/* 
 * dhcpcd - DHCP client daemon
 * Copyright (c) 2006-2010 Roy Marples <roy@marples.name>
 * All rights reserved

 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/param.h>
#include <sys/socket.h>
#include <sys/time.h>

#include <arpa/inet.h>
#include <net/if.h>
#include <net/if_arp.h>
#ifdef AF_LINK
#  include <net/if_dl.h>
#  include <net/if_types.h>
#endif
#include <netinet/in_systm.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#define __FAVOR_BSD /* Nasty glibc hack so we can use BSD semantics for UDP */
#include <netinet/udp.h>
#undef __FAVOR_BSD
#ifdef AF_PACKET
#  include <netpacket/packet.h>
#endif
#ifdef SIOCGIFMEDIA
#  include <net/if_media.h>
#endif

#include <ctype.h>
#include <errno.h>
#include <ifaddrs.h>
#include <fnmatch.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "common.h"
#include "dhcp.h"
#include "if-options.h"
#include "net.h"

#include <rump/rump_syscalls.h>

static char hwaddr_buffer[(HWADDR_LEN * 3) + 1];

int socket_afnet = -1;

int
inet_ntocidr(struct in_addr address)
{
        int cidr = 0;
        uint32_t mask = htonl(address.s_addr);

        while (mask) {
                cidr++;
                mask <<= 1;
        }
        return cidr;
}

int
inet_cidrtoaddr(int cidr, struct in_addr *addr)
{
        int ocets;

        if (cidr < 1 || cidr > 32) {
                errno = EINVAL;
                return -1;
        }
        ocets = (cidr + 7) / 8;

        addr->s_addr = 0;
        if (ocets > 0) {
                memset(&addr->s_addr, 255, (size_t)ocets - 1);
                memset((unsigned char *)&addr->s_addr + (ocets - 1),
                    (256 - (1 << (32 - cidr) % 8)), 1);
        }

        return 0;
}

uint32_t
get_netmask(uint32_t addr)
{
        uint32_t dst;

        if (addr == 0)
                return 0;

        dst = htonl(addr);
        if (IN_CLASSA(dst))
                return ntohl(IN_CLASSA_NET);
        if (IN_CLASSB(dst))
                return ntohl(IN_CLASSB_NET);
        if (IN_CLASSC(dst))
                return ntohl(IN_CLASSC_NET);

        return 0;
}

char *
hwaddr_ntoa(const unsigned char *hwaddr, size_t hwlen)
{
        char *p = hwaddr_buffer;
        size_t i;

        for (i = 0; i < hwlen && i < HWADDR_LEN; i++) {
                if (i > 0)
                        *p ++= ':';
                p += snprintf(p, 3, "%.2x", hwaddr[i]);
        }

        *p ++= '\0';

        return hwaddr_buffer;
}

size_t
hwaddr_aton(unsigned char *buffer, const char *addr)
{
        char c[3];
        const char *p = addr;
        unsigned char *bp = buffer;
        size_t len = 0;

        c[2] = '\0';
        while (*p) {
                c[0] = *p++;
                c[1] = *p++;
                /* Ensure that digits are hex */
                if (isxdigit((unsigned char)c[0]) == 0 ||
                    isxdigit((unsigned char)c[1]) == 0)
                {
                        errno = EINVAL;
                        return 0;
                }
                /* We should have at least two entries 00:01 */
                if (len == 0 && *p == '\0') {
                        errno = EINVAL;
                        return 0;
                }
                /* Ensure that next data is EOL or a separator with data */
                if (!(*p == '\0' || (*p == ':' && *(p + 1) != '\0'))) {
                        errno = EINVAL;
                        return 0;
                }
                if (*p)
                        p++;
                if (bp)
                        *bp++ = (unsigned char)strtol(c, NULL, 16);
                len++;
        }
        return len;
}

struct interface *
init_interface(const char *ifname)
{
        struct ifreq ifr;
        struct interface *iface = NULL;

        memset(&ifr, 0, sizeof(ifr));
        strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
        if (rump_sys_ioctl(socket_afnet, SIOCGIFFLAGS, &ifr) == -1)
                goto eexit;

        iface = xzalloc(sizeof(*iface));
        strlcpy(iface->name, ifname, sizeof(iface->name));
        iface->flags = ifr.ifr_flags;
        /* We reserve the 100 range for virtual interfaces, if and when
         * we can work them out. */
        iface->metric = 200 + if_nametoindex(iface->name);
        if (getifssid(ifname, iface->ssid) != -1) {
                iface->wireless = 1;
                iface->metric += 100;
        }

        if (rump_sys_ioctl(socket_afnet, SIOCGIFMTU, &ifr) == -1)
                goto eexit;
        /* Ensure that the MTU is big enough for DHCP */
        if (ifr.ifr_mtu < MTU_MIN) {
                ifr.ifr_mtu = MTU_MIN;
                strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
                if (rump_sys_ioctl(socket_afnet, SIOCSIFMTU, &ifr) == -1)
                        goto eexit;
        }

