Function send_batch

src/platform/linux/misc.cpp:449–654

  }

  bool send_batch(batched_send_info_t &send_info) {
    auto sockfd = (int) send_info.native_socket;
    struct msghdr msg = {};

    // Convert the target address into a sockaddr
    struct sockaddr_in taddr_v4 = {};
    struct sockaddr_in6 taddr_v6 = {};
    if (send_info.target_address.is_v6()) {
      taddr_v6 = to_sockaddr(send_info.target_address.to_v6(), send_info.target_port);

      msg.msg_name = (struct sockaddr *) &taddr_v6;
      msg.msg_namelen = sizeof(taddr_v6);
    } else {
      taddr_v4 = to_sockaddr(send_info.target_address.to_v4(), send_info.target_port);

      msg.msg_name = (struct sockaddr *) &taddr_v4;
      msg.msg_namelen = sizeof(taddr_v4);
    }

    union {
      char buf[CMSG_SPACE(sizeof(uint16_t)) + std::max(CMSG_SPACE(sizeof(struct in_pktinfo)), CMSG_SPACE(sizeof(struct in6_pktinfo)))];
      struct cmsghdr alignment;
    } cmbuf = {};  // Must be zeroed for CMSG_NXTHDR()

    socklen_t cmbuflen = 0;

    msg.msg_control = cmbuf.buf;
    msg.msg_controllen = sizeof(cmbuf.buf);

    // The PKTINFO option will always be first, then we will conditionally
    // append the UDP_SEGMENT option next if applicable.
    auto pktinfo_cm = CMSG_FIRSTHDR(&msg);
    if (send_info.source_address.is_v6()) {
      struct in6_pktinfo pktInfo;

      struct sockaddr_in6 saddr_v6 = to_sockaddr(send_info.source_address.to_v6(), 0);
      pktInfo.ipi6_addr = saddr_v6.sin6_addr;
      pktInfo.ipi6_ifindex = 0;

      cmbuflen += CMSG_SPACE(sizeof(pktInfo));

      pktinfo_cm->cmsg_level = IPPROTO_IPV6;
      pktinfo_cm->cmsg_type = IPV6_PKTINFO;
      pktinfo_cm->cmsg_len = CMSG_LEN(sizeof(pktInfo));
      memcpy(CMSG_DATA(pktinfo_cm), &pktInfo, sizeof(pktInfo));
    } else {
      struct in_pktinfo pktInfo;

      struct sockaddr_in saddr_v4 = to_sockaddr(send_info.source_address.to_v4(), 0);
      pktInfo.ipi_spec_dst = saddr_v4.sin_addr;
      pktInfo.ipi_ifindex = 0;

      cmbuflen += CMSG_SPACE(sizeof(pktInfo));

      pktinfo_cm->cmsg_level = IPPROTO_IP;
      pktinfo_cm->cmsg_type = IP_PKTINFO;
      pktinfo_cm->cmsg_len = CMSG_LEN(sizeof(pktInfo));
      memcpy(CMSG_DATA(pktinfo_cm), &pktInfo, sizeof(pktInfo));