build-sys: split internal basic/ library from shared/

basic/      can be used by everything
            cannot use anything outside of basic/

libsystemd/ can use basic/
            cannot use shared/

shared/     can use libsystemd/

1 files changed, 769 insertions, 0 deletions

diff --git a/src/basic/socket-util.c b/src/basic/socket-util.c
new file mode 100644
index 0000000000..e8bb10dc9b
--- /dev/null
+++ b/src/basic/socket-util.c
@@ -0,0 +1,769 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2010 Lennart Poettering
+
+  systemd 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.
+
+  systemd 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 systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+#include <arpa/inet.h>
+#include <stdio.h>
+#include <net/if.h>
+#include <sys/types.h>
+#include <stddef.h>
+#include <netdb.h>
+
+#include "macro.h"
+#include "path-util.h"
+#include "util.h"
+#include "socket-util.h"
+#include "missing.h"
+#include "fileio.h"
+#include "formats-util.h"
+
+int socket_address_parse(SocketAddress *a, const char *s) {
+        char *e, *n;
+        unsigned u;
+        int r;
+
+        assert(a);
+        assert(s);
+
+        zero(*a);
+        a->type = SOCK_STREAM;
+
+        if (*s == '[') {
+                /* IPv6 in [x:.....:z]:p notation */
+
+                e = strchr(s+1, ']');
+                if (!e)
+                        return -EINVAL;
+
+                n = strndupa(s+1, e-s-1);
+
+                errno = 0;
+                if (inet_pton(AF_INET6, n, &a->sockaddr.in6.sin6_addr) <= 0)
+                        return errno > 0 ? -errno : -EINVAL;
+
+                e++;
+                if (*e != ':')
+                        return -EINVAL;
+
+                e++;
+                r = safe_atou(e, &u);
+                if (r < 0)
+                        return r;
+
+                if (u <= 0 || u > 0xFFFF)
+                        return -EINVAL;
+
+                a->sockaddr.in6.sin6_family = AF_INET6;
+                a->sockaddr.in6.sin6_port = htons((uint16_t) u);
+                a->size = sizeof(struct sockaddr_in6);
+
+        } else if (*s == '/') {
+                /* AF_UNIX socket */
+
+                size_t l;
+
+                l = strlen(s);
+                if (l >= sizeof(a->sockaddr.un.sun_path))
+                        return -EINVAL;
+
+                a->sockaddr.un.sun_family = AF_UNIX;
+                memcpy(a->sockaddr.un.sun_path, s, l);
+                a->size = offsetof(struct sockaddr_un, sun_path) + l + 1;
+
+        } else if (*s == '@') {
+                /* Abstract AF_UNIX socket */
+                size_t l;
+
+                l = strlen(s+1);
+                if (l >= sizeof(a->sockaddr.un.sun_path) - 1)
+                        return -EINVAL;
+
+                a->sockaddr.un.sun_family = AF_UNIX;
+                memcpy(a->sockaddr.un.sun_path+1, s+1, l);
+                a->size = offsetof(struct sockaddr_un, sun_path) + 1 + l;
+
+        } else {
+                e = strchr(s, ':');
+                if (e) {
+                        r = safe_atou(e+1, &u);
+                        if (r < 0)
+                                return r;
+
+                        if (u <= 0 || u > 0xFFFF)
+                                return -EINVAL;
+
+                        n = strndupa(s, e-s);
+
+                        /* IPv4 in w.x.y.z:p notation? */
+                        r = inet_pton(AF_INET, n, &a->sockaddr.in.sin_addr);
+                        if (r < 0)
+                                return -errno;
+
+                        if (r > 0) {
+                                /* Gotcha, it's a traditional IPv4 address */
+                                a->sockaddr.in.sin_family = AF_INET;
+                                a->sockaddr.in.sin_port = htons((uint16_t) u);
+                                a->size = sizeof(struct sockaddr_in);
+                        } else {
+                                unsigned idx;
+
+                                if (strlen(n) > IF_NAMESIZE-1)
+                                        return -EINVAL;
+
