From 4002f8dc03d9825e8504c18648d9fc3d5a41ee99 Mon Sep 17 00:00:00 2001 From: Jerome Magnin Date: Sun, 26 Jul 2020 12:13:12 +0200 Subject: [PATCH] BUG/MAJOR: dns: don't treat Authority records as an error Support for DNS Service Discovery by means of SRV records was enhanced with commit 13a9232eb ("MEDIUM: dns: use Additional records from SRV responses") to use the content of the answers Additional records when present. If there are Authority records before the Additional records we mistakenly treat that as an invalid response. To fix this, just ignore the Authority section if it exist and skip to the Additional records. As 13a9232eb was introduced during 2.2-dev, it must be backported to 2.2. This is a fix for issue #778 --- src/dns.c | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) diff --git a/src/dns.c b/src/dns.c index 6a8ab831c..f5bce4261 100644 --- a/src/dns.c +++ b/src/dns.c @@ -1044,6 +1044,34 @@ static int dns_validate_dns_response(unsigned char *resp, unsigned char *bufend, if (dns_query->type != DNS_RTYPE_SRV) goto skip_parsing_additional_records; + /* if we find Authority records, just skip them */ + for (i = 0; i < dns_p->header.nscount; i++) { + offset = 0; + len = dns_read_name(resp, bufend, reader, tmpname, DNS_MAX_NAME_SIZE, + &offset, 0); + if (len == 0) + continue; + + if (reader + offset + 10 >= bufend) + goto invalid_resp; + + reader += offset; + /* skip 2 bytes for class */ + reader += 2; + /* skip 2 bytes for type */ + reader += 2; + /* skip 4 bytes for ttl */ + reader += 4; + /* read data len */ + len = reader[0] * 256 + reader[1]; + reader += 2; + + if (reader + len >= bufend) + goto invalid_resp; + + reader += len; + } + nb_saved_records = 0; for (i = 0; i < dns_p->header.arcount; i++) { if (reader >= bufend)