// SPDX-License-Identifier: GPL-2.0
/*
 * This testsuite provides conformance testing for GRO coalescing.
 *
 * Test cases:
 *
 * 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.
 *   - data_same:    same size packets coalesce
 *   - data_lrg_sml: large then small coalesces
 *   - data_sml_lrg: small then large doesn't coalesce
 *
 * ack:
 *  Pure ACK does not coalesce.
 *
 * flags_*:
 *  No packets with PSH, SYN, URG, RST, CWR set will be coalesced.
 *   - flags_psh, flags_syn, flags_rst, flags_urg, flags_cwr
 *
 * 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 padded differently would not be coalesced.
 *   - tcp_csum: incorrect checksum
 *   - tcp_seq:  non-consecutive sequence numbers
 *   - tcp_ts:   different timestamps
 *   - tcp_opt:  different TCP options
 *
 * ip_*:
 *  Packets with different (ECN, TTL, TOS) header, IP options or
 *  IP fragments shouldn't coalesce.
 *   - ip_ecn, ip_tos:            shared between IPv4/IPv6
 *   - ip_ttl, ip_opt, ip_frag4:  IPv4 only
 *   - ip_id_df*:                 IPv4 IP ID field coalescing tests
 *   - ip_frag6, ip_v6ext_*:      IPv6 only
 *
 * large_*:
 *  Packets larger than GRO_MAX_SIZE packets shouldn't coalesce.
 *   - large_max: exceeding max size
 *   - large_rem: remainder handling
 *
 * 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>

#include "kselftest.h"
#include "../../net/lib/ksft.h"

#define DPORT 8000
#define SPORT 1500
#define PAYLOAD_LEN 100
#define NUM_PACKETS 4
#define START_SEQ 100
#define START_ACK 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))
#define MIN_EXTHDR_SIZE 8
#define EXT_PAYLOAD_1 "\x00\x00\x00\x00\x00\x00"
#define EXT_PAYLOAD_2 "\x11\x11\x11\x11\x11\x11"

#define ipv6_optlen(p)  (((p)->hdrlen+1) << 3) /* calculate IPv6 extension header len */
#define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)]))

enum flush_id_case {
        FLUSH_ID_DF1_INC,
        FLUSH_ID_DF1_FIXED,
        FLUSH_ID_DF0_INC,
        FLUSH_ID_DF0_FIXED,
        FLUSH_ID_DF1_INC_FIXED,
        FLUSH_ID_DF1_FIXED_INC,
};

static const char *addr6_src = "fdaa::2";
static const char *addr6_dst = "fdaa::1";
static const char *addr4_src = "192.168.1.200";
static const char *addr4_dst = "192.168.1.100";
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 bool ipip;

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, opt_ipproto_off;
        int next_off;

        if (ipip)
                next_off = sizeof(struct iphdr) + offsetof(struct iphdr, protocol);
        else if (proto == PF_INET)
                next_off = offsetof(struct iphdr, protocol);
        else
                next_off = offsetof(struct ipv6hdr, nexthdr);
        ipproto_off = ETH_HLEN + next_off;

        /* Overridden later if exthdrs are used: */
        opt_ipproto_off = ipproto_off;

        if (strcmp(testname, "ip_opt") == 0) {
                optlen = sizeof(struct ip_timestamp);
        } else if (strcmp(testname, "ip_frag6") == 0 ||
                   strcmp(testname, "ip_v6ext_same") == 0 ||
                   strcmp(testname, "ip_v6ext_diff") == 0) {
                BUILD_BUG_ON(sizeof(struct ip6_hbh) > MIN_EXTHDR_SIZE);
                BUILD_BUG_ON(sizeof(struct ip6_dest) > MIN_EXTHDR_SIZE);
                BUILD_BUG_ON(sizeof(struct ip6_frag) > MIN_EXTHDR_SIZE);

