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diff --git a/lisp/dns/message.lisp b/lisp/dns/message.lisp new file mode 100644 index 0000000000..46243ac8d3 --- /dev/null +++ b/lisp/dns/message.lisp @@ -0,0 +1,407 @@ +(in-package :dns) + +;; 3.3. Standard RRs + +;; The following RR definitions are expected to occur, at least +;; potentially, in all classes. In particular, NS, SOA, CNAME, and PTR +;; will be used in all classes, and have the same format in all classes. +;; Because their RDATA format is known, all domain names in the RDATA +;; section of these RRs may be compressed. + +;; <domain-name> is a domain name represented as a series of labels, and +;; terminated by a label with zero length. <character-string> is a single +;; length octet followed by that number of characters. <character-string> +;; is treated as binary information, and can be up to 256 characters in +;; length (including the length octet). + + +;; 3.3.11. NS RDATA format + +;; +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ +;; / NSDNAME / +;; / / +;; +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ + +;; where: + +;; NSDNAME A <domain-name> which specifies a host which should be +;; authoritative for the specified class and domain. + +;; NS records cause both the usual additional section processing to locate +;; a type A record, and, when used in a referral, a special search of the +;; zone in which they reside for glue information. + +;; The NS RR states that the named host should be expected to have a zone +;; starting at owner name of the specified class. Note that the class may +;; not indicate the protocol family which should be used to communicate +;; with the host, although it is typically a strong hint. For example, +;; hosts which are name servers for either Internet (IN) or Hesiod (HS) +;; class information are normally queried using IN class protocols. + +;; 3.3.12. PTR RDATA format + +;; +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ +;; / PTRDNAME / +;; +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ + +;; where: + +;; PTRDNAME A <domain-name> which points to some location in the +;; domain name space. + +;; PTR records cause no additional section processing. These RRs are used +;; in special domains to point to some other location in the domain space. +;; These records are simple data, and don't imply any special processing +;; similar to that performed by CNAME, which identifies aliases. See the +;; description of the IN-ADDR.ARPA domain for an example. + +;; 3.3.13. SOA RDATA format + +;; +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ +;; / MNAME / +;; / / +;; +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ +;; / RNAME / +;; +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ +;; | SERIAL | +;; | | +;; +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ +;; | REFRESH | +;; | | +;; +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ +;; | RETRY | +;; | | +;; +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ +;; | EXPIRE | +;; | | +;; +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ +;; | MINIMUM | +;; | | +;; +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ + +;; where: + +;; MNAME The <domain-name> of the name server that was the +;; original or primary source of data for this zone. + +;; RNAME A <domain-name> which specifies the mailbox of the +;; person responsible for this zone. + +;; SERIAL The unsigned 32 bit version number of the original copy +;; of the zone. Zone transfers preserve this value. This +;; value wraps and should be compared using sequence space +;; arithmetic. + +;; REFRESH A 32 bit time interval before the zone should be +;; refreshed. + +;; RETRY A 32 bit time interval that should elapse before a +;; failed refresh should be retried. + +;; EXPIRE A 32 bit time value that specifies the upper limit on +;; the time interval that can elapse before the zone is no +;; longer authoritative. + +;; MINIMUM The unsigned 32 bit minimum TTL field that should be +;; exported with any RR from this zone. + +;; SOA records cause no additional section processing. + +;; All times are in units of seconds. + +;; Most of these fields are pertinent only for name server maintenance +;; operations. However, MINIMUM is used in all query operations that +;; retrieve RRs from a zone. Whenever a RR is sent in a response to a +;; query, the TTL field is set to the maximum of the TTL field from the RR +;; and the MINIMUM field in the appropriate SOA. Thus MINIMUM is a lower +;; bound on the TTL field for all RRs in a zone. Note that this use of +;; MINIMUM should occur when the RRs are copied into the response and not +;; when the zone is loaded from a master file or via a zone transfer. The +;; reason for this provison is to allow future