Commit fda61e03 authored by Yawning Angel's avatar Yawning Angel
Browse files

Implement "TOR_PT_EXIT_ON_STDIN_CLOSE". 

Background processes spawned by Tor now will have a valid stdin.
Pluggable transports can detect this behavior with the aformentioned
enviornment variable, and exit if stdin ever gets closed.
parent 732322b7

changes/feature15435

0 → 100644
+5 −0
Original line number Diff line number Diff line 
  o Minor features (pluggable Transports):

    - When launching managed pluggable transports, setup a valid open stdin

      in the child process that can be used to detect if tor has terminated.

      The "TOR_PT_EXIT_ON_STDIN_CLOSE" enviornment variable can be used by

      implementations to detect this new behavior. Resolves ticket 15435.

src/common/util.c

+67 −14
Original line number Diff line number Diff line
@@ -3939,9 +3939,11 @@ process_handle_new(void) 
  process_handle_t *out = tor_malloc_zero(sizeof(process_handle_t));



#ifdef _WIN32

  out->stdin_pipe = INVALID_HANDLE_VALUE;

  out->stdout_pipe = INVALID_HANDLE_VALUE;

  out->stderr_pipe = INVALID_HANDLE_VALUE;

#else

  out->stdin_pipe = -1;

  out->stdout_pipe = -1;

  out->stderr_pipe = -1;

#endif
@@ -3981,7 +3983,7 @@ process_handle_waitpid_cb(int status, void *arg) 
#define CHILD_STATE_FORK 3

#define CHILD_STATE_DUPOUT 4

#define CHILD_STATE_DUPERR 5

#define CHILD_STATE_REDIRECT 6

#define CHILD_STATE_DUPIN 6

#define CHILD_STATE_CLOSEFD 7

#define CHILD_STATE_EXEC 8

#define CHILD_STATE_FAILEXEC 9
@@ -4015,6 +4017,8 @@ tor_spawn_background(const char *const filename, const char **argv, 
  HANDLE stdout_pipe_write = NULL;

  HANDLE stderr_pipe_read = NULL;

  HANDLE stderr_pipe_write = NULL;

  HANDLE stdin_pipe_read = NULL;

  HANDLE stdin_pipe_write = NULL;

  process_handle_t *process_handle;

  int status;
@@ -4060,6 +4064,20 @@ tor_spawn_background(const char *const filename, const char **argv, 
    return status;

  }



  /* Set up pipe for stdin */

  if (!CreatePipe(&stdin_pipe_read, &stdin_pipe_write, &saAttr, 0)) {

    log_warn(LD_GENERAL,

      "Failed to create pipe for stdin communication with child process: %s",

      format_win32_error(GetLastError()));

    return status;

  }

  if (!SetHandleInformation(stderr_pipe_write, HANDLE_FLAG_INHERIT, 0)) {

    log_warn(LD_GENERAL,

      "Failed to configure pipe for stdin communication with child "

      "process: %s", format_win32_error(GetLastError()));

    return status;

  }



  /* Create the child process */



  /* Windows expects argv to be a whitespace delimited string, so join argv up
@@ -4074,7 +4092,7 @@ tor_spawn_background(const char *const filename, const char **argv, 
  siStartInfo.cb = sizeof(STARTUPINFO);

  siStartInfo.hStdError = stderr_pipe_write;

  siStartInfo.hStdOutput = stdout_pipe_write;

  siStartInfo.hStdInput = NULL;

  siStartInfo.hStdInput = stdin_pipe_read;

  siStartInfo.dwFlags |= STARTF_USESTDHANDLES;



  /* Create the child process */
@@ -4104,6 +4122,7 @@ tor_spawn_background(const char *const filename, const char **argv, 
    /* TODO: Close hProcess and hThread in process_handle->pid? */

    process_handle->stdout_pipe = stdout_pipe_read;

    process_handle->stderr_pipe = stderr_pipe_read;

    process_handle->stdin_pipe = stdin_pipe_write;

    status = process_handle->status = PROCESS_STATUS_RUNNING;

  }
@@ -4114,6 +4133,7 @@ tor_spawn_background(const char *const filename, const char **argv, 
  pid_t pid;

  int stdout_pipe[2];

  int stderr_pipe[2];

  int stdin_pipe[2];

  int fd, retval;

  ssize_t nbytes;

  process_handle_t *process_handle;
@@ -4138,7 +4158,7 @@ tor_spawn_background(const char *const filename, const char **argv, 


  child_state = CHILD_STATE_PIPE;



  /* Set up pipe for redirecting stdout and stderr of child */

  /* Set up pipe for redirecting stdout, stderr, and stdin of child */

  retval = pipe(stdout_pipe);

  if (-1 == retval) {

    log_warn(LD_GENERAL,
@@ -4159,6 +4179,20 @@ tor_spawn_background(const char *const filename, const char **argv, 
    return status;

  }



  retval = pipe(stdin_pipe);

  if (-1 == retval) {

    log_warn(LD_GENERAL,

      "Failed to set up pipe for stdin communication with child process: %s",

       strerror(errno));



    close(stdout_pipe[0]);

    close(stdout_pipe[1]);

    close(stderr_pipe[0]);

    close(stderr_pipe[1]);



    return status;

  }



  child_state = CHILD_STATE_MAXFD;



#ifdef _SC_OPEN_MAX
@@ -4194,13 +4228,11 @@ tor_spawn_background(const char *const filename, const char **argv, 
    if (-1 == retval)

        goto error;



    child_state = CHILD_STATE_REDIRECT;

    child_state = CHILD_STATE_DUPIN;