                /* same size for HBH and Fragment extension header types */
                optlen = MIN_EXTHDR_SIZE;
                opt_ipproto_off = ETH_HLEN + sizeof(struct ipv6hdr)
                        + offsetof(struct ip6_ext, ip6e_nxt);
        }

        /* this filter validates the following:
         *      - packet is IPv4/IPv6 according to the running test.
         *      - packet is TCP. Also handles the case of one extension header and then TCP.
         *      - checks the packet tcp dport equals to DPORT. Also handles the case of one
         *        extension header and then TCP.
         */
        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, 9),
                        BPF_STMT(BPF_LD  + BPF_B   + BPF_ABS, ipproto_off),
                        BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, IPPROTO_TCP, 2, 0),
                        BPF_STMT(BPF_LD  + BPF_B   + BPF_ABS, opt_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, addr6_src, &ph6.saddr) != 1)
                        error(1, errno, "inet_pton6 source ip pseudo");
                if (inet_pton(AF_INET6, addr6_dst, &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, addr4_src, &ph4.saddr) != 1)
                        error(1, errno, "inet_pton source ip pseudo");
                if (inet_pton(AF_INET, addr4_dst, &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, int protocol)
{
        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 = protocol;
                ip6h->hop_limit = 8;
                if (inet_pton(AF_INET6, addr6_src, &ip6h->saddr) != 1)
                        error(1, errno, "inet_pton source ip6");
                if (inet_pton(AF_INET6, addr6_dst, &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   = protocol;
                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, addr4_src, &iph->saddr) != 1)
                        error(1, errno, "inet_pton source ip");
                if (inet_pton(AF_INET, addr4_dst, &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);

        if (ipip) {
                fill_networklayer(buf + ETH_HLEN, payload_len + sizeof(struct iphdr),
                                  IPPROTO_IPIP);
                fill_networklayer(buf + ETH_HLEN + sizeof(struct iphdr),
                                  payload_len, IPPROTO_TCP);
        } else {
                fill_networklayer(buf + ETH_HLEN, payload_len, IPPROTO_TCP);
        }

        fill_datalinklayer(buf);
}

#ifndef TH_CWR
#define TH_CWR 0x80
#endif
static void set_flags(struct tcphdr *tcph, int payload_len, int psh, int syn,
                      int rst, int urg, int cwr)
{
        tcph->psh = psh;
        tcph->syn = syn;
        tcph->rst = rst;
        tcph->urg = urg;
        if (cwr)
                tcph->th_flags |= TH_CWR;
        else
                tcph->th_flags &= ~TH_CWR;
        tcph->check = 0;
        tcph->check = tcp_checksum(tcph, payload_len);
}

/* send extra flags of the (NUM_PACKETS / 2) and (NUM_PACKETS / 2 - 1)
 * pkts, not first and not last pkt
 */
static void send_flags(int fd, struct sockaddr_ll *daddr, int psh, int syn,
                       int rst, int urg, int cwr)
{
        static char flag_buf[2][MAX_HDR_LEN + PAYLOAD_LEN];
        static char buf[MAX_HDR_LEN + PAYLOAD_LEN];
        int payload_len, pkt_size, i;
        struct tcphdr *tcph;
        int flag[2];

        payload_len = PAYLOAD_LEN * (psh || cwr);
        pkt_size = total_hdr_len + payload_len;
        flag[0] = NUM_PACKETS / 2;
        flag[1] = NUM_PACKETS / 2 - 1;

        /* Create and configure packets with flags
         */
        for (i = 0; i < 2; i++) {
                if (flag[i] > 0) {
                        create_packet(flag_buf[i], flag[i] * payload_len, 0,
                                      payload_len, 0);
                        tcph = (struct tcphdr *)(flag_buf[i] + tcp_offset);
                        set_flags(tcph, payload_len, psh, syn, rst, urg, cwr);
                }
        }

        for (i = 0; i < NUM_PACKETS + 1; i++) {
                if (i == flag[0]) {
                        write_packet(fd, flag_buf[0], pkt_size, daddr);
                        continue;
                } else if (i == flag[1] && cwr) {
                        write_packet(fd, flag_buf[1], 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);

