Linux network interface functions

Implement various interface routines from libnetlink. More...

Files
file	interface.c
	Wrapper arround Linux libnetlink for managing network interfaces.

Data Structures
struct	iplink_req
	IP Netlink request. More...
struct	ipaddr_req
	IP Netlink IP addr request. More...

Enumerations
enum	ipv4_score { IPV4_SCORE_ZEROCONF = 1 << 0, IPV4_SCORE_RESERVED = 1 << 1, IPV4_SCORE_ROUTABLE = 1 << 2 }
	Order of precidence of ipv4. More...
enum	ipv6_score { IPV6_SCORE_RESERVED = 1 << 0, IPV6_SCORE_SIXIN4 = 1 << 1, IPV6_SCORE_ROUTABLE = 1 << 2 }
	Return best ipv6 address in order of FFC/7 2002/16 ... More...

Functions
void	closenetlink ()
	Close netlink socket on application termination. More...
int	get_iface_index (const char *ifname)
	Get the netlink interface for a named interface. More...
int	delete_kernvlan (char *ifname, int vid)
	Delete a VLAN. More...
int	create_kernvlan (char *ifname, unsigned short vid)
	Create a VLAN on a interface. More...
int	delete_kernmac (char *ifname)
	Delete Kernel MAC VLAN. More...
int	create_kernmac (char *ifname, char *macdev, unsigned char *mac)
	Create a kernal MAC VLAN. More...
int	set_interface_flags (int ifindex, int set, int clear)
	Alter interface flags. More...
int	set_interface_addr (int ifindex, const unsigned char *hwaddr)
	Set interface MAC addr. More...
int	set_interface_name (int ifindex, const char *name)
	Rename interface. More...
int	interface_bind (char *iface, int protocol)
	Bind to device fd may be a existing socket. More...
void	randhwaddr (unsigned char *addr)
	create random MAC address More...
int	create_tun (const char *ifname, const unsigned char *hwaddr, int flags)
	Create a tunnel device. More...
int	ifdown (const char *ifname, int flags)
	Set interface down. More...
int	ifup (const char *ifname, int flags)
	Set interface up. More...
int	ifrename (const char *oldname, const char *newname)
	Rename interface helper. More...
int	ifhwaddr (const char *ifname, unsigned char *hwaddr)
	Get MAC addr for interface. More...
int	set_interface_ipaddr (char *ifname, char *ipaddr)
	Set IP addr on interface. More...
const char *	get_ifipaddr (const char *iface, int family)
	Find best IP adress for a interface. More...

Detailed Description

Implement various interface routines from libnetlink.

Enumeration Type Documentation

enum ipv4_score

Order of precidence of ipv4.

Enumerator
IPV4_SCORE_ZEROCONF	Zeroconf IP's 169.254/16.
IPV4_SCORE_RESERVED	Reseverd "private" ip addresses.
IPV4_SCORE_ROUTABLE	Routable IP's.

Definition at line 63 of file interface.c.

                {
    IPV4_SCORE_ZEROCONF = 1 << 0,
    IPV4_SCORE_RESERVED = 1 << 1,
    IPV4_SCORE_ROUTABLE = 1 << 2
};

enum ipv6_score

Return best ipv6 address in order of FFC/7 2002/16 ...

Enumerator
IPV6_SCORE_RESERVED	Adminstrivly allocated addresses (FC/7)
IPV6_SCORE_SIXIN4	6in4 address space
IPV6_SCORE_ROUTABLE	Other routable addresses.

Definition at line 73 of file interface.c.

                {
    IPV6_SCORE_RESERVED = 1 << 0,
    IPV6_SCORE_SIXIN4 = 1 << 1,
    IPV6_SCORE_ROUTABLE = 1 << 2
};

Function Documentation

void closenetlink

(

void

)

Close netlink socket on application termination.

Definition at line 130 of file interface.c.

References objunref().

                           {
    if (nlh) {
        objunref(nlh);
    }
}

int create_kernmac	(	char *	ifname,
		char *	macdev,
		unsigned char *	mac
	)

Create a kernal MAC VLAN.

