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authorLennart Poettering <lennart@poettering.net>2014-12-03 21:42:58 +0100
committerLennart Poettering <lennart@poettering.net>2014-12-03 21:48:45 +0100
commite9140aff750e4f251f5f09b67412fed995fe9c47 (patch)
tree30f2c292e0154cfee8ce91bdf2c47674030255e9 /src
parent144232a8e0ea77eed8c5a456832758681b5b3511 (diff)
nss-myhostname: always resolve the host name "gateway" to the local default gateway
This is useful inside of containers or local networks to intrdouce a stable name of the default gateway host (in case of containers usually the host, in case of LANs usually local router).
Diffstat (limited to 'src')
-rw-r--r--src/libsystemd/sd-rtnl/local-addresses.c117
-rw-r--r--src/libsystemd/sd-rtnl/local-addresses.h3
-rw-r--r--src/libsystemd/sd-rtnl/rtnl-message.c15
-rw-r--r--src/libsystemd/sd-rtnl/test-local-addresses.c58
-rw-r--r--src/nss-myhostname/nss-myhostname.c78
-rw-r--r--src/systemd/sd-rtnl.h1
6 files changed, 249 insertions, 23 deletions
diff --git a/src/libsystemd/sd-rtnl/local-addresses.c b/src/libsystemd/sd-rtnl/local-addresses.c
index c5508856c8..3ab99420a3 100644
--- a/src/libsystemd/sd-rtnl/local-addresses.c
+++ b/src/libsystemd/sd-rtnl/local-addresses.c
@@ -30,14 +30,19 @@ static int address_compare(const void *_a, const void *_b) {
/* Order lowest scope first, IPv4 before IPv6, lowest interface index first */
+ if (a->family == AF_INET && b->family == AF_INET6)
+ return -1;
+ if (a->family == AF_INET6 && b->family == AF_INET)
+ return 1;
+
if (a->scope < b->scope)
return -1;
if (a->scope > b->scope)
return 1;
- if (a->family == AF_INET && b->family == AF_INET6)
+ if (a->metric < b->metric)
return -1;
- if (a->family == AF_INET6 && b->family == AF_INET)
+ if (a->metric > b->metric)
return 1;
if (a->ifindex < b->ifindex)
@@ -105,7 +110,7 @@ int local_addresses(sd_rtnl *context, int ifindex, struct local_address **ret) {
if (flags & IFA_F_DEPRECATED)
continue;
- if (!GREEDY_REALLOC(list, n_allocated, n_list+1))
+ if (!GREEDY_REALLOC0(list, n_allocated, n_list+1))
return -ENOMEM;
a = list + n_list;
@@ -150,7 +155,111 @@ int local_addresses(sd_rtnl *context, int ifindex, struct local_address **ret) {
n_list++;
};
- if (n_list)
+ if (n_list > 0)
+ qsort(list, n_list, sizeof(struct local_address), address_compare);
+
+ *ret = list;
+ list = NULL;
+
+ return (int) n_list;
+}
+
+int local_gateways(sd_rtnl *context, int ifindex, struct local_address **ret) {
+ _cleanup_rtnl_message_unref_ sd_rtnl_message *req = NULL, *reply = NULL;
+ _cleanup_rtnl_unref_ sd_rtnl *rtnl = NULL;
+ _cleanup_free_ struct local_address *list = NULL;
+ sd_rtnl_message *m = NULL;
+ size_t n_list = 0, n_allocated = 0;
+ int r;
+
+ assert(ret);
+
+ if (context)
+ rtnl = sd_rtnl_ref(context);
+ else {
+ r = sd_rtnl_open(&rtnl, 0);
+ if (r < 0)
+ return r;
+ }
+
+ r = sd_rtnl_message_new_route(rtnl, &req, RTM_GETROUTE, AF_UNSPEC, RTPROT_UNSPEC);
+ if (r < 0)
+ return r;
+
+ r = sd_rtnl_message_request_dump(req, true);
+ if (r < 0)
+ return r;
+
+ r = sd_rtnl_call(rtnl, req, 0, &reply);
+ if (r < 0)
+ return r;
+
+ for (m = reply; m; m = sd_rtnl_message_next(m)) {
+ struct local_address *a;
+ uint16_t type;
+ unsigned char dst_len;
+ uint32_t ifi;
+
+ r = sd_rtnl_message_get_errno(m);
+ if (r < 0)
+ return r;
+
+ r = sd_rtnl_message_get_type(m, &type);
+ if (r < 0)
+ return r;
+
+ if (type != RTM_NEWROUTE)
+ continue;
+
+ r = sd_rtnl_message_route_get_dst_len(m, &dst_len);
+ if (r < 0)
+ return r;
+
+ /* We only care for default routes */
