[PATCH 4/4] examples/nf-queue: receive large gso packets

[Florian Westphal <fw@strlen.de>]

Signed-off-by: Florian Westphal <fw@strlen.de>
---
 examples/nf-queue.c |   29 +++++++++++++++++++++++++++--
 1 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/examples/nf-queue.c b/examples/nf-queue.c
index 6641a24..1f465ad 100644
--- a/examples/nf-queue.c
+++ b/examples/nf-queue.c
@@ -51,7 +51,7 @@ static int queue_cb(const struct nlmsghdr *nlh, void *data)
 {
 	struct nfqnl_msg_packet_hdr *ph = NULL;
 	struct nlattr *attr[NFQA_MAX+1] = {};
-	uint32_t id = 0;
+	uint32_t id = 0, skbinfo;
 	struct nfgenmsg *nfg;
 	uint16_t plen;
 
@@ -72,10 +72,32 @@ static int queue_cb(const struct nlmsghdr *nlh, void *data)
 	plen = mnl_attr_get_payload_len(attr[NFQA_PAYLOAD]);
 	/* void *payload = mnl_attr_get_payload(attr[NFQA_PAYLOAD]); */
 
+	skbinfo = attr[NFQA_SKB_INFO] ? ntohl(mnl_attr_get_u32(attr[NFQA_SKB_INFO])) : 0;
+
+	if (attr[NFQA_CAP_LEN]) {
+		uint32_t orig_len = ntohl(mnl_attr_get_u32(attr[NFQA_CAP_LEN]));
+		if (orig_len != plen)
+			printf("truncated ");
+	}
+
+	if (skbinfo & NFQA_SKB_GSO)
+		printf("GSO ");
+
 	id = ntohl(ph->packet_id);
-	printf("packet received (id=%u hw=0x%04x hook=%u, payload len %u)\n",
+	printf("packet received (id=%u hw=0x%04x hook=%u, payload len %u",
 		id, ntohs(ph->hw_protocol), ph->hook, plen);
 
+	/*
+	 * ip/tcp checksums are not yet valid, e.g. due to GRO/GSO.
+	 * The application should behave as if the checksums are correct.
+	 *
+	 * If these packets are later forwarded/sent out, the checksums will
+	 * be corrected by kernel/hardware.
+	 */
+	if (skbinfo & NFQA_SKB_CSUMNOTREADY)
+		printf(", checksum not ready");
+	puts(")");
+
 	nfq_send_verdict(ntohs(nfg->res_id), id);
 
 	return MNL_CB_OK;
@@ -141,6 +163,9 @@ int main(int argc, char *argv[])
 	nlh = nfq_hdr_put(buf, NFQNL_MSG_CONFIG, queue_num);
 	nfq_nlmsg_cfg_put_params(nlh, NFQNL_COPY_PACKET, 0xffff);
 
+	mnl_attr_put_u32(nlh, NFQA_CFG_FLAGS, htonl(NFQA_CFG_F_GSO));
+	mnl_attr_put_u32(nlh, NFQA_CFG_MASK, htonl(NFQA_CFG_F_GSO));
+
 	if (mnl_socket_sendto(nl, nlh, nlh->nlmsg_len) < 0) {
 		perror("mnl_socket_send");
 		exit(EXIT_FAILURE);
-- 
1.7.8.6