+                                /* Uh, our last resort, an interface name */
+                                idx = if_nametoindex(n);
+                                if (idx == 0)
+                                        return -EINVAL;
+
+                                a->sockaddr.in6.sin6_family = AF_INET6;
+                                a->sockaddr.in6.sin6_port = htons((uint16_t) u);
+                                a->sockaddr.in6.sin6_scope_id = idx;
+                                a->sockaddr.in6.sin6_addr = in6addr_any;
+                                a->size = sizeof(struct sockaddr_in6);
+                        }
+                } else {
+
+                        /* Just a port */
+                        r = safe_atou(s, &u);
+                        if (r < 0)
+                                return r;
+
+                        if (u <= 0 || u > 0xFFFF)
+                                return -EINVAL;
+
+                        if (socket_ipv6_is_supported()) {
+                                a->sockaddr.in6.sin6_family = AF_INET6;
+                                a->sockaddr.in6.sin6_port = htons((uint16_t) u);
+                                a->sockaddr.in6.sin6_addr = in6addr_any;
+                                a->size = sizeof(struct sockaddr_in6);
+                        } else {
+                                a->sockaddr.in.sin_family = AF_INET;
+                                a->sockaddr.in.sin_port = htons((uint16_t) u);
+                                a->sockaddr.in.sin_addr.s_addr = INADDR_ANY;
+                                a->size = sizeof(struct sockaddr_in);
+                        }
+                }
+        }
+
+        return 0;
+}
+
+int socket_address_parse_and_warn(SocketAddress *a, const char *s) {
+        SocketAddress b;
+        int r;
+
+        /* Similar to socket_address_parse() but warns for IPv6 sockets when we don't support them. */
+
+        r = socket_address_parse(&b, s);
+        if (r < 0)
+                return r;
+
+        if (!socket_ipv6_is_supported() && b.sockaddr.sa.sa_family == AF_INET6) {
+                log_warning("Binding to IPv6 address not available since kernel does not support IPv6.");
+                return -EAFNOSUPPORT;
+        }
+
+        *a = b;
+        return 0;
+}
+
+int socket_address_parse_netlink(SocketAddress *a, const char *s) {
+        int family;
+        unsigned group = 0;
+        _cleanup_free_ char *sfamily = NULL;
+        assert(a);
+        assert(s);
+
+        zero(*a);
+        a->type = SOCK_RAW;
+
+        errno = 0;
+        if (sscanf(s, "%ms %u", &sfamily, &group) < 1)
+                return errno > 0 ? -errno : -EINVAL;
+
+        family = netlink_family_from_string(sfamily);
+        if (family < 0)
+                return -EINVAL;
+
+        a->sockaddr.nl.nl_family = AF_NETLINK;
+        a->sockaddr.nl.nl_groups = group;
+
+        a->type = SOCK_RAW;
+        a->size = sizeof(struct sockaddr_nl);
+        a->protocol = family;
+
+        return 0;
+}
+
+int socket_address_verify(const SocketAddress *a) {
+        assert(a);
+
+        switch (socket_address_family(a)) {
+
+        case AF_INET:
+                if (a->size != sizeof(struct sockaddr_in))
+                        return -EINVAL;
+
+                if (a->sockaddr.in.sin_port == 0)
+                        return -EINVAL;
+
+                if (a->type != SOCK_STREAM && a->type != SOCK_DGRAM)
+                        return -EINVAL;
+
+                return 0;
+
+        case AF_INET6:
+                if (a->size != sizeof(struct sockaddr_in6))
+                        return -EINVAL;
+
+                if (a->sockaddr.in6.sin6_port == 0)
+                        return -EINVAL;
+
+                if (a->type != SOCK_STREAM && a->type != SOCK_DGRAM)
+                        return -EINVAL;
+
+                return 0;
+
+        case AF_UNIX:
+                if (a->size < offsetof(struct sockaddr_un, sun_path))
+                        return -EINVAL;
+
+                if (a->size > offsetof(struct sockaddr_un, sun_path)) {
+
+                        if (a->sockaddr.un.sun_path[0] != 0) {
