networkd: add address pool support

When an address is configured to be all zeroes, networkd will now
automatically find a locally unused network of the right size from a
list of pre-configured pools. Currently those pools are 10.0.0.0/8,
172.16.0.0/12, 192.168.0.0/16 and fc00::/7, i.e. the network ranges for
private networks. They are compiled in, but should be configurable
eventually.

This allows applying the same configuration to a large number of
interfaces with each time a different IP range block, and management of
these IP ranges is fully automatic.

When allocating an address range from the pool it is made sure the range
is not used otherwise.

1 files changed, 166 insertions, 0 deletions

diff --git a/src/network/networkd-address-pool.c b/src/network/networkd-address-pool.c
new file mode 100644
index 0000000000..a5079add02
--- /dev/null
+++ b/src/network/networkd-address-pool.c
@@ -0,0 +1,166 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2014 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 <arpa/inet.h>
+
+#include "networkd.h"
+
+int address_pool_new(
+                Manager *m,
+                AddressPool **ret,
+                unsigned family,
+                const union in_addr_union *u,
+                unsigned prefixlen) {
+
+        AddressPool *p;
+
+        assert(m);
+        assert(ret);
+        assert(u);
+
+        p = new0(AddressPool, 1);
+        if (!p)
+                return -ENOMEM;
+
+        p->manager = m;
+        p->family = family;
+        p->prefixlen = prefixlen;
+        p->in_addr = *u;
+
+        LIST_PREPEND(address_pools, m->address_pools, p);
+
+        *ret = p;
+        return 0;
+}
+
+int address_pool_new_from_string(
+                Manager *m,
+                AddressPool **ret,
+                unsigned family,
+                const char *p,
+                unsigned prefixlen) {
+
+        union in_addr_union u;
+        int r;
+
+        assert(m);
+        assert(ret);
+        assert(p);
+
+        r = in_addr_from_string(family, p, &u);
+        if (r < 0)
+                return r;
+
+        return address_pool_new(m, ret, family, &u, prefixlen);
+}
+
+void address_pool_free(AddressPool *p) {
+
+        if (!p)
+                return;
+
+        if (p->manager)
+                LIST_REMOVE(address_pools, p->manager->address_pools, p);
+
+        free(p);
+}
+
+static bool address_pool_prefix_is_taken(
+                AddressPool *p,
+                const union in_addr_union *u,
+                unsigned prefixlen) {
+
+        Iterator i;
+        Link *l;
+        Network *n;
+
+        assert(p);
+        assert(u);
+
+        HASHMAP_FOREACH(l, p->manager->links, i) {
+                Address *a;
+
+                /* Don't clash with assigned addresses */
+                LIST_FOREACH(addresses, a, l->addresses) {
+                        if (a->family != p->family)
+                                continue;
+
+                        if (in_addr_prefix_intersect(p->family, u, prefixlen, &a->in_addr, a->prefixlen))
+                                return true;
+                }
+
+                /* Don't clash with addresses already pulled from the pool, but not assigned yet */
+                LIST_FOREACH(addresses, a, l->pool_addresses) {
+                        if (a->family != p->family)
+                                continue;
+
+                        if (in_addr_prefix_intersect(p->family, u, prefixlen, &a->in_addr, a->prefixlen))
+                                return true;
+                }
+        }
+
+        /* And don't clash with configured but un-assigned addresses either */
+        LIST_FOREACH(networks, n, p->manager->networks) {
+                Address *a;
+
+                LIST_FOREACH(addresses, a, n->static_addresses) {
+                        if (a->family != p->family)
+                                continue;
+
+                        if (in_addr_prefix_intersect(p->family, u, prefixlen, &a->in_addr, a->prefixlen))
+                                return true;
+                }
+        }
+
+        return false;
+}
+
+int address_pool_acquire(AddressPool *p, unsigned prefixlen, union in_addr_union *found) {
+        union in_addr_union u;
+
+        assert(p);
+        assert(prefixlen > 0);
+        assert(found);
+
+        if (p->prefixlen > prefixlen)
+                return 0;
+
+        u = p->in_addr;
+        for (;;) {
+                if (!address_pool_prefix_is_taken(p, &u, prefixlen)) {
+                        _cleanup_free_ char *s = NULL;
+
+                        in_addr_to_string(p->family, &u, &s);
+                        log_debug("Found range %s/%u", strna(s), prefixlen);
+
+                        *found = u;
+                        return 1;
+                }
+
+                if (!in_addr_prefix_next(p->family, &u, prefixlen))
+                        return 0;
+
+                if (!in_addr_prefix_intersect(p->family, &p->in_addr, p->prefixlen, &u, prefixlen))
+                        return 0;
+        }
+
+        return 0;
+}