/**
* @return TRUE if the request was sent succesfully. FALSE
* if the request could not be sent. This isn't
* necessarily an error. If the child has expired,
* for example, we won't be able to send the message.
*/
static gboolean
send_dns_request_to_child(PurpleDnsQueryData *query_data,
PurpleDnsQueryResolverProcess *resolver)
{
pid_t pid;
dns_params_t dns_params;
ssize_t rc;
/* This waitpid might return the child's PID if it has recently
* exited, or it might return an error if it exited "long
* enough" ago that it has already been reaped; in either
* instance, we can't use it. */
pid = waitpid(resolver->dns_pid, NULL, WNOHANG);
if (pid > 0) {
purple_debug_warning("dns", "DNS child %d no longer exists\n",
resolver->dns_pid);
purple_dnsquery_resolver_destroy(resolver);
return FALSE;
} else if (pid < 0) {
purple_debug_warning("dns", "Wait for DNS child %d failed: %s\n",
resolver->dns_pid, g_strerror(errno));
purple_dnsquery_resolver_destroy(resolver);
return FALSE;
}
/* Copy the hostname and port into a single data structure */
strncpy(dns_params.hostname, query_data->hostname, sizeof(dns_params.hostname) - 1);
dns_params.hostname[sizeof(dns_params.hostname) - 1] = '\0';
dns_params.port = query_data->port;
/* Send the data structure to the child */
rc = write(resolver->fd_in, &dns_params, sizeof(dns_params));
if (rc < 0) {
purple_debug_error("dns", "Unable to write to DNS child %d: %s\n",
resolver->dns_pid, g_strerror(errno));
purple_dnsquery_resolver_destroy(resolver);
return FALSE;
}
if ((gsize)rc < sizeof(dns_params)) {
purple_debug_error("dns", "Tried to write %" G_GSSIZE_FORMAT
" bytes to child but only wrote %" G_GSSIZE_FORMAT "\n",
sizeof(dns_params), rc);
purple_dnsquery_resolver_destroy(resolver);
return FALSE;
}
purple_debug_info("dns",
"Successfully sent DNS request to child %d\n",
resolver->dns_pid);
query_data->resolver = resolver;
return TRUE;
}
void
purple_dnsquery_uninit(void)
{
#if defined(__unix__) || defined(__APPLE__)
while (free_dns_children != NULL)
{
purple_dnsquery_resolver_destroy(free_dns_children->data);
free_dns_children = g_slist_remove(free_dns_children, free_dns_children->data);
}
#endif
}
void
purple_dnsquery_uninit(void)
{
#if defined(PURPLE_DNSQUERY_USE_FORK)
while (free_dns_children != NULL)
{
purple_dnsquery_resolver_destroy(free_dns_children->data);
free_dns_children = g_slist_remove(free_dns_children, free_dns_children->data);
}
#endif /* end PURPLE_DNSQUERY_USE_FORK */
}
static PurpleDnsQueryResolverProcess *
purple_dnsquery_resolver_new(gboolean show_debug)
{
PurpleDnsQueryResolverProcess *resolver;
int child_out[2], child_in[2];
/* Create pipes for communicating with the child process */
if (pipe(child_out) || pipe(child_in)) {
purple_debug_error("dns",
"Could not create pipes: %s\n", strerror(errno));
return NULL;
}
resolver = g_new(PurpleDnsQueryResolverProcess, 1);
resolver->inpa = 0;
cope_with_gdb_brokenness();
/* "Go fork and multiply." --Tommy Caldwell (Emily's dad, not the climber) */
resolver->dns_pid = fork();
/* If we are the child process... */
if (resolver->dns_pid == 0) {
/* We should not access the parent's side of the pipes, so close them */
close(child_out[0]);
close(child_in[1]);
purple_dnsquery_resolver_run(child_out[1], child_in[0], show_debug);
/* The thread calls _exit() rather than returning, so we never get here */
}
/* We should not access the child's side of the pipes, so close them */
close(child_out[1]);
close(child_in[0]);
if (resolver->dns_pid == -1) {
purple_debug_error("dns",
"Could not create child process for DNS: %s\n",
strerror(errno));
purple_dnsquery_resolver_destroy(resolver);
return NULL;
}
resolver->fd_out = child_out[0];
resolver->fd_in = child_in[1];
number_of_dns_children++;
purple_debug_info("dns",
"Created new DNS child %d, there are now %d children.\n",
resolver->dns_pid, number_of_dns_children);
return resolver;
}
void
purple_dnsquery_destroy(PurpleDnsQueryData *query_data)
{
PurpleDnsQueryUiOps *ops = purple_dnsquery_get_ui_ops();
if (ops && ops->destroy)
ops->destroy(query_data);
#if defined(PURPLE_DNSQUERY_USE_FORK)
queued_requests = g_slist_remove(queued_requests, query_data);
if (query_data->resolver != NULL)
/*
* This is only non-NULL when we're cancelling an in-progress
* query. Ideally we would tell our resolver child to stop
* resolving shit and then we would add it back to the
* free_dns_children linked list. However, it's hard to tell
* children stuff, they just don't listen. So we'll just
* kill the process and allow a new child to be started if we
* have more stuff to resolve.
