getifaddrs.cpp

/* -*- mode: C++; indent-tabs-mode: nil; c-basic-offset: 4; fill-column: 99; -*- */
/* vim: set ts=4 sw=4 et tw=99:  */
/* getifaddrs -- get names and addresses of all network interfaces
   Copyright (C) 1999,2002 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   This library 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
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with this library; if not, write to the Free Software
   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
*/

/**
 * 02-12-26, tim@tjansen.de: put in kde_ namespace, C++ fixes,
 *                           included ifreq.h
 *                           removed glibc dependencies
 */

#include "config.h"

#ifndef HAVE_IFADDRS_H

#include "getifaddrs.h"
#include <net/if.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <netinet/in.h>
#include <stdio.h>

#ifndef IF_NAMESIZE
#define IF_NAMESIZE IFNAMSIZ
#endif

#ifdef SIOCGIFCONF

#define old_siocgifconf 0

static inline void __ifreq(struct ifreq **ifreqs, int *num_ifs, int sockfd)
{
    int fd = sockfd;
    struct ifconf ifc;
    int rq_len;
    int nifs;
# define RQ_IFS 4

    if (fd < 0) {
        fd = socket(AF_INET, SOCK_DGRAM, 0);
    }

    if (fd < 0) {
        *num_ifs = 0;
        *ifreqs = NULL;
        return;
    }

    ifc.ifc_buf = NULL;

    /* We may be able to get the needed buffer size directly, rather than
       guessing.  */
    if (! old_siocgifconf) {
        ifc.ifc_buf = NULL;
        ifc.ifc_len = 0;

        if (ioctl(fd, SIOCGIFCONF, &ifc) < 0 || ifc.ifc_len == 0) {
            rq_len = RQ_IFS * sizeof(struct ifreq);
        } else {
            rq_len = ifc.ifc_len;
        }
    } else {
        rq_len = RQ_IFS * sizeof(struct ifreq);
    }

    /* Read all the interfaces out of the kernel.  */
    while (1) {
        ifc.ifc_len = rq_len;
        ifc.ifc_buf = (char *) realloc(ifc.ifc_buf, ifc.ifc_len);

        if (ifc.ifc_buf == NULL || ioctl(fd, SIOCGIFCONF, &ifc) < 0) {
            if (ifc.ifc_buf) {
                free(ifc.ifc_buf);
            }

            if (fd != sockfd) {
                if ((-1 == close(fd)) && (errno != EBADF)){
                    log_perror("close failed");
                }
            }

            *num_ifs = 0;
            *ifreqs = NULL;
            return;
        }

        if (!old_siocgifconf || ifc.ifc_len < rq_len) {
            break;
        }

        rq_len *= 2;
    }

    nifs = ifc.ifc_len / sizeof(struct ifreq);

    if (fd != sockfd) {
        if ((-1 == close(fd)) && (errno != EBADF)){
            log_perror("close failed");
        }
    }

    *num_ifs = nifs;
    *ifreqs = (ifreq *)realloc(ifc.ifc_buf, nifs * sizeof(struct ifreq));
}

static inline struct ifreq *__if_nextreq(struct ifreq *ifr) {
    return ifr + 1;
}

static inline void __if_freereq(struct ifreq *ifreqs, int num_ifs)
{
    free(ifreqs);
}

/* Create a linked list of `struct kde_ifaddrs' structures, one for each
   network interface on the host machine.  If successful, store the
   list in *IFAP and return 0.  On errors, return -1 and set `errno'.  */
int kde_getifaddrs(struct kde_ifaddrs **ifap)
{
    /* This implementation handles only IPv4 interfaces.
       The various ioctls below will only work on an AF_INET socket.
       Some different mechanism entirely must be used for IPv6.  */
    int fd = socket(AF_INET, SOCK_DGRAM, 0);
    struct ifreq *ifreqs;
    int nifs;

    if (fd < 0) {
        return -1;
    }

    __ifreq(&ifreqs, &nifs, fd);

    if (ifreqs == NULL) {     /* XXX doesn't distinguish error vs none */
        if (-1 == close(fd)){
            log_perror("close failed");
        }
        return -1;
    }

