arp-bsd.c

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/*
 * arp-bsd.c
 * 
 * Copyright (c) 2000 Dug Song <dugsong@monkey.org>
 *
 * $Id: arp-bsd.c,v 1.14 2005/01/23 07:36:54 dugsong Exp $
 */

#include "config.h"

#include <sys/param.h>
#include <sys/types.h>
#include <sys/socket.h>
#ifdef HAVE_SYS_SYSCTL_H
#include <sys/sysctl.h>
#endif
#ifdef HAVE_STREAMS_ROUTE
#include <sys/stream.h>
#include <sys/stropts.h>
#endif

#include <net/if.h>
#include <net/if_dl.h>
#include <net/route.h>
#include <netinet/in.h>
#include <netinet/if_ether.h>

#include <assert.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "dnet.h"

struct arp_handle {
        int     fd;
        int     seq;
};

struct arpmsg {
        struct rt_msghdr        rtm;
        u_char                  addrs[256];
};

arp_t *
arp_open(void)
{
        arp_t *arp;

        if ((arp = calloc(1, sizeof(*arp))) != NULL) {
#ifdef HAVE_STREAMS_ROUTE
                if ((arp->fd = open("/dev/route", O_RDWR, 0)) < 0)
#else
                if ((arp->fd = socket(PF_ROUTE, SOCK_RAW, 0)) < 0)
#endif
                        return (arp_close(arp));
        }
        return (arp);
}

static int
arp_msg(arp_t *arp, struct arpmsg *msg)
{
        struct arpmsg smsg;
        int len, i = 0;
        pid_t pid;
        
        msg->rtm.rtm_version = RTM_VERSION;
        msg->rtm.rtm_seq = ++arp->seq; 
        memcpy(&smsg, msg, sizeof(smsg));
        
#ifdef HAVE_STREAMS_ROUTE
        return (ioctl(arp->fd, RTSTR_SEND, &msg->rtm));
#else
        if (write(arp->fd, &smsg, smsg.rtm.rtm_msglen) < 0) {
                if (errno != ESRCH || msg->rtm.rtm_type != RTM_DELETE)
                        return (-1);
        }
        pid = getpid();
        
        /* XXX - should we only read RTM_GET responses here? */
        while ((len = read(arp->fd, msg, sizeof(*msg))) > 0) {
                if (len < (int)sizeof(msg->rtm))
                        return (-1);

                if (msg->rtm.rtm_pid == pid) {
                        if (msg->rtm.rtm_seq == arp->seq)
                                break;
                        continue;
                } else if ((i++ % 2) == 0)
                        continue;
                
                /* Repeat request. */
                if (write(arp->fd, &smsg, smsg.rtm.rtm_msglen) < 0) {
                        if (errno != ESRCH || msg->rtm.rtm_type != RTM_DELETE)
                                return (-1);
                }
        }
        if (len < 0)
                return (-1);
        
        return (0);
#endif
}

int
arp_add(arp_t *arp, const struct arp_entry *entry)
{
        struct arpmsg msg;
        struct sockaddr_in *sin;
        struct sockaddr *sa;
        int index, type;
        
        if (entry->arp_pa.addr_type != ADDR_TYPE_IP ||
            entry->arp_ha.addr_type != ADDR_TYPE_ETH) {
                errno = EAFNOSUPPORT;
                return (-1);
        }
        sin = (struct sockaddr_in *)msg.addrs;
        sa = (struct sockaddr *)(sin + 1);
        
        if (addr_ntos(&entry->arp_pa, (struct sockaddr *)sin) < 0)
                return (-1);
        
        memset(&msg.rtm, 0, sizeof(msg.rtm));
        msg.rtm.rtm_type = RTM_GET;
        msg.rtm.rtm_addrs = RTA_DST;
        msg.rtm.rtm_msglen = sizeof(msg.rtm) + sizeof(*sin);
        
        if (arp_msg(arp, &msg) < 0)
                return (-1);
        
        if (msg.rtm.rtm_msglen < (int)sizeof(msg.rtm) +
            sizeof(*sin) + sizeof(*sa)) {
                errno = EADDRNOTAVAIL;
                return (-1);
        }
        if (sin->sin_addr.s_addr == entry->arp_pa.addr_ip) {
                if ((msg.rtm.rtm_flags & RTF_LLINFO) == 0 ||
                    (msg.rtm.rtm_flags & RTF_GATEWAY) != 0) {
                        errno = EADDRINUSE;
                        return (-1);
                }
        }
        if (sa->sa_family != AF_LINK) {
                errno = EADDRNOTAVAIL;
                return (-1);
        } else {
                index = ((struct sockaddr_dl *)sa)->sdl_index;
                type = ((struct sockaddr_dl *)sa)->sdl_type;
        }
        if (addr_ntos(&entry->arp_pa, (struct sockaddr *)sin) < 0 ||
            addr_ntos(&entry->arp_ha, sa) < 0)
                return (-1);

