selftests/net: GRO coalesce test

Implement a GRO testsuite that expects Linux kernel GRO behavior.
All tests pass with the kernel software GRO stack. Run against a device
with hardware GRO to verify that it matches the software stack.

gro.c generates packets and sends them out through a packet socket. The
receiver in gro.c (run separately) receives the packets on a packet
socket, filters them by destination ports using BPF and checks the
packet geometry to see whether GRO was applied.

gro.sh provides a wrapper to run the gro.c in NIC loopback mode.
It is not included in continuous testing because it modifies network
configuration around a physical NIC: gro.sh sets the NIC in loopback
mode, creates macvlan devices on the physical device in separate
namespaces, and sends traffic generated by gro.c between the two
namespaces to observe coalescing behavior.

GRO coalescing is time sensitive.
Some tests may prove flaky on some hardware.

Note that this test suite tests for software GRO unless hardware GRO is
enabled (ethtool -K $DEV rx-gro-hw on).

To test, run ./gro.sh.
The wrapper will output success or failed test names, and generate
log.txt and stderr.

Sample log.txt result:
...
pure data packet of same size: Test succeeded

large data packets followed by a smaller one: Test succeeded

small data packets followed by a larger one: Test succeeded
...

Sample stderr result:
...
carrier ready
running test ipv4 data
Expected {200 }, Total 1 packets
Received {200 }, Total 1 packets.
...
Signed-off-by: Coco Li <lixiaoyan@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

tools/testing/selftests/net/Makefile

@@ -38,6 +38,7 @@ TEST_GEN_FILES += reuseaddr_ports_exhausted
 TEST_GEN_FILES += hwtstamp_config rxtimestamp timestamping txtimestamp
 TEST_GEN_FILES += ipsec
 TEST_GEN_FILES += ioam6_parser
+TEST_GEN_FILES += gro
 TEST_GEN_PROGS = reuseport_bpf reuseport_bpf_cpu reuseport_bpf_numa
 TEST_GEN_PROGS += reuseport_dualstack reuseaddr_conflict tls
 

