[tor-commits] [obfsproxy/master] Improvements on the signal handling code.
nickm at torproject.org
nickm at torproject.org
Thu Jul 14 15:39:26 UTC 2011
commit 9d96eb9422b23fecacc198bf110e3a944ab182be
Author: George Kadianakis <desnacked at gmail.com>
Date: Fri Jul 8 18:15:55 2011 +0200
Improvements on the signal handling code.
* Implemented a generic double linked list, which is now used for
connections and listeners.
* We now close the listeners when we are shutting down instead of
closing their sockets.
---
src/main.c | 69 ++++++++++++++++++++------
src/network.c | 153 ++++++++++++++++++--------------------------------------
src/network.h | 1 +
src/util.c | 141 ++++++++++++++++++++++++++++++++++++++++++++++++++++
src/util.h | 19 +++++++
5 files changed, 264 insertions(+), 119 deletions(-)
diff --git a/src/main.c b/src/main.c
index 81e8c31..56ea9c9 100644
--- a/src/main.c
+++ b/src/main.c
@@ -35,6 +35,9 @@ extern int n_supported_protocols;
static struct event_base *the_event_base=NULL;
+/** Doubly linked list holding all our listeners. */
+static dll_t *ll=NULL;
+
/**
Prints the obfsproxy usage instructions then exits.
*/
@@ -58,6 +61,24 @@ usage(void)
}
/**
+ Disables all active listeners.
+*/
+static void
+disable_all_listeners(void)
+{
+ if (!ll)
+ return;
+ log_info("Disabling all listeners.");
+
+ /* Iterate listener doubly linked list and disable them all. */
+ dll_node_t *ll_node = ll->head;
+ while (ll_node) {
+ listener_disable(ll_node->data);
+ ll_node = ll_node->next;
+ }
+}
+
+/**
This is called when we receive a signal.
It figures out the signal type and acts accordingly.
@@ -73,17 +94,29 @@ handle_signal_cb(evutil_socket_t fd, short what, void *arg)
{
int signum = (int) fd;
static int got_sigint=0;
+ static int disabled_listeners=0;
switch (signum) {
case SIGINT:
+ if (!disabled_listeners) {
+ disable_all_listeners();
+ disabled_listeners++;
+ }
if (!got_sigint) {
+ log_info("Got SIGINT. Preparing shutdown.");
start_shutdown(0);
got_sigint++;
} else {
+ log_info("Got SIGINT for the second time. Terminating.");
start_shutdown(1);
}
break;
case SIGTERM:
+ if (!disabled_listeners) {
+ disable_all_listeners();
+ disabled_listeners++;
+ }
+ log_info("Got SIGTERM. Terminating.");
start_shutdown(1);
break;
}
@@ -348,18 +381,10 @@ main(int argc, const char **argv)
/*Let's open a new listener for each protocol. */
int h;
- listener_t **listeners;
listener_t *temp_listener;
int n_listeners=0;
protocol_params_t *proto_params=NULL;
- listeners = calloc(sizeof(listener_t*), actual_protocols);
- if (!listeners) {
- log_warn("Allocation failure: %s", strerror(errno));
- return 1;
- }
-
for (h=0;h<actual_protocols;h++) {
-
log_debug("Spawning listener %d!", h+1);
/** normally free'd in listener_free() */
@@ -379,8 +404,16 @@ main(int argc, const char **argv)
continue;
log_info("Succesfully created listener %d.", h+1);
- listeners[n_listeners] = temp_listener;
-
+
+ /* If we don't have a listener dll, create one now. */
+ if (!ll) {
+ ll = calloc(1, sizeof(dll_t));
+ if (!ll)
+ return 1;
+ }
+
+ /* Append our new listener in the listener dll. */
+ dll_append(ll, temp_listener);
n_listeners++;
}
@@ -398,11 +431,17 @@ main(int argc, const char **argv)
if (close_obfsproxy_logfile() < 0)
printf("Failed closing logfile!\n");
- /* We are exiting. Clean everything. */
- for (h=0;h<n_listeners;h++)
- listener_free(listeners[h]);
- if (listeners)
- free(listeners);
+ /* Free all listeners in our listener dll. */
+ if (ll) {
+ dll_node_t *ll_node = ll->head;
+ while (ll_node) {
+ listener_free(ll_node->data);
+ dll_remove(ll, ll_node);
+ ll_node = ll->head;
+ }
+ /* free dll memory */
+ free(ll);
+ }
free(protocol_options);
free(n_options_array);
diff --git a/src/network.c b/src/network.c
index fc53564..1103eeb 100644
--- a/src/network.c
+++ b/src/network.c
@@ -26,19 +26,8 @@ struct listener_t {
protocol_params_t *proto_params;
};
-/**
- Linked list carrying all currently active connections.