Parameters

ifname	Interface name to create
macdev	Base interface
mac	MAC address to use or random if NULL.

Returns

-1 on error.

Definition at line 282 of file interface.c.

References get_iface_index(), iplink_req::n, objalloc(), objlock(), objref(), objunlock(), objunref(), randhwaddr(), and strlenzero().

                                                                          {
    struct iplink_req *req;
    struct rtattr *data, *linkinfo;
    unsigned char lmac[ETH_ALEN];
    char *type = "macvlan";
    int ifindex, ret;

    if (strlenzero(ifname) || (strlen(ifname) > IFNAMSIZ) ||
            strlenzero(macdev) || (strlen(macdev) > IFNAMSIZ) ||
            (!objref(nlh) && !(nlh = nlhandle(0)))) {
        return (-1);
    }

    /*set the index of base interface*/
    if (!(ifindex = get_iface_index(ifname))) {
        objunref(nlh);
        return (-1);
    }

    if (!mac) {
        randhwaddr(lmac);
    } else {
        strncpy((char *)lmac, (char *)mac, ETH_ALEN);
    }

    if (!(req = objalloc(sizeof(*req), NULL))) {
        objunref(nlh);
        return (-1);
    }

    req->n.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg));
    req->n.nlmsg_type = RTM_NEWLINK;
    req->n.nlmsg_flags = NLM_F_CREATE | NLM_F_EXCL | NLM_F_REQUEST;

    /*config base/dev/mac*/
    addattr_l(&req->n, sizeof(*req), IFLA_LINK, &ifindex, 4);
    addattr_l(&req->n, sizeof(*req), IFLA_IFNAME, macdev, strlen(macdev));
    addattr_l(&req->n, sizeof(*req), IFLA_ADDRESS, lmac, ETH_ALEN);

    /*type*/
    linkinfo  = NLMSG_TAIL(&req->n);
    addattr_l(&req->n, sizeof(*req), IFLA_LINKINFO, NULL, 0);
    addattr_l(&req->n, sizeof(*req), IFLA_INFO_KIND, type, strlen(type));

    /*mode*/
    data = NLMSG_TAIL(&req->n);
    addattr_l(&req->n, sizeof(*req), IFLA_INFO_DATA, NULL, 0);
    addattr32(&req->n, sizeof(*req), IFLA_MACVLAN_MODE, MACVLAN_MODE_PRIVATE);
    data->rta_len = (char *)NLMSG_TAIL(&req->n) - (char *)data;
    linkinfo->rta_len = (char *)NLMSG_TAIL(&req->n) - (char *)linkinfo;

    objlock(nlh);
    ret = rtnl_talk(nlh, &req->n, 0, 0, NULL);
    objunlock(nlh);

    objunref(nlh);
    objunref(req);

    return (ret);
}

int create_kernvlan	(	char *	ifname,
		unsigned short	vid
	)

Create a VLAN on a interface.

Parameters

ifname	Interface to add VLAN to.
vid	VLAN id to add.

Returns

-1 on error.

Definition at line 214 of file interface.c.

References get_iface_index(), iplink_req::n, objalloc(), objlock(), objref(), objunlock(), objunref(), and strlenzero().

                                                             {
    struct iplink_req *req;
    char iface[IFNAMSIZ+1];
    struct rtattr *data, *linkinfo;
    char *type = "vlan";
    int ifindex, ret;

    if (strlenzero(ifname) || (strlen(ifname) > IFNAMSIZ) ||
            (!objref(nlh) && !(nlh = nlhandle(0)))) {
        return (-1);
    }

    /*set the index of base interface*/
    if (!(ifindex = get_iface_index(ifname))) {
        objunref(nlh);
        return (-1);
    }

    if (!(req = objalloc(sizeof(*req), NULL))) {
        objunref(nlh);
        return (-1);
    }

    snprintf(iface, IFNAMSIZ, "%s.%i", ifname, vid);
    req->n.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg));
    req->n.nlmsg_type = RTM_NEWLINK;
    req->n.nlmsg_flags = NLM_F_CREATE | NLM_F_EXCL | NLM_F_REQUEST;

