commit fda61e030e12cbd66a2be9905e6855ec6c6a3c63 Author: Yawning Angel yawning@schwanenlied.me Date: Thu Mar 26 12:55:12 2015 +0000

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. --- changes/feature15435 | 5 +++ src/common/util.c | 81 +++++++++++++++++++++++++++++++++++++-------- src/common/util.h | 3 ++ src/or/transports.c | 5 +++ src/test/test_util_slow.c | 2 ++ 5 files changed, 82 insertions(+), 14 deletions(-)

diff --git a/changes/feature15435 b/changes/feature15435 new file mode 100644 index 0000000..afe3603 --- /dev/null +++ b/changes/feature15435 @@ -0,0 +1,5 @@ + 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. diff --git a/src/common/util.c b/src/common/util.c index 2c3a1a1..7096e24 100644 --- a/src/common/util.c +++ b/src/common/util.c @@ -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

diff --git a/src/common/util.h b/src/common/util.h index 3584a87..21ac5b3 100644 --- a/src/common/util.h +++ b/src/common/util.h @@ -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; diff --git a/src/or/transports.c b/src/or/transports.c index 6f07054..ba2c784 100644 --- a/src/or/transports.c +++ b/src/or/transports.c @@ -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. diff --git a/src/test/test_util_slow.c b/src/test/test_util_slow.c index a597ef3..dcd0c9a 100644 --- a/src/test/test_util_slow.c +++ b/src/test/test_util_slow.c @@ -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 */