
+ cmd.Cmd = exec.Command(meekClientPath, args...)
// Give the subprocess a stdin for TOR_PT_EXIT_ON_STDIN_CLOSE purposes.
// https://bugs.torproject.org/24642
- _, err = cmd.StdinPipe()
+ cmd.Env = append(os.Environ(), "TOR_PT_EXIT_ON_STDIN_CLOSE=1")
+ cmd.StdinCloser, err = cmd.StdinPipe()
if err != nil {
return
}
@@ -320,7 +333,7 @@ func runMeekClient(helperAddr string, meekClientCommandLine
[]string) (cmd *exec
// may have failed to start. If a process did not start, its corresponding
// return value will be nil. The caller is responsible for terminating whatever
// processes were started, whether or not err is nil.
-func startProcesses(sigChan <-chan os.Signal, meekClientCommandLine []string)
(firefoxCmd *exec.Cmd, meekClientCmd *exec.Cmd, err error) {
+func startProcesses(sigChan <-chan os.Signal, meekClientCommandLine []string)
(firefoxCmd *exec.Cmd, meekClientCmd *ptCmd, err error) {
// Start firefox.
var stdout io.Reader
firefoxCmd, stdout, err = runFirefox()
@@ -414,7 +427,6 @@ func main() {
// we are instructed to stop.
sig := <-sigChan
log.Printf("sig %s", sig)
- logSignal(meekClientCmd.Process, sig)
} else {
// Otherwise don't wait, go ahead and terminate whatever
// processes were started.
@@ -425,6 +437,9 @@ func main() {
logKill(firefoxCmd.Process)
}
if meekClientCmd != nil {
- logKill(firefoxCmd.Process)
+ err := terminatePTCmd(meekClientCmd)
+ if err != nil {
+ log.Printf("error terminating meek-client: %v", err)
+ }
}
}
diff --git a/meek-client-torbrowser/terminate_other.go
b/meek-client-torbrowser/terminate_other.go
new file mode 100644
index 0000000..d38e27b
--- /dev/null
+++ b/meek-client-torbrowser/terminate_other.go
@@ -0,0 +1,33 @@
+// +build !windows
+
+// Process termination code for platforms that have SIGTERM (i.e., not
Windows).
+
+package main
+
+import (
+ "syscall"
+ "time"
+)
+
+// Terminate a PT subprocess: first close its stdin and send it SIGTERM; then
+// kill it if that doesn't work.
+func terminatePTCmd(cmd *ptCmd) error {
+ err := cmd.StdinCloser.Close()
+ err2 := cmd.Process.Signal(syscall.SIGTERM)
+ if err == nil {
+ err = err2
+ }
+ ch := make(chan error, 1)
+ go func() {
+ ch <- cmd.Wait()
+ }()
+ select {
+ case <-time.After(terminateTimeout):
+ err2 = cmd.Process.Kill()
+ case err2 = <-ch:
+ }
+ if err == nil {
+ err = err2
+ }
+ return err
+}
diff --git a/meek-client-torbrowser/terminate_windows.go
b/meek-client-torbrowser/terminate_windows.go
new file mode 100644
index 0000000..c00c44f
--- /dev/null
+++ b/meek-client-torbrowser/terminate_windows.go
@@ -0,0 +1,30 @@
+// +build windows
+
+// Process termination code for platforms that don't have SIGTERM (i.e.,
+// Windows).
+
+package main
+
+import (
+ "time"
+)
+
+// Terminate a PT subprocess: first close its stdin; then kill it if that
+// doesn't work.
+func terminatePTCmd(cmd *ptCmd) error {
+ err := cmd.StdinCloser.Close()
+ ch := make(chan error, 1)
+ go func() {
+ ch <- cmd.Wait()
+ }()
+ var err2 error
+ select {
+ case <-time.After(terminateTimeout):
+ err2 = cmd.Process.Kill()
+ case err2 = <-ch:
+ }
+ if err == nil {
+ err = err2
+ }
+ return err
+}
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