+ if (dst_len != 0)
+ continue;
+
+ r = sd_rtnl_message_read_u32(m, RTA_OIF, &ifi);
+ if (r < 0)
+ return r;
+
+ if (ifindex > 0 && (int) ifi != ifindex)
+ continue;
+
+ if (!GREEDY_REALLOC0(list, n_allocated, n_list + 1))
+ return -ENOMEM;
+
+ a = list + n_list;
+
+ r = sd_rtnl_message_route_get_family(m, &a->family);
+ if (r < 0)
+ return r;
+
+ switch (a->family) {
+ case AF_INET:
+ r = sd_rtnl_message_read_in_addr(m, RTA_GATEWAY, &a->address.in);
+ if (r < 0)
+ continue;
+
+ break;
+ case AF_INET6:
+ r = sd_rtnl_message_read_in6_addr(m, RTA_GATEWAY, &a->address.in6);
+ if (r < 0)
+ continue;
+
+ break;
+ default:
+ continue;
+ }
+
+ sd_rtnl_message_read_u32(m, RTA_PRIORITY, &a->metric);
+
+ a->ifindex = ifi;
+ n_list++;
+
+ }
+
+ if (n_list > 0)
qsort(list, n_list, sizeof(struct local_address), address_compare);
*ret = list;
diff --git a/src/libsystemd/sd-rtnl/local-addresses.h b/src/libsystemd/sd-rtnl/local-addresses.h
index b1ed6341f6..2a9b2f42b7 100644
--- a/src/libsystemd/sd-rtnl/local-addresses.h
+++ b/src/libsystemd/sd-rtnl/local-addresses.h
@@ -32,7 +32,10 @@
struct local_address {
int family, ifindex;
unsigned char scope;
+ uint32_t metric;
union in_addr_union address;
};
int local_addresses(sd_rtnl *rtnl, int ifindex, struct local_address **ret);
+
+int local_gateways(sd_rtnl *rtnl, int ifindex, struct local_address **ret);
diff --git a/src/libsystemd/sd-rtnl/rtnl-message.c b/src/libsystemd/sd-rtnl/rtnl-message.c
index 7ec6143da6..076c822e6f 100644
--- a/src/libsystemd/sd-rtnl/rtnl-message.c
+++ b/src/libsystemd/sd-rtnl/rtnl-message.c
@@ -143,6 +143,21 @@ int sd_rtnl_message_route_get_family(sd_rtnl_message *m, int *family) {
return 0;
}
+int sd_rtnl_message_route_get_dst_len(sd_rtnl_message *m, unsigned char *dst_len) {
+ struct rtmsg *rtm;
+
+ assert_return(m, -EINVAL);
+ assert_return(m->hdr, -EINVAL);
+ assert_return(rtnl_message_type_is_route(m->hdr->nlmsg_type), -EINVAL);
+ assert_return(dst_len, -EINVAL);
+
+ rtm = NLMSG_DATA(m->hdr);
+
+ *dst_len = rtm->rtm_dst_len;
+
+ return 0;
+}
+
int sd_rtnl_message_new_route(sd_rtnl *rtnl, sd_rtnl_message **ret,
uint16_t nlmsg_type, int rtm_family,
unsigned char rtm_protocol) {
diff --git a/src/libsystemd/sd-rtnl/test-local-addresses.c b/src/libsystemd/sd-rtnl/test-local-addresses.c
new file mode 100644
index 0000000000..4cf2c08312
--- /dev/null
+++ b/src/libsystemd/sd-rtnl/test-local-addresses.c
@@ -0,0 +1,58 @@
+/*-*- 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 "in-addr-util.h"
+#include "local-addresses.h"
+#include "af-list.h"
+
+static void print_local_addresses(struct local_address *a, unsigned n) {
+ unsigned i;
+
+ for (i = 0; i < n; i++) {
+ _cleanup_free_ char *b = NULL;
+
+ assert_se(in_addr_to_string(a[i].family, &a[i].address, &b) >= 0);
+ printf("%s if%i scope=%i metric=%u address=%s\n", af_to_name(a[i].family), a[i].ifindex, a[i].scope, a[i].metric, b);
+ }
+}
+
+int main(int argc, char *argv[]) {
+ struct local_address *a;
+ int n;
+
+ a = NULL;
+ n = local_addresses(NULL, 0, &a);
+ assert_se(n >= 0);
+
+ printf("Local Addresses:\n");
+ print_local_addresses(a, (unsigned) n);
+ free(a);
+
+ a = NULL;
+ n = local_gateways(NULL, 0, &a);
+ assert_se(n >= 0);
+
+ printf("Local Gateways:\n");
+ print_local_addresses(a, (unsigned) n);
+ free(a);
+
+ return 0;
+}
diff --git a/src/nss-myhostname/nss-myhostname.c b/src/nss-myhostname/nss-myhostname.c
index 86e7be2aa1..4a5bf759a9 100644
--- a/src/nss-myhostname/nss-myhostname.c
+++ b/src/nss-myhostname/nss-myhostname.c
