// SPDX-License-Identifier: GPL-2.0

/* Test hardware checksum offload: Rx + Tx, IPv4 + IPv6, TCP + UDP.
 *
 * The test runs on two machines to exercise the NIC. For this reason it
 * is not integrated in kselftests.
 *
 *     CMD=$((./csum -[46] -[tu] -S $SADDR -D $DADDR -[RT] -r 1 $EXTRA_ARGS))
 *
 * Rx:
 *
 * The sender sends packets with a known checksum field using PF_INET(6)
 * SOCK_RAW sockets.
 *
 * good packet: $CMD [-t]
 * bad packet:  $CMD [-t] -E
 *
 * The receiver reads UDP packets with a UDP socket. This is not an
 * option for TCP packets ('-t'). Optionally insert an iptables filter
 * to avoid these entering the real protocol stack.
 *
 * The receiver also reads all packets with a PF_PACKET socket, to
 * observe whether both good and bad packets arrive on the host. And to
 * read the optional TP_STATUS_CSUM_VALID bit. This requires setting
 * option PACKET_AUXDATA, and works only for CHECKSUM_UNNECESSARY.
 *
 * Tx:
 *
 * The sender needs to build CHECKSUM_PARTIAL packets to exercise tx
 * checksum offload.
 *
 * The sender can sends packets with a UDP socket.
 *
 * Optionally crafts a packet that sums up to zero to verify that the
 * device writes negative zero 0xFFFF in this case to distinguish from
 * 0x0000 (checksum disabled), as required by RFC 768. Hit this case
 * by choosing a specific source port.
 *
 * good packet: $CMD -U
 * zero csum:   $CMD -U -Z
 *
 * The sender can also build packets with PF_PACKET with PACKET_VNET_HDR,
 * to cover more protocols. PF_PACKET requires passing src and dst mac
 * addresses.
 *
 * good packet: $CMD -s $smac -d $dmac -p [-t]
 *
 * Argument '-z' sends UDP packets with a 0x000 checksum disabled field,
 * to verify that the NIC passes these packets unmodified.
 *
 * Argument '-e' adds a transport mode encapsulation header between
 * network and transport header. This will fail for devices that parse
 *  headers. Should work on devices that implement protocol agnostic tx
 * checksum offload (NETIF_F_HW_CSUM).
 *
 * Argument '-r $SEED' optionally randomizes header, payload and length
 * to increase coverage between packets sent. SEED 1 further chooses a
 * different seed for each run (and logs this for reproducibility). It
 * is advised to enable this for extra coverage in continuous testing.
 */

#define _GNU_SOURCE

#include <arpa/inet.h>
#include <asm/byteorder.h>
#include <errno.h>
#include <error.h>
#include <linux/filter.h>
#include <linux/if_packet.h>
#include <linux/ipv6.h>
#include <linux/virtio_net.h>
#include <net/ethernet.h>
#include <net/if.h>
#include <netinet/if_ether.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/ip6.h>
#include <netinet/tcp.h>
#include <netinet/udp.h>
#include <poll.h>
#include <sched.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>

#include "kselftest.h"

static bool cfg_bad_csum;
static int cfg_family = PF_INET6;
static int cfg_num_pkt = 4;
static bool cfg_do_rx = true;
static bool cfg_do_tx = true;
static bool cfg_encap;
static char *cfg_ifname = "eth0";
static char *cfg_mac_dst;
static char *cfg_mac_src;
static int cfg_proto = IPPROTO_UDP;
static int cfg_payload_char = 'a';
static int cfg_payload_len = 100;
static uint16_t cfg_port_dst = 34000;
static uint16_t cfg_port_src = 33000;
static uint16_t cfg_port_src_encap = 33001;
static unsigned int cfg_random_seed;
static int cfg_rcvbuf = 1 << 22;        /* be able to queue large cfg_num_pkt */
static bool cfg_send_pfpacket;
static bool cfg_send_udp;
static int cfg_timeout_ms = 2000;
static bool cfg_zero_disable; /* skip checksum: set to zero (udp only) */
static bool cfg_zero_sum;     /* create packet that adds up to zero */

static struct sockaddr_in cfg_daddr4 = {.sin_family = AF_INET};
static struct sockaddr_in cfg_saddr4 = {.sin_family = AF_INET};
static struct sockaddr_in6 cfg_daddr6 = {.sin6_family = AF_INET6};
static struct sockaddr_in6 cfg_saddr6 = {.sin6_family = AF_INET6};