tools/testing/selftests/net/gro.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * This testsuite provides conformance testing for GRO coalescing.
+ *
+ * Test cases:
+ * 1.data
+ *  Data packets of the same size and same header setup with correct
+ *  sequence numbers coalesce. The one exception being the last data
+ *  packet coalesced: it can be smaller than the rest and coalesced
+ *  as long as it is in the same flow.
+ * 2.ack
+ *  Pure ACK does not coalesce.
+ * 3.flags
+ *  Specific test cases: no packets with PSH, SYN, URG, RST set will
+ *  be coalesced.
+ * 4.tcp
+ *  Packets with incorrect checksum, non-consecutive seqno and
+ *  different TCP header options shouldn't coalesce. Nit: given that
+ *  some extension headers have paddings, such as timestamp, headers
+ *  that are padding differently would not be coalesced.
+ * 5.ip:
+ *  Packets with different (ECN, TTL, TOS) header, ip options or
+ *  ip fragments (ipv6) shouldn't coalesce.
+ * 6.large:
+ *  Packets larger than GRO_MAX_SIZE packets shouldn't coalesce.
+ *
+ * MSS is defined as 4096 - header because if it is too small
+ * (i.e. 1500 MTU - header), it will result in many packets,
+ * increasing the "large" test case's flakiness. This is because
+ * due to time sensitivity in the coalescing window, the receiver
+ * may not coalesce all of the packets.
+ *
+ * Note the timing issue applies to all of the test cases, so some
+ * flakiness is to be expected.
+ *
+ */
+
+#define _GNU_SOURCE
+
+#include <arpa/inet.h>
+#include <errno.h>
+#include <error.h>
+#include <getopt.h>
+#include <linux/filter.h>
+#include <linux/if_packet.h>
+#include <linux/ipv6.h>
+#include <net/ethernet.h>
+#include <net/if.h>
+#include <netinet/in.h>
+#include <netinet/ip.h>
+#include <netinet/ip6.h>
+#include <netinet/tcp.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdarg.h>
+#include <string.h>
+#include <unistd.h>
+
+#define DPORT 8000
+#define SPORT 1500
+#define PAYLOAD_LEN 100
+#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
+#define NUM_PACKETS 4
+#define START_SEQ 100
+#define START_ACK 100
+#define SIP6 "fdaa::2"
+#define DIP6 "fdaa::1"
+#define SIP4 "192.168.1.200"
+#define DIP4 "192.168.1.100"
+#define ETH_P_NONE 0
+#define TOTAL_HDR_LEN (ETH_HLEN + sizeof(struct ipv6hdr) + sizeof(struct tcphdr))
+#define MSS (4096 - sizeof(struct tcphdr) - sizeof(struct ipv6hdr))
+#define MAX_PAYLOAD (IP_MAXPACKET - sizeof(struct tcphdr) - sizeof(struct ipv6hdr))
+#define NUM_LARGE_PKT (MAX_PAYLOAD / MSS)
+#define MAX_HDR_LEN (ETH_HLEN + sizeof(struct ipv6hdr) + sizeof(struct tcphdr))
+
+static int proto = -1;
+static uint8_t src_mac[ETH_ALEN], dst_mac[ETH_ALEN];
+static char *testname = "data";
+static char *ifname = "eth0";
+static char *smac = "aa:00:00:00:00:02";
+static char *dmac = "aa:00:00:00:00:01";
+static bool verbose;
+static bool tx_socket = true;
+static int tcp_offset = -1;
+static int total_hdr_len = -1;
+static int ethhdr_proto = -1;
+
+static void vlog(const char *fmt, ...)
+{
+	va_list args;
+
+	if (verbose) {
+		va_start(args, fmt);
+		vfprintf(stderr, fmt, args);
+		va_end(args);
+	}
+}
+
+static void setup_sock_filter(int fd)
+{
+	const int dport_off = tcp_offset + offsetof(struct tcphdr, dest);
+	const int ethproto_off = offsetof(struct ethhdr, h_proto);
+	int optlen = 0;
+	int ipproto_off;
+	int next_off;
+
+	if (proto == PF_INET)
+		next_off = offsetof(struct iphdr, protocol);
+	else
+		next_off = offsetof(struct ipv6hdr, nexthdr);
+	ipproto_off = ETH_HLEN + next_off;
+
+	if (strcmp(testname, "ip") == 0) {
+		if (proto == PF_INET)
+			optlen = sizeof(struct ip_timestamp);
+		else
+			optlen = sizeof(struct ip6_frag);
+	}
+
+	struct sock_filter filter[] = {
+			BPF_STMT(BPF_LD  + BPF_H   + BPF_ABS, ethproto_off),
+			BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ntohs(ethhdr_proto), 0, 7),
+			BPF_STMT(BPF_LD  + BPF_B   + BPF_ABS, ipproto_off),
+			BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, IPPROTO_TCP, 0, 5),
+			BPF_STMT(BPF_LD  + BPF_H   + BPF_ABS, dport_off),
+			BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, DPORT, 2, 0),
+			BPF_STMT(BPF_LD  + BPF_H   + BPF_ABS, dport_off + optlen),
+			BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, DPORT, 0, 1),
+			BPF_STMT(BPF_RET + BPF_K, 0xFFFFFFFF),
+			BPF_STMT(BPF_RET + BPF_K, 0),
+	};
+
+	struct sock_fprog bpf = {
+		.len = ARRAY_SIZE(filter),
+		.filter = filter,
+	};
+
+	if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &bpf, sizeof(bpf)) < 0)
+		error(1, errno, "error setting filter");
+}
+
+static uint32_t checksum_nofold(void *data, size_t len, uint32_t sum)
+{
+	uint16_t *words = data;
+	int i;
+
+	for (i = 0; i < len / 2; i++)
+		sum += words[i];
+	if (len & 1)
+		sum += ((char *)data)[len - 1];
+	return sum;
+}
+
+static uint16_t checksum_fold(void *data, size_t len, uint32_t sum)
+{
+	sum = checksum_nofold(data, len, sum);
+	while (sum > 0xFFFF)
+		sum = (sum & 0xFFFF) + (sum >> 16);
+	return ~sum;
+}
+
+static uint16_t tcp_checksum(void *buf, int payload_len)
+{
+	struct pseudo_header6 {
+		struct in6_addr saddr;
+		struct in6_addr daddr;
+		uint16_t protocol;
+		uint16_t payload_len;
+	} ph6;
+	struct pseudo_header4 {
+		struct in_addr saddr;
+		struct in_addr daddr;
+		uint16_t protocol;
+		uint16_t payload_len;
+	} ph4;
+	uint32_t sum = 0;
+
+	if (proto == PF_INET6) {
+		if (inet_pton(AF_INET6, SIP6, &ph6.saddr) != 1)
+			error(1, errno, "inet_pton6 source ip pseudo");
+		if (inet_pton(AF_INET6, DIP6, &ph6.daddr) != 1)
+			error(1, errno, "inet_pton6 dest ip pseudo");
+		ph6.protocol = htons(IPPROTO_TCP);
+		ph6.payload_len = htons(sizeof(struct tcphdr) + payload_len);
+
+		sum = checksum_nofold(&ph6, sizeof(ph6), 0);
