receiver, C (clang)

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#include <arpa/inet.h>
#include <errno.h>
#include <inttypes.h>
#include <linux/errqueue.h>
#include <linux/net_tstamp.h>
#include <linux/sockios.h>
#include <net/if.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>

#define UDP_MAX_LENGTH 1500

typedef struct {
  int fd;
  int port;
  int err_no;
  struct sockaddr_in local;
  struct sockaddr_in remote;
  struct timeval time_kernel;
  struct timeval time_user;
  int64_t prev_serialnum;
} socket_info;

static int setup_udp_receiver(socket_info *inf, int port) {
  inf->port = port;
  inf->fd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
  if (inf->fd < 0) {
    inf->err_no = errno;
    fprintf(stderr, "setup_udp_server: socket failed: %s\n",
            strerror(inf->err_no));
    return inf->fd;
  }

int timestampOn =
      SOF_TIMESTAMPING_RX_SOFTWARE | SOF_TIMESTAMPING_TX_SOFTWARE |
      SOF_TIMESTAMPING_SOFTWARE | SOF_TIMESTAMPING_RX_HARDWARE |
      SOF_TIMESTAMPING_TX_HARDWARE | SOF_TIMESTAMPING_RAW_HARDWARE |
      // SOF_TIMESTAMPING_OPT_TSONLY |
      0;
  int r = setsockopt(inf->fd, SOL_SOCKET, SO_TIMESTAMPING, &timestampOn,
                     sizeof timestampOn);
  if (r < 0) {
    inf->err_no = errno;
    fprintf(stderr, "setup_udp_server: setsockopt failed: %s\n",
            strerror(inf->err_no));
    return r;
  }

int on = 1;
  r = setsockopt(inf->fd, SOL_SOCKET, SO_REUSEPORT, &on, sizeof on);
  if (r < 0) {
    inf->err_no = errno;
    fprintf(stderr, "setup_udp_server: setsockopt2 failed: %s\n",
            strerror(inf->err_no));
    return r;
  }

inf->local = (struct sockaddr_in){.sin_family = AF_INET,
                                    .sin_port = htons((uint16_t)port),
                                    .sin_addr.s_addr = htonl(INADDR_ANY)};
  r = bind(inf->fd, (struct sockaddr *)&inf->local, sizeof inf->local);
  if (r < 0) {
    inf->err_no = errno;
    fprintf(stderr, "setup_udp_server: bind failed: %s\n",
            strerror(inf->err_no));
    return r;
  }

inf->prev_serialnum = -1;

return 0;
}

static void handle_scm_timestamping(struct scm_timestamping *ts) {
  for (size_t i = 0; i < sizeof ts->ts / sizeof *ts->ts; i++) {
    printf("timestamp: %lld.%.9lds\n", (long long)ts->ts[i].tv_sec,
           ts->ts[i].tv_nsec);
  }
}

static void handle_time(struct msghdr *msg) {

for (struct cmsghdr *cmsg = CMSG_FIRSTHDR(msg); cmsg;
       cmsg = CMSG_NXTHDR(msg, cmsg)) {
    printf("level=%d, type=%d, len=%zu\n", cmsg->cmsg_level, cmsg->cmsg_type,
           cmsg->cmsg_len);

if (cmsg->cmsg_level == SOL_IP && cmsg->cmsg_type == IP_RECVERR) {
      struct sock_extended_err *ext =
          (struct sock_extended_err *)CMSG_DATA(cmsg);
      printf("errno=%d, origin=%d\n", ext->ee_errno, ext->ee_origin);
      continue;
    }

if (cmsg->cmsg_level != SOL_SOCKET)
      continue;

switch (cmsg->cmsg_type) {
    case SO_TIMESTAMPNS: {
      struct scm_timestamping *ts = (struct scm_timestamping *)CMSG_DATA(cmsg);
      handle_scm_timestamping(ts);
    } break;
    case SO_TIMESTAMPING: {
      struct scm_timestamping *ts = (struct scm_timestamping *)CMSG_DATA(cmsg);
      handle_scm_timestamping(ts);
    } break;
    default:
      /* Ignore other cmsg options */
      break;
    }
  }
  printf("End messages\n");
}

static ssize_t udp_receive(socket_info *inf, char *buf, size_t len) {
  char ctrl[2048];
  struct iovec iov = (struct iovec){.iov_base = buf, .iov_len = len};
  struct msghdr msg = (struct msghdr){.msg_control = ctrl,
                                      .msg_controllen = sizeof ctrl,
                                      .msg_name = &inf->remote,
                                      .msg_namelen = sizeof inf->remote,
                                      .msg_iov = &iov,
                                      .msg_iovlen = 1};
  ssize_t recv_len = recvmsg(inf->fd, &msg, 0);
  gettimeofday(&inf->time_user, NULL);

if (recv_len < 0) {
    inf->err_no = errno;
    fprintf(stderr, "udp_receive: recvfrom failed: %s\n",
            strerror(inf->err_no));
  }

handle_time(&msg);

return recv_len;
}

static void receiver_loop(void) {
  socket_info inf;
  int ret = setup_udp_receiver(&inf, 8000);
  if (ret < 0) {
    return;
  }

for (int i = 0; i < 10; i++) {
    char packet_buffer[4096];
    udp_receive(&inf, packet_buffer, sizeof packet_buffer);
  }
}

int main(void) {
    receiver_loop();
}

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Compilation time: 0.23 sec, absolute running time: 2.75 sec, cpu time: 1.25 sec, memory peak: 3 Mb, absolute service time: 3,07 sec