#define ENC_HEADER_LEN  (sizeof(struct udphdr) + sizeof(struct udp_encap_hdr))
#define MAX_HEADER_LEN  (sizeof(struct ipv6hdr) + ENC_HEADER_LEN + sizeof(struct tcphdr))
#define MAX_PAYLOAD_LEN 1024

/* Trivial demo encap. Stand-in for transport layer protocols like ESP or PSP */
struct udp_encap_hdr {
        uint8_t nexthdr;
        uint8_t padding[3];
};

/* Ipaddrs, for pseudo csum. Global var is ugly, pass through funcs was worse */
static void *iph_addr_p;

static unsigned long gettimeofday_ms(void)
{
        struct timeval tv;

        gettimeofday(&tv, NULL);
        return (tv.tv_sec * 1000UL) + (tv.tv_usec / 1000UL);
}

static uint32_t checksum_nofold(char *data, size_t len, uint32_t sum)
{
        uint16_t *words = (uint16_t *)data;
        int i;

        for (i = 0; i < len / 2; i++)
                sum += words[i];

        if (len & 1)
                sum += ((unsigned 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 checksum(void *th, uint16_t proto, size_t len)
{
        uint32_t sum;
        int alen;

        alen = cfg_family == PF_INET6 ? 32 : 8;

        sum = checksum_nofold(iph_addr_p, alen, 0);
        sum += htons(proto);
        sum += htons(len);

        /* With CHECKSUM_PARTIAL kernel expects non-inverted pseudo csum */
        if (cfg_do_tx && cfg_send_pfpacket)
                return ~checksum_fold(NULL, 0, sum);
        else
                return checksum_fold(th, len, sum);
}

static void *build_packet_ipv4(void *_iph, uint8_t proto, unsigned int len)
{
        struct iphdr *iph = _iph;

        memset(iph, 0, sizeof(*iph));

        iph->version = 4;
        iph->ihl = 5;
        iph->ttl = 8;
        iph->protocol = proto;
        iph->saddr = cfg_saddr4.sin_addr.s_addr;
        iph->daddr = cfg_daddr4.sin_addr.s_addr;
        iph->tot_len = htons(sizeof(*iph) + len);
        iph->check = checksum_fold(iph, sizeof(*iph), 0);

        iph_addr_p = &iph->saddr;

        return iph + 1;
}

static void *build_packet_ipv6(void *_ip6h, uint8_t proto, unsigned int len)
{
        struct ipv6hdr *ip6h = _ip6h;

        memset(ip6h, 0, sizeof(*ip6h));

        ip6h->version = 6;
        ip6h->payload_len = htons(len);
        ip6h->nexthdr = proto;
        ip6h->hop_limit = 64;
        ip6h->saddr = cfg_saddr6.sin6_addr;
        ip6h->daddr = cfg_daddr6.sin6_addr;

        iph_addr_p = &ip6h->saddr;

        return ip6h + 1;
}

static void *build_packet_udp(void *_uh)
{
        struct udphdr *uh = _uh;

        uh->source = htons(cfg_port_src);
        uh->dest = htons(cfg_port_dst);
        uh->len = htons(sizeof(*uh) + cfg_payload_len);
        uh->check = 0;

        /* choose source port so that uh->check adds up to zero */
        if (cfg_zero_sum) {
                uh->source = 0;
                uh->source = checksum(uh, IPPROTO_UDP, sizeof(*uh) + cfg_payload_len);

                fprintf(stderr, "tx: changing sport: %hu -> %hu\n",
                        cfg_port_src, ntohs(uh->source));
                cfg_port_src = ntohs(uh->source);
        }

        if (cfg_zero_disable)
                uh->check = 0;
        else
                uh->check = checksum(uh, IPPROTO_UDP, sizeof(*uh) + cfg_payload_len);

        if (cfg_bad_csum)
                uh->check = ~uh->check;

        fprintf(stderr, "tx: sending checksum: 0x%x\n", uh->check);
        return uh + 1;
}

static void *build_packet_tcp(void *_th)
{
        struct tcphdr *th = _th;

        th->source = htons(cfg_port_src);
        th->dest = htons(cfg_port_dst);
        th->doff = 5;
        th->check = 0;

        th->check = checksum(th, IPPROTO_TCP, sizeof(*th) + cfg_payload_len);

        if (cfg_bad_csum)
                th->check = ~th->check;

        fprintf(stderr, "tx: sending checksum: 0x%x\n", th->check);
        return th + 1;
}

static char *build_packet_udp_encap(void *_uh)
{
        struct udphdr *uh = _uh;
        struct udp_encap_hdr *eh = _uh + sizeof(*uh);