        /* 0 is a valid fd, so init to -1 */
        iface->raw_fd = -1;
        iface->udp_fd = -1;
        iface->arp_fd = -1;
        goto exit;

eexit:
        free(iface);
        iface = NULL;
exit:
        return iface;
}

int
carrier_status(struct interface *iface)
{
        int ret;
        struct ifreq ifr;
#ifdef SIOCGIFMEDIA
        struct ifmediareq ifmr;
#endif
#ifdef __linux__
        char *p;
#endif

        memset(&ifr, 0, sizeof(ifr));
        strlcpy(ifr.ifr_name, iface->name, sizeof(ifr.ifr_name));
#ifdef __linux__
        /* We can only test the real interface up */
        if ((p = strchr(ifr.ifr_name, ':')))
                *p = '\0';
#endif

        if (rump_sys_ioctl(socket_afnet, SIOCGIFFLAGS, &ifr) == -1)
                return -1;
        iface->flags = ifr.ifr_flags;

        ret = -1;
#ifdef SIOCGIFMEDIA
        memset(&ifmr, 0, sizeof(ifmr));
        strlcpy(ifmr.ifm_name, iface->name, sizeof(ifmr.ifm_name));
        if (rump_sys_ioctl(socket_afnet, SIOCGIFMEDIA, &ifmr) != -1 &&
            ifmr.ifm_status & IFM_AVALID)
                ret = (ifmr.ifm_status & IFM_ACTIVE) ? 1 : 0;
#endif
        if (ret == -1)
                ret = (ifr.ifr_flags & IFF_RUNNING) ? 1 : 0;
        return ret;
}

int
up_interface(struct interface *iface)
{
        struct ifreq ifr;
        int retval = -1;
#ifdef __linux__
        char *p;
#endif

        memset(&ifr, 0, sizeof(ifr));
        strlcpy(ifr.ifr_name, iface->name, sizeof(ifr.ifr_name));
#ifdef __linux__
        /* We can only bring the real interface up */
        if ((p = strchr(ifr.ifr_name, ':')))
                *p = '\0';
#endif
        if (rump_sys_ioctl(socket_afnet, SIOCGIFFLAGS, &ifr) == 0) {
                if ((ifr.ifr_flags & IFF_UP))
                        retval = 0;
                else {
                        ifr.ifr_flags |= IFF_UP;
                        if (rump_sys_ioctl(socket_afnet, SIOCSIFFLAGS, &ifr) == 0)
                                retval = 0;
                }
                iface->flags = ifr.ifr_flags;
        }
        return retval;
}

int
do_address(const char *ifname,
    struct in_addr *addr, struct in_addr *net, struct in_addr *dst, int act)
{
        struct ifaddrs *ifaddrs, *ifa;
        const struct sockaddr_in *a, *n, *d;
        int retval;

        if (getifaddrs(&ifaddrs) == -1)
                return -1;

        retval = 0;
        for (ifa = ifaddrs; ifa; ifa = ifa->ifa_next) {
                if (ifa->ifa_addr == NULL ||
                    ifa->ifa_addr->sa_family != AF_INET ||
                    strcmp(ifa->ifa_name, ifname) != 0)
                        continue;
                a = (const struct sockaddr_in *)(void *)ifa->ifa_addr;
                n = (const struct sockaddr_in *)(void *)ifa->ifa_netmask;
                if (ifa->ifa_flags & IFF_POINTOPOINT)
                        d = (const struct sockaddr_in *)(void *)
                            ifa->ifa_dstaddr;
                else
                        d = NULL;
                if (act == 1) {
                        addr->s_addr = a->sin_addr.s_addr;
                        net->s_addr = n->sin_addr.s_addr;
                        if (dst) {
                                if (ifa->ifa_flags & IFF_POINTOPOINT)
                                        dst->s_addr = d->sin_addr.s_addr;
                                else
                                        dst->s_addr = INADDR_ANY;
                        }
                        retval = 1;
                        break;
                }
                if (addr->s_addr == a->sin_addr.s_addr &&
                    (net == NULL || net->s_addr == n->sin_addr.s_addr))
                {
                        retval = 1;
                        break;
                }
        }
        freeifaddrs(ifaddrs);
        return retval;
}

int
do_mtu(const char *ifname, short int mtu)
{
        struct ifreq ifr;
        int r;