                if (ipip) {
                        iph += 1;
                        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);
}

static void add_ipv6_exthdr(void *buf, void *optpkt, __u8 exthdr_type, char *ext_payload)
{
        struct ipv6_opt_hdr *exthdr = (struct ipv6_opt_hdr *)(optpkt + tcp_offset);
        struct ipv6hdr *iph = (struct ipv6hdr *)(optpkt + ETH_HLEN);
        char *exthdr_payload_start = (char *)(exthdr + 1);

        exthdr->hdrlen = 0;
        exthdr->nexthdr = IPPROTO_TCP;

        memcpy(exthdr_payload_start, ext_payload, MIN_EXTHDR_SIZE - sizeof(*exthdr));

        memcpy(optpkt, buf, tcp_offset);
        memcpy(optpkt + tcp_offset + MIN_EXTHDR_SIZE, buf + tcp_offset,
                sizeof(struct tcphdr) + PAYLOAD_LEN);

        iph->nexthdr = exthdr_type;
        iph->payload_len = htons(ntohs(iph->payload_len) + MIN_EXTHDR_SIZE);
}

static void fix_ip4_checksum(struct iphdr *iph)
{
        iph->check = 0;
        iph->check = checksum_fold(iph, sizeof(struct iphdr), 0);
}

static void send_flush_id_case(int fd, struct sockaddr_ll *daddr,
                               enum flush_id_case tcase)
{
        static char buf1[MAX_HDR_LEN + PAYLOAD_LEN];
        static char buf2[MAX_HDR_LEN + PAYLOAD_LEN];
        static char buf3[MAX_HDR_LEN + PAYLOAD_LEN];
        bool send_three = false;
        struct iphdr *iph1;
        struct iphdr *iph2;
        struct iphdr *iph3;

        iph1 = (struct iphdr *)(buf1 + ETH_HLEN);
        iph2 = (struct iphdr *)(buf2 + ETH_HLEN);
        iph3 = (struct iphdr *)(buf3 + ETH_HLEN);

        create_packet(buf1, 0, 0, PAYLOAD_LEN, 0);
        create_packet(buf2, PAYLOAD_LEN, 0, PAYLOAD_LEN, 0);
        create_packet(buf3, PAYLOAD_LEN * 2, 0, PAYLOAD_LEN, 0);

        switch (tcase) {
        case FLUSH_ID_DF1_INC: /* DF=1, Incrementing - should coalesce */
                iph1->frag_off |= htons(IP_DF);
                iph1->id = htons(8);

                iph2->frag_off |= htons(IP_DF);
                iph2->id = htons(9);
                break;

        case FLUSH_ID_DF1_FIXED: /* DF=1, Fixed - should coalesce */
                iph1->frag_off |= htons(IP_DF);
                iph1->id = htons(8);

                iph2->frag_off |= htons(IP_DF);
                iph2->id = htons(8);
                break;

        case FLUSH_ID_DF0_INC: /* DF=0, Incrementing - should coalesce */
                iph1->frag_off &= ~htons(IP_DF);
                iph1->id = htons(8);

                iph2->frag_off &= ~htons(IP_DF);
                iph2->id = htons(9);
                break;

        case FLUSH_ID_DF0_FIXED: /* DF=0, Fixed - should coalesce */
                iph1->frag_off &= ~htons(IP_DF);
                iph1->id = htons(8);

                iph2->frag_off &= ~htons(IP_DF);
                iph2->id = htons(8);
                break;

        case FLUSH_ID_DF1_INC_FIXED: /* DF=1, two packets incrementing, and
                                      * one fixed - should coalesce only the
                                      * first two packets
                                      */
                iph1->frag_off |= htons(IP_DF);
                iph1->id = htons(8);

                iph2->frag_off |= htons(IP_DF);
                iph2->id = htons(9);

                iph3->frag_off |= htons(IP_DF);
                iph3->id = htons(9);
                send_three = true;
                break;

