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hostnamed: watch system hostname changes and update LLMNR RRs accordingly

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This commit is contained in:
Lennart Poettering 2014-07-31 19:54:43 +02:00
parent 8581858257
commit eb60f9cd4e
2 changed files with 119 additions and 14 deletions
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128
src/resolve/resolved-manager.c
View File

@ -34,6 +34,8 @@
#include "socket-util.h"
#include "af-list.h"
#include "resolved.h"
#include "utf8.h"
#include "resolved-dns-domain.h"
#define SEND_TIMEOUT_USEC (200 * USEC_PER_MSEC)
@ -384,6 +386,92 @@ int manager_parse_config_file(Manager *m) {
false, false, true, m);
}
static int determine_hostname(char **ret) {
_cleanup_free_ char *h = NULL, *n = NULL;
int r;
assert(ret);
h = gethostname_malloc();
if (!h)
return log_oom();
if (!utf8_is_valid(h)) {
log_error("System hostname is not UTF-8 clean.");
return -EINVAL;
}
r = dns_name_normalize(h, &n);
if (r < 0) {
log_error("System hostname '%s' cannot be normalized.", h);
return r;
}
*ret = n;
n = NULL;
return 0;
}
static int on_hostname_change(sd_event_source *es, int fd, uint32_t revents, void *userdata) {
_cleanup_free_ char *h = NULL;
Manager *m = userdata;
int r;
assert(m);
r = determine_hostname(&h);
if (r < 0)
return 0; /* ignore invalid hostnames */
if (streq(h, m->hostname))
return 0;
log_info("System hostname changed to '%s'.", h);
free(m->hostname);
m->hostname = h;
h = NULL;
manager_refresh_rrs(m);
return 0;
}
static int manager_watch_hostname(Manager *m) {
_cleanup_free_ char *h = NULL;
int r;
assert(m);
m->hostname_fd = open("/proc/sys/kernel/hostname", O_RDONLY|O_CLOEXEC|O_NDELAY|O_NOCTTY);
if (m->hostname_fd < 0) {
log_warning("Failed to watch hostname: %m");
return 0;
}
r = sd_event_add_io(m->event, &m->hostname_event_source, m->hostname_fd, 0, on_hostname_change, m);
if (r < 0) {
if (r == -EPERM)
/* kernels prior to 3.2 don't support polling this file. Ignore the failure. */
m->hostname_fd = safe_close(m->hostname_fd);
else {
log_error("Failed to add hostname event source: %s", strerror(-r));
return r;
}
}
r = determine_hostname(&m->hostname);
if (r < 0) {
log_info("Defaulting to hostname 'linux'.");
m->hostname = strdup("linux");
if (!m->hostname)
return log_oom();
} else
log_info("Using system hostname '%s'.", m->hostname);
return 0;
}
int manager_new(Manager **ret) {
_cleanup_(manager_freep) Manager *m = NULL;
int r;
@ -397,6 +485,7 @@ int manager_new(Manager **ret) {
m->dns_ipv4_fd = m->dns_ipv6_fd = -1;
m->llmnr_ipv4_udp_fd = m->llmnr_ipv6_udp_fd = -1;
m->llmnr_ipv4_tcp_fd = m->llmnr_ipv6_tcp_fd = -1;
m->hostname_fd = -1;
m->use_llmnr = true;
@ -404,10 +493,6 @@ int manager_new(Manager **ret) {
if (r < 0)
return r;
m->hostname = gethostname_malloc();
if (!m->hostname)
return -ENOMEM;
r = sd_event_default(&m->event);
if (r < 0)
return r;
@ -417,6 +502,10 @@ int manager_new(Manager **ret) {
sd_event_set_watchdog(m->event, true);
r = manager_watch_hostname(m);
if (r < 0)
return r;
r = dns_scope_new(m, &m->unicast_scope, NULL, DNS_PROTOCOL_DNS, AF_UNSPEC);
if (r < 0)
return r;
@ -497,7 +586,11 @@ Manager *manager_free(Manager *m) {
dns_resource_key_unref(m->host_ipv4_key);
dns_resource_key_unref(m->host_ipv6_key);
safe_close(m->hostname_fd);
sd_event_source_unref(m->hostname_event_source);
free(m->hostname);
free(m);
return NULL;
@ -1408,12 +1501,25 @@ int manager_find_ifindex(Manager *m, int family, const union in_addr_union *in_a
return 0;
}
void manager_refresh_rrs(Manager *m) {
Iterator i;
Link *l;
assert(m);
m->host_ipv4_key = dns_resource_key_unref(m->host_ipv4_key);
m->host_ipv6_key = dns_resource_key_unref(m->host_ipv6_key);
HASHMAP_FOREACH(l, m->links, i) {
link_add_rrs(l, true);
link_add_rrs(l, false);
}
}
int manager_next_hostname(Manager *m) {
const char *p;
Iterator i;
uint64_t u;
char *h;
Link *l;
assert(m);
@ -1435,18 +1541,12 @@ int manager_next_hostname(Manager *m) {
if (asprintf(&h, "%.*s%" PRIu64, (int) (p - m->hostname), m->hostname, u) < 0)
return -ENOMEM;
log_info("Hostname conflict, changing local hostname from '%s' to '%s'.", m->hostname, h);
log_info("Hostname conflict, changing published hostname from '%s' to '%s'.", m->hostname, h);
free(m->hostname);
m->hostname = h;
m->host_ipv4_key = dns_resource_key_unref(m->host_ipv4_key);
m->host_ipv6_key = dns_resource_key_unref(m->host_ipv6_key);
HASHMAP_FOREACH(l, m->links, i) {
link_add_rrs(l, true);
link_add_rrs(l, false);
}
manager_refresh_rrs(m);
return 0;
}

5
src/resolve/resolved.h
View File

@ -90,6 +90,10 @@ struct Manager {
char *hostname;
DnsResourceKey *host_ipv4_key;
DnsResourceKey *host_ipv6_key;
/* Watch the system hostname */
int hostname_fd;
sd_event_source *hostname_event_source;
};
/* Manager */
@ -120,6 +124,7 @@ int manager_ifindex_is_loopback(Manager *m, int ifindex);
int manager_find_ifindex(Manager *m, int family, const union in_addr_union *in_addr);
LinkAddress* manager_find_address(Manager *m, int family, const union in_addr_union *in_addr);
void manager_refresh_rrs(Manager *m);
int manager_next_hostname(Manager *m);
int manager_our_packet(Manager *m, DnsPacket *p);