*/
purple_dnsquery_resolver_destroy(query_data->resolver);
#elif defined _WIN32 /* end PURPLE_DNSQUERY_USE_FORK */
if (query_data->resolver != NULL)
{
/*
* It's not really possible to kill a thread. So instead we
* just set the callback to NULL and let the DNS lookup
* finish.
*/
query_data->callback = NULL;
return;
}
while (query_data->hosts != NULL)
{
/* Discard the length... */
query_data->hosts = g_slist_remove(query_data->hosts, query_data->hosts->data);
/* Free the address... */
g_free(query_data->hosts->data);
query_data->hosts = g_slist_remove(query_data->hosts, query_data->hosts->data);
}
g_free(query_data->error_message);
#endif /* end _WIN32 */
if (query_data->timeout > 0)
purple_timeout_remove(query_data->timeout);
g_free(query_data->hostname);
g_free(query_data);
}
void
purple_dnsquery_destroy(PurpleDnsQueryData *query_data)
{
PurpleDnsQueryUiOps *ops = purple_dnsquery_get_ui_ops();
if (ops && ops->destroy)
ops->destroy(query_data);
#if defined(__unix__) || defined(__APPLE__)
queued_requests = g_slist_remove(queued_requests, query_data);
if (query_data->resolver != NULL)
/*
* Ideally we would tell our resolver child to stop resolving
* shit and then we would add it back to the free_dns_children
* linked list. However, it's hard to tell children stuff,
* they just don't listen.
*/
purple_dnsquery_resolver_destroy(query_data->resolver);
#elif defined _WIN32 /* end __unix__ || __APPLE__ */
if (query_data->resolver != NULL)
{
/*
* It's not really possible to kill a thread. So instead we
* just set the callback to NULL and let the DNS lookup
* finish.
*/
query_data->callback = NULL;
return;
}
while (query_data->hosts != NULL)
{
/* Discard the length... */
query_data->hosts = g_slist_remove(query_data->hosts, query_data->hosts->data);
/* Free the address... */
g_free(query_data->hosts->data);
query_data->hosts = g_slist_remove(query_data->hosts, query_data->hosts->data);
}
g_free(query_data->error_message);
#endif
if (query_data->timeout > 0)
purple_timeout_remove(query_data->timeout);
g_free(query_data->hostname);
g_free(query_data);
}
/**
* @return TRUE if the request was sent succesfully. FALSE
* if the request could not be sent. This isn't
* necessarily an error. If the child has expired,
* for example, we won't be able to send the message.
*/
static gboolean
send_dns_request_to_child(PurpleDnsQueryData *query_data,
PurpleDnsQueryResolverProcess *resolver)
{
pid_t pid;
dns_params_t dns_params;
int rc;
char ch;
/* This waitpid might return the child's PID if it has recently
* exited, or it might return an error if it exited "long
* enough" ago that it has already been reaped; in either
* instance, we can't use it. */
pid = waitpid(resolver->dns_pid, NULL, WNOHANG);
if (pid > 0) {
purple_debug_warning("dns", "DNS child %d no longer exists\n",
resolver->dns_pid);
purple_dnsquery_resolver_destroy(resolver);
return FALSE;
} else if (pid < 0) {
purple_debug_warning("dns", "Wait for DNS child %d failed: %s\n",
resolver->dns_pid, strerror(errno));
purple_dnsquery_resolver_destroy(resolver);
return FALSE;
}
/* Copy the hostname and port into a single data structure */
strncpy(dns_params.hostname, query_data->hostname, sizeof(dns_params.hostname) - 1);
dns_params.hostname[sizeof(dns_params.hostname) - 1] = '\0';
dns_params.port = query_data->port;
/* Send the data structure to the child */
rc = write(resolver->fd_in, &dns_params, sizeof(dns_params));
if (rc < 0) {
purple_debug_error("dns", "Unable to write to DNS child %d: %d\n",
resolver->dns_pid, strerror(errno));
purple_dnsquery_resolver_destroy(resolver);
return FALSE;
}
g_return_val_if_fail(rc == sizeof(dns_params), -1);
/* Did you hear me? (This avoids some race conditions) */
rc = read(resolver->fd_out, &ch, sizeof(ch));
if (rc != 1 || ch != 'Y')
{
purple_debug_warning("dns",
"DNS child %d not responding. Killing it!\n",
resolver->dns_pid);
purple_dnsquery_resolver_destroy(resolver);
return FALSE;
}
purple_debug_info("dns",
"Successfully sent DNS request to child %d\n",
resolver->dns_pid);
query_data->resolver = resolver;
return TRUE;
}