    /* Now we have the list of interfaces and each one's address.
       Put it into the expected format and fill in the remaining details.  */
    if (nifs == 0) {
        *ifap = NULL;
    } else {
        struct Storage {
            struct kde_ifaddrs ia;
            struct sockaddr addr, netmask, broadaddr;
            char name[IF_NAMESIZE];
        } *storage;
        struct ifreq *ifr;
        int i;

        storage = (Storage *) malloc(nifs * sizeof storage[0]);

        if (storage == NULL) {
            if (-1 == close(fd)){
                log_perror("close failed");
            }
            __if_freereq(ifreqs, nifs);
            return -1;
        }

        i = 0;
        ifr = ifreqs;

        do {
            /* Fill in all pointers to the storage we've already allocated.  */
            storage[i].ia.ifa_next = &storage[i + 1].ia;
            storage[i].ia.ifa_addr = &storage[i].addr;
            storage[i].ia.ifa_netmask = &storage[i].netmask;
            storage[i].ia.ifa_broadaddr = &storage[i].broadaddr; /* & dstaddr */

            /* Now copy the information we already have from SIOCGIFCONF.  */
            storage[i].ia.ifa_name = strncpy(storage[i].name, ifr->ifr_name,
                                             sizeof storage[i].name);
            storage[i].addr = ifr->ifr_addr;

            /* The SIOCGIFCONF call filled in only the name and address.
               Now we must also ask for the other information we need.  */

            if (ioctl(fd, SIOCGIFFLAGS, ifr) < 0) {
                break;
            }

            storage[i].ia.ifa_flags = ifr->ifr_flags;

            ifr->ifr_addr = storage[i].addr;

            if (ioctl(fd, SIOCGIFNETMASK, ifr) < 0) {
                break;
            }

            storage[i].netmask = ifr->ifr_netmask;

            if (ifr->ifr_flags & IFF_BROADCAST) {
                ifr->ifr_addr = storage[i].addr;

                if (ioctl(fd, SIOCGIFBRDADDR, ifr) < 0) {
                    break;
                }

                storage[i].broadaddr = ifr->ifr_broadaddr;
            } else if (ifr->ifr_flags & IFF_POINTOPOINT) {
                ifr->ifr_addr = storage[i].addr;
// Needed on Cygwin
#ifndef SIOCGIFDSTADDR
#define SIOCGIFDSTADDR 0x8917
#endif

                if (ioctl(fd, SIOCGIFDSTADDR, ifr) < 0) {
                    break;
                }

#if HAVE_IFR_DSTADDR
                storage[i].broadaddr = ifr->ifr_dstaddr;
#else
                // Fix for Cygwin
                storage[i].broadaddr = ifr->ifr_broadaddr;
#endif
            } else
                /* Just 'cause.  */
            {
                memset(&storage[i].broadaddr, 0, sizeof storage[i].broadaddr);
            }

            storage[i].ia.ifa_data = NULL; /* Nothing here for now.  */

            ifr = __if_nextreq(ifr);
        } while (++i < nifs);

        if (i < nifs) {   /* Broke out early on error.  */
            if (-1 == close(fd)){
                log_perror("close failed");
            }
            free(storage);
            __if_freereq(ifreqs, nifs);
            return -1;
        }

        storage[i - 1].ia.ifa_next = NULL;

        *ifap = &storage[0].ia;

        if (-1 == close(fd)){
            log_perror("close failed");
        }
        __if_freereq(ifreqs, nifs);
    }

    return 0;
}

void kde_freeifaddrs(struct kde_ifaddrs *ifa)
{
    free(ifa);
}

#else
int kde_getifaddrs(struct kde_ifaddrs **)
{
    return 1;
}
void kde_freeifaddrs(struct kde_ifaddrs *)
{
}
struct { } kde_ifaddrs;

#endif

#endif