+	} else if (proto == PF_INET) {
+		if (inet_pton(AF_INET, SIP4, &ph4.saddr) != 1)
+			error(1, errno, "inet_pton source ip pseudo");
+		if (inet_pton(AF_INET, DIP4, &ph4.daddr) != 1)
+			error(1, errno, "inet_pton dest ip pseudo");
+		ph4.protocol = htons(IPPROTO_TCP);
+		ph4.payload_len = htons(sizeof(struct tcphdr) + payload_len);
+
+		sum = checksum_nofold(&ph4, sizeof(ph4), 0);
+	}
+
+	return checksum_fold(buf, sizeof(struct tcphdr) + payload_len, sum);
+}
+
+static void read_MAC(uint8_t *mac_addr, char *mac)
+{
+	if (sscanf(mac, "%hhx:%hhx:%hhx:%hhx:%hhx:%hhx",
+		   &mac_addr[0], &mac_addr[1], &mac_addr[2],
+		   &mac_addr[3], &mac_addr[4], &mac_addr[5]) != 6)
+		error(1, 0, "sscanf");
+}
+
+static void fill_datalinklayer(void *buf)
+{
+	struct ethhdr *eth = buf;
+
+	memcpy(eth->h_dest, dst_mac, ETH_ALEN);
+	memcpy(eth->h_source, src_mac, ETH_ALEN);
+	eth->h_proto = ethhdr_proto;
+}
+
+static void fill_networklayer(void *buf, int payload_len)
+{
+	struct ipv6hdr *ip6h = buf;
+	struct iphdr *iph = buf;
+
+	if (proto == PF_INET6) {
+		memset(ip6h, 0, sizeof(*ip6h));
+
+		ip6h->version = 6;
+		ip6h->payload_len = htons(sizeof(struct tcphdr) + payload_len);
+		ip6h->nexthdr = IPPROTO_TCP;
+		ip6h->hop_limit = 8;
+		if (inet_pton(AF_INET6, SIP6, &ip6h->saddr) != 1)
+			error(1, errno, "inet_pton source ip6");
+		if (inet_pton(AF_INET6, DIP6, &ip6h->daddr) != 1)
+			error(1, errno, "inet_pton dest ip6");
+	} else if (proto == PF_INET) {
+		memset(iph, 0, sizeof(*iph));
+
+		iph->version = 4;
+		iph->ihl = 5;
+		iph->ttl = 8;
+		iph->protocol	= IPPROTO_TCP;
+		iph->tot_len = htons(sizeof(struct tcphdr) +
+				payload_len + sizeof(struct iphdr));
+		iph->frag_off = htons(0x4000); /* DF = 1, MF = 0 */
+		if (inet_pton(AF_INET, SIP4, &iph->saddr) != 1)
+			error(1, errno, "inet_pton source ip");
+		if (inet_pton(AF_INET, DIP4, &iph->daddr) != 1)
+			error(1, errno, "inet_pton dest ip");
+		iph->check = checksum_fold(buf, sizeof(struct iphdr), 0);
+	}
+}
+
+static void fill_transportlayer(void *buf, int seq_offset, int ack_offset,
+				int payload_len, int fin)
+{
+	struct tcphdr *tcph = buf;
+
+	memset(tcph, 0, sizeof(*tcph));
+
+	tcph->source = htons(SPORT);
+	tcph->dest = htons(DPORT);
+	tcph->seq = ntohl(START_SEQ + seq_offset);
+	tcph->ack_seq = ntohl(START_ACK + ack_offset);
+	tcph->ack = 1;
+	tcph->fin = fin;
+	tcph->doff = 5;
+	tcph->window = htons(TCP_MAXWIN);
+	tcph->urg_ptr = 0;
+	tcph->check = tcp_checksum(tcph, payload_len);
+}
+
+static void write_packet(int fd, char *buf, int len, struct sockaddr_ll *daddr)
+{
+	int ret = -1;
+
+	ret = sendto(fd, buf, len, 0, (struct sockaddr *)daddr, sizeof(*daddr));
+	if (ret == -1)
+		error(1, errno, "sendto failure");
+	if (ret != len)
+		error(1, errno, "sendto wrong length");
+}
+
+static void create_packet(void *buf, int seq_offset, int ack_offset,
+			  int payload_len, int fin)
+{
+	memset(buf, 0, total_hdr_len);
+	memset(buf + total_hdr_len, 'a', payload_len);
+	fill_transportlayer(buf + tcp_offset, seq_offset, ack_offset,
+			    payload_len, fin);
+	fill_networklayer(buf + ETH_HLEN, payload_len);
+	fill_datalinklayer(buf);
+}
+
+/* send one extra flag, not first and not last pkt */
+static void send_flags(int fd, struct sockaddr_ll *daddr, int psh, int syn,
+		       int rst, int urg)
+{
+	static char flag_buf[MAX_HDR_LEN + PAYLOAD_LEN];
+	static char buf[MAX_HDR_LEN + PAYLOAD_LEN];
+	int payload_len, pkt_size, flag, i;
+	struct tcphdr *tcph;
+
+	payload_len = PAYLOAD_LEN * psh;
+	pkt_size = total_hdr_len + payload_len;
+	flag = NUM_PACKETS / 2;
+
+	create_packet(flag_buf, flag * payload_len, 0, payload_len, 0);
+
+	tcph = (struct tcphdr *)(flag_buf + tcp_offset);
+	tcph->psh = psh;
+	tcph->syn = syn;
+	tcph->rst = rst;
+	tcph->urg = urg;
+	tcph->check = 0;
+	tcph->check = tcp_checksum(tcph, payload_len);
+
+	for (i = 0; i < NUM_PACKETS + 1; i++) {
+		if (i == flag) {
+			write_packet(fd, flag_buf, pkt_size, daddr);
+			continue;
+		}
+		create_packet(buf, i * PAYLOAD_LEN, 0, PAYLOAD_LEN, 0);
+		write_packet(fd, buf, total_hdr_len + PAYLOAD_LEN, daddr);
+	}
+}
+
+/* Test for data of same length, smaller than previous
+ * and of different lengths
+ */
+static void send_data_pkts(int fd, struct sockaddr_ll *daddr,
+			   int payload_len1, int payload_len2)
+{
+	static char buf[ETH_HLEN + IP_MAXPACKET];
+
+	create_packet(buf, 0, 0, payload_len1, 0);
+	write_packet(fd, buf, total_hdr_len + payload_len1, daddr);
+	create_packet(buf, payload_len1, 0, payload_len2, 0);
+	write_packet(fd, buf, total_hdr_len + payload_len2, daddr);
+}
+
+/* If incoming segments make tracked segment length exceed
+ * legal IP datagram length, do not coalesce
+ */
+static void send_large(int fd, struct sockaddr_ll *daddr, int remainder)
+{
+	static char pkts[NUM_LARGE_PKT][TOTAL_HDR_LEN + MSS];
+	static char last[TOTAL_HDR_LEN + MSS];
+	static char new_seg[TOTAL_HDR_LEN + MSS];
+	int i;
+
+	for (i = 0; i < NUM_LARGE_PKT; i++)
+		create_packet(pkts[i], i * MSS, 0, MSS, 0);
+	create_packet(last, NUM_LARGE_PKT * MSS, 0, remainder, 0);
+	create_packet(new_seg, (NUM_LARGE_PKT + 1) * MSS, 0, remainder, 0);
+
+	for (i = 0; i < NUM_LARGE_PKT; i++)
+		write_packet(fd, pkts[i], total_hdr_len + MSS, daddr);
+	write_packet(fd, last, total_hdr_len + remainder, daddr);
+	write_packet(fd, new_seg, total_hdr_len + remainder, daddr);
+}
+
+/* Pure acks and dup acks don't coalesce */
+static void send_ack(int fd, struct sockaddr_ll *daddr)
+{
+	static char buf[MAX_HDR_LEN];
+
+	create_packet(buf, 0, 0, 0, 0);
+	write_packet(fd, buf, total_hdr_len, daddr);
+	write_packet(fd, buf, total_hdr_len, daddr);
+	create_packet(buf, 0, 1, 0, 0);
+	write_packet(fd, buf, total_hdr_len, daddr);
+}
+