    /*config base/dev/mac*/
    addattr_l(&req->n, sizeof(*req), IFLA_LINK, &ifindex, sizeof(ifindex));
    addattr_l(&req->n, sizeof(*req), IFLA_IFNAME, iface, strlen(iface));

    /*type*/
    linkinfo  = NLMSG_TAIL(&req->n);
    addattr_l(&req->n, sizeof(*req), IFLA_LINKINFO, NULL, 0);
    addattr_l(&req->n, sizeof(*req), IFLA_INFO_KIND, type, strlen(type));

    /*vid*/
    data = NLMSG_TAIL(&req->n);
    addattr_l(&req->n, sizeof(*req), IFLA_INFO_DATA, NULL, 0);
    addattr_l(&req->n, sizeof(*req), IFLA_VLAN_ID, &vid, sizeof(vid));

    data->rta_len = (char *)NLMSG_TAIL(&req->n) - (char *)data;
    linkinfo->rta_len = (char *)NLMSG_TAIL(&req->n) - (char *)linkinfo;

    objlock(nlh);
    ret = rtnl_talk(nlh, &req->n, 0, 0, NULL);
    objunlock(nlh);

    objunref(nlh);
    objunref(req);

    return (ret);
}

int create_tun	(	const char *	ifname,
		const unsigned char *	hwaddr,
		int	flags
	)

Create a tunnel device.

Parameters

ifname	Interface name to create..
hwaddr	Hardware address to assign (optionally).
flags	Flags to set device properties.

Returns

Tunnel FD or -1 on error.

Definition at line 496 of file interface.c.

References get_iface_index(), set_interface_addr(), and set_interface_flags().

                                                                                  {
    struct ifreq ifr;
    int fd, ifindex;
    char *tundev = "/dev/net/tun";

    /* open the tun/tap clone dev*/
    if ((fd = open(tundev, O_RDWR)) < 0) {
        return (-1);
    }

    /* configure the device*/
    memset(&ifr, 0, sizeof(ifr));
    ifr.ifr_flags = flags;
    strncpy(ifr.ifr_name, ifname, IFNAMSIZ);
    if (ioctl(fd, TUNSETIFF, (void *)&ifr) < 0 ) {
        perror("ioctl(TUNSETIFF) failed\n");
        close(fd);
        return (-1);
    }

    if (!(ifindex = get_iface_index(ifname))) {
        return (-1);
    }

    /* set the MAC address*/
    if (hwaddr) {
        set_interface_addr(ifindex, hwaddr);
    }

    /*set the network dev up*/
    set_interface_flags(ifindex, IFF_UP | IFF_RUNNING | IFF_MULTICAST | IFF_BROADCAST, 0);

    return (fd);
}

int delete_kernmac

(

char *

ifname

)

Delete Kernel MAC VLAN.

Parameters

ifname

Interface to delete.

Returns

-1 on error.

Definition at line 272 of file interface.c.

                                        {

    return (delete_interface(ifname));
}

int delete_kernvlan	(	char *	ifname,
		int	vid
	)

Delete a VLAN.

Parameters

ifname	Interface we deleting vlan from.
vid	VLAN id to delete.

Returns

-1 on error.

Definition at line 201 of file interface.c.

                                                  {
    char iface[IFNAMSIZ+1];

    /*check ifname grab a ref to nlh or open it*/
    snprintf(iface, IFNAMSIZ, "%s.%i", ifname, vid);
    return (delete_interface(iface));
}

int get_iface_index

(

const char *

ifname

)

Get the netlink interface for a named interface.

Parameters

ifname

Interface name.

Returns

Index of the interface.

Definition at line 139 of file interface.c.

References objlock(), objref(), objunlock(), and objunref().

Referenced by create_kernmac(), create_kernvlan(), create_tun(), ifdown(), ifhwaddr(), ifrename(), ifup(), interface_bind(), mcast_socket(), and set_interface_ipaddr().

                                               {
    int ifindex;

    if (!objref(nlh) && !(nlh = nlhandle(0))) {
        return (0);
    }

    objlock(nlh);
    ll_init_map(nlh, 1);
    objunlock(nlh);

    ifindex = ll_name_to_index(ifname);

    objunref(nlh);
    return (ifindex);
}

const char* get_ifipaddr	(	const char *	iface,
		int	family
	)

Find best IP adress for a interface.

