/* Standalone DNS parsing, RFC10350 * * Copyright (c) 2003 Jeremie Miller * Copyright (c) 2016-2026 Joachim Wiberg * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are met: * * Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * Neither the name of the copyright holders nor the names of its * contributors may be used to endorse or promote products derived from * this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */ /* Familiarize yourself with RFC1035 if you want to know what all the * variable names mean. This file hides most of the dirty work all of * this code depends on the buffer space a packet is in being 4096 and * zero'd before the packet is copied in also conveniently decodes srv * rr's, type 33, see RFC2782 */ #ifndef MDNS_1035_H_ #define MDNS_1035_H_ #include #include #include /* * At least FreeBSD, OpenBSD and NexentaCore do not define the * s6_addr32, s6_addr8, and s6_addr16 for user land. */ #if !defined s6_addr32 && defined __sun__ # define s6_addr32 _S6_un._S6_u32 #elif !defined s6_addr32 && ( defined __OpenBSD__ || defined __FreeBSD__ || defined __NetBSD__ ) # define s6_addr32 __u6_addr.__u6_addr32 #endif /* !defined s6_addr32 */ /* Should be reasonably large, for UDP */ #define MAX_PACKET_LEN 65535 #define MAX_NUM_LABELS 512 struct question { char *name; unsigned short int type, class; }; #define QTYPE_A 1 #define QTYPE_NS 2 #define QTYPE_CNAME 5 #define QTYPE_PTR 12 #define QTYPE_TXT 16 #define QTYPE_AAAA 28 #define QTYPE_SRV 33 #define QTYPE_ANY 255 struct resource { char *name; unsigned short int type, class; unsigned long int ttl; unsigned short int rdlength; unsigned char *rdata; union { struct { struct in_addr ip; char *name; } a; struct { struct in6_addr ip6; char *name; } aaaa; struct { char *name; } ns; struct { char *name; } cname; struct { char *name; } ptr; struct { unsigned short int priority, weight, port; char *name; } srv; } known; }; struct message { /* External data */ unsigned short int id; struct { unsigned short qr:1, opcode:4, aa:1, tc:1, rd:1, ra:1, z:3, rcode:4; } header; unsigned short int qdcount, ancount, nscount, arcount; struct question *qd; struct resource *an, *ns, *ar; /* Internal variables */ unsigned char *_buf; char *_labels[MAX_NUM_LABELS]; int _len, _label; /* Packet acts as padding, easier mem management */ unsigned char _packet[MAX_PACKET_LEN]; }; /** * Returns the next short/long off the buffer (and advances it) */ unsigned short int net2short(unsigned char **buf); unsigned long int net2long (unsigned char **buf); /** * copies the short/long into the buffer (and advances it) */ void short2net(unsigned short int i, unsigned char **buf); void long2net (unsigned long int l, unsigned char **buf); /** * parse packet into message, packet must be at least MAX_PACKET_LEN and * message must be zero'd for safety * @returns 0 if OK, else parser error. */ int message_parse(struct message *m, unsigned char *packet); /** * create a message for sending out on the wire */ struct message *message_wire(void); /** * append a question to the wire message */ void message_qd(struct message *m, char *name, unsigned short int type, unsigned short int class); /** * append a resource record to the message, all called in order! */ void message_an(struct message *m, char *name, unsigned short int type, unsigned short int class, unsigned long int ttl); void message_ns(struct message *m, char *name, unsigned short int type, unsigned short int class, unsigned long int ttl); void message_ar(struct message *m, char *name, unsigned short int type, unsigned short int class, unsigned long int ttl); /** * Append various special types of resource data blocks */ void message_rdata_long (struct message *m, unsigned long l); void message_rdata_ipv4 (struct message *m, struct in_addr a); void message_rdata_ipv6 (struct message *m, struct in6_addr a6); void message_rdata_name (struct message *m, char *name); void message_rdata_srv (struct message *m, unsigned short int priority, unsigned short int weight, unsigned short int port, char *name); void message_rdata_raw (struct message *m, unsigned char *rdata, unsigned short int rdlength); /** * Return the wire format (and length) of the message, just free message * when done */ unsigned char *message_packet (struct message *m); int message_packet_len (struct message *m); #endif /* MDNS_1035_H_ */