- [linked list code was copied off tor.]
-*/
-typedef struct conn_list_t {
- conn_t *conn;
- struct conn_list_t *next;
-} conn_list_t;
-
-/** First and last elements in the linked list of active
- connections. */
-static conn_list_t *cl_list=NULL;
-static conn_list_t *cl_tail=NULL;
+/** Doubly linked list holding all connections. */
+static dll_t *cl=NULL;
/** Active connection counter */
static int n_connections=0;
@@ -68,6 +57,8 @@ static void output_event_cb(struct bufferevent *bev, short what, void *arg);
If 'barbaric' is set, we forcefully close all open connections and
finish shutdown.
+
+ (Only called by signal handlers)
*/
void
start_shutdown(int barbaric)
@@ -76,6 +67,8 @@ start_shutdown(int barbaric)
shutting_down=1;
if (!n_connections) {
+ if (cl)
+ free(cl);
finish_shutdown();
return;
}
@@ -83,7 +76,6 @@ start_shutdown(int barbaric)
if (barbaric) {
if (n_connections)
close_all_connections();
- finish_shutdown();
return;
}
}
@@ -94,87 +86,18 @@ start_shutdown(int barbaric)
static void
close_all_connections(void)
{
- conn_t *conn;
-
- while (cl_list) {
- assert(cl_list->conn);
- assert(n_connections > 0);
- conn = cl_list->conn;
- conn_free(conn);
- }
-}
-
-/**
- Places 'conn' to the end of the linked list of active connections.
- Returns 1 on success, -1 on fail.
-*/
-static int
-cl_add(conn_t *conn)
-{
- conn_list_t *cl;
-
- cl = calloc(1, sizeof(conn_list_t));
- if (!cl)
- return -1;
-
- cl->conn = conn;
-
- if (!cl_tail) {
- assert(!cl_list);
- assert(!n_connections);
- cl_list=cl;
- cl_tail=cl;
- } else {
- assert(cl_list);
- assert(!cl_tail->next);
- cl_tail->next = cl;
- cl_tail = cl;
- }
-
- n_connections++;
-
- return 1;
-}
-
-/**
- Removes 'conn' from the linked list of connections:
- It frees the list node carrying 'conn', but leaves 'conn' itself intact.
