/* 
 * Copyright (C) 2008-2011 Teluu Inc. (http://www.teluu.com)
 * Copyright (C) 2003-2008 Benny Prijono <benny@prijono.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA 
 */
#include <pj/ip_helper.h>
#include <pj/addr_resolv.h>
#include <pj/assert.h>
#include <pj/errno.h>
#include <pj/string.h>
#include <pj/compat/socket.h>
#include <pj/sock.h>


#if defined(PJ_LINUX) && PJ_LINUX!=0
/* The following headers are used to get DEPRECATED addresses */
#include <arpa/inet.h>
#include <asm/types.h>
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
#include <sys/socket.h>
#include <unistd.h>
#endif

/* Set to 1 to enable tracing */
#if 0
#   include <pj/log.h>
#   define THIS_FILE    "ip_helper_generic.c"
#   define TRACE_(exp)  PJ_LOG(5,exp)
    static const char *get_os_errmsg(void)
    {
        static char errmsg[PJ_ERR_MSG_SIZE];
        pj_strerror(pj_get_os_error(), errmsg, sizeof(errmsg));
        return errmsg;
    }
    static const char *get_addr(void *addr)
    {
        static char txt[PJ_INET6_ADDRSTRLEN];
        struct sockaddr *ad = (struct sockaddr*)addr;
        if (ad->sa_family != PJ_AF_INET && ad->sa_family != PJ_AF_INET6)
            return "?";
        return pj_inet_ntop2(ad->sa_family, pj_sockaddr_get_addr(ad), 
                             txt, sizeof(txt));
    }
#else
#   define TRACE_(exp)
#endif


#if 0
    /* dummy */

#elif defined(PJ_HAS_IFADDRS_H) && PJ_HAS_IFADDRS_H != 0 && \
      defined(PJ_HAS_NET_IF_H) && PJ_HAS_NET_IF_H != 0
/* Using getifaddrs() is preferred since it can work with both IPv4 and IPv6 */
static pj_status_t if_enum_by_af(int af,
                                 unsigned *p_cnt,
                                 pj_sockaddr ifs[])
{
    struct ifaddrs *ifap = NULL, *it;
    unsigned max;

    PJ_ASSERT_RETURN(af==PJ_AF_INET || af==PJ_AF_INET6, PJ_EINVAL);
    
    TRACE_((THIS_FILE, "Starting interface enum with getifaddrs() for af=%d",
            af));

    if (getifaddrs(&ifap) != 0) {
        TRACE_((THIS_FILE, " getifarrds() failed: %s", get_os_errmsg()));
        return PJ_RETURN_OS_ERROR(pj_get_netos_error());
    }

    it = ifap;
    max = *p_cnt;
    *p_cnt = 0;
    for (; it!=NULL && *p_cnt < max; it = it->ifa_next) {
        struct sockaddr *ad = it->ifa_addr;

        TRACE_((THIS_FILE, " checking %s", it->ifa_name));

        if ((it->ifa_flags & IFF_UP)==0) {
            TRACE_((THIS_FILE, "  interface is down"));
            continue; /* Skip when interface is down */
        }

        if ((it->ifa_flags & IFF_RUNNING)==0) {
            TRACE_((THIS_FILE, "  interface is not running"));
            continue; /* Skip when interface is not running */
        }

#if PJ_IP_HELPER_IGNORE_LOOPBACK_IF
        if (it->ifa_flags & IFF_LOOPBACK) {
            TRACE_((THIS_FILE, "  loopback interface"));
            continue; /* Skip loopback interface */
        }
#endif

        if (ad==NULL) {
            TRACE_((THIS_FILE, "  NULL address ignored"));
            continue; /* reported to happen on Linux 2.6.25.9 
                         with ppp interface */
        }

        if (ad->sa_family != af) {
            TRACE_((THIS_FILE, "  address %s ignored (af=%d)", 
                    get_addr(ad), ad->sa_family));
            continue; /* Skip when interface is down */
        }