        /* outer dst == inner dst, to simplify BPF filter
         * outer src != inner src, to demultiplex on recv
         */
        uh->dest = htons(cfg_port_dst);
        uh->source = htons(cfg_port_src_encap);
        uh->check = 0;
        uh->len = htons(sizeof(*uh) +
                        sizeof(*eh) +
                        sizeof(struct tcphdr) +
                        cfg_payload_len);

        eh->nexthdr = IPPROTO_TCP;

        return build_packet_tcp(eh + 1);
}

static char *build_packet(char *buf, int max_len, int *len)
{
        uint8_t proto;
        char *off;
        int tlen;

        if (cfg_random_seed) {
                int *buf32 = (void *)buf;
                int i;

                for (i = 0; i < (max_len / sizeof(int)); i++)
                        buf32[i] = rand();
        } else {
                memset(buf, cfg_payload_char, max_len);
        }

        if (cfg_proto == IPPROTO_UDP)
                tlen = sizeof(struct udphdr) + cfg_payload_len;
        else
                tlen = sizeof(struct tcphdr) + cfg_payload_len;

        if (cfg_encap) {
                proto = IPPROTO_UDP;
                tlen += ENC_HEADER_LEN;
        } else {
                proto = cfg_proto;
        }

        if (cfg_family == PF_INET)
                off = build_packet_ipv4(buf, proto, tlen);
        else
                off = build_packet_ipv6(buf, proto, tlen);

        if (cfg_encap)
                off = build_packet_udp_encap(off);
        else if (cfg_proto == IPPROTO_UDP)
                off = build_packet_udp(off);
        else
                off = build_packet_tcp(off);

        /* only pass the payload, but still compute headers for cfg_zero_sum */
        if (cfg_send_udp) {
                *len = cfg_payload_len;
                return off;
        }

        *len = off - buf + cfg_payload_len;
        return buf;
}

static int open_inet(int ipproto, int protocol)
{
        int fd;

        fd = socket(cfg_family, ipproto, protocol);
        if (fd == -1)
                error(1, errno, "socket inet");

        if (cfg_family == PF_INET6) {
                /* may have been updated by cfg_zero_sum */
                cfg_saddr6.sin6_port = htons(cfg_port_src);

                if (bind(fd, (void *)&cfg_saddr6, sizeof(cfg_saddr6)))
                        error(1, errno, "bind dgram 6");
                if (connect(fd, (void *)&cfg_daddr6, sizeof(cfg_daddr6)))
                        error(1, errno, "connect dgram 6");
        } else {
                /* may have been updated by cfg_zero_sum */
                cfg_saddr4.sin_port = htons(cfg_port_src);

                if (bind(fd, (void *)&cfg_saddr4, sizeof(cfg_saddr4)))
                        error(1, errno, "bind dgram 4");
                if (connect(fd, (void *)&cfg_daddr4, sizeof(cfg_daddr4)))
                        error(1, errno, "connect dgram 4");
        }

        return fd;
}

static int open_packet(void)
{
        int fd, one = 1;

        fd = socket(PF_PACKET, SOCK_RAW, 0);
        if (fd == -1)
                error(1, errno, "socket packet");

        if (setsockopt(fd, SOL_PACKET, PACKET_VNET_HDR, &one, sizeof(one)))
                error(1, errno, "setsockopt packet_vnet_ndr");

        return fd;
}

static void send_inet(int fd, const char *buf, int len)
{
        int ret;

        ret = write(fd, buf, len);
        if (ret == -1)
                error(1, errno, "write");
        if (ret != len)
                error(1, 0, "write: %d", ret);
}

