source: vendor/current/ctdb/common/system_common.c

/* 
   ctdb system specific code to manage raw sockets on linux

   Copyright (C) Ronnie Sahlberg  2007
   Copyright (C) Andrew Tridgell  2007

   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 3 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, see <http://www.gnu.org/licenses/>.
*/

#include "replace.h"
#include "system/network.h"

#include "lib/util/debug.h"

#include "protocol/protocol.h"

#include "common/logging.h"
#include "common/system.h"

/*
  uint16 checksum for n bytes
 */
uint32_t uint16_checksum(uint16_t *data, size_t n)
{
        uint32_t sum=0;
        while (n>=2) {
                sum += (uint32_t)ntohs(*data);
                data++;
                n -= 2;
        }
        if (n == 1) {
                sum += (uint32_t)ntohs(*(uint8_t *)data);
        }
        return sum;
}

/*
  see if we currently have an interface with the given IP

  we try to bind to it, and if that fails then we don't have that IP
  on an interface
 */
bool ctdb_sys_have_ip(ctdb_sock_addr *_addr)
{
        int s;
        int ret;
        ctdb_sock_addr __addr = *_addr;
        ctdb_sock_addr *addr = &__addr;
        socklen_t addrlen = 0;

        switch (addr->sa.sa_family) {
        case AF_INET:
                addr->ip.sin_port = 0;
                addrlen = sizeof(struct sockaddr_in);
                break;
        case AF_INET6:
                addr->ip6.sin6_port = 0;
                addrlen = sizeof(struct sockaddr_in6);
                break;
        }

        s = socket(addr->sa.sa_family, SOCK_STREAM, IPPROTO_TCP);
        if (s == -1) {
                return false;
        }

        ret = bind(s, (struct sockaddr *)addr, addrlen);

        close(s);
        return ret == 0;
}


/* find which interface an ip address is currently assigned to */
char *ctdb_sys_find_ifname(ctdb_sock_addr *addr)
{
        int s;
        int size;
        struct ifconf ifc;
        char *ptr;

        s = socket(AF_INET, SOCK_RAW, IPPROTO_RAW);
        if (s == -1) {
                DEBUG(DEBUG_CRIT,(__location__ " failed to open raw socket (%s)\n",
                         strerror(errno)));
                return NULL;
        }


        size = sizeof(struct ifreq);
        ifc.ifc_buf = NULL;
        ifc.ifc_len = size;

        while(ifc.ifc_len > (size - sizeof(struct ifreq))) {
                size *= 2;

                free(ifc.ifc_buf);      
                ifc.ifc_len = size;
                ifc.ifc_buf = malloc(size);
                memset(ifc.ifc_buf, 0, size);
                if (ioctl(s, SIOCGIFCONF, (caddr_t)&ifc) < 0) {
                        DEBUG(DEBUG_CRIT,("Failed to read ifc buffer from socket\n"));
                        free(ifc.ifc_buf);      
                        close(s);
                        return NULL;
                }
        }

        for (ptr =(char *)ifc.ifc_buf; ptr < ((char *)ifc.ifc_buf) + ifc.ifc_len; ) {
                char *ifname;
                struct ifreq *ifr;

                ifr = (struct ifreq *)ptr;

#ifdef HAVE_SOCKADDR_LEN
                if (ifr->ifr_addr.sa_len > sizeof(struct sockaddr)) {
                        ptr += sizeof(ifr->ifr_name) + ifr->ifr_addr.sa_len;
                } else {
                        ptr += sizeof(ifr->ifr_name) + sizeof(struct sockaddr);
                }
#else
                ptr += sizeof(struct ifreq);
#endif

                if (ifr->ifr_addr.sa_family != addr->sa.sa_family) {
                        continue;
                }

                switch (addr->sa.sa_family) {
                case AF_INET:


                        if (memcmp(&addr->ip.sin_addr, &((struct sockaddr_in *)&ifr->ifr_addr)->sin_addr, sizeof(addr->ip.sin_addr))) {
                                continue;
                        }
                        break;
                case AF_INET6:
                        if (memcmp(&addr->ip6.sin6_addr, &((struct sockaddr_in6 *)&ifr->ifr_addr)->sin6_addr, sizeof(addr->ip6.sin6_addr))) {
                                continue;
                        }
                        break;
                }

                ifname = strdup(ifr->ifr_name);
                free(ifc.ifc_buf);      
                close(s);
                return ifname;
        }


        free(ifc.ifc_buf);      
        close(s);

        return NULL;
}