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ntp: ignore order of resolved addresses when replacing tentative source

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If the replaced source never had a valid reply (e.g. because it was a
bad replacement), ignore the order of addresses from the resolver to not
get stuck to a pair of addresses if the order doesn't change, or a group
of IPv4/IPv6 addresses if the resolver prefers inaccessible IP family.
This commit is contained in:
Miroslav Lichvar 2016-04-05 17:15:26 +02:00
parent 62e66bda60
commit dec1d2bfb2
1 changed files with 14 additions and 3 deletions
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17
ntp_sources.c
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@ -70,6 +70,7 @@ static int auto_start_sources = 0;
struct UnresolvedSource {
char *name;
int port;
int random_order;
int replacement;
union {
struct {
@ -367,13 +368,17 @@ process_resolved_name(struct UnresolvedSource *us, IPAddr *ip_addrs, int n_addrs
{
NTP_Remote_Address address;
int i, added;
unsigned short first = 0;
if (us->random_order)
UTI_GetRandomBytes(&first, sizeof (first));
for (i = added = 0; i < n_addrs; i++) {
DEBUG_LOG(LOGF_NtpSources, "(%d) %s", i + 1, UTI_IPToString(&ip_addrs[i]));
address.ip_addr = ip_addrs[i];
address.ip_addr = ip_addrs[((unsigned int)i + first) % n_addrs];
address.port = us->port;
DEBUG_LOG(LOGF_NtpSources, "(%d) %s", i + 1, UTI_IPToString(&address.ip_addr));
if (us->replacement) {
if (replace_source(&us->replace_source, &address) != NSR_AlreadyInUse)
break;
@ -516,6 +521,7 @@ NSR_AddSourceByName(char *name, int port, int pool, NTP_Source_Type type, Source
us = MallocNew(struct UnresolvedSource);
us->name = Strdup(name);
us->port = port;
us->random_order = 0;
us->replacement = 0;
us->new_source.type = type;
us->new_source.params = *params;
@ -657,6 +663,11 @@ resolve_source_replacement(SourceRecord *record)
us = MallocNew(struct UnresolvedSource);
us->name = Strdup(record->name);
us->port = record->remote_addr->port;
/* If there never was a valid reply from this source (e.g. it was a bad
replacement), ignore the order of addresses from the resolver to not get
stuck to a pair of addresses if the order doesn't change, or a group of
IPv4/IPv6 addresses if the resolver prefers inaccessible IP family */
us->random_order = record->tentative;
us->replacement = 1;
us->replace_source = *record->remote_addr;