diff options
| author | Lennart Poettering <lennart@poettering.net> | 2014-07-29 19:50:28 +0200 |
|---|---|---|
| committer | Lennart Poettering <lennart@poettering.net> | 2014-07-29 20:57:58 +0200 |
| commit | ea917db9e662ae6e6d0ae07e0118b323688c8616 (patch) | |
| tree | 94ed26994aacebc43fcc4945df9c0af3e909828a /src/resolve/resolved-dns-packet.c | |
| parent | 49ee032fc3b694a1b45be9d08a2b97ab3eb93f75 (diff) | |
resolved: discard more invalid llmnr messages
Diffstat (limited to 'src/resolve/resolved-dns-packet.c')
| -rw-r--r-- | src/resolve/resolved-dns-packet.c | 30 |
1 files changed, 27 insertions, 3 deletions
diff --git a/src/resolve/resolved-dns-packet.c b/src/resolve/resolved-dns-packet.c index 1ff56875e6..5eaee2cb4f 100644 --- a/src/resolve/resolved-dns-packet.c +++ b/src/resolve/resolved-dns-packet.c @@ -72,10 +72,26 @@ int dns_packet_new_query(DnsPacket **ret, DnsProtocol protocol, size_t mtu) { h = DNS_PACKET_HEADER(p); - if (protocol == DNS_PROTOCOL_DNS) - h->flags = htobe16(DNS_PACKET_MAKE_FLAGS(0, 0, 0, 0, 1, 0, 0, 0, 0)); /* ask for recursion */ + if (protocol == DNS_PROTOCOL_LLMNR) + h->flags = htobe16(DNS_PACKET_MAKE_FLAGS(0 /* qr */, + 0 /* opcode */, + 0 /* c */, + 0 /* tc */, + 0 /* t */, + 0 /* ra */, + 0 /* ad */, + 0 /* cd */, + 0 /* rcode */)); else - h->flags = htobe16(DNS_PACKET_MAKE_FLAGS(0, 0, 0, 0, 0, 0, 0, 0, 0)); + h->flags = htobe16(DNS_PACKET_MAKE_FLAGS(0 /* qr */, + 0 /* opcode */, + 0 /* aa */, + 0 /* tc */, + 1 /* rd (ask for recursion) */, + 0 /* ra */, + 0 /* ad */, + 0 /* cd */, + 0 /* rcode */)); *ret = p; return 0; @@ -148,6 +164,11 @@ int dns_packet_validate_reply(DnsPacket *p) { if (DNS_PACKET_OPCODE(p) != 0) return -EBADMSG; + /* RFC 4795, Section 2.1.1. says to discard all replies with QDCOUNT != 1 */ + if (p->protocol == DNS_PROTOCOL_LLMNR && + DNS_PACKET_QDCOUNT(p) != 1) + return -EBADMSG; + return 1; } @@ -169,13 +190,16 @@ int dns_packet_validate_query(DnsPacket *p) { if (DNS_PACKET_TC(p)) return -EBADMSG; + /* RFC 4795, Section 2.1.1. says to discard all queries with QDCOUNT != 1 */ if (p->protocol == DNS_PROTOCOL_LLMNR && DNS_PACKET_QDCOUNT(p) != 1) return -EBADMSG; + /* RFC 4795, Section 2.1.1. says to discard all queries with ANCOUNT != 0 */ if (DNS_PACKET_ANCOUNT(p) > 0) return -EBADMSG; + /* RFC 4795, Section 2.1.1. says to discard all queries with NSCOUNT != 0 */ if (DNS_PACKET_NSCOUNT(p) > 0) return -EBADMSG; |