Todo:

WIN32 Support

Parameters

iface	Interface name.
family	PF_INET or PF_INET6.

Returns

Best matching IP address for the interface.

Definition at line 783 of file interface.c.

References score_ipv4(), score_ipv6(), and strlenzero().

Referenced by mcast_socket().

                                                        {
    struct ifaddrs *ifaddr, *ifa;
    struct sockaddr_in *ipv4addr;
    int score = 0, nscore, iflen;
    uint32_t subnet = 0, match;
    char host[NI_MAXHOST] = "", tmp[NI_MAXHOST];

    if (!iface || getifaddrs(&ifaddr) == -1) {
        return NULL;
    }

    for (ifa = ifaddr; ifa != NULL; ifa = ifa->ifa_next) {
        iflen = strlen(iface);
        if ((ifa->ifa_addr == NULL) ||  strncmp(ifa->ifa_name, iface, iflen) || (ifa->ifa_addr->sa_family != family)) {
            continue;
        }

        /* Match aliases not vlans*/
        if ((strlen(ifa->ifa_name) > iflen) && (ifa->ifa_name[iflen] != ':')) {
            continue;
        }

        switch (ifa->ifa_addr->sa_family) {
            case AF_INET:
                /* Find best ip address for a interface lowest priority is given to zeroconf then reserved ip's
                 * finally find hte ip with shortest subnet bits.*/
                ipv4addr = (struct sockaddr_in*)ifa->ifa_netmask;
                match = ntohl(~ipv4addr->sin_addr.s_addr);

                nscore = score_ipv4((struct sockaddr_in*)ifa->ifa_addr, tmp, NI_MAXHOST);

                /* match score and subnet*/
                if  ((nscore > score) || ((nscore == score) && (match > subnet))) {
                    score = nscore;
                    subnet = match;
                    strncpy(host, tmp, NI_MAXHOST);
                }
                break;
            case AF_INET6:
                nscore = score_ipv6((struct sockaddr_in6*)ifa->ifa_addr, tmp, NI_MAXHOST);

                if (nscore > score) {
                    score = nscore;
                    strncpy(host, tmp, NI_MAXHOST);
                }
                break;
        }
    }
    freeifaddrs(ifaddr);
    return (strlenzero(host)) ? NULL : strdup(host);
}

int ifdown	(	const char *	ifname,
		int	flags
	)

Set interface down.

Parameters

ifname	Interface name.
flags	Additional flags to clear.

Returns

-1 on error 0 on success.

Definition at line 535 of file interface.c.

References get_iface_index(), and set_interface_flags().

Referenced by ifrename().

                                                 {
    int ifindex;

    /*down the device*/
    if (!(ifindex = get_iface_index(ifname))) {
        return (-1);
    }

    /*set the network dev up*/
    set_interface_flags(ifindex, 0, IFF_UP | IFF_RUNNING | flags);

    return (0);
}

int ifhwaddr	(	const char *	ifname,
		unsigned char *	hwaddr
	)

Get MAC addr for interface.

Parameters

ifname	Interface name
hwaddr	Buffer to place MAC in char[ETH_ALEN]

Returns

0 on success.

Definition at line 588 of file interface.c.

References get_iface_index(), objref(), objunref(), and strlenzero().

Referenced by get_ip6_addrprefix().

                                                               {
    int ifindex;

    if (!hwaddr || strlenzero(ifname) || (strlen(ifname) > IFNAMSIZ) ||
            (!objref(nlh) && !(nlh = nlhandle(0)))) {
        return (-1);
    }

    /*set the index of base interface*/
    if (!(ifindex = get_iface_index(ifname))) {
        objunref(nlh);
        return (-1);
    }

    ll_index_to_addr(ifindex, hwaddr, ETH_ALEN);
    objunref(nlh);
    return (0);
}

int ifrename	(	const char *	oldname,
		const char *	newname
	)

Rename interface helper.

Parameters

oldname	Original name.
newname	New name.

