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-rw-r--r--tools/testing/selftests/net/gro.c1095
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diff --git a/tools/testing/selftests/net/gro.c b/tools/testing/selftests/net/gro.c
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+++ b/tools/testing/selftests/net/gro.c
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+// 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;
+}