From eb60f9cd4e93ff5016dc1b5486fd1b7e1565fd92 Mon Sep 17 00:00:00 2001 From: Lennart Poettering Date: Thu, 31 Jul 2014 19:54:43 +0200 Subject: [PATCH] hostnamed: watch system hostname changes and update LLMNR RRs accordingly --- src/resolve/resolved-manager.c | 128 +++++++++++++++++++++++++++++---- src/resolve/resolved.h | 5 ++ 2 files changed, 119 insertions(+), 14 deletions(-) diff --git a/src/resolve/resolved-manager.c b/src/resolve/resolved-manager.c index 72034c1f4..6987c29e0 100644 --- a/src/resolve/resolved-manager.c +++ b/src/resolve/resolved-manager.c @@ -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; } diff --git a/src/resolve/resolved.h b/src/resolve/resolved.h index 07560553b..34eb7b5c5 100644 --- a/src/resolve/resolved.h +++ b/src/resolve/resolved.h @@ -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); -- 2.30.2