+static void recompute_packet(char *buf, char *no_ext, int extlen)
+{
+	struct tcphdr *tcphdr = (struct tcphdr *)(buf + tcp_offset);
+	struct ipv6hdr *ip6h = (struct ipv6hdr *)(buf + ETH_HLEN);
+	struct iphdr *iph = (struct iphdr *)(buf + ETH_HLEN);
+
+	memmove(buf, no_ext, total_hdr_len);
+	memmove(buf + total_hdr_len + extlen,
+		no_ext + total_hdr_len, PAYLOAD_LEN);
+
+	tcphdr->doff = tcphdr->doff + (extlen / 4);
+	tcphdr->check = 0;
+	tcphdr->check = tcp_checksum(tcphdr, PAYLOAD_LEN + extlen);
+	if (proto == PF_INET) {
+		iph->tot_len = htons(ntohs(iph->tot_len) + extlen);
+		iph->check = 0;
+		iph->check = checksum_fold(iph, sizeof(struct iphdr), 0);
+	} else {
+		ip6h->payload_len = htons(ntohs(ip6h->payload_len) + extlen);
+	}
+}
+
+static void tcp_write_options(char *buf, int kind, int ts)
+{
+	struct tcp_option_ts {
+		uint8_t kind;
+		uint8_t len;
+		uint32_t tsval;
+		uint32_t tsecr;
+	} *opt_ts = (void *)buf;
+	struct tcp_option_window {
+		uint8_t kind;
+		uint8_t len;
+		uint8_t shift;
+	} *opt_window = (void *)buf;
+
+	switch (kind) {
+	case TCPOPT_NOP:
+		buf[0] = TCPOPT_NOP;
+		break;
+	case TCPOPT_WINDOW:
+		memset(opt_window, 0, sizeof(struct tcp_option_window));
+		opt_window->kind = TCPOPT_WINDOW;
+		opt_window->len = TCPOLEN_WINDOW;
+		opt_window->shift = 0;
+		break;
+	case TCPOPT_TIMESTAMP:
+		memset(opt_ts, 0, sizeof(struct tcp_option_ts));
+		opt_ts->kind = TCPOPT_TIMESTAMP;
+		opt_ts->len = TCPOLEN_TIMESTAMP;
+		opt_ts->tsval = ts;
+		opt_ts->tsecr = 0;
+		break;
+	default:
+		error(1, 0, "unimplemented TCP option");
+		break;
+	}
+}
+
+/* TCP with options is always a permutation of {TS, NOP, NOP}.
+ * Implement different orders to verify coalescing stops.
+ */
+static void add_standard_tcp_options(char *buf, char *no_ext, int ts, int order)
+{
+	switch (order) {
+	case 0:
+		tcp_write_options(buf + total_hdr_len, TCPOPT_NOP, 0);
+		tcp_write_options(buf + total_hdr_len + 1, TCPOPT_NOP, 0);
+		tcp_write_options(buf + total_hdr_len + 2 /* two NOP opts */,
+				  TCPOPT_TIMESTAMP, ts);
+		break;
+	case 1:
+		tcp_write_options(buf + total_hdr_len, TCPOPT_NOP, 0);
+		tcp_write_options(buf + total_hdr_len + 1,
+				  TCPOPT_TIMESTAMP, ts);
+		tcp_write_options(buf + total_hdr_len + 1 + TCPOLEN_TIMESTAMP,
+				  TCPOPT_NOP, 0);
+		break;
+	case 2:
+		tcp_write_options(buf + total_hdr_len, TCPOPT_TIMESTAMP, ts);
+		tcp_write_options(buf + total_hdr_len + TCPOLEN_TIMESTAMP + 1,
+				  TCPOPT_NOP, 0);
+		tcp_write_options(buf + total_hdr_len + TCPOLEN_TIMESTAMP + 2,
+				  TCPOPT_NOP, 0);
+		break;
+	default:
+		error(1, 0, "unknown order");
+		break;
+	}
+	recompute_packet(buf, no_ext, TCPOLEN_TSTAMP_APPA);
+}
+
+/* Packets with invalid checksum don't coalesce. */
+static void send_changed_checksum(int fd, struct sockaddr_ll *daddr)
+{
+	static char buf[MAX_HDR_LEN + PAYLOAD_LEN];
+	struct tcphdr *tcph = (struct tcphdr *)(buf + tcp_offset);
+	int pkt_size = total_hdr_len + PAYLOAD_LEN;
+
+	create_packet(buf, 0, 0, PAYLOAD_LEN, 0);
+	write_packet(fd, buf, pkt_size, daddr);
+
+	create_packet(buf, PAYLOAD_LEN, 0, PAYLOAD_LEN, 0);
+	tcph->check = tcph->check - 1;
+	write_packet(fd, buf, pkt_size, daddr);
+}
+
+ /* Packets with non-consecutive sequence number don't coalesce.*/
+static void send_changed_seq(int fd, struct sockaddr_ll *daddr)
+{
+	static char buf[MAX_HDR_LEN + PAYLOAD_LEN];
+	struct tcphdr *tcph = (struct tcphdr *)(buf + tcp_offset);
+	int pkt_size = total_hdr_len + PAYLOAD_LEN;
+
+	create_packet(buf, 0, 0, PAYLOAD_LEN, 0);
+	write_packet(fd, buf, pkt_size, daddr);
+
+	create_packet(buf, PAYLOAD_LEN, 0, PAYLOAD_LEN, 0);
+	tcph->seq = ntohl(htonl(tcph->seq) + 1);
+	tcph->check = 0;
+	tcph->check = tcp_checksum(tcph, PAYLOAD_LEN);
+	write_packet(fd, buf, pkt_size, daddr);
+}
+
+ /* Packet with different timestamp option or different timestamps
+  * don't coalesce.
+  */
+static void send_changed_ts(int fd, struct sockaddr_ll *daddr)
+{
+	static char buf[MAX_HDR_LEN + PAYLOAD_LEN];
+	static char extpkt[sizeof(buf) + TCPOLEN_TSTAMP_APPA];
+	int pkt_size = total_hdr_len + PAYLOAD_LEN + TCPOLEN_TSTAMP_APPA;
+
+	create_packet(buf, 0, 0, PAYLOAD_LEN, 0);
+	add_standard_tcp_options(extpkt, buf, 0, 0);
+	write_packet(fd, extpkt, pkt_size, daddr);
+
+	create_packet(buf, PAYLOAD_LEN, 0, PAYLOAD_LEN, 0);
+	add_standard_tcp_options(extpkt, buf, 0, 0);
+	write_packet(fd, extpkt, pkt_size, daddr);
+
+	create_packet(buf, PAYLOAD_LEN * 2, 0, PAYLOAD_LEN, 0);
+	add_standard_tcp_options(extpkt, buf, 100, 0);
+	write_packet(fd, extpkt, pkt_size, daddr);
+
+	create_packet(buf, PAYLOAD_LEN * 3, 0, PAYLOAD_LEN, 0);
+	add_standard_tcp_options(extpkt, buf, 100, 1);
+	write_packet(fd, extpkt, pkt_size, daddr);
+
+	create_packet(buf, PAYLOAD_LEN * 4, 0, PAYLOAD_LEN, 0);
+	add_standard_tcp_options(extpkt, buf, 100, 2);
+	write_packet(fd, extpkt, pkt_size, daddr);
+}
+
+/* Packet with different tcp options don't coalesce. */
+static void send_diff_opt(int fd, struct sockaddr_ll *daddr)
+{
+	static char buf[MAX_HDR_LEN + PAYLOAD_LEN];
+	static char extpkt1[sizeof(buf) + TCPOLEN_TSTAMP_APPA];
+	static char extpkt2[sizeof(buf) + TCPOLEN_MAXSEG];
+	int extpkt1_size = total_hdr_len + PAYLOAD_LEN + TCPOLEN_TSTAMP_APPA;
+	int extpkt2_size = total_hdr_len + PAYLOAD_LEN + TCPOLEN_MAXSEG;
+
+	create_packet(buf, 0, 0, PAYLOAD_LEN, 0);
+	add_standard_tcp_options(extpkt1, buf, 0, 0);
+	write_packet(fd, extpkt1, extpkt1_size, daddr);
+
+	create_packet(buf, PAYLOAD_LEN, 0, PAYLOAD_LEN, 0);
+	add_standard_tcp_options(extpkt1, buf, 0, 0);
+	write_packet(fd, extpkt1, extpkt1_size, daddr);
+
+	create_packet(buf, PAYLOAD_LEN * 2, 0, PAYLOAD_LEN, 0);
+	tcp_write_options(extpkt2 + MAX_HDR_LEN, TCPOPT_NOP, 0);
+	tcp_write_options(extpkt2 + MAX_HDR_LEN + 1, TCPOPT_WINDOW, 0);