+                                char *e;
+
+                                /* path */
+                                e = memchr(a->sockaddr.un.sun_path, 0, sizeof(a->sockaddr.un.sun_path));
+                                if (!e)
+                                        return -EINVAL;
+
+                                if (a->size != offsetof(struct sockaddr_un, sun_path) + (e - a->sockaddr.un.sun_path) + 1)
+                                        return -EINVAL;
+                        }
+                }
+
+                if (a->type != SOCK_STREAM && a->type != SOCK_DGRAM && a->type != SOCK_SEQPACKET)
+                        return -EINVAL;
+
+                return 0;
+
+        case AF_NETLINK:
+
+                if (a->size != sizeof(struct sockaddr_nl))
+                        return -EINVAL;
+
+                if (a->type != SOCK_RAW && a->type != SOCK_DGRAM)
+                        return -EINVAL;
+
+                return 0;
+
+        default:
+                return -EAFNOSUPPORT;
+        }
+}
+
+int socket_address_print(const SocketAddress *a, char **ret) {
+        int r;
+
+        assert(a);
+        assert(ret);
+
+        r = socket_address_verify(a);
+        if (r < 0)
+                return r;
+
+        if (socket_address_family(a) == AF_NETLINK) {
+                _cleanup_free_ char *sfamily = NULL;
+
+                r = netlink_family_to_string_alloc(a->protocol, &sfamily);
+                if (r < 0)
+                        return r;
+
+                r = asprintf(ret, "%s %u", sfamily, a->sockaddr.nl.nl_groups);
+                if (r < 0)
+                        return -ENOMEM;
+
+                return 0;
+        }
+
+        return sockaddr_pretty(&a->sockaddr.sa, a->size, false, true, ret);
+}
+
+bool socket_address_can_accept(const SocketAddress *a) {
+        assert(a);
+
+        return
+                a->type == SOCK_STREAM ||
+                a->type == SOCK_SEQPACKET;
+}
+
+bool socket_address_equal(const SocketAddress *a, const SocketAddress *b) {
+        assert(a);
+        assert(b);
+
+        /* Invalid addresses are unequal to all */
+        if (socket_address_verify(a) < 0 ||
+            socket_address_verify(b) < 0)
+                return false;
+
+        if (a->type != b->type)
+                return false;
+
+        if (socket_address_family(a) != socket_address_family(b))
+                return false;
+
+        switch (socket_address_family(a)) {
+
+        case AF_INET:
+                if (a->sockaddr.in.sin_addr.s_addr != b->sockaddr.in.sin_addr.s_addr)
+                        return false;
+
+                if (a->sockaddr.in.sin_port != b->sockaddr.in.sin_port)
+                        return false;
+
+                break;
+
+        case AF_INET6:
+                if (memcmp(&a->sockaddr.in6.sin6_addr, &b->sockaddr.in6.sin6_addr, sizeof(a->sockaddr.in6.sin6_addr)) != 0)
+                        return false;
+
+                if (a->sockaddr.in6.sin6_port != b->sockaddr.in6.sin6_port)
+                        return false;
+
+                break;
+
+        case AF_UNIX:
+                if (a->size <= offsetof(struct sockaddr_un, sun_path) ||
+                    b->size <= offsetof(struct sockaddr_un, sun_path))
+                        return false;
+
+                if ((a->sockaddr.un.sun_path[0] == 0) != (b->sockaddr.un.sun_path[0] == 0))
+                        return false;
+
+                if (a->sockaddr.un.sun_path[0]) {
+                        if (!path_equal_or_files_same(a->sockaddr.un.sun_path, b->sockaddr.un.sun_path))
+                                return false;
+                } else {
+                        if (a->size != b->size)
+                                return false;
+
+                        if (memcmp(a->sockaddr.un.sun_path, b->sockaddr.un.sun_path, a->size) != 0)
+                                return false;
+                }
+
+                break;
+
+        case AF_NETLINK:
+                if (a->protocol != b->protocol)
+                        return false;
+
+                if (a->sockaddr.nl.nl_groups != b->sockaddr.nl.nl_groups)