Returns

0 on success.

Definition at line 571 of file interface.c.

References get_iface_index(), ifdown(), and set_interface_name().

                                                              {
    int ifindex;

    ifdown(oldname, 0);

    if (!(ifindex = get_iface_index(oldname))) {
        return (-1);
    }
    set_interface_name(ifindex, newname);

    return (0);
}

int ifup	(	const char *	ifname,
		int	flags
	)

Set interface up.

Parameters

ifname	Interface name.
flags	Additional flags to set.

Returns

-1 on error 0 on success.

Definition at line 553 of file interface.c.

References get_iface_index(), and set_interface_flags().

                                               {
    int ifindex;

    /*down the device*/
    if (!(ifindex = get_iface_index(ifname))) {
        return (-1);
    }

    /*set the network dev up*/
    set_interface_flags(ifindex, IFF_UP | IFF_RUNNING | flags, 0);

    return (0);
}

int interface_bind	(	char *	iface,
		int	protocol
	)

Bind to device fd may be a existing socket.

Parameters

iface	Interface to bind too.
protocol	Protocol to use.

Returns

-1 on error.

Definition at line 453 of file interface.c.

References get_iface_index(), and set_interface_flags().

                                                     {
    struct sockaddr_ll sll;
    int proto = htons(protocol);
    int fd, ifindex;

    /*set the network dev up*/
    if (!(ifindex = get_iface_index(iface))) {
        return (-1);
    }
    set_interface_flags(ifindex, IFF_UP | IFF_RUNNING, 0);

    /* open network raw socket */
    if ((fd = socket(PF_PACKET, SOCK_RAW,  proto)) < 0) {
        return (-1);
    }

    /*bind to the interface*/
    memset(&sll, 0, sizeof(sll));
    sll.sll_family = PF_PACKET;
    sll.sll_protocol = proto;
    sll.sll_ifindex = ifindex;
    if (bind(fd, (struct sockaddr *)&sll, sizeof(sll)) < 0) {
        perror("bind failed");
        close(fd);
        return (-1);
    }

    return (fd);
}

void randhwaddr

(

unsigned char *

addr

)

create random MAC address

Parameters

addr	Buffer char[ETH_ALEN] filled with the new address.

Definition at line 485 of file interface.c.

References genrand().

Referenced by create_kernmac().

                                            {
    genrand(addr, ETH_ALEN);
    addr [0] &= 0xfe;       /* clear multicast bit */
    addr [0] |= 0x02;       /* set local assignment bit (IEEE802) */
}

int set_interface_addr	(	int	ifindex,
		const unsigned char *	hwaddr
	)

Set interface MAC addr.

Parameters

ifindex	Interface index.
hwaddr	MAC address to set.

Returns

-1 on error.

Definition at line 388 of file interface.c.

References iplink_req::i, iplink_req::n, objalloc(), objlock(), objref(), objunlock(), and objunref().

Referenced by create_tun().

                                                                        {
    struct iplink_req *req;

    if ((!objref(nlh) && !(nlh = nlhandle(0)))) {
        return (-1);
    }

    if (!(req = objalloc(sizeof(*req), NULL))) {
        objunref(nlh);
        return (-1);
    }

    req->n.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg));
    req->n.nlmsg_type = RTM_NEWLINK;
    req->n.nlmsg_flags = NLM_F_REQUEST;
    req->i.ifi_index = ifindex;

    /*config base/dev/mac*/
    addattr_l(&req->n, sizeof(*req), IFLA_ADDRESS, hwaddr, ETH_ALEN);

    objlock(nlh);
    rtnl_talk(nlh, &req->n, 0, 0, NULL);
    objunlock(nlh);

    objunref(nlh);
    objunref(req);
    return (0);
}

int set_interface_flags	(	int	ifindex,
		int	set,
		int	clear
	)

Alter interface flags.

Parameters

ifindex	Interface index.
set	Flags to set.
clear	Flags to clear.

Returns

-1 on error.

Definition at line 348 of file interface.c.

References iplink_req::i, iplink_req::n, objalloc(), objlock(), objref(), objunlock(), and objunref().

