// SPDX-License-Identifier: GPL-2.0

/*
 * Verify that consecutive sends over packet tx_ring are mirrored
 * with their original content intact.
 */

#define _GNU_SOURCE

#include <arpa/inet.h>
#include <assert.h>
#include <error.h>
#include <errno.h>
#include <fcntl.h>
#include <linux/filter.h>
#include <linux/if_packet.h>
#include <net/ethernet.h>
#include <net/if.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/udp.h>
#include <poll.h>
#include <pthread.h>
#include <sched.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/utsname.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

const int eth_off = TPACKET_HDRLEN - sizeof(struct sockaddr_ll);
const int cfg_frame_size = 1000;

static void build_packet(void *buffer, size_t blen, char payload_char)
{
        struct udphdr *udph;
        struct ethhdr *eth;
        struct iphdr *iph;
        size_t off = 0;

        memset(buffer, 0, blen);

        eth = buffer;
        eth->h_proto = htons(ETH_P_IP);

        off += sizeof(*eth);
        iph = buffer + off;
        iph->ttl        = 8;
        iph->ihl        = 5;
        iph->version    = 4;
        iph->saddr      = htonl(INADDR_LOOPBACK);
        iph->daddr      = htonl(INADDR_LOOPBACK + 1);
        iph->protocol   = IPPROTO_UDP;
        iph->tot_len    = htons(blen - off);
        iph->check      = 0;

        off += sizeof(*iph);
        udph = buffer + off;
        udph->dest      = htons(8000);
        udph->source    = htons(8001);
        udph->len       = htons(blen - off);
        udph->check     = 0;

        off += sizeof(*udph);
        memset(buffer + off, payload_char, blen - off);
}

static int setup_rx(void)
{
        int fdr;

        fdr = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_IP));
        if (fdr == -1)
                error(1, errno, "socket r");

        return fdr;
}

static int setup_tx(char **ring)
{
        struct sockaddr_ll laddr = {};
        struct tpacket_req req = {};
        int fdt;

        fdt = socket(PF_PACKET, SOCK_RAW, 0);
        if (fdt == -1)
                error(1, errno, "socket t");

        laddr.sll_family = AF_PACKET;
        laddr.sll_protocol = htons(0);
        laddr.sll_ifindex = if_nametoindex("lo");
        if (!laddr.sll_ifindex)
                error(1, errno, "if_nametoindex");

        if (bind(fdt, (void *)&laddr, sizeof(laddr)))
                error(1, errno, "bind fdt");

        req.tp_block_size = getpagesize();
        req.tp_block_nr   = 1;
        req.tp_frame_size = getpagesize();
        req.tp_frame_nr   = 1;

        if (setsockopt(fdt, SOL_PACKET, PACKET_TX_RING,
                       (void *)&req, sizeof(req)))
                error(1, errno, "setsockopt ring");

        *ring = mmap(0, req.tp_block_size * req.tp_block_nr,
                     PROT_READ | PROT_WRITE, MAP_SHARED, fdt, 0);
        if (*ring == MAP_FAILED)
                error(1, errno, "mmap");

        return fdt;
}

static void send_pkt(int fdt, void *slot, char payload_char)
{
        struct tpacket_hdr *header = slot;
        int ret;

        while (header->tp_status != TP_STATUS_AVAILABLE)
                usleep(1000);

        build_packet(slot + eth_off, cfg_frame_size, payload_char);

        header->tp_len = cfg_frame_size;
        header->tp_status = TP_STATUS_SEND_REQUEST;

        ret = sendto(fdt, NULL, 0, 0, NULL, 0);
        if (ret == -1)
                error(1, errno, "kick tx");
}

static int read_verify_pkt(int fdr, char payload_char)
{
        char buf[100];
        int ret;

        ret = read(fdr, buf, sizeof(buf));
        if (ret != sizeof(buf))
                error(1, errno, "read");

        if (buf[60] != payload_char) {
                printf("wrong pattern: 0x%x != 0x%x\n", buf[60], payload_char);
                return 1;
        }

        printf("read: %c (0x%x)\n", buf[60], buf[60]);
        return 0;
}

int main(int argc, char **argv)
{
        const char payload_patterns[] = "ab";
        char *ring;
        int fdr, fdt, ret = 0;

        fdr = setup_rx();
        fdt = setup_tx(&ring);

        send_pkt(fdt, ring, payload_patterns[0]);
        send_pkt(fdt, ring, payload_patterns[1]);

        ret |= read_verify_pkt(fdr, payload_patterns[0]);
        ret |= read_verify_pkt(fdr, payload_patterns[1]);

        if (close(fdt))
                error(1, errno, "close t");
        if (close(fdr))
                error(1, errno, "close r");

        return ret;
}