+	recompute_packet(extpkt2, buf, TCPOLEN_WINDOW + 1);
+	write_packet(fd, extpkt2, extpkt2_size, daddr);
+}
+
+static void add_ipv4_ts_option(void *buf, void *optpkt)
+{
+	struct ip_timestamp *ts = (struct ip_timestamp *)(optpkt + tcp_offset);
+	int optlen = sizeof(struct ip_timestamp);
+	struct iphdr *iph;
+
+	if (optlen % 4)
+		error(1, 0, "ipv4 timestamp length is not a multiple of 4B");
+
+	ts->ipt_code = IPOPT_TS;
+	ts->ipt_len = optlen;
+	ts->ipt_ptr = 5;
+	ts->ipt_flg = IPOPT_TS_TSONLY;
+
+	memcpy(optpkt, buf, tcp_offset);
+	memcpy(optpkt + tcp_offset + optlen, buf + tcp_offset,
+	       sizeof(struct tcphdr) + PAYLOAD_LEN);
+
+	iph = (struct iphdr *)(optpkt + ETH_HLEN);
+	iph->ihl = 5 + (optlen / 4);
+	iph->tot_len = htons(ntohs(iph->tot_len) + optlen);
+	iph->check = 0;
+	iph->check = checksum_fold(iph, sizeof(struct iphdr) + optlen, 0);
+}
+
+/* IPv4 options shouldn't coalesce */
+static void send_ip_options(int fd, struct sockaddr_ll *daddr)
+{
+	static char buf[MAX_HDR_LEN + PAYLOAD_LEN];
+	static char optpkt[sizeof(buf) + sizeof(struct ip_timestamp)];
+	int optlen = sizeof(struct ip_timestamp);
+	int pkt_size = total_hdr_len + PAYLOAD_LEN + optlen;
+
+	create_packet(buf, 0, 0, PAYLOAD_LEN, 0);
+	write_packet(fd, buf, total_hdr_len + PAYLOAD_LEN, daddr);
+
+	create_packet(buf, PAYLOAD_LEN * 1, 0, PAYLOAD_LEN, 0);
+	add_ipv4_ts_option(buf, optpkt);
+	write_packet(fd, optpkt, pkt_size, daddr);
+
+	create_packet(buf, PAYLOAD_LEN * 2, 0, PAYLOAD_LEN, 0);
+	write_packet(fd, buf, total_hdr_len + PAYLOAD_LEN, daddr);
+}
+
+/*  IPv4 fragments shouldn't coalesce */
+static void send_fragment4(int fd, struct sockaddr_ll *daddr)
+{
+	static char buf[IP_MAXPACKET];
+	struct iphdr *iph = (struct iphdr *)(buf + ETH_HLEN);
+	int pkt_size = total_hdr_len + PAYLOAD_LEN;
+
+	create_packet(buf, 0, 0, PAYLOAD_LEN, 0);
+	write_packet(fd, buf, pkt_size, daddr);
+
+	/* Once fragmented, packet would retain the total_len.
+	 * Tcp header is prepared as if rest of data is in follow-up frags,
+	 * but follow up frags aren't actually sent.
+	 */
+	memset(buf + total_hdr_len, 'a', PAYLOAD_LEN * 2);
+	fill_transportlayer(buf + tcp_offset, PAYLOAD_LEN, 0, PAYLOAD_LEN * 2, 0);
+	fill_networklayer(buf + ETH_HLEN, PAYLOAD_LEN);
+	fill_datalinklayer(buf);
+
+	iph->frag_off = htons(0x6000); // DF = 1, MF = 1
+	iph->check = 0;
+	iph->check = checksum_fold(iph, sizeof(struct iphdr), 0);
+	write_packet(fd, buf, pkt_size, daddr);
+}
+
+/* IPv4 packets with different ttl don't coalesce.*/
+static void send_changed_ttl(int fd, struct sockaddr_ll *daddr)
+{
+	int pkt_size = total_hdr_len + PAYLOAD_LEN;
+	static char buf[MAX_HDR_LEN + PAYLOAD_LEN];
+	struct iphdr *iph = (struct iphdr *)(buf + ETH_HLEN);
+
+	create_packet(buf, 0, 0, PAYLOAD_LEN, 0);
+	write_packet(fd, buf, pkt_size, daddr);
+
+	create_packet(buf, PAYLOAD_LEN, 0, PAYLOAD_LEN, 0);
+	iph->ttl = 7;
+	iph->check = 0;
+	iph->check = checksum_fold(iph, sizeof(struct iphdr), 0);
+	write_packet(fd, buf, pkt_size, daddr);
+}
+
+/* Packets with different tos don't coalesce.*/
+static void send_changed_tos(int fd, struct sockaddr_ll *daddr)
+{
+	int pkt_size = total_hdr_len + PAYLOAD_LEN;
+	static char buf[MAX_HDR_LEN + PAYLOAD_LEN];
+	struct iphdr *iph = (struct iphdr *)(buf + ETH_HLEN);
+	struct ipv6hdr *ip6h = (struct ipv6hdr *)(buf + ETH_HLEN);
+
+	create_packet(buf, 0, 0, PAYLOAD_LEN, 0);
+	write_packet(fd, buf, pkt_size, daddr);
+
+	create_packet(buf, PAYLOAD_LEN, 0, PAYLOAD_LEN, 0);
+	if (proto == PF_INET) {
+		iph->tos = 1;
+		iph->check = 0;
+		iph->check = checksum_fold(iph, sizeof(struct iphdr), 0);
+	} else if (proto == PF_INET6) {
+		ip6h->priority = 0xf;
+	}
+	write_packet(fd, buf, pkt_size, daddr);
+}
+
+/* Packets with different ECN don't coalesce.*/
+static void send_changed_ECN(int fd, struct sockaddr_ll *daddr)
+{
+	int pkt_size = total_hdr_len + PAYLOAD_LEN;
+	static char buf[MAX_HDR_LEN + PAYLOAD_LEN];
+	struct iphdr *iph = (struct iphdr *)(buf + ETH_HLEN);
+
+	create_packet(buf, 0, 0, PAYLOAD_LEN, 0);
+	write_packet(fd, buf, pkt_size, daddr);
+
+	create_packet(buf, PAYLOAD_LEN, 0, PAYLOAD_LEN, 0);
+	if (proto == PF_INET) {
+		buf[ETH_HLEN + 1] ^= 0x2; // ECN set to 10
+		iph->check = 0;
+		iph->check = checksum_fold(iph, sizeof(struct iphdr), 0);
+	} else {
+		buf[ETH_HLEN + 1] ^= 0x20; // ECN set to 10
+	}
+	write_packet(fd, buf, pkt_size, daddr);
+}
+
+/* IPv6 fragments and packets with extensions don't coalesce.*/
+static void send_fragment6(int fd, struct sockaddr_ll *daddr)
+{
+	static char buf[MAX_HDR_LEN + PAYLOAD_LEN];
+	static char extpkt[MAX_HDR_LEN + PAYLOAD_LEN +
+			   sizeof(struct ip6_frag)];
+	struct ipv6hdr *ip6h = (struct ipv6hdr *)(buf + ETH_HLEN);
+	struct ip6_frag *frag = (void *)(extpkt + tcp_offset);
+	int extlen = sizeof(struct ip6_frag);
+	int bufpkt_len = total_hdr_len + PAYLOAD_LEN;
+	int extpkt_len = bufpkt_len + extlen;
+	int i;
+
+	for (i = 0; i < 2; i++) {
+		create_packet(buf, PAYLOAD_LEN * i, 0, PAYLOAD_LEN, 0);
+		write_packet(fd, buf, bufpkt_len, daddr);
+	}
+
+	create_packet(buf, PAYLOAD_LEN * 2, 0, PAYLOAD_LEN, 0);
+	memset(extpkt, 0, extpkt_len);
+
+	ip6h->nexthdr = IPPROTO_FRAGMENT;
+	ip6h->payload_len = htons(ntohs(ip6h->payload_len) + extlen);
+	frag->ip6f_nxt = IPPROTO_TCP;
+
+	memcpy(extpkt, buf, tcp_offset);
+	memcpy(extpkt + tcp_offset + extlen, buf + tcp_offset,
+	       sizeof(struct tcphdr) + PAYLOAD_LEN);
+	write_packet(fd, extpkt, extpkt_len, daddr);
+
+	create_packet(buf, PAYLOAD_LEN * 3, 0, PAYLOAD_LEN, 0);
+	write_packet(fd, buf, bufpkt_len, daddr);
+}
+
+static void bind_packetsocket(int fd)
+{
+	struct sockaddr_ll daddr = {};
+
+	daddr.sll_family = AF_PACKET;
+	daddr.sll_protocol = ethhdr_proto;