        case FLUSH_ID_DF1_FIXED_INC: /* DF=1, two packets fixed, and one
                                      * incrementing - should coalesce only
                                      * the first two packets
                                      */
                iph1->frag_off |= htons(IP_DF);
                iph1->id = htons(8);

                iph2->frag_off |= htons(IP_DF);
                iph2->id = htons(8);

                iph3->frag_off |= htons(IP_DF);
                iph3->id = htons(9);
                send_three = true;
                break;
        }

        fix_ip4_checksum(iph1);
        fix_ip4_checksum(iph2);
        write_packet(fd, buf1, total_hdr_len + PAYLOAD_LEN, daddr);
        write_packet(fd, buf2, total_hdr_len + PAYLOAD_LEN, daddr);

        if (send_three) {
                fix_ip4_checksum(iph3);
                write_packet(fd, buf3, total_hdr_len + PAYLOAD_LEN, daddr);
        }
}

static void send_ipv6_exthdr(int fd, struct sockaddr_ll *daddr, char *ext_data1, char *ext_data2)
{
        static char buf[MAX_HDR_LEN + PAYLOAD_LEN];
        static char exthdr_pck[sizeof(buf) + MIN_EXTHDR_SIZE];

        create_packet(buf, 0, 0, PAYLOAD_LEN, 0);
        add_ipv6_exthdr(buf, exthdr_pck, IPPROTO_DSTOPTS, ext_data1);
        write_packet(fd, exthdr_pck, total_hdr_len + PAYLOAD_LEN + MIN_EXTHDR_SIZE, daddr);

        create_packet(buf, PAYLOAD_LEN * 1, 0, PAYLOAD_LEN, 0);
        add_ipv6_exthdr(buf, exthdr_pck, IPPROTO_DSTOPTS, ext_data2);
        write_packet(fd, exthdr_pck, total_hdr_len + PAYLOAD_LEN + MIN_EXTHDR_SIZE, daddr);
}

/* 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, IPPROTO_TCP);
        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);
        }
        sleep(1);
        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 = 3;
        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 set_rcvbuf(int fd)
{
        int bufsize = 1 * 1024 * 1024; /* 1 MB */

        if (setsockopt(fd, SOL_SOCKET, SO_RCVBUF, &bufsize, sizeof(bufsize)))
                error(1, errno, "cannot set rcvbuf size, setsockopt failed");
}

static void recv_error(int fd, int rcv_errno)
{
        struct tpacket_stats stats;
        socklen_t len;

        len = sizeof(stats);
        if (getsockopt(fd, SOL_PACKET, PACKET_STATISTICS, &stats, &len))
                error(1, errno, "can't get stats");

        fprintf(stderr, "Socket stats: packets=%u, drops=%u\n",
                stats.tp_packets, stats.tp_drops);
        error(1, rcv_errno, "could not receive");
}

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) {
                ip_ext_len = 0;
                pkt_size = recv(fd, buffer, IP_MAXPACKET + ETH_HLEN + 1, 0);
                if (pkt_size < 0)
                        recv_error(fd, errno);

                if (iph->version == 4)
                        ip_ext_len = (iph->ihl - 5) * 4;
                else if (ip6h->version == 6 && ip6h->nexthdr != IPPROTO_TCP)
                        ip_ext_len = MIN_EXTHDR_SIZE;

                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)
{
        const int fin_delay_us = 100 * 1000;
        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);

        /* data sub-tests */
        if (strcmp(testname, "data_same") == 0) {
                send_data_pkts(txfd, &daddr, PAYLOAD_LEN, PAYLOAD_LEN);
                write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
        } else if (strcmp(testname, "data_lrg_sml") == 0) {
                send_data_pkts(txfd, &daddr, PAYLOAD_LEN, PAYLOAD_LEN / 2);
                write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
        } else if (strcmp(testname, "data_sml_lrg") == 0) {
                send_data_pkts(txfd, &daddr, PAYLOAD_LEN / 2, PAYLOAD_LEN);
                write_packet(txfd, fin_pkt, total_hdr_len, &daddr);