        /* Ignore 192.0.0.0/29 address.
         * Ref: https://datatracker.ietf.org/doc/html/rfc7335#section-4
         */
        if (af==pj_AF_INET() &&
            (pj_ntohl(((pj_sockaddr_in*)ad)->sin_addr.s_addr) >> 4) ==
             201326592) /* 0b1100000000000000000000000000 which is
                           192.0.0.0 >> 4 */
        {
            TRACE_((THIS_FILE, "  address %s ignored (192.0.0.0/29 class)",
                    get_addr(ad), ad->sa_family));
            continue;
        }

        /* Ignore 0.0.0.0/8 address. This is a special address
         * which doesn't seem to have practical use.
         */
        if (af==pj_AF_INET() &&
            (pj_ntohl(((pj_sockaddr_in*)ad)->sin_addr.s_addr) >> 24) == 0)
        {
            TRACE_((THIS_FILE, "  address %s ignored (0.0.0.0/8 class)", 
                    get_addr(ad), ad->sa_family));
            continue;
        }

        TRACE_((THIS_FILE, "  address %s (af=%d) added at index %d", 
                get_addr(ad), ad->sa_family, *p_cnt));

        pj_bzero(&ifs[*p_cnt], sizeof(ifs[0]));
        pj_memcpy(&ifs[*p_cnt], ad, pj_sockaddr_get_len(ad));
        PJ_SOCKADDR_RESET_LEN(&ifs[*p_cnt]);
        (*p_cnt)++;
    }

    freeifaddrs(ifap);
    TRACE_((THIS_FILE, "done, found %d address(es)", *p_cnt));
    return (*p_cnt != 0) ? PJ_SUCCESS : PJ_ENOTFOUND;
}

#elif defined(SIOCGIFCONF) && \
      defined(PJ_HAS_NET_IF_H) && PJ_HAS_NET_IF_H != 0

/* Note: this does not work with IPv6 */
static pj_status_t if_enum_by_af(int af,
                                 unsigned *p_cnt,
                                 pj_sockaddr ifs[])
{
    pj_sock_t sock;
    char buf[512];
    struct ifconf ifc;
    struct ifreq *ifr;
    int i, count;
    pj_status_t status;

    PJ_ASSERT_RETURN(af==PJ_AF_INET || af==PJ_AF_INET6, PJ_EINVAL);
    
    TRACE_((THIS_FILE, "Starting interface enum with SIOCGIFCONF for af=%d",
            af));

    status = pj_sock_socket(af, PJ_SOCK_DGRAM, 0, &sock);
    if (status != PJ_SUCCESS)
        return status;

    /* Query available interfaces */
    ifc.ifc_len = sizeof(buf);
    ifc.ifc_buf = buf;

    if (ioctl(sock, SIOCGIFCONF, &ifc) < 0) {
        int oserr = pj_get_netos_error();
        TRACE_((THIS_FILE, " ioctl(SIOCGIFCONF) failed: %s", get_os_errmsg()));
        pj_sock_close(sock);
        return PJ_RETURN_OS_ERROR(oserr);
    }

    /* Interface interfaces */
    ifr = (struct ifreq*) ifc.ifc_req;
    count = ifc.ifc_len / sizeof(struct ifreq);
    if (count > *p_cnt)
        count = *p_cnt;

    *p_cnt = 0;
    for (i=0; i<count; ++i) {
        struct ifreq *itf = &ifr[i];
        struct ifreq iff = *itf;
        struct sockaddr *ad = &itf->ifr_addr;
        
        TRACE_((THIS_FILE, " checking interface %s", itf->ifr_name));