@@ -77,6 +77,18 @@ enum nss_status _nss_myhostname_gethostbyname4_r(
canonical = "localhost";
local_address_ipv4 = htonl(INADDR_LOOPBACK);
+
+ } else if (streq(name, "gateway")) {
+
+ n_addresses = local_gateways(NULL, 0, &addresses);
+ if (n_addresses <= 0) {
+ *errnop = ENOENT;
+ *h_errnop = HOST_NOT_FOUND;
+ return NSS_STATUS_NOTFOUND;
+ }
+
+ canonical = "gateway";
+
} else {
hn = gethostname_malloc();
if (!hn) {
@@ -314,7 +326,7 @@ enum nss_status _nss_myhostname_gethostbyname3_r(
_cleanup_free_ struct local_address *addresses = NULL;
const char *canonical, *additional = NULL;
_cleanup_free_ char *hn = NULL;
- uint32_t local_address_ipv4;
+ uint32_t local_address_ipv4 = 0;
int n_addresses = 0;
assert(name);
@@ -335,6 +347,18 @@ enum nss_status _nss_myhostname_gethostbyname3_r(
if (is_localhost(name)) {
canonical = "localhost";
local_address_ipv4 = htonl(INADDR_LOOPBACK);
+
+ } else if (streq(name, "gateway")) {
+
+ n_addresses = local_gateways(NULL, af, &addresses);
+ if (n_addresses <= 0) {
+ *errnop = ENOENT;
+ *h_errnop = HOST_NOT_FOUND;
+ return NSS_STATUS_NOTFOUND;
+ }
+
+ canonical = "gateway";
+
} else {
hn = gethostname_malloc();
if (!hn) {
@@ -349,7 +373,7 @@ enum nss_status _nss_myhostname_gethostbyname3_r(
return NSS_STATUS_NOTFOUND;
}
- n_addresses = local_addresses(NULL, 0, &addresses);
+ n_addresses = local_addresses(NULL, af, &addresses);
if (n_addresses < 0)
n_addresses = 0;
@@ -426,15 +450,41 @@ enum nss_status _nss_myhostname_gethostbyaddr2_r(
}
n_addresses = local_addresses(NULL, 0, &addresses);
- if (n_addresses < 0)
- n_addresses = 0;
+ if (n_addresses > 0) {
+ for (a = addresses, n = 0; (int) n < n_addresses; n++, a++) {
+ if (af != a->family)
+ continue;
- for (a = addresses, n = 0; (int) n < n_addresses; n++, a++) {
- if (af != a->family)
- continue;
+ if (memcmp(addr, &a->address, FAMILY_ADDRESS_SIZE(af)) == 0) {
- if (memcmp(addr, &a->address, FAMILY_ADDRESS_SIZE(af)) == 0)
- goto found;
+ hn = gethostname_malloc();
+ if (!hn) {
+ *errnop = ENOMEM;
+ *h_errnop = NO_RECOVERY;
+ return NSS_STATUS_TRYAGAIN;
+ }
+
+ canonical = hn;
+ goto found;
+ }
+ }
+ }
+
+ free(addresses);
+ addresses = NULL;
+
+ n_addresses = local_gateways(NULL, 0, &addresses);
+ if (n_addresses > 0) {
+ for (a = addresses, n = 0; (int) n < n_addresses; n++, a++) {
+ if (af != a->family)
+ continue;
+
+ if (memcmp(addr, &a->address, FAMILY_ADDRESS_SIZE(af)) == 0) {
+
+ canonical = "gateway";
+ goto found;
+ }
+ }
}
*errnop = ENOENT;
@@ -443,16 +493,6 @@ enum nss_status _nss_myhostname_gethostbyaddr2_r(
return NSS_STATUS_NOTFOUND;
found:
- if (!canonical) {
- hn = gethostname_malloc();
- if (!hn) {
- *errnop = ENOMEM;
- *h_errnop = NO_RECOVERY;
- return NSS_STATUS_TRYAGAIN;
- }
-
- canonical = hn;
- }
return fill_in_hostent(
canonical, additional,
diff --git a/src/systemd/sd-rtnl.h b/src/systemd/sd-rtnl.h
index 15eaa26878..554fc8bbfe 100644
--- a/src/systemd/sd-rtnl.h
+++ b/src/systemd/sd-rtnl.h
@@ -104,6 +104,7 @@ int sd_rtnl_message_link_get_type(sd_rtnl_message *m, unsigned *type);
int sd_rtnl_message_route_set_dst_prefixlen(sd_rtnl_message *m, unsigned char prefixlen);
int sd_rtnl_message_route_set_scope(sd_rtnl_message *m, unsigned char scope);
int sd_rtnl_message_route_get_family(sd_rtnl_message *m, int *family);
+int sd_rtnl_message_route_get_dst_len(sd_rtnl_message *m, unsigned char *dst_len);
int sd_rtnl_message_neigh_get_family(sd_rtnl_message *m, int *family);
int sd_rtnl_message_neigh_get_ifindex(sd_rtnl_message *m, int *family);