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authorFlorian Westphal <fw@strlen.de>2013-04-26 10:21:16 +0200
committerFlorian Westphal <fw@strlen.de>2013-04-30 16:57:22 +0200
commit6c7b3366eae8a912c56d1940ba221a1d7f8eb680 (patch)
tree4596d6ed89513d98797ce2cdb0e0daf7fab700f9 /src/libnetfilter_queue.c
parent0052078cf4cb03b23c49ef1cd65f69df746890b4 (diff)
src: add new GSO handling capabilities
allows userspace to ask for large gso packets via nfqueue. Signed-off-by: Florian Westphal <fw@strlen.de>
Diffstat (limited to 'src/libnetfilter_queue.c')
-rw-r--r--src/libnetfilter_queue.c17
1 files changed, 17 insertions, 0 deletions
diff --git a/src/libnetfilter_queue.c b/src/libnetfilter_queue.c
index 2894ccd..c59bc63 100644
--- a/src/libnetfilter_queue.c
+++ b/src/libnetfilter_queue.c
@@ -639,6 +639,23 @@ int nfq_set_mode(struct nfq_q_handle *qh,
* - NFQA_CFG_F_CONNTRACK (requires Linux kernel >= 3.6): the kernel will
* include the Connection Tracking system information.
*
+ * - NFQA_CFG_F_GSO (requires Linux kernel >= 3.10): the kernel will
+ * not normalize offload packets, i.e. your application will need to
+ * be able to handle packets larger than the mtu (up to 64k).
+ *
+ * If your application validates checksums (e.g., tcp checksum),
+ * then you must also check if the NFQA_SKB_INFO attribute is present.
+ * If it is, you need to test the NFQA_SKB_CSUMNOTREADY bit:
+ * \verbatim
+ if (attr[NFQA_SKB_INFO]) {
+ uint32_t info = ntohl(mnl_attr_get_u32(attr[NFQA_SKB_INFO]));
+ if (info & NFQA_SKB_CSUMNOTREADY)
+ validate_checksums = false;
+ }
+\endverbatim
+ * if this bit is set, the layer 3/4 checksums of the packet appear incorrect,
+ * but are not (because they will be corrected later by the kernel).
+ *
* Here's a little code snippet to show how to use this API:
* \verbatim
uint32_t flags = NFQA_CFG_F_FAIL_OPEN;