+	daddr.sll_ifindex = if_nametoindex(ifname);
+	if (daddr.sll_ifindex == 0)
+		error(1, errno, "if_nametoindex");
+
+	if (bind(fd, (void *)&daddr, sizeof(daddr)) < 0)
+		error(1, errno, "could not bind socket");
+}
+
+static void set_timeout(int fd)
+{
+	struct timeval timeout;
+
+	timeout.tv_sec = 120;
+	timeout.tv_usec = 0;
+	if (setsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, (char *)&timeout,
+		       sizeof(timeout)) < 0)
+		error(1, errno, "cannot set timeout, setsockopt failed");
+}
+
+static void check_recv_pkts(int fd, int *correct_payload,
+			    int correct_num_pkts)
+{
+	static char buffer[IP_MAXPACKET + ETH_HLEN + 1];
+	struct iphdr *iph = (struct iphdr *)(buffer + ETH_HLEN);
+	struct ipv6hdr *ip6h = (struct ipv6hdr *)(buffer + ETH_HLEN);
+	struct tcphdr *tcph;
+	bool bad_packet = false;
+	int tcp_ext_len = 0;
+	int ip_ext_len = 0;
+	int pkt_size = -1;
+	int data_len = 0;
+	int num_pkt = 0;
+	int i;
+
+	vlog("Expected {");
+	for (i = 0; i < correct_num_pkts; i++)
+		vlog("%d ", correct_payload[i]);
+	vlog("}, Total %d packets\nReceived {", correct_num_pkts);
+
+	while (1) {
+		pkt_size = recv(fd, buffer, IP_MAXPACKET + ETH_HLEN + 1, 0);
+		if (pkt_size < 0)
+			error(1, errno, "could not receive");
+
+		if (iph->version == 4)
+			ip_ext_len = (iph->ihl - 5) * 4;
+		else if (ip6h->version == 6 && ip6h->nexthdr != IPPROTO_TCP)
+			ip_ext_len = sizeof(struct ip6_frag);
+
+		tcph = (struct tcphdr *)(buffer + tcp_offset + ip_ext_len);
+
+		if (tcph->fin)
+			break;
+
+		tcp_ext_len = (tcph->doff - 5) * 4;
+		data_len = pkt_size - total_hdr_len - tcp_ext_len - ip_ext_len;
+		/* Min ethernet frame payload is 46(ETH_ZLEN - ETH_HLEN) by RFC 802.3.
+		 * Ipv4/tcp packets without at least 6 bytes of data will be padded.
+		 * Packet sockets are protocol agnostic, and will not trim the padding.
+		 */
+		if (pkt_size == ETH_ZLEN && iph->version == 4) {
+			data_len = ntohs(iph->tot_len)
+				- sizeof(struct tcphdr) - sizeof(struct iphdr);
+		}
+		vlog("%d ", data_len);
+		if (data_len != correct_payload[num_pkt]) {
+			vlog("[!=%d]", correct_payload[num_pkt]);
+			bad_packet = true;
+		}
+		num_pkt++;
+	}
+	vlog("}, Total %d packets.\n", num_pkt);
+	if (num_pkt != correct_num_pkts)
+		error(1, 0, "incorrect number of packets");
+	if (bad_packet)
+		error(1, 0, "incorrect packet geometry");
+
+	printf("Test succeeded\n\n");
+}
+
+static void gro_sender(void)
+{
+	static char fin_pkt[MAX_HDR_LEN];
+	struct sockaddr_ll daddr = {};
+	int txfd = -1;
+
+	txfd = socket(PF_PACKET, SOCK_RAW, IPPROTO_RAW);
+	if (txfd < 0)
+		error(1, errno, "socket creation");
+
+	memset(&daddr, 0, sizeof(daddr));
+	daddr.sll_ifindex = if_nametoindex(ifname);
+	if (daddr.sll_ifindex == 0)
+		error(1, errno, "if_nametoindex");
+	daddr.sll_family = AF_PACKET;
+	memcpy(daddr.sll_addr, dst_mac, ETH_ALEN);
+	daddr.sll_halen = ETH_ALEN;
+	create_packet(fin_pkt, PAYLOAD_LEN * 2, 0, 0, 1);
+
+	if (strcmp(testname, "data") == 0) {
+		send_data_pkts(txfd, &daddr, PAYLOAD_LEN, PAYLOAD_LEN);
+		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
+
+		send_data_pkts(txfd, &daddr, PAYLOAD_LEN, PAYLOAD_LEN / 2);
+		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
+
+		send_data_pkts(txfd, &daddr, PAYLOAD_LEN / 2, PAYLOAD_LEN);
+		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
+	} else if (strcmp(testname, "ack") == 0) {
+		send_ack(txfd, &daddr);
+		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
+	} else if (strcmp(testname, "flags") == 0) {
+		send_flags(txfd, &daddr, 1, 0, 0, 0);
+		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
+
+		send_flags(txfd, &daddr, 0, 1, 0, 0);
+		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
+
+		send_flags(txfd, &daddr, 0, 0, 1, 0);
+		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
+
+		send_flags(txfd, &daddr, 0, 0, 0, 1);
+		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
+	} else if (strcmp(testname, "tcp") == 0) {
+		send_changed_checksum(txfd, &daddr);
+		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
+
+		send_changed_seq(txfd, &daddr);
+		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
+
+		send_changed_ts(txfd, &daddr);
+		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
+
+		send_diff_opt(txfd, &daddr);
+		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
+	} else if (strcmp(testname, "ip") == 0) {
+		send_changed_ECN(txfd, &daddr);
+		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
+
+		send_changed_tos(txfd, &daddr);
+		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
+		if (proto == PF_INET) {
+			/* Modified packets may be received out of order.
+			 * Sleep function added to enforce test boundaries
+			 * so that fin pkts are not received prior to other pkts.
+			 */
+			sleep(1);
+			send_changed_ttl(txfd, &daddr);
+			write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
+
+			sleep(1);
+			send_ip_options(txfd, &daddr);
+			sleep(1);
+			write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
+
+			sleep(1);
+			send_fragment4(txfd, &daddr);
+			sleep(1);
+			write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
+		} else if (proto == PF_INET6) {
+			send_fragment6(txfd, &daddr);
+			write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
+		}
+	} else if (strcmp(testname, "large") == 0) {
+		/* 20 is the difference between min iphdr size
+		 * and min ipv6hdr size. Like MAX_HDR_SIZE,
+		 * MAX_PAYLOAD is defined with the larger header of the two.
+		 */
+		int offset = proto == PF_INET ? 20 : 0;
+		int remainder = (MAX_PAYLOAD + offset) % MSS;
+
+		send_large(txfd, &daddr, remainder);
+		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
+
+		send_large(txfd, &daddr, remainder + 1);