static void eth_str_to_addr(const char *str, unsigned char *eth)
{
        if (sscanf(str, "%hhx:%hhx:%hhx:%hhx:%hhx:%hhx",
                   &eth[0], &eth[1], &eth[2], &eth[3], &eth[4], &eth[5]) != 6)
                error(1, 0, "cannot parse mac addr %s", str);
}

static void send_packet(int fd, const char *buf, int len)
{
        struct virtio_net_hdr vh = {0};
        struct sockaddr_ll addr = {0};
        struct msghdr msg = {0};
        struct ethhdr eth;
        struct iovec iov[3];
        int ret;

        addr.sll_family = AF_PACKET;
        addr.sll_halen = ETH_ALEN;
        addr.sll_ifindex = if_nametoindex(cfg_ifname);
        if (!addr.sll_ifindex)
                error(1, errno, "if_nametoindex %s", cfg_ifname);

        vh.flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
        if (cfg_family == PF_INET6) {
                vh.csum_start = sizeof(struct ethhdr) + sizeof(struct ipv6hdr);
                addr.sll_protocol = htons(ETH_P_IPV6);
        } else {
                vh.csum_start = sizeof(struct ethhdr) + sizeof(struct iphdr);
                addr.sll_protocol = htons(ETH_P_IP);
        }

        if (cfg_encap)
                vh.csum_start += ENC_HEADER_LEN;

        if (cfg_proto == IPPROTO_TCP) {
                vh.csum_offset = __builtin_offsetof(struct tcphdr, check);
                vh.hdr_len = vh.csum_start + sizeof(struct tcphdr);
        } else {
                vh.csum_offset = __builtin_offsetof(struct udphdr, check);
                vh.hdr_len = vh.csum_start + sizeof(struct udphdr);
        }

        eth_str_to_addr(cfg_mac_src, eth.h_source);
        eth_str_to_addr(cfg_mac_dst, eth.h_dest);
        eth.h_proto = addr.sll_protocol;

        iov[0].iov_base = &vh;
        iov[0].iov_len = sizeof(vh);

        iov[1].iov_base = &eth;
        iov[1].iov_len = sizeof(eth);

        iov[2].iov_base = (void *)buf;
        iov[2].iov_len = len;

        msg.msg_iov = iov;
        msg.msg_iovlen = ARRAY_SIZE(iov);

        msg.msg_name = &addr;
        msg.msg_namelen = sizeof(addr);

        ret = sendmsg(fd, &msg, 0);
        if (ret == -1)
                error(1, errno, "sendmsg packet");
        if (ret != sizeof(vh) + sizeof(eth) + len)
                error(1, errno, "sendmsg packet: %u", ret);
}

static int recv_prepare_udp(void)
{
        int fd;

        fd = socket(cfg_family, SOCK_DGRAM, 0);
        if (fd == -1)
                error(1, errno, "socket r");

        if (setsockopt(fd, SOL_SOCKET, SO_RCVBUF,
                       &cfg_rcvbuf, sizeof(cfg_rcvbuf)))
                error(1, errno, "setsockopt SO_RCVBUF r");

        if (cfg_family == PF_INET6) {
                if (bind(fd, (void *)&cfg_daddr6, sizeof(cfg_daddr6)))
                        error(1, errno, "bind r");
        } else {
                if (bind(fd, (void *)&cfg_daddr4, sizeof(cfg_daddr4)))
                        error(1, errno, "bind r");
        }

        return fd;
}

/* Filter out all traffic that is not cfg_proto with our destination port.
 *
 * Otherwise background noise may cause PF_PACKET receive queue overflow,
 * dropping the expected packets and failing the test.
 */
static void __recv_prepare_packet_filter(int fd, int off_nexthdr, int off_dport)
{
        struct sock_filter filter[] = {
                BPF_STMT(BPF_LD + BPF_B + BPF_ABS, SKF_AD_OFF + SKF_AD_PKTTYPE),
                BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, PACKET_HOST, 0, 4),
                BPF_STMT(BPF_LD + BPF_B + BPF_ABS, off_nexthdr),
                BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, cfg_encap ? IPPROTO_UDP : cfg_proto, 0, 2),
                BPF_STMT(BPF_LD + BPF_H + BPF_ABS, off_dport),
                BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, cfg_port_dst, 1, 0),
                BPF_STMT(BPF_RET + BPF_K, 0),
                BPF_STMT(BPF_RET + BPF_K, 0xFFFF),
        };
        struct sock_fprog prog = {};