+                        return false;
+
+                break;
+
+        default:
+                /* Cannot compare, so we assume the addresses are different */
+                return false;
+        }
+
+        return true;
+}
+
+bool socket_address_is(const SocketAddress *a, const char *s, int type) {
+        struct SocketAddress b;
+
+        assert(a);
+        assert(s);
+
+        if (socket_address_parse(&b, s) < 0)
+                return false;
+
+        b.type = type;
+
+        return socket_address_equal(a, &b);
+}
+
+bool socket_address_is_netlink(const SocketAddress *a, const char *s) {
+        struct SocketAddress b;
+
+        assert(a);
+        assert(s);
+
+        if (socket_address_parse_netlink(&b, s) < 0)
+                return false;
+
+        return socket_address_equal(a, &b);
+}
+
+const char* socket_address_get_path(const SocketAddress *a) {
+        assert(a);
+
+        if (socket_address_family(a) != AF_UNIX)
+                return NULL;
+
+        if (a->sockaddr.un.sun_path[0] == 0)
+                return NULL;
+
+        return a->sockaddr.un.sun_path;
+}
+
+bool socket_ipv6_is_supported(void) {
+        _cleanup_free_ char *l = NULL;
+
+        if (access("/sys/module/ipv6", F_OK) != 0)
+                return false;
+
+        /* If we can't check "disable" parameter, assume enabled */
+        if (read_one_line_file("/sys/module/ipv6/parameters/disable", &l) < 0)
+                return true;
+
+        /* If module was loaded with disable=1 no IPv6 available */
+        return l[0] == '0';
+}
+
+bool socket_address_matches_fd(const SocketAddress *a, int fd) {
+        SocketAddress b;
+        socklen_t solen;
+
+        assert(a);
+        assert(fd >= 0);
+
+        b.size = sizeof(b.sockaddr);
+        if (getsockname(fd, &b.sockaddr.sa, &b.size) < 0)
+                return false;
+
+        if (b.sockaddr.sa.sa_family != a->sockaddr.sa.sa_family)
+                return false;
+
+        solen = sizeof(b.type);
+        if (getsockopt(fd, SOL_SOCKET, SO_TYPE, &b.type, &solen) < 0)
+                return false;
+
+        if (b.type != a->type)
+                return false;
+
+        if (a->protocol != 0)  {
+                solen = sizeof(b.protocol);
+                if (getsockopt(fd, SOL_SOCKET, SO_PROTOCOL, &b.protocol, &solen) < 0)
+                        return false;
+
+                if (b.protocol != a->protocol)
+                        return false;
+        }
+
+        return socket_address_equal(a, &b);
+}
+
+int sockaddr_port(const struct sockaddr *_sa) {
+        union sockaddr_union *sa = (union sockaddr_union*) _sa;
+
+        assert(sa);
+
+        if (!IN_SET(sa->sa.sa_family, AF_INET, AF_INET6))
+                return -EAFNOSUPPORT;
+
+        return ntohs(sa->sa.sa_family == AF_INET6 ?
+                       sa->in6.sin6_port :
+                       sa->in.sin_port);
+}
+
+int sockaddr_pretty(const struct sockaddr *_sa, socklen_t salen, bool translate_ipv6, bool include_port, char **ret) {
+        union sockaddr_union *sa = (union sockaddr_union*) _sa;
+        char *p;
+        int r;
+
+        assert(sa);
+        assert(salen >= sizeof(sa->sa.sa_family));
+
+        switch (sa->sa.sa_family) {
+
+        case AF_INET: {
+                uint32_t a;
+
+                a = ntohl(sa->in.sin_addr.s_addr);
+
+                if (include_port)
+                        r = asprintf(&p,
+                                     "%u.%u.%u.%u:%u",
+                                     a >> 24, (a >> 16) & 0xFF, (a >> 8) & 0xFF, a & 0xFF,
+                                     ntohs(sa->in.sin_port));
+                else
+                        r = asprintf(&p,
+                                     "%u.%u.%u.%u",
+                                     a >> 24, (a >> 16) & 0xFF, (a >> 8) & 0xFF, a & 0xFF);
+                if (r < 0)
+                        return -ENOMEM;
+                break;
+        }
+
+        case AF_INET6: {
+                static const unsigned char ipv4_prefix[] = {
+                        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xFF, 0xFF