        /* Skip address with different family */
        if (ad->sa_family != af) {
            TRACE_((THIS_FILE, "  address %s (af=%d) ignored",
                    get_addr(ad), (int)ad->sa_family));
            continue;
        }

        if (ioctl(sock, SIOCGIFFLAGS, &iff) != 0) {
            TRACE_((THIS_FILE, "  ioctl(SIOCGIFFLAGS) failed: %s",
                    get_os_errmsg()));
            continue;   /* Failed to get flags, continue */
        }

        if ((iff.ifr_flags & IFF_UP)==0) {
            TRACE_((THIS_FILE, "  interface is down"));
            continue; /* Skip when interface is down */
        }

        if ((iff.ifr_flags & IFF_RUNNING)==0) {
            TRACE_((THIS_FILE, "  interface is not running"));
            continue; /* Skip when interface is not running */
        }

#if PJ_IP_HELPER_IGNORE_LOOPBACK_IF
        if (iff.ifr_flags & IFF_LOOPBACK) {
            TRACE_((THIS_FILE, "  loopback interface"));
            continue; /* Skip loopback interface */
        }
#endif

        /* Ignore 192.0.0.0/29 address.
         * Ref: https://datatracker.ietf.org/doc/html/rfc7335#section-4
         */
        if (af==pj_AF_INET() &&
            (pj_ntohl(((pj_sockaddr_in*)ad)->sin_addr.s_addr) >> 4) ==
             201326592) /* 0b1100000000000000000000000000 which is
                           192.0.0.0 >> 4 */
        {
            TRACE_((THIS_FILE, "  address %s ignored (192.0.0.0/29 class)",
                    get_addr(ad), ad->sa_family));
            continue;
        }

        /* Ignore 0.0.0.0/8 address. This is a special address
         * which doesn't seem to have practical use.
         */
        if (af==pj_AF_INET() &&
            (pj_ntohl(((pj_sockaddr_in*)ad)->sin_addr.s_addr) >> 24) == 0)
        {
            TRACE_((THIS_FILE, "  address %s ignored (0.0.0.0/8 class)", 
                    get_addr(ad), ad->sa_family));
            continue;
        }

        TRACE_((THIS_FILE, "  address %s (af=%d) added at index %d", 
                get_addr(ad), ad->sa_family, *p_cnt));

        pj_bzero(&ifs[*p_cnt], sizeof(ifs[0]));
        pj_memcpy(&ifs[*p_cnt], ad, pj_sockaddr_get_len(ad));
        PJ_SOCKADDR_RESET_LEN(&ifs[*p_cnt]);
        (*p_cnt)++;
    }

    /* Done with socket */
    pj_sock_close(sock);

    TRACE_((THIS_FILE, "done, found %d address(es)", *p_cnt));
    return (*p_cnt != 0) ? PJ_SUCCESS : PJ_ENOTFOUND;
}


#elif defined(PJ_HAS_NET_IF_H) && PJ_HAS_NET_IF_H != 0
/* Note: this does not work with IPv6 */
static pj_status_t if_enum_by_af(int af, unsigned *p_cnt, pj_sockaddr ifs[])
{
    struct if_nameindex *if_list;
    struct ifreq ifreq;
    pj_sock_t sock;
    unsigned i, max_count;
    pj_status_t status;

    PJ_ASSERT_RETURN(af==PJ_AF_INET || af==PJ_AF_INET6, PJ_EINVAL);

    TRACE_((THIS_FILE, "Starting if_nameindex() for af=%d", af));

    status = pj_sock_socket(af, PJ_SOCK_DGRAM, 0, &sock);
    if (status != PJ_SUCCESS)
        return status;

    if_list = if_nameindex();
    if (if_list == NULL)
        return PJ_ENOTFOUND;

    max_count = *p_cnt;
    *p_cnt = 0;
    for (i=0; if_list[i].if_index && *p_cnt<max_count; ++i) {
        struct sockaddr *ad;
        int rc;

        pj_ansi_strxcpy(ifreq.ifr_name, if_list[i].if_name, IFNAMSIZ);

