conntrackd: allow to remove file descriptors from set

With this patch, we can remove file descriptors dinamically
from our own file descriptor pool.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

2 files changed, 55 insertions, 0 deletions

diff --git a/include/fds.h b/include/fds.h
index 019d3f9..f3728d7 100644
--- a/include/fds.h
+++ b/include/fds.h
@@ -1,13 +1,22 @@
 #ifndef _FDS_H_
 #define _FDS_H_
 
+#include "linux_list.h"
+
 struct fds {
 	int	maxfd;
 	fd_set	readfds;
+	struct list_head list;
+};
+
+struct fds_item {
+	struct list_head        head;
+	int                     fd;
 };
 
 struct fds *create_fds(void);
 void destroy_fds(struct fds *);
 int register_fd(int fd, struct fds *fds);
+int unregister_fd(int fd, struct fds *fds);
 
 #endif
diff --git a/src/fds.c b/src/fds.c
index fac3482..6304fcd 100644
--- a/src/fds.c
+++ b/src/fds.c
@@ -27,20 +27,66 @@ struct fds *create_fds(void)
 	if (fds == NULL)
 		return NULL;
 
+	INIT_LIST_HEAD(&fds->list);
+
 	return fds;
 }
 
 void destroy_fds(struct fds *fds)
 {
+	struct fds_item *this, *tmp;
+
+	list_for_each_entry_safe(this, tmp, &fds->list, head) {
+		list_del(&this->head);
+		FD_CLR(this->fd, &fds->readfds);
+		free(this);
+	}
 	free(fds);
 }
 
 int register_fd(int fd, struct fds *fds)
 {
+	struct fds_item *item;
+	
 	FD_SET(fd, &fds->readfds);
 
 	if (fd > fds->maxfd)
 		fds->maxfd = fd;
 
+	item = calloc(sizeof(struct fds_item), 1);
+	if (item == NULL)
+		return -1;
+
+	item->fd = fd;
+	list_add(&item->head, &fds->list);
+
 	return 0;
 }
+
+int unregister_fd(int fd, struct fds *fds)
+{
+	int found = 0, maxfd = -1;
+	struct fds_item *this, *tmp;
+
+	list_for_each_entry_safe(this, tmp, &fds->list, head) {
+		if (this->fd == fd) {
+			list_del(&this->head);
+			FD_CLR(this->fd, &fds->readfds);
+			free(this);
+			found = 1;
+			/* ... and recalculate maxfd, see below. */
+		}
+	}
+	/* not found, report an error. */
+	if (!found)
+		return -1;
+
+	/* calculate the new maximum fd. */
+	list_for_each_entry(this, &fds->list, head) {
+		if (maxfd < this->fd) {
+			maxfd = this->fd;
+		}
+	}
+	return 0;
+}
+