ipyml/address.h

#ifndef _IPYML_ADDRESS_H
#define _IPYML_ADDRESS_H

#include "inet6_address.h"
#include "inet_address.h"
#include "yaml.h"

#include <bits/socket.h>   // AF_*
#include <libmnl/libmnl.h> // mnl_attr_get_type
#include <linux/if_addr.h> // struct ifaddrmsg
#include <linux/netlink.h> // struct nlattr
#include <ostream>         // std::ostream

// https://git.kernel.org/pub/scm/network/iproute2/iproute2.git/tree/ip/ipaddress.c
// print_addrinfo()

class Address : public YamlObject {
public:
  unsigned int ifindex;

private:
  unsigned char family, prefixlen;
  union {
    InetAddress inet_addr;
    Inet6Address inet6_addr;
  };

public:
  Address(const ifaddrmsg *msg) {
    /*
    struct ifaddrmsg {
        unsigned char ifa_family;    // Address type
        unsigned char ifa_prefixlen; // Prefixlength of address
        unsigned char ifa_flags;     // Address flags
        unsigned char ifa_scope;     // Address scope
        int           ifa_index;     // Interface index
    };
    */
    ifindex = msg->ifa_index;
    family = msg->ifa_family;
    assert(family == AF_INET || family == AF_INET6);
    prefixlen = msg->ifa_prefixlen;
  }

  // typedef int (*mnl_attr_cb_t)(const struct nlattr *attr, void *data);
  static int mnl_attr_cb(const nlattr *attr, void *data) {
    Address *addr = (Address *)data;
    assert(addr->family != AF_UNSPEC);
    // /usr/include/linux/if_addr.h
    switch (mnl_attr_get_type(attr)) {
    case IFA_ADDRESS:
      if (addr->family == AF_INET) {
        addr->inet_addr = attr;
      } else if (addr->family == AF_INET6) {
        addr->inet6_addr = attr;
      }
      break;
    }
  }

  void write_yaml(std::ostream &stream,
                  const yaml_indent_level_t indent_level = 0) const {
    // const std::string indent(indent_level, ' ');
    if (family == AF_INET) {
      stream << inet_addr.format();
    } else if (family == AF_INET6) {
      stream << inet6_addr.format();
    }
    stream << '/' << (int)prefixlen << '\n';
  }
};

#endif