        TRACE_((THIS_FILE, " checking interface %s", ifreq.ifr_name));

        if ((rc=ioctl(sock, SIOCGIFFLAGS, &ifreq)) != 0) {
            TRACE_((THIS_FILE, "  ioctl(SIOCGIFFLAGS) failed: %s",
                    get_os_errmsg()));
            continue;   /* Failed to get flags, continue */
        }

        if ((ifreq.ifr_flags & IFF_UP)==0) {
            TRACE_((THIS_FILE, "  interface is down"));
            continue; /* Skip when interface is down */
        }

        if ((ifreq.ifr_flags & IFF_RUNNING)==0) {
            TRACE_((THIS_FILE, "  interface is not running"));
            continue; /* Skip when interface is not running */
        }

#if PJ_IP_HELPER_IGNORE_LOOPBACK_IF
        if (ifreq.ifr_flags & IFF_LOOPBACK) {
            TRACE_((THIS_FILE, "  loopback interface"));
            continue; /* Skip loopback interface */
        }
#endif

        /* Note: SIOCGIFADDR does not work for IPv6! */
        if ((rc=ioctl(sock, SIOCGIFADDR, &ifreq)) != 0) {
            TRACE_((THIS_FILE, "  ioctl(SIOCGIFADDR) failed: %s",
                    get_os_errmsg()));
            continue;   /* Failed to get address, continue */
        }

        ad = (struct sockaddr*) &ifreq.ifr_addr;

        if (ad->sa_family != af) {
            TRACE_((THIS_FILE, "  address %s family %d ignored", 
                               get_addr(&ifreq.ifr_addr),
                               ifreq.ifr_addr.sa_family));
            continue;   /* Not address family that we want, continue */
        }

        /* Ignore 192.0.0.0/29 address.
         * Ref: https://datatracker.ietf.org/doc/html/rfc7335#section-4
         */
        if (af==pj_AF_INET() &&
            (pj_ntohl(((pj_sockaddr_in*)ad)->sin_addr.s_addr) >> 4) ==
             201326592) /* 0b1100000000000000000000000000 which is
                           192.0.0.0 >> 4 */
        {
            TRACE_((THIS_FILE, "  address %s ignored (192.0.0.0/29 class)",
                    get_addr(ad), ad->sa_family));
            continue;
        }

        /* Ignore 0.0.0.0/8 address. This is a special address
         * which doesn't seem to have practical use.
         */
        if (af==pj_AF_INET() &&
            (pj_ntohl(((pj_sockaddr_in*)ad)->sin_addr.s_addr) >> 24) == 0)
        {
            TRACE_((THIS_FILE, "  address %s ignored (0.0.0.0/8 class)", 
                    get_addr(ad), ad->sa_family));
            continue;
        }

        /* Got an address ! */
        TRACE_((THIS_FILE, "  address %s (af=%d) added at index %d", 
                get_addr(ad), ad->sa_family, *p_cnt));

        pj_bzero(&ifs[*p_cnt], sizeof(ifs[0]));
        pj_memcpy(&ifs[*p_cnt], ad, pj_sockaddr_get_len(ad));
        PJ_SOCKADDR_RESET_LEN(&ifs[*p_cnt]);
        (*p_cnt)++;
    }

    if_freenameindex(if_list);
    pj_sock_close(sock);

    TRACE_((THIS_FILE, "done, found %d address(es)", *p_cnt));
    return (*p_cnt != 0) ? PJ_SUCCESS : PJ_ENOTFOUND;
}

#else
static pj_status_t if_enum_by_af(int af,
                                 unsigned *p_cnt,
                                 pj_sockaddr ifs[])
{
    pj_status_t status;

    PJ_ASSERT_RETURN(p_cnt && *p_cnt > 0 && ifs, PJ_EINVAL);

    pj_bzero(ifs, sizeof(ifs[0]) * (*p_cnt));

    /* Just get one default route */
    status = pj_getdefaultipinterface(af, &ifs[0]);
    if (status != PJ_SUCCESS)
        return status;