        ((struct sockaddr_dl *)sa)->sdl_index = index;
        ((struct sockaddr_dl *)sa)->sdl_type = type;
        
        memset(&msg.rtm, 0, sizeof(msg.rtm));
        msg.rtm.rtm_type = RTM_ADD;
        msg.rtm.rtm_addrs = RTA_DST | RTA_GATEWAY;
        msg.rtm.rtm_inits = RTV_EXPIRE;
        msg.rtm.rtm_flags = RTF_HOST | RTF_STATIC;
#ifdef HAVE_SOCKADDR_SA_LEN
        msg.rtm.rtm_msglen = sizeof(msg.rtm) + sin->sin_len + sa->sa_len;
#else
        msg.rtm.rtm_msglen = sizeof(msg.rtm) + sizeof(*sin) + sizeof(*sa);
#endif
        return (arp_msg(arp, &msg));
}

int
arp_delete(arp_t *arp, const struct arp_entry *entry)
{
        struct arpmsg msg;
        struct sockaddr_in *sin;
        struct sockaddr *sa;

        if (entry->arp_pa.addr_type != ADDR_TYPE_IP) {
                errno = EAFNOSUPPORT;
                return (-1);
        }
        sin = (struct sockaddr_in *)msg.addrs;
        sa = (struct sockaddr *)(sin + 1);

        if (addr_ntos(&entry->arp_pa, (struct sockaddr *)sin) < 0)
                return (-1);

        memset(&msg.rtm, 0, sizeof(msg.rtm));
        msg.rtm.rtm_type = RTM_GET;
        msg.rtm.rtm_addrs = RTA_DST;
        msg.rtm.rtm_msglen = sizeof(msg.rtm) + sizeof(*sin);
        
        if (arp_msg(arp, &msg) < 0)
                return (-1);
        
        if (msg.rtm.rtm_msglen < (int)sizeof(msg.rtm) +
            sizeof(*sin) + sizeof(*sa)) {
                errno = ESRCH;
                return (-1);
        }
        if (sin->sin_addr.s_addr == entry->arp_pa.addr_ip) {
                if ((msg.rtm.rtm_flags & RTF_LLINFO) == 0 ||
                    (msg.rtm.rtm_flags & RTF_GATEWAY) != 0) {
                        errno = EADDRINUSE;
                        return (-1);
                }
        }
        if (sa->sa_family != AF_LINK) {
                errno = ESRCH;
                return (-1);
        }
        msg.rtm.rtm_type = RTM_DELETE;
        
        return (arp_msg(arp, &msg));
}

int
arp_get(arp_t *arp, struct arp_entry *entry)
{
        struct arpmsg msg;
        struct sockaddr_in *sin;
        struct sockaddr *sa;
        
        if (entry->arp_pa.addr_type != ADDR_TYPE_IP) {
                errno = EAFNOSUPPORT;
                return (-1);
        }
        sin = (struct sockaddr_in *)msg.addrs;
        sa = (struct sockaddr *)(sin + 1);
        
        if (addr_ntos(&entry->arp_pa, (struct sockaddr *)sin) < 0)
                return (-1);
        
        memset(&msg.rtm, 0, sizeof(msg.rtm));
        msg.rtm.rtm_type = RTM_GET;
        msg.rtm.rtm_addrs = RTA_DST;
        msg.rtm.rtm_flags = RTF_LLINFO;
        msg.rtm.rtm_msglen = sizeof(msg.rtm) + sizeof(*sin);
        
        if (arp_msg(arp, &msg) < 0)
                return (-1);
        
        if (msg.rtm.rtm_msglen < (int)sizeof(msg.rtm) +
            sizeof(*sin) + sizeof(*sa) ||
            sin->sin_addr.s_addr != entry->arp_pa.addr_ip ||
            sa->sa_family != AF_LINK) {
                errno = ESRCH;
                return (-1);
        }
        if (addr_ston(sa, &entry->arp_ha) < 0)
                return (-1);
        
        return (0);
}

#ifdef HAVE_SYS_SYSCTL_H
int
arp_loop(arp_t *arp, arp_handler callback, void *arg)
{
        struct arp_entry entry;
        struct rt_msghdr *rtm;
        struct sockaddr_in *sin;
        struct sockaddr *sa;
        char *buf, *lim, *next;
        size_t len;
        int ret, mib[6] = { CTL_NET, PF_ROUTE, 0, AF_INET,
                            NET_RT_FLAGS, RTF_LLINFO };

        if (sysctl(mib, 6, NULL, &len, NULL, 0) < 0)
                return (-1);

        if (len == 0)
                return (0);

        if ((buf = malloc(len)) == NULL)
                return (-1);
        
        if (sysctl(mib, 6, buf, &len, NULL, 0) < 0) {
                free(buf);
                return (-1);
        }
        lim = buf + len;
        ret = 0;
        
        for (next = buf; next < lim; next += rtm->rtm_msglen) {
                rtm = (struct rt_msghdr *)next;
                sin = (struct sockaddr_in *)(rtm + 1);
                sa = (struct sockaddr *)(sin + 1);
                
                if (addr_ston((struct sockaddr *)sin, &entry.arp_pa) < 0 ||
                    addr_ston(sa, &entry.arp_ha) < 0)
                        continue;
                
                if ((ret = callback(&entry, arg)) != 0)
                        break;
        }
        free(buf);
        
        return (ret);
}
#else
int
arp_loop(arp_t *arp, arp_handler callback, void *arg)
{
        errno = ENOSYS;
        return (-1);
}
#endif

arp_t *
arp_close(arp_t *arp)
{
        if (arp != NULL) {
                if (arp->fd >= 0)
                        close(arp->fd);
                free(arp);
        }
        return (NULL);
}

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