dynamic update facilities to +;; change the SOA RR with known semantics. + + +;; 3.3.14. TXT RDATA format + +;; +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ +;; / TXT-DATA / +;; +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ + +;; where: + +;; TXT-DATA + +;; TXT RRs are used to hold descriptive text. The semantics of the text +;; depends on the domain where it is found. + +(defbinary dns-header (:byte-order :big-endian) + ;; A 16 bit identifier assigned by the program that + ;; generates any kind of query. This identifier is copied + ;; the corresponding reply and can be used by the requester + ;; to match up replies to outstanding queries. + (id 0 :type 16) + + ;; A one bit field that specifies whether this message is a + ;; query (0), or a response (1). + (qr 0 :type 1) + + ;; A four bit field that specifies kind of query in this + ;; message. This value is set by the originator of a query + ;; and copied into the response. The values are: + ;; + ;; 0 a standard query (QUERY) + ;; 1 an inverse query (IQUERY) + ;; 2 a server status request (STATUS) + ;; 3-15 reserved for future use + (opcode 0 :type 4) + + ;; Authoritative Answer - this bit is valid in responses, + ;; and specifies that the responding name server is an + ;; authority for the domain name in question section. + (aa nil :type 1) + + ;; TrunCation - specifies that this message was truncated + ;; due to length greater than that permitted on the + ;; transmission channel. + (tc nil :type 1) + + ;; Recursion Desired - this bit may be set in a query and + ;; is copied into the response. If RD is set, it directs + ;; the name server to pursue the query recursively. + ;; Recursive query support is optional. + (rd nil :type 1) + + ;; Recursion Available - this be is set or cleared in a + ;; response, and denotes whether recursive query support is + ;; available in the name server. + (ra nil :type 1) + + ;; Reserved for future use. Must be zero in all queries and + ;; responses. + (z 0 :type 3) + + ;; Response code - this 4 bit field is set as part of + ;; responses. The values have the following + ;; interpretation: + ;; 0 No error condition + ;; 1 Format error - The name server was + ;; unable to interpret the query. + ;; 2 Server failure - The name server was + ;; unable to process this query due to a + ;; problem with the name server. + ;; 3 Name Error - Meaningful only for + ;; responses from an authoritative name + ;; server, this code signifies that the + ;; domain name referenced in the query does + ;; not exist. + ;; 4 Not Implemented - The name server does + ;; not support the requested kind of query. + ;; 5 Refused - The name server refuses to + ;; perform the specified operation for + ;; policy reasons. For example, a name + ;; server may not wish to provide the + ;; information to the particular requester, + ;; or a name server may not wish to perform + ;; a particular operation (e.g., zone + ;; transfer) for particular data. + ;; 6-15 Reserved for future use. + (rcode 0 :type 4) + + ;; an unsigned 16 bit integer specifying the number of + ;; entries in the question section. + (qdcount 0 :type 16) + + ;; an unsigned 16 bit integer specifying the number of + ;; resource records in the answer section. + (ancount 0 :type 16) + + ;; an unsigned 16 bit integer specifying the number of name + ;; server resource records in the authority records + ;; section. + (nscount 0 :type 16) + + ;; an unsigned 16 bit integer specifying the number of + ;; resource records in the additional records section. + (arcount 0 :type 16)) + + +;; Representation of DNS QNAMEs. +;; +;; A QNAME can be either made up entirely of labels, which is +;; basically a list of strings, or be terminated with a pointer to an +;; offset within the original message. + +(deftype qname-field () + '(or + ;; pointer + (unsigned-byte 14) + ;; label + string)) + +(defstruct qname + (start-at 0 :type (unsigned-byte 14)) + (names #() :type (vector qname-field))) + +;; Domain names in questions and resource records are represented as a +;; sequence of labels, where each label consists of a length octet +;; followed by that number of octets. +;; +;; The domain name terminates with the zero length octet for the null +;; label of the root. Note that this field may be an odd number of +;; octets; no padding is used. +(declaim (ftype (function (stream) (values qname integer)) read-qname)) +(defun read-qname (stream) + "Reads a DNS QNAME from STREAM." + + (let ((start-at (file-position stream))) + (iter (for byte next (read-byte stream)) + ;; Each fragment is collected into this byte vector pre-allocated + ;; with the correct size. + (for fragment = (make-array byte :element-type '(unsigned-byte 8) + :fill-pointer 0)) + + ;; If the bit sequence (1 1) is encountered