+		write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
+	} else {
+		error(1, 0, "Unknown testcase");
+	}
+
+	if (close(txfd))
+		error(1, errno, "socket close");
+}
+
+static void gro_receiver(void)
+{
+	static int correct_payload[NUM_PACKETS];
+	int rxfd = -1;
+
+	rxfd = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_NONE));
+	if (rxfd < 0)
+		error(1, 0, "socket creation");
+	setup_sock_filter(rxfd);
+	set_timeout(rxfd);
+	bind_packetsocket(rxfd);
+
+	memset(correct_payload, 0, sizeof(correct_payload));
+
+	if (strcmp(testname, "data") == 0) {
+		printf("pure data packet of same size: ");
+		correct_payload[0] = PAYLOAD_LEN * 2;
+		check_recv_pkts(rxfd, correct_payload, 1);
+
+		printf("large data packets followed by a smaller one: ");
+		correct_payload[0] = PAYLOAD_LEN * 1.5;
+		check_recv_pkts(rxfd, correct_payload, 1);
+
+		printf("small data packets followed by a larger one: ");
+		correct_payload[0] = PAYLOAD_LEN / 2;
+		correct_payload[1] = PAYLOAD_LEN;
+		check_recv_pkts(rxfd, correct_payload, 2);
+	} else if (strcmp(testname, "ack") == 0) {
+		printf("duplicate ack and pure ack: ");
+		check_recv_pkts(rxfd, correct_payload, 3);
+	} else if (strcmp(testname, "flags") == 0) {
+		correct_payload[0] = PAYLOAD_LEN * 3;
+		correct_payload[1] = PAYLOAD_LEN * 2;
+
+		printf("psh flag ends coalescing: ");
+		check_recv_pkts(rxfd, correct_payload, 2);
+
+		correct_payload[0] = PAYLOAD_LEN * 2;
+		correct_payload[1] = 0;
+		correct_payload[2] = PAYLOAD_LEN * 2;
+		printf("syn flag ends coalescing: ");
+		check_recv_pkts(rxfd, correct_payload, 3);
+
+		printf("rst flag ends coalescing: ");
+		check_recv_pkts(rxfd, correct_payload, 3);
+
+		printf("urg flag ends coalescing: ");
+		check_recv_pkts(rxfd, correct_payload, 3);
+	} else if (strcmp(testname, "tcp") == 0) {
+		correct_payload[0] = PAYLOAD_LEN;
+		correct_payload[1] = PAYLOAD_LEN;
+		correct_payload[2] = PAYLOAD_LEN;
+		correct_payload[3] = PAYLOAD_LEN;
+
+		printf("changed checksum does not coalesce: ");
+		check_recv_pkts(rxfd, correct_payload, 2);
+
+		printf("Wrong Seq number doesn't coalesce: ");
+		check_recv_pkts(rxfd, correct_payload, 2);
+
+		printf("Different timestamp doesn't coalesce: ");
+		correct_payload[0] = PAYLOAD_LEN * 2;
+		check_recv_pkts(rxfd, correct_payload, 4);
+
+		printf("Different options doesn't coalesce: ");
+		correct_payload[0] = PAYLOAD_LEN * 2;
+		check_recv_pkts(rxfd, correct_payload, 2);
+	} else if (strcmp(testname, "ip") == 0) {
+		correct_payload[0] = PAYLOAD_LEN;
+		correct_payload[1] = PAYLOAD_LEN;
+
+		printf("different ECN doesn't coalesce: ");
+		check_recv_pkts(rxfd, correct_payload, 2);
+
+		printf("different tos doesn't coalesce: ");
+		check_recv_pkts(rxfd, correct_payload, 2);
+
+		if (proto == PF_INET) {
+			printf("different ttl doesn't coalesce: ");
+			check_recv_pkts(rxfd, correct_payload, 2);
+
+			printf("ip options doesn't coalesce: ");
+			correct_payload[2] = PAYLOAD_LEN;
+			check_recv_pkts(rxfd, correct_payload, 3);
+
+			printf("fragmented ip4 doesn't coalesce: ");
+			check_recv_pkts(rxfd, correct_payload, 2);
+		} else if (proto == PF_INET6) {
+			/* GRO doesn't check for ipv6 hop limit when flushing.
+			 * Hence no corresponding test to the ipv4 case.
+			 */
+			printf("fragmented ip6 doesn't coalesce: ");
+			correct_payload[0] = PAYLOAD_LEN * 2;
+			check_recv_pkts(rxfd, correct_payload, 2);
+		}
+	} else if (strcmp(testname, "large") == 0) {
+		int offset = proto == PF_INET ? 20 : 0;
+		int remainder = (MAX_PAYLOAD + offset) % MSS;
+
+		correct_payload[0] = (MAX_PAYLOAD + offset);
+		correct_payload[1] = remainder;
+		printf("Shouldn't coalesce if exceed IP max pkt size: ");
+		check_recv_pkts(rxfd, correct_payload, 2);
+
+		/* last segment sent individually, doesn't start new segment */
+		correct_payload[0] = correct_payload[0] - remainder;
+		correct_payload[1] = remainder + 1;
+		correct_payload[2] = remainder + 1;
+		check_recv_pkts(rxfd, correct_payload, 3);
+	} else {
+		error(1, 0, "Test case error, should never trigger");
+	}
+
+	if (close(rxfd))
+		error(1, 0, "socket close");
+}
+
+static void parse_args(int argc, char **argv)
+{
+	static const struct option opts[] = {
+		{ "dmac", required_argument, NULL, 'D' },
+		{ "iface", required_argument, NULL, 'i' },
+		{ "ipv4", no_argument, NULL, '4' },
+		{ "ipv6", no_argument, NULL, '6' },
+		{ "rx", no_argument, NULL, 'r' },
+		{ "smac", required_argument, NULL, 'S' },
+		{ "test", required_argument, NULL, 't' },
+		{ "verbose", no_argument, NULL, 'v' },
+		{ 0, 0, 0, 0 }
+	};
+	int c;
+
+	while ((c = getopt_long(argc, argv, "46D:i:rS:t:v", opts, NULL)) != -1) {
+		switch (c) {
+		case '4':
+			proto = PF_INET;
+			ethhdr_proto = htons(ETH_P_IP);
+			break;
+		case '6':
+			proto = PF_INET6;
+			ethhdr_proto = htons(ETH_P_IPV6);
+			break;
+		case 'D':
+			dmac = optarg;
+			break;
+		case 'i':
+			ifname = optarg;
+			break;
+		case 'r':
+			tx_socket = false;
+			break;
+		case 'S':
+			smac = optarg;
+			break;
+		case 't':
+			testname = optarg;
+			break;
+		case 'v':
+			verbose = true;
+			break;
+		default:
+			error(1, 0, "%s invalid option %c\n", __func__, c);
+			break;
+		}
+	}
+}
+
+int main(int argc, char **argv)
+{
+	parse_args(argc, argv);
+
+	if (proto == PF_INET) {
+		tcp_offset = ETH_HLEN + sizeof(struct iphdr);
+		total_hdr_len = tcp_offset + sizeof(struct tcphdr);
+	} else if (proto == PF_INET6) {
+		tcp_offset = ETH_HLEN + sizeof(struct ipv6hdr);
+		total_hdr_len = MAX_HDR_LEN;
+	} else {
+		error(1, 0, "Protocol family is not ipv4 or ipv6");
+	}
+
+	read_MAC(src_mac, smac);
+	read_MAC(dst_mac, dmac);
+
+	if (tx_socket)
+		gro_sender();
+	else
+		gro_receiver();
+	return 0;
+}