-*/
-static void
-cl_remove(conn_t *conn)
-{
- conn_list_t *tmpo, *victim;
-
- if (!cl_list)
- return; /* nothing here. */
-
- /* first check to see if it's the first entry */
- tmpo = cl_list;
- if (tmpo->conn == conn) {
- /* it's the first one. remove it from the list. */
- cl_list = tmpo->next;
- if (!cl_list)
- cl_tail = NULL;
- n_connections--;
- victim = tmpo;
- } else { /* we need to hunt through the rest of the list */
- for ( ;tmpo->next && tmpo->next->conn != conn; tmpo=tmpo->next) ;
- if (!tmpo->next) {
- return;
+ /** Traverse the dll and close all connections */
+ dll_node_t *cl_node = cl->head;
+ while (cl_node) {
+ conn_free(cl_node->data);
+
+ if (cl) { /* last conn_free() wipes the cl. */
+ cl_node = cl->head; /* move to next connection */
+ } else {
+ assert(!n_connections);
+ return; /* connections are now all closed. */
}
- /* now we know tmpo->next->conn == conn */
- victim = tmpo->next;
- tmpo->next = victim->next;
- if (cl_tail == victim)
- cl_tail = tmpo;
- n_connections--;
- }
-
- assert(n_connections>=0);
-
- /* now victim points to the element that needs to be removed */
- free(victim);
- victim = NULL;
+ }
}
/**
@@ -197,6 +120,13 @@ listener_new(struct event_base *base,
return NULL;
}
+ /** If we don't have a connection dll, create one now. */
+ if (!cl) {
+ cl = calloc(1, sizeof(dll_t));
+ if (!cl)
+ return NULL;
+ }
+
lsn->proto_params = proto_params;
lsn->listener = evconnlistener_new_bind(base, simple_listener_cb, lsn,
@@ -214,6 +144,17 @@ listener_new(struct event_base *base,
return lsn;
}
+/**
+ Disable listener 'lsn'.
+*/
+void
+listener_disable(listener_t *lsn)
+{
+ assert(lsn);
+
+ evconnlistener_disable(lsn->listener);
+}
+
void
listener_free(listener_t *lsn)
{
@@ -229,12 +170,6 @@ static void
simple_listener_cb(struct evconnlistener *evcl,
evutil_socket_t fd, struct sockaddr *sourceaddr, int socklen, void *arg)
{
- if (shutting_down) {
- if (fd >= 0)
- evutil_closesocket(fd);
- return ;
- }
-
listener_t *lsn = arg;
struct event_base *base;
conn_t *conn = calloc(1, sizeof(conn_t));
@@ -315,8 +250,9 @@ simple_listener_cb(struct evconnlistener *evcl,
}
/* add conn to the linked list of connections */
- if (cl_add(conn)<0)
+ if (dll_append(cl, conn)<0)
goto err;
+ n_connections++;
log_debug("Connection setup completed. "
"We currently have %d connections!", n_connections);
@@ -340,18 +276,27 @@ conn_free(conn_t *conn)
bufferevent_free(conn->input);
if (conn->output)
bufferevent_free(conn->output);
- memset(conn, 0x99, sizeof(conn_t));
+
/* remove conn from the linked list of connections */
- cl_remove(conn);
+ dll_remove_with_data(cl, conn);
+ n_connections--;
+
+ memset(conn, 0x99, sizeof(conn_t));
free(conn);
+ assert(n_connections>=0);
log_debug("Connection destroyed. "
"We currently have %d connections!", n_connections);
/** If this was the last connection AND we are shutting down,
finish shutdown. */
- if (!n_connections && shutting_down)
+ if (!n_connections && shutting_down) {
+ if (cl) { /* free connection dll */
+ free(cl);
+ cl = NULL;
+ }
finish_shutdown();
+ }
}
static void
diff --git a/src/network.h b/src/network.h
index 28a0d7d..a8c02ac 100644
--- a/src/network.h
+++ b/src/network.h
@@ -46,6 +46,7 @@ struct addrinfo;
listener_t *listener_new(struct event_base *base,
struct protocol_params_t *params);
void listener_free(listener_t *listener);
+void listener_disable(listener_t *lsn);
void start_shutdown(int barbaric);
diff --git a/src/util.c b/src/util.c
index 7e3e747..1ee7bcb 100644
--- a/src/util.c
+++ b/src/util.c
@@ -148,6 +148,146 @@ obfs_vsnprintf(char *str, size_t size, const char *format, va_list args)
return r;
}
+/************************ Doubly Linked List (DLL) ******************/
+
+/**
+ Insert 'new_node' after 'node' in the doubly linked list 'list'.
+*/
+static void
+dll_insert_after(dll_t *list, dll_node_t *node, dll_node_t *new_node)
+{
+ assert(node);
+ assert(new_node);
+
+ if (!list)
+ return;
+
+ new_node->prev = node;
+ new_node->next = node->next;
+ if (!node->next)
+ list->tail = new_node;
+ else
+ node->next->prev = new_node;
+ node->next = new_node;
+}
+
+/**
+ Insert 'new_node' before 'node' in the doubly linked list 'list'.
