stvpn/works/iprouter_w_list.cpp

extern "C" {
#include <arpa/inet.h>
#include <linux/rtnetlink.h>
#include <net/route.h>
#include <netinet/in.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <unistd.h>
}

#define BUFSIZE 8192

#include <expected>
#include <vector>
#include <format>
#include <cstring>

#include <iprouter.hpp>

std::expected<void, std::string> Router::AddRoute(std::string address, uint64_t prefix, std::string gateway) {
        struct sockaddr_in sa;
        if (inet_pton(AF_INET, address.data(), &(sa.sin_addr)) == 1) {
        } else {
                return std::unexpected(std::format("Incorrect address {}", address));
        }

        struct rtentry rt;
        memset(&rt, 0, sizeof(rt));

        struct sockaddr_in *sin;
        sin = (struct sockaddr_in*)&rt.rt_dst;
        sin->sin_family = AF_INET;
        if (inet_pton(AF_INET, address.data(), &sin->sin_addr) != 1){
                int errnoCopy = errno;
                std::string error = std::strerror(errnoCopy);
                return std::unexpected(std::format("Incorrect address {}, error: {}", address, error));
        };

        sin = (struct sockaddr_in*) &rt.rt_gateway;
        sin->sin_family = AF_INET;
        if (inet_pton(AF_INET, gateway.data(), &sin->sin_addr) != 1) {
                int errnoCopy = errno;
                std::string error = std::strerror(errnoCopy);
                return std::unexpected(std::format("Incorrect address {}, error: {}", gateway, error));
        };

        char buffer[INET_ADDRSTRLEN];
        uint32_t mask = (prefix == 0) ? 0 : htonl(~((1U << (32 - prefix)) - 1));
        //uint32_t mask = (prefix == 0) ? 0 : (~0U << (32 - prefix));

        struct in_addr addr;
        addr.s_addr = mask;

        const char *dottedmask;
        if ((dottedmask = inet_ntop(AF_INET, &addr, buffer, INET_ADDRSTRLEN)) == NULL) {
                int errnoCopy = errno;
                std::string error = std::strerror(errnoCopy);
                return std::unexpected(std::format("Incorrect prefix {}, error: {}", prefix, error));
        };

        sin = (struct sockaddr_in*) &rt.rt_genmask;
        sin->sin_family = AF_INET;
        if (inet_pton(AF_INET, dottedmask, &sin->sin_addr) != 1) {
                int errnoCopy = errno;
                std::string error = std::strerror(errnoCopy);
                return std::unexpected(std::format("Incorrect address {}, error: {}", gateway, error));
        };

        rt.rt_flags = RTF_UP | RTF_GATEWAY;
        //rt.rt_dev = std::string("eth0").data();

        int sockfd = 0;
        if ((sockfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
                int errnoCopy = errno;
                std::string error = std::strerror(errnoCopy);
                return std::unexpected(std::format("Error: {}", error));
        }

        if (ioctl(sockfd, SIOCADDRT, &rt) < 0) {
                close(sockfd);
                int errnoCopy = errno;
                std::string error = std::strerror(errnoCopy);
                return std::unexpected(std::format("Cannot set route, error: {}", error));
        }
        close(sockfd);
        return {};
}



std::expected<Routes, std::string> Router::List(void) {
        std::vector<Route> routes;

        struct {
                struct nlmsghdr n;
                struct rtmsg r;
        } req;
        std::string buffer(1024 * 10, 0);
        struct nlmsghdr *nlh;
        int sock, len;

        if ((sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE)) < 0) {
                return std::unexpected("Create netlink socket error");
        }

        memset(&req, 0, sizeof(req));
        req.n.nlmsg_len = NLMSG_LENGTH(sizeof(struct rtmsg));
        req.n.nlmsg_flags = NLM_F_REQUEST | NLM_F_DUMP;
        req.n.nlmsg_type = RTM_GETROUTE;
        req.r.rtm_family = AF_INET;

        send(sock, &req, req.n.nlmsg_len, 0);

        while ((len = recv(sock, buffer.data(), buffer.size(), 0)) > 0) {
                nlh = (struct nlmsghdr *)buffer.data();
                while (NLMSG_OK(nlh, len)) {
                        if (nlh->nlmsg_type == NLMSG_DONE) {
                                return {};
                        };
                        struct rtmsg *route = (struct rtmsg *)NLMSG_DATA(nlh);
                        struct rtattr *rta = (struct rtattr *)RTM_RTA(route);
                        int len = RTM_PAYLOAD(nlh);

                        char dest_ip[INET_ADDRSTRLEN] = "0.0.0.0";
                        char gw_ip[INET_ADDRSTRLEN] = "0.0.0.0";

                        for (; RTA_OK(rta, len); rta = RTA_NEXT(rta, len)) {
                                switch (rta->rta_type) {
                                case RTA_DST:
                                        inet_ntop(AF_INET, RTA_DATA(rta), dest_ip, sizeof(dest_ip));
                                        break;
                                case RTA_GATEWAY:
                                        inet_ntop(AF_INET, RTA_DATA(rta), gw_ip, sizeof(gw_ip));
                                        break;
                                case RTA_OIF:
                                        int if_idx = *(int *)RTA_DATA(rta);
                                        printf("Interface Index: %d ", if_idx);
                                        break;
                                }
                        }
                        printf("Found route: dest %s / %d, gw %s\n", dest_ip, route->rtm_dst_len, gw_ip);
                        nlh = NLMSG_NEXT(nlh, len);
                }
        }
        close(sock);
        return routes;
}