tools/testing/selftests/net/gro.sh

+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+source setup_loopback.sh
+readonly SERVER_MAC="aa:00:00:00:00:02"
+readonly CLIENT_MAC="aa:00:00:00:00:01"
+readonly TESTS=("data" "ack" "flags" "tcp" "ip" "large")
+readonly PROTOS=("ipv4" "ipv6")
+dev="eth0"
+test="all"
+proto="ipv4"
+
+setup_interrupt() {
+  # Use timer on  host to trigger the network stack
+  # Also disable device interrupt to not depend on NIC interrupt
+  # Reduce test flakiness caused by unexpected interrupts
+  echo 100000 >"${FLUSH_PATH}"
+  echo 50 >"${IRQ_PATH}"
+}
+
+setup_ns() {
+  # Set up server_ns namespace and client_ns namespace
+  setup_macvlan_ns "${dev}" server_ns server "${SERVER_MAC}"
+  setup_macvlan_ns "${dev}" client_ns client "${CLIENT_MAC}"
+}
+
+cleanup_ns() {
+  cleanup_macvlan_ns server_ns server client_ns client
+}
+
+setup() {
+  setup_loopback_environment "${dev}"
+  setup_interrupt
+}
+
+cleanup() {
+  cleanup_loopback "${dev}"
+
+  echo "${FLUSH_TIMEOUT}" >"${FLUSH_PATH}"
+  echo "${HARD_IRQS}" >"${IRQ_PATH}"
+}
+
+run_test() {
+  local server_pid=0
+  local exit_code=0
+  local protocol=$1
+  local test=$2
+  local ARGS=( "--${protocol}" "--dmac" "${SERVER_MAC}" \
+  "--smac" "${CLIENT_MAC}" "--test" "${test}" "--verbose" )
+
+  setup_ns
+  # Each test is run 3 times to deflake, because given the receive timing,
+  # not all packets that should coalesce will be considered in the same flow
+  # on every try.
+  for tries in {1..3}; do
+    # Actual test starts here
+    ip netns exec server_ns ./gro "${ARGS[@]}" "--rx" "--iface" "server" \
+      1>>log.txt &
+    server_pid=$!
+    sleep 0.5  # to allow for socket init
+    ip netns exec client_ns ./gro "${ARGS[@]}" "--iface" "client" \
+      1>>log.txt
+    wait "${server_pid}"
+    exit_code=$?
+    if [[ "${exit_code}" -eq 0 ]]; then
+        break;
+    fi
+  done
+  cleanup_ns
+  echo ${exit_code}
+}
+
+run_all_tests() {
+  local failed_tests=()
+  for proto in "${PROTOS[@]}"; do
+    for test in "${TESTS[@]}"; do
+      echo "running test ${proto} ${test}" >&2
+      exit_code=$(run_test $proto $test)
+      if [[ "${exit_code}" -ne 0 ]]; then
+        failed_tests+=("${proto}_${test}")
+      fi;
+    done;
+  done
+  if [[ ${#failed_tests[@]} -ne 0 ]]; then
+    echo "failed tests: ${failed_tests[*]}. \
+    Please see log.txt for more logs"
+    exit 1
+  else
+    echo "All Tests Succeeded!"
+  fi;
+}
+
+usage() {
+  echo "Usage: $0 \
+  [-i <DEV>] \
+  [-t data|ack|flags|tcp|ip|large] \
+  [-p <ipv4|ipv6>]" 1>&2;
+  exit 1;
+}
+
+while getopts "i:t:p:" opt; do
+  case "${opt}" in
+    i)
+      dev="${OPTARG}"
+      ;;
+    t)
+      test="${OPTARG}"
+      ;;
+    p)
+      proto="${OPTARG}"
+      ;;
+    *)
+      usage
+      ;;
+  esac
+done
+
+readonly FLUSH_PATH="/sys/class/net/${dev}/gro_flush_timeout"
+readonly IRQ_PATH="/sys/class/net/${dev}/napi_defer_hard_irqs"
+readonly FLUSH_TIMEOUT="$(< ${FLUSH_PATH})"
+readonly HARD_IRQS="$(< ${IRQ_PATH})"
+setup
+trap cleanup EXIT
+if [[ "${test}" == "all" ]]; then
+  run_all_tests
+else
+  run_test "${proto}" "${test}"
+fi;

tools/testing/selftests/net/setup_loopback.sh

+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+netdev_check_for_carrier() {
+	local -r dev="$1"
+
+	for i in {1..5}; do
+		carrier="$(cat /sys/class/net/${dev}/carrier)"
+		if [[ "${carrier}" -ne 1 ]] ; then
+			echo "carrier not ready yet..." >&2
+			sleep 1
+		else
+			echo "carrier ready" >&2
+			break
+		fi
+	done
+	echo "${carrier}"
+}
+
+# Assumes that there is no existing ipvlan device on the physical device
+setup_loopback_environment() {
+    local dev="$1"
+
+	# Fail hard if cannot turn on loopback mode for current NIC
+	ethtool -K "${dev}" loopback on || exit 1
+	sleep 1
+
+	# Check for the carrier
+	carrier=$(netdev_check_for_carrier ${dev})
+	if [[ "${carrier}" -ne 1 ]] ; then
+		echo "setup_loopback_environment failed"
+		exit 1
+	fi
+}
+
+setup_macvlan_ns(){
+	local -r link_dev="$1"
+	local -r ns_name="$2"
+	local -r ns_dev="$3"
+	local -r ns_mac="$4"
+	local -r addr="$5"
+
+	ip link add link "${link_dev}" dev "${ns_dev}" \
+		address "${ns_mac}" type macvlan
+	exit_code=$?
+	if [[ "${exit_code}" -ne 0 ]]; then
+		echo "setup_macvlan_ns failed"
+		exit $exit_code
+	fi
+
+	[[ -e /var/run/netns/"${ns_name}" ]] || ip netns add "${ns_name}"
+	ip link set dev "${ns_dev}" netns "${ns_name}"
+	ip -netns "${ns_name}" link set dev "${ns_dev}" up
+	if [[ -n "${addr}" ]]; then
+		ip -netns "${ns_name}" addr add dev "${ns_dev}" "${addr}"
+	fi
+
+	sleep 1
+}
+
+cleanup_macvlan_ns(){
+	while (( $# >= 2 )); do
+		ns_name="$1"
+		ns_dev="$2"
+		ip -netns "${ns_name}" link del dev "${ns_dev}"
+		ip netns del "${ns_name}"
+		shift 2
+	done
+}
+
+cleanup_loopback(){
+	local -r dev="$1"
+
+	ethtool -K "${dev}" loopback off
+	sleep 1
+
+	# Check for the carrier
+	carrier=$(netdev_check_for_carrier ${dev})
+	if [[ "${carrier}" -ne 1 ]] ; then
+		echo "setup_loopback_environment failed"
+		exit 1
+	fi
+}