Referenced by create_tun(), ifdown(), ifup(), and interface_bind().

                                                                {
    struct iplink_req *req;
    int flags;

    if (!objref(nlh) && !(nlh = nlhandle(0))) {
        return (-1);
    }

    flags = ll_index_to_flags(ifindex);

    flags |= set;
    flags &= ~(clear);

    if (!(req = objalloc(sizeof(*req), NULL))) {
        objunref(nlh);
        return (-1);
    }

    req->n.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg));
    req->n.nlmsg_type = RTM_NEWLINK;
    req->n.nlmsg_flags = NLM_F_REQUEST;

    /*config base/dev/mac*/
    req->i.ifi_index = ifindex;
    req->i.ifi_flags = flags;
    req->i.ifi_change = set | clear;

    objlock(nlh);
    rtnl_talk(nlh, &req->n, 0, 0, NULL);
    objunlock(nlh);

    objunref(nlh);
    objunref(req);
    return (0);
}

int set_interface_ipaddr	(	char *	ifname,
		char *	ipaddr
	)

Set IP addr on interface.

Parameters

ifname	Interface to assign IP to
ipaddr	IP Addr to assign.

Returns

-1 on error.

Definition at line 611 of file interface.c.

References get_iface_index(), ipaddr_req::i, ipaddr_req::n, objalloc(), objlock(), objref(), objunlock(), and objunref().

                                                            {
    struct ipaddr_req *req;
    inet_prefix lcl;
    int ifindex, bcast;

    if ((!objref(nlh) && !(nlh = nlhandle(0)))) {
        return (-1);
    }

    if (!(req = objalloc(sizeof(*req), NULL))) {
        objunref(nlh);
        return (-1);
    }

    /*set the index of base interface*/
    if (!(ifindex = get_iface_index(ifname))) {
        objunref(nlh);
        return (-1);
    }

    req->n.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifaddrmsg));
    req->n.nlmsg_type = RTM_NEWADDR;
    req->n.nlmsg_flags = NLM_F_REQUEST | NLM_F_EXCL | NLM_F_CREATE;

    req->i.ifa_scope = RT_SCOPE_HOST;
    req->i.ifa_index = ifindex;

    get_prefix(&lcl, ipaddr, AF_UNSPEC);
    req->i.ifa_family = lcl.family;
    req->i.ifa_prefixlen = lcl.bitlen;

    addattr_l(&req->n, sizeof(*req), IFA_LOCAL, &lcl.data, lcl.bytelen);
    addattr_l(&req->n, sizeof(*req), IFA_ADDRESS, &lcl.data, lcl.bytelen);
    if (lcl.family == AF_INET) {
        bcast = htonl((1 << (32 - lcl.bitlen)) - 1);
        addattr32(&req->n, sizeof(*req), IFA_BROADCAST, lcl.data[0] | bcast);
    }

    objlock(nlh);
    rtnl_talk(nlh, &req->n, 0, 0, NULL);
    objunlock(nlh);

    objunref(nlh);
    objunref(req);
    return (0);
}

int set_interface_name	(	int	ifindex,
		const char *	name
	)

Rename interface.

Parameters

ifindex	Interface index.
name	New interface name.

Returns

-1 on error.

Definition at line 421 of file interface.c.

References iplink_req::i, iplink_req::n, objalloc(), objlock(), objref(), objunlock(), and objunref().

Referenced by ifrename().

                                                             {
    struct iplink_req *req;

    if ((!objref(nlh) && !(nlh = nlhandle(0)))) {
        return (-1);
    }

    if (!(req = objalloc(sizeof(*req), NULL))) {
        objunref(nlh);
        return (-1);
    }

    req->n.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg));
    req->n.nlmsg_type = RTM_NEWLINK;
    req->n.nlmsg_flags = NLM_F_REQUEST;
    req->i.ifi_index = ifindex;

    addattr_l(&req->n, sizeof(*req), IFLA_IFNAME, name, strlen((char *)name));

    objlock(nlh);
    rtnl_talk(nlh, &req->n, 0, 0, NULL);
    objunlock(nlh);

    objunref(nlh);
    objunref(req);
    return (0);
}