        /* ack test */
        } else if (strcmp(testname, "ack") == 0) {
                send_ack(txfd, &daddr);
                write_packet(txfd, fin_pkt, total_hdr_len, &daddr);

        /* flags sub-tests */
        } else if (strcmp(testname, "flags_psh") == 0) {
                send_flags(txfd, &daddr, 1, 0, 0, 0, 0);
                write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
        } else if (strcmp(testname, "flags_syn") == 0) {
                send_flags(txfd, &daddr, 0, 1, 0, 0, 0);
                write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
        } else if (strcmp(testname, "flags_rst") == 0) {
                send_flags(txfd, &daddr, 0, 0, 1, 0, 0);
                write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
        } else if (strcmp(testname, "flags_urg") == 0) {
                send_flags(txfd, &daddr, 0, 0, 0, 1, 0);
                write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
        } else if (strcmp(testname, "flags_cwr") == 0) {
                send_flags(txfd, &daddr, 0, 0, 0, 0, 1);
                write_packet(txfd, fin_pkt, total_hdr_len, &daddr);

        /* tcp sub-tests */
        } else if (strcmp(testname, "tcp_csum") == 0) {
                send_changed_checksum(txfd, &daddr);
                usleep(fin_delay_us);
                write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
        } else if (strcmp(testname, "tcp_seq") == 0) {
                send_changed_seq(txfd, &daddr);
                usleep(fin_delay_us);
                write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
        } else if (strcmp(testname, "tcp_ts") == 0) {
                send_changed_ts(txfd, &daddr);
                usleep(fin_delay_us);
                write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
        } else if (strcmp(testname, "tcp_opt") == 0) {
                send_diff_opt(txfd, &daddr);
                usleep(fin_delay_us);
                write_packet(txfd, fin_pkt, total_hdr_len, &daddr);

        /* ip sub-tests - shared between IPv4 and IPv6 */
        } else if (strcmp(testname, "ip_ecn") == 0) {
                send_changed_ECN(txfd, &daddr);
                write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
        } else if (strcmp(testname, "ip_tos") == 0) {
                send_changed_tos(txfd, &daddr);
                write_packet(txfd, fin_pkt, total_hdr_len, &daddr);

        /* ip sub-tests - IPv4 only */
        } else if (strcmp(testname, "ip_ttl") == 0) {
                send_changed_ttl(txfd, &daddr);
                write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
        } else if (strcmp(testname, "ip_opt") == 0) {
                send_ip_options(txfd, &daddr);
                usleep(fin_delay_us);
                write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
        } else if (strcmp(testname, "ip_frag4") == 0) {
                send_fragment4(txfd, &daddr);
                usleep(fin_delay_us);
                write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
        } else if (strcmp(testname, "ip_id_df1_inc") == 0) {
                send_flush_id_case(txfd, &daddr, FLUSH_ID_DF1_INC);
                usleep(fin_delay_us);
                write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
        } else if (strcmp(testname, "ip_id_df1_fixed") == 0) {
                send_flush_id_case(txfd, &daddr, FLUSH_ID_DF1_FIXED);
                usleep(fin_delay_us);
                write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
        } else if (strcmp(testname, "ip_id_df0_inc") == 0) {
                send_flush_id_case(txfd, &daddr, FLUSH_ID_DF0_INC);
                usleep(fin_delay_us);
                write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
        } else if (strcmp(testname, "ip_id_df0_fixed") == 0) {
                send_flush_id_case(txfd, &daddr, FLUSH_ID_DF0_FIXED);
                usleep(fin_delay_us);
                write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
        } else if (strcmp(testname, "ip_id_df1_inc_fixed") == 0) {
                send_flush_id_case(txfd, &daddr, FLUSH_ID_DF1_INC_FIXED);
                usleep(fin_delay_us);
                write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
        } else if (strcmp(testname, "ip_id_df1_fixed_inc") == 0) {
                send_flush_id_case(txfd, &daddr, FLUSH_ID_DF1_FIXED_INC);
                usleep(fin_delay_us);
                write_packet(txfd, fin_pkt, total_hdr_len, &daddr);