        prog.filter = filter;
        prog.len = ARRAY_SIZE(filter);
        if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &prog, sizeof(prog)))
                error(1, errno, "setsockopt filter");
}

static void recv_prepare_packet_filter(int fd)
{
        const int off_dport = offsetof(struct tcphdr, dest); /* same for udp */

        if (cfg_family == AF_INET)
                __recv_prepare_packet_filter(fd, offsetof(struct iphdr, protocol),
                                             sizeof(struct iphdr) + off_dport);
        else
                __recv_prepare_packet_filter(fd, offsetof(struct ipv6hdr, nexthdr),
                                             sizeof(struct ipv6hdr) + off_dport);
}

static void recv_prepare_packet_bind(int fd)
{
        struct sockaddr_ll laddr = {0};

        laddr.sll_family = AF_PACKET;

        if (cfg_family == PF_INET)
                laddr.sll_protocol = htons(ETH_P_IP);
        else
                laddr.sll_protocol = htons(ETH_P_IPV6);

        laddr.sll_ifindex = if_nametoindex(cfg_ifname);
        if (!laddr.sll_ifindex)
                error(1, 0, "if_nametoindex %s", cfg_ifname);

        if (bind(fd, (void *)&laddr, sizeof(laddr)))
                error(1, errno, "bind pf_packet");
}

static int recv_prepare_packet(void)
{
        int fd, one = 1;

        fd = socket(PF_PACKET, SOCK_DGRAM, 0);
        if (fd == -1)
                error(1, errno, "socket p");

        if (setsockopt(fd, SOL_SOCKET, SO_RCVBUF,
                       &cfg_rcvbuf, sizeof(cfg_rcvbuf)))
                error(1, errno, "setsockopt SO_RCVBUF p");

        /* enable auxdata to recv checksum status (valid vs unknown) */
        if (setsockopt(fd, SOL_PACKET, PACKET_AUXDATA, &one, sizeof(one)))
                error(1, errno, "setsockopt auxdata");

        /* install filter to restrict packet flow to match */
        recv_prepare_packet_filter(fd);

        /* bind to address family to start packet flow */
        recv_prepare_packet_bind(fd);

        return fd;
}

static int recv_udp(int fd)
{
        static char buf[MAX_PAYLOAD_LEN];
        int ret, count = 0;

        while (1) {
                ret = recv(fd, buf, sizeof(buf), MSG_DONTWAIT);
                if (ret == -1 && errno == EAGAIN)
                        break;
                if (ret == -1)
                        error(1, errno, "recv r");

                fprintf(stderr, "rx: udp: len=%u\n", ret);
                count++;
        }

        return count;
}

static int recv_verify_csum(void *th, int len, uint16_t sport, uint16_t csum_field)
{
        uint16_t csum;

        csum = checksum(th, cfg_proto, len);

        fprintf(stderr, "rx: pkt: sport=%hu len=%u csum=0x%hx verify=0x%hx\n",
                sport, len, csum_field, csum);

        /* csum must be zero unless cfg_bad_csum indicates bad csum */
        if (csum && !cfg_bad_csum) {
                fprintf(stderr, "pkt: bad csum\n");
                return 1;
        } else if (cfg_bad_csum && !csum) {
                fprintf(stderr, "pkt: good csum, while bad expected\n");
                return 1;
        }

        if (cfg_zero_sum && csum_field != 0xFFFF) {
                fprintf(stderr, "pkt: zero csum: field should be 0xFFFF, is 0x%hx\n", csum_field);
                return 1;
        }

        return 0;
}

static int recv_verify_packet_tcp(void *th, int len)
{
        struct tcphdr *tcph = th;

        if (len < sizeof(*tcph) || tcph->dest != htons(cfg_port_dst))
                return -1;

        return recv_verify_csum(th, len, ntohs(tcph->source), tcph->check);
}

static int recv_verify_packet_udp_encap(void *th, int len)
{
        struct udp_encap_hdr *eh = th;

        if (len < sizeof(*eh) || eh->nexthdr != IPPROTO_TCP)
                return -1;

