[PATCH libnetfilter_queue v2 08/15] src: Incorporate nfnl_rcvbufsiz() in libnetfilter_queue

[Duncan Roe <duncan_roe@optusnet.com.au>]

nfnl_rcvbufsiz() is the first bullet point in the Performance section
of the libnetfilter_queue HTML main page.
We have to assume people have used it,
so supply a version that uses libmnl.

Signed-off-by: Duncan Roe <duncan_roe@optusnet.com.au>
---
 v2: rebase to account for updated patches

 .../libnetfilter_queue/libnetfilter_queue.h   |  2 ++
 src/libnetfilter_queue.c                      | 36 +++++++++++++++++++
 2 files changed, 38 insertions(+)

diff --git a/include/libnetfilter_queue/libnetfilter_queue.h b/include/libnetfilter_queue/libnetfilter_queue.h
index f7e68d8..9327f8c 100644
--- a/include/libnetfilter_queue/libnetfilter_queue.h
+++ b/include/libnetfilter_queue/libnetfilter_queue.h
@@ -35,6 +35,8 @@ typedef int  nfq_callback(struct nfq_q_handle *gh, struct nfgenmsg *nfmsg,
 		       struct nfq_data *nfad, void *data);
 
 
+extern unsigned int nfnl_rcvbufsiz(const struct nfnl_handle *h,
+				   unsigned int size);
 extern struct nfq_handle *nfq_open(void);
 extern struct nfq_handle *nfq_open_nfnl(struct nfnl_handle *nfnlh);
 extern int nfq_close(struct nfq_handle *h);
diff --git a/src/libnetfilter_queue.c b/src/libnetfilter_queue.c
index 3fa8d2d..f26b65f 100644
--- a/src/libnetfilter_queue.c
+++ b/src/libnetfilter_queue.c
@@ -585,6 +585,42 @@ out_free:
  * @{
  */
 
+/**
+ * nfnl_rcvbufsiz - set the socket buffer size
+ * \param h nfnetlink connection handle obtained via call to \b nfq_nfnlh()
+ * \param size size of the buffer we want to set
+ *
+ * This nfnl-API function sets the new size of the socket buffer.
+ * Use this setting
+ * to increase the socket buffer size if your system is reporting ENOBUFS
+ * errors.
+ *
+ * \return new size of kernel socket buffer
+ */
+
+EXPORT_SYMBOL
+unsigned int nfnl_rcvbufsiz(const struct nfnl_handle *h, unsigned int size)
+{
+	int status;
+	socklen_t socklen = sizeof(size);
+	unsigned int read_size = 0;
+
+	/* first we try the FORCE option, which is introduced in kernel
+	 * 2.6.14 to give "root" the ability to override the system wide
+	 * maximum
+	 */
+	status = setsockopt(h->fd, SOL_SOCKET, SO_RCVBUFFORCE, &size, socklen);
+	if (status < 0) {
+		/* if this didn't work, we try at least to get the system
+		 * wide maximum (or whatever the user requested)
+		 */
+		setsockopt(h->fd, SOL_SOCKET, SO_RCVBUF, &size, socklen);
+	}
+	getsockopt(h->fd, SOL_SOCKET, SO_RCVBUF, &read_size, &socklen);
+
+	return read_size;
+}
+
 /**
  * nfq_close - close a nfqueue handler
  * \param h Netfilter queue connection handle obtained via call to nfq_open()
-- 
2.35.8