OS X(MACOS) C/C++ 遍历系统所有的IP路由表配置。

 以下源实现为遍历MAC苹果电脑系统上配置的所有IP路由表配置，回调 predicate 过滤函数只在 AF_INET(IPV4)的时候跳出，其它时不处理，人们可以根据自己的需求改动。

无需依赖MAC OS框架库提供的函数，最小依赖才有可能更容易移植代码到 Apple Inc. 其它操作系统平台上面，另外是 MAC OS 平台依赖不容易受高版本限制。

        static int FetchAllRouteNtreeStuff(const ppp::function<bool(int interface_index, uint32_t ip, uint32_t gw, uint32_t mask)>& predicate) noexcept /* sysctlbyname("net.route.0.0.dump", buf, &len, NULL, 0) */{if (NULL == predicate){return -1;}int mib[] = { CTL_NET, PF_ROUTE, 0, AF_INET, NET_RT_FLAGS, RTF_GATEWAY };size_t needed = 0;if (sysctl(mib, arraysizeof(mib), NULL, &needed, NULL, 0) < 0){return -1;}std::shared_ptr<Byte> buffer_managed = ppp::make_shared_alloc<Byte>(needed);if (NULL == buffer_managed){return -1;}char* buffer = (char*)buffer_managed.get();if (sysctl(mib, arraysizeof(mib), buffer, &needed, NULL, 0) < 0){return -1;}struct rt_msghdr* rtm = NULL;char* buffer_needed = buffer + needed;for (char* i = buffer; i < buffer_needed; i += rtm->rtm_msglen){rtm = (struct rt_msghdr*)(i); /* RTAX_NETMASK */if (rtm->rtm_type != RTM_GET){continue;}/* inet_ntop(AF_INET, &sa->sin_addr.s_addr, line, sizeof(line) - 1); */if (!(rtm->rtm_flags & RTF_UP)){continue;}/* MAXHOSTNAMELEN; */if (!(rtm->rtm_flags & RTF_GATEWAY)){continue;}struct sockaddr* sa_tab[RTAX_MAX];if (struct sockaddr* sa = (struct sockaddr*)(rtm + 1); NULL != sa){for (int j = 0; j < RTAX_MAX; j++){if (rtm->rtm_addrs & (1 << j)){sa_tab[j] = sa;sa = (struct sockaddr*)((char*)sa + ROUNDUP(sa->sa_len));}else{sa_tab[j] = NULL;}}}uint32_t ip = IPEndPoint::AnyAddress;uint32_t gw = IPEndPoint::AnyAddress;uint32_t mask = IPEndPoint::AnyAddress;if (rtm->rtm_addrs & (1 << RTAX_DST)){struct sockaddr_in* sa = (struct sockaddr_in*)(sa_tab[RTAX_DST]);if (sa->sin_family != AF_INET){continue;}ip = sa->sin_addr.s_addr;}if (rtm->rtm_addrs & (1 << RTAX_GATEWAY)){struct sockaddr_in* sa = (struct sockaddr_in*)(sa_tab[RTAX_GATEWAY]);if (sa->sin_family != AF_INET){continue;}gw = sa->sin_addr.s_addr;}if (rtm->rtm_addrs & (1 << RTAX_NETMASK)){struct sockaddr_in* sa = (struct sockaddr_in*)(sa_tab[RTAX_NETMASK]);mask = sa->sin_addr.s_addr;}if (predicate(rtm->rtm_index, ip, gw, mask)){break;}}return 0;}