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resolved: default to the compile-time fallback hostname

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This changes resolved to use the compile-time fallback hostname the
configured one is not set. Note that if the local hostname is set to
"localhost" then we'll instead default to "linux" here, as for
mDNS/LLMNR exposing "localhost" is actively dangerous.
This commit is contained in:
Lennart Poettering 2017-02-16 12:04:51 +01:00
parent 8341d4fa04
commit a25b0dc82d
1 changed files with 60 additions and 18 deletions
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78
src/resolve/resolved-manager.c
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@ -332,19 +332,18 @@ static int determine_hostname(char **full_hostname, char **llmnr_hostname, char
assert(llmnr_hostname);
assert(mdns_hostname);
/* Extract and normalize the first label of the locally
* configured hostname, and check it's not "localhost". */
/* Extract and normalize the first label of the locally configured hostname, and check it's not "localhost". */
h = gethostname_malloc();
if (!h)
return log_oom();
r = gethostname_strict(&h);
if (r < 0)
return log_debug_errno(r, "Can't determine system hostname: %m");
p = h;
r = dns_label_unescape(&p, label, sizeof(label));
if (r < 0)
return log_error_errno(r, "Failed to unescape host name: %m");
if (r == 0) {
log_error("Couldn't find a single label in hosntame.");
log_error("Couldn't find a single label in hostname.");
return -EINVAL;
}
@ -381,6 +380,57 @@ static int determine_hostname(char **full_hostname, char **llmnr_hostname, char
return 0;
}
static const char *fallback_hostname(void) {
/* Determine the fall back hostname. For exposing this system to the outside world, we cannot have it to be
* "localhost" even if that's the compiled in hostname. In this case, let's revert to "linux" instead. */
if (is_localhost(FALLBACK_HOSTNAME))
return "linux";
return FALLBACK_HOSTNAME;
}
static int make_fallback_hostnames(char **full_hostname, char **llmnr_hostname, char **mdns_hostname) {
_cleanup_free_ char *n = NULL, *m = NULL;
char label[DNS_LABEL_MAX], *h;
const char *p;
int r;
assert(full_hostname);
assert(llmnr_hostname);
assert(mdns_hostname);
p = fallback_hostname();
r = dns_label_unescape(&p, label, sizeof(label));
if (r < 0)
return log_error_errno(r, "Failed to unescape fallback host name: %m");
assert(r > 0); /* The fallback hostname must have at least one label */
r = dns_label_escape_new(label, r, &n);
if (r < 0)
return log_error_errno(r, "Failed to escape fallback hostname: %m");
r = dns_name_concat(n, "local", &m);
if (r < 0)
return log_error_errno(r, "Failed to concatenate mDNS hostname: %m");
h = strdup(fallback_hostname());
if (!h)
return log_oom();
*llmnr_hostname = n;
n = NULL;
*mdns_hostname = m;
m = NULL;
*full_hostname = h;
return 0;
}
static int on_hostname_change(sd_event_source *es, int fd, uint32_t revents, void *userdata) {
_cleanup_free_ char *full_hostname = NULL, *llmnr_hostname = NULL, *mdns_hostname = NULL;
Manager *m = userdata;
@ -432,19 +482,11 @@ static int manager_watch_hostname(Manager *m) {
r = determine_hostname(&m->full_hostname, &m->llmnr_hostname, &m->mdns_hostname);
if (r < 0) {
log_info("Defaulting to hostname 'linux'.");
log_info("Defaulting to hostname '%s'.", fallback_hostname());
m->full_hostname = strdup("linux");
if (!m->full_hostname)
return log_oom();
m->llmnr_hostname = strdup("linux");
if (!m->llmnr_hostname)
return log_oom();
m->mdns_hostname = strdup("linux.local");
if (!m->mdns_hostname)
return log_oom();
r = make_fallback_hostnames(&m->full_hostname, &m->llmnr_hostname, &m->mdns_hostname);
if (r < 0)
return r;
} else
log_info("Using system hostname '%s'.", m->full_hostname);