+*/
+static void
+dll_insert_before(dll_t *list, dll_node_t *node, dll_node_t *new_node)
+{
+ assert(node);
+ assert(new_node);
+
+ if (!list)
+ return;
+
+ new_node->prev = node->prev;
+ new_node->next = node;
+ if (!node->prev)
+ list->head = new_node;
+ else
+ node->prev->next = new_node;
+ node->prev = new_node;
+}
+
+/**
+ Insert 'node' in the beginning of the doubly linked 'list'.
+*/
+static void
+dll_insert_beginning(dll_t *list, dll_node_t *node)
+{
+ assert(node);
+
+ if (!list)
+ return;
+
+ if (!list->head) {
+ list->head = node;
+ list->tail = node;
+ node->prev = NULL;
+ node->next = NULL;
+ } else {
+ dll_insert_before(list, list->head, node);
+ }
+}
+
+/**
+ Appends 'data' to the end of the doubly linked 'list'.
+ Returns 1 on success, -1 on fail.
+*/
+int
+dll_append(dll_t *list, void *data)
+{
+ assert(data);
+
+ if (!list)
+ return -1;
+
+ dll_node_t *node;
+
+ node = calloc(1, sizeof(dll_node_t));
+ if (!node)
+ return -1;
+ node->data = data;
+
+ if (!list->tail)
+ dll_insert_beginning(list, node);
+ else
+ dll_insert_after(list, list->tail, node);
+
+ return 1;
+}
+
+/**
+ Removes 'node' from the doubly linked list 'list'.
+ It frees the list node, but leaves its data intact.
+*/
+void
+dll_remove(dll_t *list, dll_node_t *node)
+{
+ assert(node);
+
+ if (!list)
+ return;
+
+ if (!node->prev)
+ list->head = node->next;
+ else
+ node->prev->next = node->next;
+ if (!node->next)
+ list->tail = node->prev;
+ else
+ node->next->prev = node->prev;
+
+ free(node);
+}
+
+/**
+ Removes node carrying 'data' from the doubly linked list 'list'.
+ It frees the list node, but leaves 'data' intact.
+*/
+void
+dll_remove_with_data(dll_t *list, void *data)
+{
+ assert(data);
+
+ if (!list)
+ return;
+
+ dll_node_t *node = list->head;
+ while (node) {
+ if (node->data == data) {
+ dll_remove(list, node);
+ return;
+ } else {
+ node = node->next;
+ }
+ }
+ assert(0); /*too brutal?*/
+}
+
/************************ Logging Subsystem *************************/
/** The code of this section was to a great extend shamelessly copied
off tor. It's basicaly a stripped down version of tor's logging
@@ -404,3 +544,4 @@ log_debug(const char *format, ...)
va_end(ap);
}
#endif
+
diff --git a/src/util.h b/src/util.h
index 2705d51..999c5df 100644
--- a/src/util.h
+++ b/src/util.h
@@ -50,6 +50,25 @@ int obfs_snprintf(char *str, size_t size,
const char *format, ...)
__attribute__((format(printf, 3, 4)));
+/***** Doubly Linked List stuff. *****/
+
+/** A doubly linked list node.
+ [algorithms ripped off Wikipedia (Doubly_linked_list) ] */
+typedef struct dll_node_t {
+ struct dll_node_t *next, *prev;
+ void *data;
+} dll_node_t;
+
+/** A doubly linked list. */
+typedef struct dll_t {
+ struct dll_node_t *head;
+ struct dll_node_t *tail;
+} dll_t;
+
+int dll_append(dll_t *list, void *data);
+void dll_remove(dll_t *list, dll_node_t *node);
+void dll_remove_with_data(dll_t *list, void *data);
+
/***** Logging subsystem stuff. *****/
void log_fn(int severity, const char *format, ...)
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