+                };
+
+                if (translate_ipv6 &&
+                    memcmp(&sa->in6.sin6_addr, ipv4_prefix, sizeof(ipv4_prefix)) == 0) {
+                        const uint8_t *a = sa->in6.sin6_addr.s6_addr+12;
+                        if (include_port)
+                                r = asprintf(&p,
+                                             "%u.%u.%u.%u:%u",
+                                             a[0], a[1], a[2], a[3],
+                                             ntohs(sa->in6.sin6_port));
+                        else
+                                r = asprintf(&p,
+                                             "%u.%u.%u.%u",
+                                             a[0], a[1], a[2], a[3]);
+                        if (r < 0)
+                                return -ENOMEM;
+                } else {
+                        char a[INET6_ADDRSTRLEN];
+
+                        inet_ntop(AF_INET6, &sa->in6.sin6_addr, a, sizeof(a));
+
+                        if (include_port) {
+                                r = asprintf(&p,
+                                             "[%s]:%u",
+                                             a,
+                                             ntohs(sa->in6.sin6_port));
+                                if (r < 0)
+                                        return -ENOMEM;
+                        } else {
+                                p = strdup(a);
+                                if (!p)
+                                        return -ENOMEM;
+                        }
+                }
+
+                break;
+        }
+
+        case AF_UNIX:
+                if (salen <= offsetof(struct sockaddr_un, sun_path)) {
+                        p = strdup("<unnamed>");
+                        if (!p)
+                                return -ENOMEM;
+
+                } else if (sa->un.sun_path[0] == 0) {
+                        /* abstract */
+
+                        /* FIXME: We assume we can print the
+                         * socket path here and that it hasn't
+                         * more than one NUL byte. That is
+                         * actually an invalid assumption */
+
+                        p = new(char, sizeof(sa->un.sun_path)+1);
+                        if (!p)
+                                return -ENOMEM;
+
+                        p[0] = '@';
+                        memcpy(p+1, sa->un.sun_path+1, sizeof(sa->un.sun_path)-1);
+                        p[sizeof(sa->un.sun_path)] = 0;
+
+                } else {
+                        p = strndup(sa->un.sun_path, sizeof(sa->un.sun_path));
+                        if (!ret)
+                                return -ENOMEM;
+                }
+
+                break;
+
+        default:
+                return -EOPNOTSUPP;
+        }
+
+
+        *ret = p;
+        return 0;
+}
+
+int getpeername_pretty(int fd, char **ret) {
+        union sockaddr_union sa;
+        socklen_t salen = sizeof(sa);
+        int r;
+
+        assert(fd >= 0);
+        assert(ret);
+
+        if (getpeername(fd, &sa.sa, &salen) < 0)
+                return -errno;
+
+        if (sa.sa.sa_family == AF_UNIX) {
+                struct ucred ucred = {};
+
+                /* UNIX connection sockets are anonymous, so let's use
+                 * PID/UID as pretty credentials instead */
+
+                r = getpeercred(fd, &ucred);
+                if (r < 0)
+                        return r;
+
+                if (asprintf(ret, "PID "PID_FMT"/UID "UID_FMT, ucred.pid, ucred.uid) < 0)
+                        return -ENOMEM;
+
+                return 0;
+        }
+
+        /* For remote sockets we translate IPv6 addresses back to IPv4
+         * if applicable, since that's nicer. */
+
+        return sockaddr_pretty(&sa.sa, salen, true, true, ret);
+}
+
+int getsockname_pretty(int fd, char **ret) {
+        union sockaddr_union sa;
+        socklen_t salen = sizeof(sa);
+
+        assert(fd >= 0);
+        assert(ret);
+
+        if (getsockname(fd, &sa.sa, &salen) < 0)
+                return -errno;
+
