From e9140aff750e4f251f5f09b67412fed995fe9c47 Mon Sep 17 00:00:00 2001 From: Lennart Poettering Date: Wed, 3 Dec 2014 21:42:58 +0100 Subject: [PATCH] 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). --- .gitignore | 1 + Makefile.am | 8 ++ src/libsystemd/sd-rtnl/local-addresses.c | 117 +++++++++++++++++- src/libsystemd/sd-rtnl/local-addresses.h | 3 + src/libsystemd/sd-rtnl/rtnl-message.c | 15 +++ src/libsystemd/sd-rtnl/test-local-addresses.c | 58 +++++++++ src/nss-myhostname/nss-myhostname.c | 78 +++++++++--- src/systemd/sd-rtnl.h | 1 + 8 files changed, 258 insertions(+), 23 deletions(-) create mode 100644 src/libsystemd/sd-rtnl/test-local-addresses.c diff --git a/.gitignore b/.gitignore index 4e7ad2ad2..06d411a93 100644 --- a/.gitignore +++ b/.gitignore @@ -203,6 +203,7 @@ /test-list /test-unaligned /test-locale-util +/test-local-addresses /test-log /test-login /test-login-shared diff --git a/Makefile.am b/Makefile.am index 5b46243e6..d4d96e134 100644 --- a/Makefile.am +++ b/Makefile.am @@ -2782,6 +2782,7 @@ tests += \ test-bus-gvariant \ test-event \ test-rtnl \ + test-local-addresses \ test-resolve bin_PROGRAMS += \ @@ -2940,6 +2941,13 @@ test_rtnl_LDADD = \ libsystemd-internal.la \ libsystemd-shared.la +test_local_addresses_SOURCES = \ + src/libsystemd/sd-rtnl/test-local-addresses.c + +test_local_addresses_LDADD = \ + libsystemd-internal.la \ + libsystemd-shared.la + test_resolve_SOURCES = \ src/libsystemd/sd-resolve/test-resolve.c diff --git a/src/libsystemd/sd-rtnl/local-addresses.c b/src/libsystemd/sd-rtnl/local-addresses.c index c5508856c..3ab99420a 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 b1ed6341f..2a9b2f42b 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 7ec6143da..076c822e6 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 000000000..4cf2c0831 --- /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 . +***/ + +#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 86e7be2aa..4a5bf759a 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 15eaa2687..554fc8bbf 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); -- 2.30.2