        return recv_verify_packet_tcp(eh + 1, len - sizeof(*eh));
}

static int recv_verify_packet_udp(void *th, int len)
{
        struct udphdr *udph = th;

        if (len < sizeof(*udph))
                return -1;

        if (udph->dest != htons(cfg_port_dst))
                return -1;

        if (udph->source == htons(cfg_port_src_encap))
                return recv_verify_packet_udp_encap(udph + 1,
                                                    len - sizeof(*udph));

        return recv_verify_csum(th, len, ntohs(udph->source), udph->check);
}

static int recv_verify_packet_ipv4(void *nh, int len)
{
        struct iphdr *iph = nh;
        uint16_t proto = cfg_encap ? IPPROTO_UDP : cfg_proto;
        uint16_t ip_len;

        if (len < sizeof(*iph) || iph->protocol != proto)
                return -1;

        ip_len = ntohs(iph->tot_len);
        if (ip_len > len || ip_len < sizeof(*iph))
                return -1;

        len = ip_len;
        iph_addr_p = &iph->saddr;
        if (proto == IPPROTO_TCP)
                return recv_verify_packet_tcp(iph + 1, len - sizeof(*iph));
        else
                return recv_verify_packet_udp(iph + 1, len - sizeof(*iph));
}

static int recv_verify_packet_ipv6(void *nh, int len)
{
        struct ipv6hdr *ip6h = nh;
        uint16_t proto = cfg_encap ? IPPROTO_UDP : cfg_proto;
        uint16_t payload_len;

        if (len < sizeof(*ip6h) || ip6h->nexthdr != proto)
                return -1;

        payload_len = ntohs(ip6h->payload_len);
        if (payload_len > len - sizeof(*ip6h))
                return -1;

        iph_addr_p = &ip6h->saddr;
        if (proto == IPPROTO_TCP)
                return recv_verify_packet_tcp(ip6h + 1, payload_len);
        else
                return recv_verify_packet_udp(ip6h + 1, payload_len);
}

/* return whether auxdata includes TP_STATUS_CSUM_VALID */
static uint32_t recv_get_packet_csum_status(struct msghdr *msg)
{
        struct tpacket_auxdata *aux = NULL;
        struct cmsghdr *cm;

        if (msg->msg_flags & MSG_CTRUNC)
                error(1, 0, "cmsg: truncated");

        for (cm = CMSG_FIRSTHDR(msg); cm; cm = CMSG_NXTHDR(msg, cm)) {
                if (cm->cmsg_level != SOL_PACKET ||
                    cm->cmsg_type != PACKET_AUXDATA)
                        error(1, 0, "cmsg: level=%d type=%d\n",
                              cm->cmsg_level, cm->cmsg_type);

                if (cm->cmsg_len != CMSG_LEN(sizeof(struct tpacket_auxdata)))
                        error(1, 0, "cmsg: len=%zu expected=%zu",
                              cm->cmsg_len, CMSG_LEN(sizeof(struct tpacket_auxdata)));

                aux = (void *)CMSG_DATA(cm);
        }

        if (!aux)
                error(1, 0, "cmsg: no auxdata");

        return aux->tp_status;
}

static int recv_packet(int fd)
{
        static char _buf[MAX_HEADER_LEN + MAX_PAYLOAD_LEN];
        unsigned long total = 0, bad_csums = 0, bad_validations = 0;
        char ctrl[CMSG_SPACE(sizeof(struct tpacket_auxdata))];
        struct pkt *buf = (void *)_buf;
        struct msghdr msg = {0};
        uint32_t tp_status;
        struct iovec iov;
        int len, ret;

        iov.iov_base = _buf;
        iov.iov_len = sizeof(_buf);

        msg.msg_iov = &iov;
        msg.msg_iovlen = 1;

        msg.msg_control = ctrl;
        msg.msg_controllen = sizeof(ctrl);

        while (1) {
                msg.msg_flags = 0;

                len = recvmsg(fd, &msg, MSG_DONTWAIT);
                if (len == -1 && errno == EAGAIN)
                        break;
                if (len == -1)
                        error(1, errno, "recv p");

                tp_status = recv_get_packet_csum_status(&msg);