+        /* For local sockets we do not translate IPv6 addresses back
+         * to IPv6 if applicable, since this is usually used for
+         * listening sockets where the difference between IPv4 and
+         * IPv6 matters. */
+
+        return sockaddr_pretty(&sa.sa, salen, false, true, ret);
+}
+
+int socknameinfo_pretty(union sockaddr_union *sa, socklen_t salen, char **_ret) {
+        int r;
+        char host[NI_MAXHOST], *ret;
+
+        assert(_ret);
+
+        r = getnameinfo(&sa->sa, salen, host, sizeof(host), NULL, 0,
+                        NI_IDN|NI_IDN_USE_STD3_ASCII_RULES);
+        if (r != 0) {
+                int saved_errno = errno;
+
+                r = sockaddr_pretty(&sa->sa, salen, true, true, &ret);
+                if (r < 0)
+                        return log_error_errno(r, "sockadd_pretty() failed: %m");
+
+                log_debug_errno(saved_errno, "getnameinfo(%s) failed: %m", ret);
+        } else {
+                ret = strdup(host);
+                if (!ret)
+                        return log_oom();
+        }
+
+        *_ret = ret;
+        return 0;
+}
+
+int getnameinfo_pretty(int fd, char **ret) {
+        union sockaddr_union sa;
+        socklen_t salen = sizeof(sa);
+
+        assert(fd >= 0);
+        assert(ret);
+
+        if (getsockname(fd, &sa.sa, &salen) < 0)
+                return log_error_errno(errno, "getsockname(%d) failed: %m", fd);
+
+        return socknameinfo_pretty(&sa, salen, ret);
+}
+
+int socket_address_unlink(SocketAddress *a) {
+        assert(a);
+
+        if (socket_address_family(a) != AF_UNIX)
+                return 0;
+
+        if (a->sockaddr.un.sun_path[0] == 0)
+                return 0;
+
+        if (unlink(a->sockaddr.un.sun_path) < 0)
+                return -errno;
+
+        return 1;
+}
+
+static const char* const netlink_family_table[] = {
+        [NETLINK_ROUTE] = "route",
+        [NETLINK_FIREWALL] = "firewall",
+        [NETLINK_INET_DIAG] = "inet-diag",
+        [NETLINK_NFLOG] = "nflog",
+        [NETLINK_XFRM] = "xfrm",
+        [NETLINK_SELINUX] = "selinux",
+        [NETLINK_ISCSI] = "iscsi",
+        [NETLINK_AUDIT] = "audit",
+        [NETLINK_FIB_LOOKUP] = "fib-lookup",
+        [NETLINK_CONNECTOR] = "connector",
+        [NETLINK_NETFILTER] = "netfilter",
+        [NETLINK_IP6_FW] = "ip6-fw",
+        [NETLINK_DNRTMSG] = "dnrtmsg",
+        [NETLINK_KOBJECT_UEVENT] = "kobject-uevent",
+        [NETLINK_GENERIC] = "generic",
+        [NETLINK_SCSITRANSPORT] = "scsitransport",
+        [NETLINK_ECRYPTFS] = "ecryptfs"
+};
+
+DEFINE_STRING_TABLE_LOOKUP_WITH_FALLBACK(netlink_family, int, INT_MAX);
+
+static const char* const socket_address_bind_ipv6_only_table[_SOCKET_ADDRESS_BIND_IPV6_ONLY_MAX] = {
+        [SOCKET_ADDRESS_DEFAULT] = "default",
+        [SOCKET_ADDRESS_BOTH] = "both",
+        [SOCKET_ADDRESS_IPV6_ONLY] = "ipv6-only"
+};
+
+DEFINE_STRING_TABLE_LOOKUP(socket_address_bind_ipv6_only, SocketAddressBindIPv6Only);
+
+bool sockaddr_equal(const union sockaddr_union *a, const union sockaddr_union *b) {
+        assert(a);
+        assert(b);
+
+        if (a->sa.sa_family != b->sa.sa_family)
+                return false;
+
+        if (a->sa.sa_family == AF_INET)
+                return a->in.sin_addr.s_addr == b->in.sin_addr.s_addr;
+
+        if (a->sa.sa_family == AF_INET6)
+                return memcmp(&a->in6.sin6_addr, &b->in6.sin6_addr, sizeof(a->in6.sin6_addr)) == 0;
+
+        return false;
+}
+
+char* ether_addr_to_string(const struct ether_addr *addr, char buffer[ETHER_ADDR_TO_STRING_MAX]) {
+        assert(addr);
+        assert(buffer);
+
+        /* Like ether_ntoa() but uses %02x instead of %x to print
+         * ethernet addresses, which makes them look less funny. Also,
+         * doesn't use a static buffer. */
+
+        sprintf(buffer, "%02x:%02x:%02x:%02x:%02x:%02x",
+                addr->ether_addr_octet[0],
+                addr->ether_addr_octet[1],
+                addr->ether_addr_octet[2],
+                addr->ether_addr_octet[3],
+                addr->ether_addr_octet[4],
+                addr->ether_addr_octet[5]);
+
+        return buffer;
+}