        /* ip sub-tests - IPv6 only */
        } else if (strcmp(testname, "ip_frag6") == 0) {
                send_fragment6(txfd, &daddr);
                usleep(fin_delay_us);
                write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
        } else if (strcmp(testname, "ip_v6ext_same") == 0) {
                send_ipv6_exthdr(txfd, &daddr, EXT_PAYLOAD_1, EXT_PAYLOAD_1);
                usleep(fin_delay_us);
                write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
        } else if (strcmp(testname, "ip_v6ext_diff") == 0) {
                send_ipv6_exthdr(txfd, &daddr, EXT_PAYLOAD_1, EXT_PAYLOAD_2);
                usleep(fin_delay_us);
                write_packet(txfd, fin_pkt, total_hdr_len, &daddr);

        /* large sub-tests */
        } else if (strcmp(testname, "large_max") == 0) {
                int offset = (proto == PF_INET && !ipip) ? 20 : 0;
                int remainder = (MAX_PAYLOAD + offset) % MSS;

                send_large(txfd, &daddr, remainder);
                write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
        } else if (strcmp(testname, "large_rem") == 0) {
                int offset = (proto == PF_INET && !ipip) ? 20 : 0;
                int remainder = (MAX_PAYLOAD + offset) % MSS;

                send_large(txfd, &daddr, remainder + 1);
                write_packet(txfd, fin_pkt, total_hdr_len, &daddr);
        } else {
                error(1, 0, "Unknown testcase: %s", testname);
        }

        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);
        set_rcvbuf(rxfd);
        bind_packetsocket(rxfd);

        ksft_ready();

        memset(correct_payload, 0, sizeof(correct_payload));

        /* data sub-tests */
        if (strcmp(testname, "data_same") == 0) {
                printf("pure data packet of same size: ");
                correct_payload[0] = PAYLOAD_LEN * 2;
                check_recv_pkts(rxfd, correct_payload, 1);
        } else if (strcmp(testname, "data_lrg_sml") == 0) {
                printf("large data packets followed by a smaller one: ");
                correct_payload[0] = PAYLOAD_LEN * 1.5;
                check_recv_pkts(rxfd, correct_payload, 1);
        } else if (strcmp(testname, "data_sml_lrg") == 0) {
                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);

        /* ack test */
        } else if (strcmp(testname, "ack") == 0) {
                printf("duplicate ack and pure ack: ");
                check_recv_pkts(rxfd, correct_payload, 3);

        /* flags sub-tests */
        } else if (strcmp(testname, "flags_psh") == 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);
        } else if (strcmp(testname, "flags_syn") == 0) {
                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);
        } else if (strcmp(testname, "flags_rst") == 0) {
                correct_payload[0] = PAYLOAD_LEN * 2;
                correct_payload[1] = 0;
                correct_payload[2] = PAYLOAD_LEN * 2;
                printf("rst flag ends coalescing: ");
                check_recv_pkts(rxfd, correct_payload, 3);
        } else if (strcmp(testname, "flags_urg") == 0) {
                correct_payload[0] = PAYLOAD_LEN * 2;
                correct_payload[1] = 0;
                correct_payload[2] = PAYLOAD_LEN * 2;
                printf("urg flag ends coalescing: ");
                check_recv_pkts(rxfd, correct_payload, 3);
        } else if (strcmp(testname, "flags_cwr") == 0) {
                correct_payload[0] = PAYLOAD_LEN;
                correct_payload[1] = PAYLOAD_LEN * 2;
                correct_payload[2] = PAYLOAD_LEN * 2;
                printf("cwr flag ends coalescing: ");
                check_recv_pkts(rxfd, correct_payload, 3);

