From af93291cc4cbd2fe2fb4af7d3c56138fb39f31dc Mon Sep 17 00:00:00 2001 From: Lennart Poettering Date: Wed, 30 Jul 2014 00:48:59 +0200 Subject: resolved: when answer A or AAAA questions, order responses by whether addresses are link-local or not --- src/resolve/resolved-dns-answer.c | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) (limited to 'src/resolve/resolved-dns-answer.c') diff --git a/src/resolve/resolved-dns-answer.c b/src/resolve/resolved-dns-answer.c index d907664527..93e51fc248 100644 --- a/src/resolve/resolved-dns-answer.c +++ b/src/resolve/resolved-dns-answer.c @@ -175,3 +175,34 @@ DnsAnswer *dns_answer_merge(DnsAnswer *a, DnsAnswer *b) { return k; } + +void dns_answer_order_by_scope(DnsAnswer *a, bool prefer_link_local) { + DnsResourceRecord **rrs; + unsigned i, start, end; + assert(a); + + if (a->n_rrs <= 1) + return; + + start = 0; + end = a->n_rrs-1; + + /* RFC 4795, Section 2.6 suggests we should order entries + * depending on whether the sender is a link-local address. */ + + rrs = newa(DnsResourceRecord*, a->n_rrs); + for (i = 0; i < a->n_rrs; i++) { + + if (a->rrs[i]->key->class == DNS_CLASS_IN && + ((a->rrs[i]->key->type == DNS_TYPE_A && in_addr_is_link_local(AF_INET, (union in_addr_union*) &a->rrs[i]->a.in_addr) != prefer_link_local) || + (a->rrs[i]->key->type == DNS_TYPE_AAAA && in_addr_is_link_local(AF_INET6, (union in_addr_union*) &a->rrs[i]->aaaa.in6_addr) != prefer_link_local))) + /* Order address records that are are not preferred to the end of the array */ + rrs[end--] = a->rrs[i]; + else + /* Order all other records to the beginning of the array */ + rrs[start++] = a->rrs[i]; + } + + assert(start == end+1); + memcpy(a->rrs, rrs, sizeof(DnsResourceRecord*) * a->n_rrs); +} -- cgit v1.2.3-54-g00ecf