                /* GRO might coalesce randomized packets. Such GSO packets are
                 * then reinitialized for csum offload (CHECKSUM_PARTIAL), with
                 * a pseudo csum. Do not try to validate these checksums.
                 */
                if (tp_status & TP_STATUS_CSUMNOTREADY) {
                        fprintf(stderr, "cmsg: GSO packet has partial csum: skip\n");
                        continue;
                }

                if (cfg_family == PF_INET6)
                        ret = recv_verify_packet_ipv6(buf, len);
                else
                        ret = recv_verify_packet_ipv4(buf, len);

                if (ret == -1 /* skip: non-matching */)
                        continue;

                total++;
                if (ret == 1)
                        bad_csums++;

                /* Fail if kernel returns valid for known bad csum.
                 * Do not fail if kernel does not validate a good csum:
                 * Absence of validation does not imply invalid.
                 */
                if (tp_status & TP_STATUS_CSUM_VALID && cfg_bad_csum) {
                        fprintf(stderr, "cmsg: expected bad csum, pf_packet returns valid\n");
                        bad_validations++;
                }
        }

        if (bad_csums || bad_validations)
                error(1, 0, "rx: errors at pf_packet: total=%lu bad_csums=%lu bad_valids=%lu\n",
                      total, bad_csums, bad_validations);

        return total;
}

static void parse_args(int argc, char *const argv[])
{
        const char *daddr = NULL, *saddr = NULL;
        int c;

        while ((c = getopt(argc, argv, "46d:D:eEi:l:L:n:r:PRs:S:tTuUzZ")) != -1) {
                switch (c) {
                case '4':
                        cfg_family = PF_INET;
                        break;
                case '6':
                        cfg_family = PF_INET6;
                        break;
                case 'd':
                        cfg_mac_dst = optarg;
                        break;
                case 'D':
                        daddr = optarg;
                        break;
                case 'e':
                        cfg_encap = true;
                        break;
                case 'E':
                        cfg_bad_csum = true;
                        break;
                case 'i':
                        cfg_ifname = optarg;
                        break;
                case 'l':
                        cfg_payload_len = strtol(optarg, NULL, 0);
                        break;
                case 'L':
                        cfg_timeout_ms = strtol(optarg, NULL, 0) * 1000;
                        break;
                case 'n':
                        cfg_num_pkt = strtol(optarg, NULL, 0);
                        break;
                case 'r':
                        cfg_random_seed = strtol(optarg, NULL, 0);
                        break;
                case 'P':
                        cfg_send_pfpacket = true;
                        break;
                case 'R':
                        /* only Rx: used with two machine tests */
                        cfg_do_tx = false;
                        break;
                case 's':
                        cfg_mac_src = optarg;
                        break;
                case 'S':
                        saddr = optarg;
                        break;
                case 't':
                        cfg_proto = IPPROTO_TCP;
                        break;
                case 'T':
                        /* only Tx: used with two machine tests */
                        cfg_do_rx = false;
                        break;
                case 'u':
                        cfg_proto = IPPROTO_UDP;
                        break;
                case 'U':
                        /* send using real udp socket,
                         * to exercise tx checksum offload
                         */
                        cfg_send_udp = true;
                        break;
                case 'z':
                        cfg_zero_disable = true;
                        break;
                case 'Z':
                        cfg_zero_sum = true;
                        break;
                default:
                        error(1, 0, "unknown arg %c", c);
                }
        }

        if (!daddr || !saddr)
                error(1, 0, "Must pass -D <daddr> and -S <saddr>");

        if (cfg_do_tx && cfg_send_pfpacket && (!cfg_mac_src || !cfg_mac_dst))
                error(1, 0, "Transmit with pf_packet requires mac addresses");

        if (cfg_payload_len > MAX_PAYLOAD_LEN)
                error(1, 0, "Payload length exceeds max");

        if (cfg_proto != IPPROTO_UDP && (cfg_zero_sum || cfg_zero_disable))
                error(1, 0, "Only UDP supports zero csum");

        if (cfg_zero_sum && !cfg_send_udp)
                error(1, 0, "Zero checksum conversion requires -U for tx csum offload");
        if (cfg_zero_sum && cfg_bad_csum)
                error(1, 0, "Cannot combine zero checksum conversion and invalid checksum");
        if (cfg_zero_sum && cfg_random_seed)
                error(1, 0, "Cannot combine zero checksum conversion with randomization");