        memset(&ifr, 0, sizeof(ifr));
        strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
        ifr.ifr_mtu = mtu;
        r = rump_sys_ioctl(socket_afnet, mtu ? SIOCSIFMTU : SIOCGIFMTU, &ifr);
        if (r == -1)
                return -1;
        return ifr.ifr_mtu;
}

void
free_routes(struct rt *routes)
{
        struct rt *r;

        while (routes) {
                r = routes->next;
                free(routes);
                routes = r;
        }
}

struct udp_dhcp_packet
{
        struct ip ip;
        struct udphdr udp;
        struct dhcp_message dhcp;
};
const size_t udp_dhcp_len = sizeof(struct udp_dhcp_packet);

static uint16_t
checksum(const void *data, uint16_t len)
{
        const uint8_t *addr = data;
        uint32_t sum = 0;

        while (len > 1) {
                sum += addr[0] * 256 + addr[1];
                addr += 2;
                len -= 2;
        }

        if (len == 1)
                sum += *addr * 256;

        sum = (sum >> 16) + (sum & 0xffff);
        sum += (sum >> 16);

        sum = htons(sum);

        return ~sum;
}

ssize_t
make_udp_packet(uint8_t **packet, const uint8_t *data, size_t length,
    struct in_addr source, struct in_addr dest)
{
        struct udp_dhcp_packet *udpp;
        struct ip *ip;
        struct udphdr *udp;

        udpp = xzalloc(sizeof(*udpp));
        ip = &udpp->ip;
        udp = &udpp->udp;

        /* OK, this is important :)
         * We copy the data to our packet and then create a small part of the
         * ip structure and an invalid ip_len (basically udp length).
         * We then fill the udp structure and put the checksum
         * of the whole packet into the udp checksum.
         * Finally we complete the ip structure and ip checksum.
         * If we don't do the ordering like so then the udp checksum will be
         * broken, so find another way of doing it! */

        memcpy(&udpp->dhcp, data, length);

        ip->ip_p = IPPROTO_UDP;
        ip->ip_src.s_addr = source.s_addr;
        if (dest.s_addr == 0)
                ip->ip_dst.s_addr = INADDR_BROADCAST;
        else
                ip->ip_dst.s_addr = dest.s_addr;

        udp->uh_sport = htons(DHCP_CLIENT_PORT);
        udp->uh_dport = htons(DHCP_SERVER_PORT);
        udp->uh_ulen = htons(sizeof(*udp) + length);
        ip->ip_len = udp->uh_ulen;
        udp->uh_sum = checksum(udpp, sizeof(*udpp));

        ip->ip_v = IPVERSION;
        ip->ip_hl = sizeof(*ip) >> 2;
        ip->ip_id = arc4random() & UINT16_MAX;
        ip->ip_ttl = IPDEFTTL;
        ip->ip_len = htons(sizeof(*ip) + sizeof(*udp) + length);
        ip->ip_sum = checksum(ip, sizeof(*ip));

        *packet = (uint8_t *)udpp;
        return sizeof(*ip) + sizeof(*udp) + length;
}

ssize_t
get_udp_data(const uint8_t **data, const uint8_t *udp)
{
        struct udp_dhcp_packet packet;

        memcpy(&packet, udp, sizeof(packet));
        *data = udp + offsetof(struct udp_dhcp_packet, dhcp);
        return ntohs(packet.ip.ip_len) -
            sizeof(packet.ip) -
            sizeof(packet.udp);
}

int
valid_udp_packet(const uint8_t *data, size_t data_len, struct in_addr *from)
{
        struct udp_dhcp_packet packet;
        uint16_t bytes, udpsum;

        if (data_len < sizeof(packet.ip)) {
                if (from)
                        from->s_addr = INADDR_ANY;
                errno = EINVAL;
                return -1;
        }
        memcpy(&packet, data, MIN(data_len, sizeof(packet)));
        if (from)
                from->s_addr = packet.ip.ip_src.s_addr;
        if (data_len > sizeof(packet)) {
                errno = EINVAL;
                return -1;
        }
        if (checksum(&packet.ip, sizeof(packet.ip)) != 0) {
                errno = EINVAL;
                return -1;
        }

        bytes = ntohs(packet.ip.ip_len);
        if (data_len < bytes) {
                errno = EINVAL;
                return -1;
        }
        udpsum = packet.udp.uh_sum;
        packet.udp.uh_sum = 0;
        packet.ip.ip_hl = 0;
        packet.ip.ip_v = 0;
        packet.ip.ip_tos = 0;
        packet.ip.ip_len = packet.udp.uh_ulen;
        packet.ip.ip_id = 0;
        packet.ip.ip_off = 0;
        packet.ip.ip_ttl = 0;
        packet.ip.ip_sum = 0;
        if (udpsum && checksum(&packet, bytes) != udpsum) {
                errno = EINVAL;
                return -1;
        }

        return 0;
}