    *p_cnt = 1;
    return PJ_SUCCESS;
}
#endif /* SIOCGIFCONF */

/*
 * Enumerate the local IP interface currently active in the host.
 */
PJ_DEF(pj_status_t) pj_enum_ip_interface(int af,
                                         unsigned *p_cnt,
                                         pj_sockaddr ifs[])
{
    unsigned start;
    pj_status_t status;

    PJ_ASSERT_RETURN(p_cnt && *p_cnt > 0 && ifs, PJ_EINVAL);
    pj_bzero(ifs, sizeof(ifs[0]) * (*p_cnt));

    start = 0;
    if (af==PJ_AF_INET6 || af==PJ_AF_UNSPEC) {
        unsigned max = *p_cnt;
        status = if_enum_by_af(PJ_AF_INET6, &max, &ifs[start]);
        if (status == PJ_SUCCESS) {
            start += max;
            (*p_cnt) -= max;
        }
    }

    if (af==PJ_AF_INET || af==PJ_AF_UNSPEC) {
        unsigned max = *p_cnt;
        status = if_enum_by_af(PJ_AF_INET, &max, &ifs[start]);
        if (status == PJ_SUCCESS) {
            start += max;
            (*p_cnt) -= max;
        }
    }

    *p_cnt = start;

    return (*p_cnt != 0) ? PJ_SUCCESS : PJ_ENOTFOUND;
}

/*
 * Enumerate the IP routing table for this host.
 */
PJ_DEF(pj_status_t) pj_enum_ip_route(unsigned *p_cnt,
                                     pj_ip_route_entry routes[])
{
    pj_sockaddr itf;
    pj_status_t status;

    PJ_ASSERT_RETURN(p_cnt && *p_cnt > 0 && routes, PJ_EINVAL);

    pj_bzero(routes, sizeof(routes[0]) * (*p_cnt));

    /* Just get one default route */
    status = pj_getdefaultipinterface(PJ_AF_INET, &itf);
    if (status != PJ_SUCCESS)
        return status;
    
    routes[0].ipv4.if_addr.s_addr = itf.ipv4.sin_addr.s_addr;
    routes[0].ipv4.dst_addr.s_addr = 0;
    routes[0].ipv4.mask.s_addr = 0;
    *p_cnt = 1;

    return PJ_SUCCESS;
}

#if defined(PJ_LINUX) && PJ_LINUX!=0
static pj_status_t get_ipv6_deprecated(unsigned *count, pj_sockaddr addr[])
{
    struct {
        struct nlmsghdr        nlmsg_info;
        struct ifaddrmsg    ifaddrmsg_info;
    } netlink_req;

    long pagesize = sysconf(_SC_PAGESIZE);
    if (pagesize <= 0)
        pagesize = 4096; /* Assume pagesize is 4096 if sysconf() failed */

    int fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
    if (fd < 0)
        return PJ_RETURN_OS_ERROR(pj_get_native_netos_error());

    bzero(&netlink_req, sizeof(netlink_req));

    netlink_req.nlmsg_info.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifaddrmsg));
    netlink_req.nlmsg_info.nlmsg_flags = NLM_F_REQUEST | NLM_F_DUMP;
    netlink_req.nlmsg_info.nlmsg_type = RTM_GETADDR;
    netlink_req.nlmsg_info.nlmsg_pid = getpid();
    netlink_req.ifaddrmsg_info.ifa_family = AF_INET6;

    int rtn = send(fd, &netlink_req, netlink_req.nlmsg_info.nlmsg_len, 0);
    if (rtn < 0) {
        close(fd);
        return PJ_RETURN_OS_ERROR(pj_get_native_netos_error());
    }

    char read_buffer[pagesize];
    size_t idx = 0;

    while(1) {
        bzero(read_buffer, pagesize);
        int read_size = recv(fd, read_buffer, pagesize, 0);
        if (read_size < 0) {
            close(fd);
            return PJ_RETURN_OS_ERROR(pj_get_native_netos_error());
        }

        struct nlmsghdr *nlmsg_ptr = (struct nlmsghdr *) read_buffer;
        int nlmsg_len = read_size;