        if (cfg_family == PF_INET6) {
                cfg_saddr6.sin6_port = htons(cfg_port_src);
                cfg_daddr6.sin6_port = htons(cfg_port_dst);

                if (inet_pton(cfg_family, daddr, &cfg_daddr6.sin6_addr) != 1)
                        error(1, errno, "Cannot parse ipv6 -D");
                if (inet_pton(cfg_family, saddr, &cfg_saddr6.sin6_addr) != 1)
                        error(1, errno, "Cannot parse ipv6 -S");
        } else {
                cfg_saddr4.sin_port = htons(cfg_port_src);
                cfg_daddr4.sin_port = htons(cfg_port_dst);

                if (inet_pton(cfg_family, daddr, &cfg_daddr4.sin_addr) != 1)
                        error(1, errno, "Cannot parse ipv4 -D");
                if (inet_pton(cfg_family, saddr, &cfg_saddr4.sin_addr) != 1)
                        error(1, errno, "Cannot parse ipv4 -S");
        }

        if (cfg_do_tx && cfg_random_seed) {
                /* special case: time-based seed */
                if (cfg_random_seed == 1)
                        cfg_random_seed = (unsigned int)gettimeofday_ms();
                srand(cfg_random_seed);
                fprintf(stderr, "randomization seed: %u\n", cfg_random_seed);
        }
}

static void do_tx(void)
{
        static char _buf[MAX_HEADER_LEN + MAX_PAYLOAD_LEN];
        char *buf;
        int fd, len, i;

        buf = build_packet(_buf, sizeof(_buf), &len);

        if (cfg_send_pfpacket)
                fd = open_packet();
        else if (cfg_send_udp)
                fd = open_inet(SOCK_DGRAM, 0);
        else
                fd = open_inet(SOCK_RAW, IPPROTO_RAW);

        for (i = 0; i < cfg_num_pkt; i++) {
                if (cfg_send_pfpacket)
                        send_packet(fd, buf, len);
                else
                        send_inet(fd, buf, len);

                /* randomize each packet individually to increase coverage */
                if (cfg_random_seed) {
                        cfg_payload_len = rand() % MAX_PAYLOAD_LEN;
                        buf = build_packet(_buf, sizeof(_buf), &len);
                }
        }

        if (close(fd))
                error(1, errno, "close tx");
}

static void do_rx(int fdp, int fdr)
{
        unsigned long count_udp = 0, count_pkt = 0;
        long tleft, tstop;
        struct pollfd pfd;

        tstop = gettimeofday_ms() + cfg_timeout_ms;
        tleft = cfg_timeout_ms;

        do {
                pfd.events = POLLIN;
                pfd.fd = fdp;
                if (poll(&pfd, 1, tleft) == -1)
                        error(1, errno, "poll");

                if (pfd.revents & POLLIN)
                        count_pkt += recv_packet(fdp);

                if (cfg_proto == IPPROTO_UDP)
                        count_udp += recv_udp(fdr);

                tleft = tstop - gettimeofday_ms();
        } while (tleft > 0);

        if (close(fdr))
                error(1, errno, "close r");
        if (close(fdp))
                error(1, errno, "close p");

        if (count_pkt < cfg_num_pkt)
                error(1, 0, "rx: missing packets at pf_packet: %lu < %u",
                      count_pkt, cfg_num_pkt);

        if (cfg_proto == IPPROTO_UDP) {
                if (cfg_bad_csum && count_udp)
                        error(1, 0, "rx: unexpected packets at udp");
                if (!cfg_bad_csum && !count_udp)
                        error(1, 0, "rx: missing packets at udp");
        }
}

int main(int argc, char *const argv[])
{
        int fdp = -1, fdr = -1;         /* -1 to silence -Wmaybe-uninitialized */

        parse_args(argc, argv);

        /* open receive sockets before transmitting */
        if (cfg_do_rx) {
                fdp = recv_prepare_packet();
                fdr = recv_prepare_udp();
        }

        if (cfg_do_tx)
                do_tx();

        if (cfg_do_rx)
                do_rx(fdp, fdr);

        fprintf(stderr, "OK\n");
        return 0;
}