at the beginning of + ;; the fragment, a qname pointer is being read. + (let ((byte-copy byte)) + (when (equal #b11 (lisp-binary/integer:pop-bits 2 8 byte-copy)) + (let ((next (read-byte stream))) + (lisp-binary/integer:push-bits byte-copy 8 next) + (collect next into fragments result-type vector) + (sum 2 into size) + (finish)))) + + ;; Total size is needed, count for each iteration byte, plus its + ;; own value. + (sum (+ 1 byte) into size) + (until (equal byte 0)) + + ;; On each iteration, this will interpret the current byte as an + ;; unsigned integer and read from STREAM an equivalent amount of + ;; times to assemble the current fragment. + ;; + ;; Advancing the stream like this also ensures that the next + ;; iteration occurs on a new fragment or the final terminating + ;; byte. + (dotimes (_ byte (collect (babel:octets-to-string fragment) + into fragments result-type vector)) + (vector-push (read-byte stream) fragment)) + + (finally (return (values (make-qname :start-at start-at + :names fragments) + size)))))) + +(declaim (ftype (function (stream qname)) write-qname)) +(defun write-qname (stream qname) + "Write a DNS qname to STREAM." + + ;; Write each fragment starting with its (byte-) length, followed by + ;; the bytes. + (iter (for fragment in-vector (qname-names qname)) + (for bytes = (babel:string-to-octets fragment)) + (write-byte (length bytes) stream) + (iter (for byte in-vector bytes) + (write-byte byte stream))) + + ;; Always finish off the serialisation with a null-byte! + (write-byte 0 stream)) + +(define-enum dns-type 2 + (:byte-order :big-endian) + + ;; http://www.iana.org/assignments/dns-parameters/dns-parameters.xhtml + (A 1) + (NS 2) + (CNAME 5) + (SOA 6) + (PTR 12) + (MX 15) + (TXT 16) + (SRV 33) + (AAAA 28) + + ;; ANY typically wants SOA, MX, NS and MX + (ANY 255)) + +(defbinary dns-question (:byte-order :big-endian :export t) + ;; a domain name represented + (qname "" :type (custom :lisp-type qname + :reader #'read-qname + :writer #'write-qname)) + + ;; a two octet code which specifies the type of the query. + (qtype 0 :type dns-type) + + ;; a two octet code that specifies the class of the query. For + ;; example, the QCLASS field is IN for the Internet. + (qclass 0 :type 16)) + +(defbinary dns-rr (:byte-order :big-endian :export t) + (name nil :type (custom :lisp-type qname + :reader #'read-qname + :writer #'write-qname)) + + ;; two octets containing one of the RR type codes. This field + ;; specifies the meaning of the data in the RDATA field. + (type 0 :type dns-type) + + ;; two octets which specify the class of the data in the RDATA + ;; field. + (class 0 :type 16) + + ;; a 32 bit unsigned integer that specifies the time interval (in + ;; seconds) that the resource record may be cached before it should + ;; be discarded. Zero values are interpreted to mean that the RR + ;; can only be used for the transaction in progress, and should not + ;; be cached. + (ttl 0 :type 32) + + ;; an unsigned 16 bit integer that specifies the length in octets + ;; of the RDATA field. + (rdlength 0 :type 16) + + ;; a variable length string of octets that describes the resource. + ;; The format of this information varies according to the TYPE and + ;; CLASS of the resource record. For example, the if the TYPE is A + ;; and the CLASS is IN, the RDATA field is a 4 octet ARPA Internet + ;; address. + (rdata #() :type (eval (case type + ;; A 32-bit internet address in its + ;; canonical representation of 4 integers. + ((A) '(simple-array (unsigned-byte 8) (4))) + + ;; TODO(tazjin): Deal with multiple strings in single RRDATA + ;; One or more <character-string>s. + ((TXT) '(counted-string 1)) + + ;; A <domain-name> which specifies the + ;; canonical or primary name for the + ;; owner. The owner name is an alias. + ((CNAME) '(custom + :lisp-type qname + :reader #'read-qname + :writer #'write-qname)) + + ;; A <domain-name> which specifies a host + ;; which should be authoritative for the + ;; specified class and domain. + ((NS) '(custom + :lisp-type qname + :reader #'read-qname + :writer #'write-qname)) + (otherwise `(simple-array (unsigned-byte 8) (,rdlength))))))) + +(defbinary dns-message (:byte-order :big-endian :export t) + (header nil :type dns-header) + + ;; the question for the name server + (question #() :type (simple-array dns-question ((dns-header-qdcount header)))) + + ;; ;; RRs answering the question + ;; (answer #() :type (simple-array (unsigned-byte 8) (16))) + (answer #() :type (simple-array dns-rr ((dns-header-ancount header)))) + + ;; ;; ;; RRs pointing toward an authority + (authority #() :type (simple-array dns-rr ((dns-header-nscount header)))) + + ;; ;; RRs holding additional information + (additional #() :type (simple-array dns-rr ((dns-header-arcount header))))) |