        /* tcp sub-tests */
        } else if (strcmp(testname, "tcp_csum") == 0) {
                correct_payload[0] = PAYLOAD_LEN;
                correct_payload[1] = PAYLOAD_LEN;
                printf("changed checksum does not coalesce: ");
                check_recv_pkts(rxfd, correct_payload, 2);
        } else if (strcmp(testname, "tcp_seq") == 0) {
                correct_payload[0] = PAYLOAD_LEN;
                correct_payload[1] = PAYLOAD_LEN;
                printf("Wrong Seq number doesn't coalesce: ");
                check_recv_pkts(rxfd, correct_payload, 2);
        } else if (strcmp(testname, "tcp_ts") == 0) {
                correct_payload[0] = PAYLOAD_LEN * 2;
                correct_payload[1] = PAYLOAD_LEN;
                correct_payload[2] = PAYLOAD_LEN;
                correct_payload[3] = PAYLOAD_LEN;
                printf("Different timestamp doesn't coalesce: ");
                check_recv_pkts(rxfd, correct_payload, 4);
        } else if (strcmp(testname, "tcp_opt") == 0) {
                correct_payload[0] = PAYLOAD_LEN * 2;
                correct_payload[1] = PAYLOAD_LEN;
                printf("Different options doesn't coalesce: ");
                check_recv_pkts(rxfd, correct_payload, 2);

        /* ip sub-tests - shared between IPv4 and IPv6 */
        } else if (strcmp(testname, "ip_ecn") == 0) {
                correct_payload[0] = PAYLOAD_LEN;
                correct_payload[1] = PAYLOAD_LEN;
                printf("different ECN doesn't coalesce: ");
                check_recv_pkts(rxfd, correct_payload, 2);
        } else if (strcmp(testname, "ip_tos") == 0) {
                correct_payload[0] = PAYLOAD_LEN;
                correct_payload[1] = PAYLOAD_LEN;
                printf("different tos doesn't coalesce: ");
                check_recv_pkts(rxfd, correct_payload, 2);

        /* ip sub-tests - IPv4 only */
        } else if (strcmp(testname, "ip_ttl") == 0) {
                correct_payload[0] = PAYLOAD_LEN;
                correct_payload[1] = PAYLOAD_LEN;
                printf("different ttl doesn't coalesce: ");
                check_recv_pkts(rxfd, correct_payload, 2);
        } else if (strcmp(testname, "ip_opt") == 0) {
                correct_payload[0] = PAYLOAD_LEN;
                correct_payload[1] = PAYLOAD_LEN;
                correct_payload[2] = PAYLOAD_LEN;
                printf("ip options doesn't coalesce: ");
                check_recv_pkts(rxfd, correct_payload, 3);
        } else if (strcmp(testname, "ip_frag4") == 0) {
                correct_payload[0] = PAYLOAD_LEN;
                correct_payload[1] = PAYLOAD_LEN;
                printf("fragmented ip4 doesn't coalesce: ");
                check_recv_pkts(rxfd, correct_payload, 2);
        } else if (strcmp(testname, "ip_id_df1_inc") == 0) {
                printf("DF=1, Incrementing - should coalesce: ");
                correct_payload[0] = PAYLOAD_LEN * 2;
                check_recv_pkts(rxfd, correct_payload, 1);
        } else if (strcmp(testname, "ip_id_df1_fixed") == 0) {
                printf("DF=1, Fixed - should coalesce: ");
                correct_payload[0] = PAYLOAD_LEN * 2;
                check_recv_pkts(rxfd, correct_payload, 1);
        } else if (strcmp(testname, "ip_id_df0_inc") == 0) {
                printf("DF=0, Incrementing - should coalesce: ");
                correct_payload[0] = PAYLOAD_LEN * 2;
                check_recv_pkts(rxfd, correct_payload, 1);
        } else if (strcmp(testname, "ip_id_df0_fixed") == 0) {
                printf("DF=0, Fixed - should coalesce: ");
                correct_payload[0] = PAYLOAD_LEN * 2;
                check_recv_pkts(rxfd, correct_payload, 1);
        } else if (strcmp(testname, "ip_id_df1_inc_fixed") == 0) {
                printf("DF=1, 2 Incrementing and one fixed - should coalesce only first 2 packets: ");
                correct_payload[0] = PAYLOAD_LEN * 2;
                correct_payload[1] = PAYLOAD_LEN;
                check_recv_pkts(rxfd, correct_payload, 2);
        } else if (strcmp(testname, "ip_id_df1_fixed_inc") == 0) {
                printf("DF=1, 2 Fixed and one incrementing - should coalesce only first 2 packets: ");
                correct_payload[0] = PAYLOAD_LEN * 2;
                correct_payload[1] = PAYLOAD_LEN;
                check_recv_pkts(rxfd, correct_payload, 2);

