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extcap: Read stdout and stderr during capture 

Read extcap stdout/stderr data when available to prevent extcap hang on
stdout/stderr write. Discard stdout data as it was not used earlier.
Store up to 1024 bytes of stderr and display it to user after capture
stops.

Fixes #17827
This commit is contained in:
Tomasz Moń 2022-08-07 18:40:56 +02:00
parent ac4e1b86b8
commit 7316b16e1d
No known key found for this signature in database
GPG Key ID: 92BA8820D4D517C8
4 changed files with 84 additions and 14 deletions
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5
capture/capture_sync.c
View File

@ -182,12 +182,13 @@ void capture_process_finished(capture_session *cap_session)
continue;
}
if (interface_opts->extcap_stderr != NULL) {
if ((interface_opts->extcap_stderr != NULL) &&
(interface_opts->extcap_stderr->len > 0)) {
if (message->len > 0) {
g_string_append(message, "\n");
}
g_string_append(message, "Error by extcap pipe: ");
g_string_append(message, interface_opts->extcap_stderr);
g_string_append(message, interface_opts->extcap_stderr->str);
}
}

7
capture_opts.c
View File

@ -67,6 +67,8 @@ capture_opts_init(capture_options *capture_opts)
capture_opts->default_options.extcap_pipedata = NULL;
capture_opts->default_options.extcap_stderr = NULL;
capture_opts->default_options.extcap_child_watch = 0;
capture_opts->default_options.extcap_stdout_watch = 0;
capture_opts->default_options.extcap_stderr_watch = 0;
#ifdef _WIN32
capture_opts->default_options.extcap_pipe_h = INVALID_HANDLE_VALUE;
capture_opts->default_options.extcap_control_in_h = INVALID_HANDLE_VALUE;
@ -788,6 +790,8 @@ capture_opts_add_iface_opt(capture_options *capture_opts, const char *optarg_str
interface_opts.extcap_pipedata = NULL;
interface_opts.extcap_stderr = NULL;
interface_opts.extcap_child_watch = 0;
interface_opts.extcap_stdout_watch = 0;
interface_opts.extcap_stderr_watch = 0;
#ifdef _WIN32
interface_opts.extcap_pipe_h = INVALID_HANDLE_VALUE;
interface_opts.extcap_control_in_h = INVALID_HANDLE_VALUE;
@ -1289,7 +1293,8 @@ capture_opts_del_iface(capture_options *capture_opts, guint if_index)
if (interface_opts->extcap_pid != WS_INVALID_PID)
ws_pipe_close((ws_pipe_t *) interface_opts->extcap_pipedata);
g_free(interface_opts->extcap_pipedata);
g_free(interface_opts->extcap_stderr);
if (interface_opts->extcap_stderr)
g_string_free(interface_opts->extcap_stderr, TRUE);
g_free(interface_opts->extcap_control_in);
g_free(interface_opts->extcap_control_out);
#ifdef HAVE_PCAP_REMOTE

4
capture_opts.h
View File

@ -210,8 +210,10 @@ typedef struct interface_options_tag {
GHashTable *extcap_args;
GPid extcap_pid; /* pid of running process or WS_INVALID_PID */
gpointer extcap_pipedata;
gchar *extcap_stderr;
GString *extcap_stderr;
guint extcap_child_watch;
guint extcap_stdout_watch;
guint extcap_stderr_watch;
#ifdef _WIN32
HANDLE extcap_pipe_h;
HANDLE extcap_control_in_h;

82
extcap.c
View File

@ -1299,6 +1299,55 @@ extcap_add_arg_and_remove_cb(gpointer key, gpointer value, gpointer data)
return FALSE;
}
static gboolean
extcap_stdout_cb(GIOChannel *source, GIOCondition condition _U_, gpointer data)
{
interface_options *interface_opts = (interface_options *)data;
char buf[128];
gsize bytes_read;
/* Discard data to prevent child process hanging on stdout write */
g_io_channel_read_chars(source, buf, sizeof(buf), &bytes_read, NULL);
if (bytes_read == 0)
{
interface_opts->extcap_stdout_watch = 0;
return G_SOURCE_REMOVE;
}
return G_SOURCE_CONTINUE;
}
static gboolean
extcap_stderr_cb(GIOChannel *source, GIOCondition condition _U_, gpointer data)
{
interface_options *interface_opts = (interface_options *)data;
char buf[128];
gsize bytes_read;
g_io_channel_read_chars(source, buf, sizeof(buf), &bytes_read, NULL);
if (bytes_read == 0)
{
interface_opts->extcap_stderr_watch = 0;
return G_SOURCE_REMOVE;
}
#define STDERR_BUFFER_SIZE 1024
if (interface_opts->extcap_stderr == NULL)
{
interface_opts->extcap_stderr = g_string_new_len(buf, bytes_read);
}
else
{
gssize remaining = STDERR_BUFFER_SIZE - interface_opts->extcap_stderr->len;
if (remaining > 0)
{
gssize bytes = bytes_read;
bytes = MIN(bytes, remaining);
g_string_append_len(interface_opts->extcap_stderr, buf, bytes);
}
}
return G_SOURCE_CONTINUE;
}
static void extcap_child_watch_cb(GPid pid, gint status _U_, gpointer user_data)
{
guint i;
@ -1320,23 +1369,30 @@ static void extcap_child_watch_cb(GPid pid, gint status _U_, gpointer user_data)
interface_opts->extcap_pid);
interface_opts->extcap_pid = WS_INVALID_PID;
if (interface_opts->extcap_stdout_watch > 0)
{
g_source_remove(interface_opts->extcap_stdout_watch);
interface_opts->extcap_stdout_watch = 0;
}
if (interface_opts->extcap_stderr_watch > 0)
{
g_source_remove(interface_opts->extcap_stderr_watch);
interface_opts->extcap_stderr_watch = 0;
}
pipedata = (ws_pipe_t *)interface_opts->extcap_pipedata;
if (pipedata != NULL)
{
g_io_channel_unref(pipedata->stdout_io);
if (pipedata->stderr_io)
while (extcap_stderr_cb(pipedata->stderr_io,
g_io_channel_get_buffer_condition(pipedata->stderr_io),
(gpointer)interface_opts) != G_SOURCE_REMOVE)
{
#define STDERR_BUFFER_SIZE 1024
gchar *buffer = (gchar *)g_malloc0(STDERR_BUFFER_SIZE + 1);
g_io_channel_read_chars(pipedata->stderr_io, buffer, STDERR_BUFFER_SIZE, NULL, NULL);
if (strlen(buffer) > 0)
{
interface_opts->extcap_stderr = g_strdup(buffer);
}
g_free(buffer);
g_io_channel_unref(pipedata->stderr_io);
/* Keep reading until there's nothing left */
}
g_io_channel_unref(pipedata->stderr_io);
g_free(pipedata);
interface_opts->extcap_pipedata = NULL;
@ -1618,6 +1674,12 @@ extcap_init_interfaces(capture_session *cap_session)
interface_opts->extcap_child_watch =
g_child_watch_add_full(G_PRIORITY_HIGH, pid, extcap_child_watch_cb,
(gpointer)cap_session, NULL);
interface_opts->extcap_stdout_watch =
g_io_add_watch(pipedata->stdout_io, G_IO_IN | G_IO_HUP,
extcap_stdout_cb, (gpointer)interface_opts);
interface_opts->extcap_stderr_watch =
g_io_add_watch(pipedata->stderr_io, G_IO_IN | G_IO_HUP,
extcap_stderr_cb, (gpointer)interface_opts);
#ifdef _WIN32
/* On Windows, wait for extcap to connect to named pipe.