        if (nlmsg_len < (int)sizeof (struct nlmsghdr)) {
            close(fd);
            return PJ_ETOOSMALL;
        }

        if (nlmsg_ptr->nlmsg_type == NLMSG_DONE)
            break;

        for(; NLMSG_OK(nlmsg_ptr, nlmsg_len);
            nlmsg_ptr = NLMSG_NEXT(nlmsg_ptr, nlmsg_len))
        {
            struct ifaddrmsg *ifaddrmsg_ptr;
            struct rtattr *rtattr_ptr;
            int ifaddrmsg_len;

            ifaddrmsg_ptr = (struct ifaddrmsg*)NLMSG_DATA(nlmsg_ptr);

            if (ifaddrmsg_ptr->ifa_flags & IFA_F_DEPRECATED ||
                ifaddrmsg_ptr->ifa_flags & IFA_F_TENTATIVE)
            {
                rtattr_ptr = (struct rtattr*)IFA_RTA(ifaddrmsg_ptr);
                ifaddrmsg_len = IFA_PAYLOAD(nlmsg_ptr);

                for(;RTA_OK(rtattr_ptr, ifaddrmsg_len);
                    rtattr_ptr = RTA_NEXT(rtattr_ptr, ifaddrmsg_len))
                {
                    switch(rtattr_ptr->rta_type) {
                    case IFA_ADDRESS:
                        // Check if addr can contains more data
                        if (idx >= *count)
                            break;
                        // Store deprecated IP
                        char deprecatedAddr[PJ_INET6_ADDRSTRLEN];
                        inet_ntop(ifaddrmsg_ptr->ifa_family,
                                  RTA_DATA(rtattr_ptr),
                                  deprecatedAddr,
                                  sizeof(deprecatedAddr));
                        pj_str_t pj_addr_str;
                        pj_cstr(&pj_addr_str, deprecatedAddr);
                        pj_sockaddr_init(pj_AF_INET6(), &addr[idx],
                                         &pj_addr_str, 0);
                        ++idx;
                    default:
                        break;
                    }
                }
            }
        }
    }

    close(fd);
    *count = idx;

    return PJ_SUCCESS;
}
#endif

/*
 * Enumerate the local IP interface currently active in the host.
 */
PJ_DEF(pj_status_t) pj_enum_ip_interface2( const pj_enum_ip_option *opt,
                                           unsigned *p_cnt,
                                           pj_sockaddr ifs[])
{
    pj_enum_ip_option opt_;

    if (opt)
        opt_ = *opt;
    else
        pj_enum_ip_option_default(&opt_);

    if (opt_.af != pj_AF_INET() && opt_.omit_deprecated_ipv6) {

#if defined(PJ_LINUX) && PJ_LINUX!=0
        pj_sockaddr addrs[*p_cnt];
        pj_sockaddr deprecatedAddrs[*p_cnt];
        unsigned deprecatedCount = *p_cnt;
        unsigned cnt = 0;
        unsigned i;
        pj_status_t status;

        status = get_ipv6_deprecated(&deprecatedCount, deprecatedAddrs);
        if (status != PJ_SUCCESS)
            return status;

        status = pj_enum_ip_interface(opt_.af, p_cnt, addrs);
        if (status != PJ_SUCCESS)
            return status;

        for (i = 0; i < *p_cnt; ++i) {
            unsigned j;

            ifs[cnt++] = addrs[i];

            if (addrs[i].addr.sa_family != pj_AF_INET6())
                continue;

            for (j = 0; j < deprecatedCount; ++j) {
                if (pj_sockaddr_cmp(&addrs[i], &deprecatedAddrs[j]) == 0) {
                    cnt--;
                    break;
                }
            }
        }

        *p_cnt = cnt;
        return *p_cnt ? PJ_SUCCESS : PJ_ENOTFOUND;
#else
        return PJ_ENOTSUP;
#endif
    }

    return pj_enum_ip_interface(opt_.af, p_cnt, ifs);
}