    /* Link stdin to /dev/null */

    fd = open("/dev/null", O_RDONLY); /* NOT cloexec, obviously. */

    if (fd != -1)

      dup2(fd, STDIN_FILENO);

    else

    /* Link child stdin to the read end of the pipe */

    retval = dup2(stdin_pipe[0], STDIN_FILENO);

    if (-1 == retval)

      goto error;



    child_state = CHILD_STATE_CLOSEFD;
@@ -4209,7 +4241,8 @@ tor_spawn_background(const char *const filename, const char **argv, 
    close(stderr_pipe[1]);

    close(stdout_pipe[0]);

    close(stdout_pipe[1]);

    close(fd);

    close(stdin_pipe[0]);

    close(stdin_pipe[1]);



    /* Close all other fds, including the read end of the pipe */

    /* XXX: We should now be doing enough FD_CLOEXEC setting to make
@@ -4259,6 +4292,8 @@ tor_spawn_background(const char *const filename, const char **argv, 


  if (-1 == pid) {

    log_warn(LD_GENERAL, "Failed to fork child process: %s", strerror(errno));

    close(stdin_pipe[0]);

    close(stdin_pipe[1]);

    close(stdout_pipe[0]);

    close(stdout_pipe[1]);

    close(stderr_pipe[0]);
@@ -4295,16 +4330,28 @@ tor_spawn_background(const char *const filename, const char **argv, 
            strerror(errno));

  }



  /* Return write end of the stdin pipe to caller, and close the read end */

  process_handle->stdin_pipe = stdin_pipe[1];

  retval = close(stdin_pipe[0]);



  if (-1 == retval) {

    log_warn(LD_GENERAL,

            "Failed to close read end of stdin pipe in parent process: %s",

            strerror(errno));

  }



  status = process_handle->status = PROCESS_STATUS_RUNNING;

  /* Set stdout/stderr pipes to be non-blocking */

  /* Set stdin/stdout/stderr pipes to be non-blocking */

  if (fcntl(process_handle->stdout_pipe, F_SETFL, O_NONBLOCK) < 0 ||

      fcntl(process_handle->stderr_pipe, F_SETFL, O_NONBLOCK) < 0) {

    log_warn(LD_GENERAL, "Failed to set stderror/stdout pipes nonblocking "

             "in parent process: %s", strerror(errno));

      fcntl(process_handle->stderr_pipe, F_SETFL, O_NONBLOCK) < 0 ||

      fcntl(process_handle->stdin_pipe, F_SETFL, O_NONBLOCK) < 0) {

    log_warn(LD_GENERAL, "Failed to set stderror/stdout/stdin pipes "

             "nonblocking in parent process: %s", strerror(errno));

  }

  /* Open the buffered IO streams */

  process_handle->stdout_handle = fdopen(process_handle->stdout_pipe, "r");

  process_handle->stderr_handle = fdopen(process_handle->stderr_pipe, "r");

  process_handle->stdin_handle = fdopen(process_handle->stdin_pipe, "r");



  *process_handle_out = process_handle;

  return process_handle->status;
@@ -4347,6 +4394,9 @@ tor_process_handle_destroy,(process_handle_t *process_handle, 


  if (process_handle->stderr_pipe)

    CloseHandle(process_handle->stderr_pipe);



  if (process_handle->stdin_pipe)

    CloseHandle(process_handle->stdin_pipe);

#else

  if (process_handle->stdout_handle)

    fclose(process_handle->stdout_handle);
@@ -4354,6 +4404,9 @@ tor_process_handle_destroy,(process_handle_t *process_handle, 
  if (process_handle->stderr_handle)

    fclose(process_handle->stderr_handle);



  if (process_handle->stdin_handle)

    fclose(process_handle->stdin_handle);



  clear_waitpid_callback(process_handle->waitpid_cb);

#endif

src/common/util.h

+3 −0
Original line number Diff line number Diff line
@@ -474,12 +474,15 @@ struct process_handle_t { 
  /** One of the PROCESS_STATUS_* values */

  int status;

#ifdef _WIN32

  HANDLE stdin_pipe;

  HANDLE stdout_pipe;

  HANDLE stderr_pipe;

  PROCESS_INFORMATION pid;

#else

  int stdin_pipe;

  int stdout_pipe;

  int stderr_pipe;

  FILE *stdin_handle;

  FILE *stdout_handle;

  FILE *stderr_handle;

  pid_t pid;

src/or/transports.c

+5 −0
Original line number Diff line number Diff line
@@ -1388,6 +1388,11 @@ create_managed_proxy_environment(const managed_proxy_t *mp) 
    } else {

      smartlist_add_asprintf(envs, "TOR_PT_EXTENDED_SERVER_PORT=");

    }



    /* All new versions of tor will keep stdin open, so PTs can use it

     * as a reliable termination detection mechanism.

     */

    smartlist_add_asprintf(envs, "TOR_PT_EXIT_ON_STDIN_CLOSE=1");

  } else {

    /* If ClientTransportPlugin has a HTTPS/SOCKS proxy configured, set the

     * TOR_PT_PROXY line.

src/test/test_util_slow.c

+2 −0
Original line number Diff line number Diff line
@@ -107,9 +107,11 @@ run_util_spawn_background(const char *argv[], const char *expected_out, 
#ifdef _WIN32

  tt_assert(process_handle->stdout_pipe != INVALID_HANDLE_VALUE);

  tt_assert(process_handle->stderr_pipe != INVALID_HANDLE_VALUE);

  tt_assert(process_handle->stdin_pipe != INVALID_HANDLE_VALUE);

#else

  tt_assert(process_handle->stdout_pipe >= 0);

  tt_assert(process_handle->stderr_pipe >= 0);

  tt_assert(process_handle->stdin_pipe >= 0);

#endif



  /* Check stdout */