        /* ip sub-tests - IPv6 only */
        } else if (strcmp(testname, "ip_frag6") == 0) {
                /* 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;
                correct_payload[1] = PAYLOAD_LEN;
                correct_payload[2] = PAYLOAD_LEN;
                check_recv_pkts(rxfd, correct_payload, 3);
        } else if (strcmp(testname, "ip_v6ext_same") == 0) {
                printf("ipv6 with ext header does coalesce: ");
                correct_payload[0] = PAYLOAD_LEN * 2;
                check_recv_pkts(rxfd, correct_payload, 1);
        } else if (strcmp(testname, "ip_v6ext_diff") == 0) {
                printf("ipv6 with ext header with different payloads doesn't coalesce: ");
                correct_payload[0] = PAYLOAD_LEN;
                correct_payload[1] = PAYLOAD_LEN;
                check_recv_pkts(rxfd, correct_payload, 2);

        /* large sub-tests */
        } else if (strcmp(testname, "large_max") == 0) {
                int offset = (proto == PF_INET && !ipip) ? 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);
        } else if (strcmp(testname, "large_rem") == 0) {
                int offset = (proto == PF_INET && !ipip) ? 20 : 0;
                int remainder = (MAX_PAYLOAD + offset) % MSS;

                /* last segment sent individually, doesn't start new segment */
                correct_payload[0] = (MAX_PAYLOAD + offset) - remainder;
                correct_payload[1] = remainder + 1;
                correct_payload[2] = remainder + 1;
                printf("last segment sent individually: ");
                check_recv_pkts(rxfd, correct_payload, 3);
        } else {
                error(1, 0, "Test case error: unknown testname %s", testname);
        }

        if (close(rxfd))
                error(1, 0, "socket close");
}

static void parse_args(int argc, char **argv)
{
        static const struct option opts[] = {
                { "daddr", required_argument, NULL, 'd' },
                { "dmac", required_argument, NULL, 'D' },
                { "iface", required_argument, NULL, 'i' },
                { "ipv4", no_argument, NULL, '4' },
                { "ipv6", no_argument, NULL, '6' },
                { "ipip", no_argument, NULL, 'e' },
                { "rx", no_argument, NULL, 'r' },
                { "saddr", required_argument, NULL, 's' },
                { "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:D:ei:rs:S: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 'e':
                        ipip = true;
                        proto = PF_INET;
                        ethhdr_proto = htons(ETH_P_IP);
                        break;
                case 'd':
                        addr4_dst = addr6_dst = optarg;
                        break;
                case 'D':
                        dmac = optarg;
                        break;
                case 'i':
                        ifname = optarg;
                        break;
                case 'r':
                        tx_socket = false;
                        break;
                case 's':
                        addr4_src = addr6_src = optarg;
                        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 (ipip) {
                tcp_offset = ETH_HLEN + sizeof(struct iphdr) * 2;
                total_hdr_len = tcp_offset + sizeof(struct tcphdr);
        } else 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 {
                /* Only the receiver exit status determines test success. */
                gro_receiver();
                fprintf(stderr, "Gro::%s test passed.\n", testname);
        }

        return 0;
}