/* * Copyright (C) Internet Systems Consortium, Inc. ("ISC") * * Permission to use, copy, modify, and/or distribute this software for any * purpose with or without fee is hereby granted, provided that the above * copyright notice and this permission notice appear in all copies. * * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY * AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT, * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR * PERFORMANCE OF THIS SOFTWARE. */ /* $Id: name.h,v 1.13 2022/12/26 19:24:11 jmc Exp $ */ #ifndef DNS_NAME_H #define DNS_NAME_H 1 /***** ***** Module Info *****/ /*! \file dns/name.h * \brief * Provides facilities for manipulating DNS names and labels, including * conversions to and from wire format and text format. * * Given the large number of names possible in a nameserver, and because * names occur in rdata, it was important to come up with a very efficient * way of storing name data, but at the same time allow names to be * manipulated. The decision was to store names in uncompressed wire format, * and not to make them fully abstracted objects; i.e. certain parts of the * server know names are stored that way. This saves a lot of memory, and * makes adding names to messages easy. Having much of the server know * the representation would be perilous, and we certainly don't want each * user of names to be manipulating such a low-level structure. This is * where the Names and Labels module comes in. The module allows name or * label handles to be created and attached to uncompressed wire format * regions. All name operations and conversions are done through these * handles. * * MP: *\li Clients of this module must impose any required synchronization. * * Reliability: *\li This module deals with low-level byte streams. Errors in any of * the functions are likely to crash the server or corrupt memory. * * Resources: *\li None. * * Security: * *\li *** WARNING *** * *\li dns_name_fromwire() deals with raw network data. An error in * this routine could result in the failure or hijacking of the server. * * Standards: *\li RFC1035 *\li Draft EDNS0 (0) *\li Draft Binary Labels (2) * */ /*** *** Imports ***/ #include <stdio.h> #include <isc/region.h> /* Required for storage size of dns_label_t. */ #include <dns/types.h> /***** ***** Labels ***** ***** A 'label' is basically a region. It contains one DNS wire format ***** label of type 00 (ordinary). *****/ /***** ***** Names ***** ***** A 'name' is a handle to a binary region. It contains a sequence of one ***** or more DNS wire format labels of type 00 (ordinary). ***** Note that all names are not required to end with the root label, ***** as they are in the actual DNS wire protocol. *****/ /*** *** Types ***/ /*% * Clients are strongly discouraged from using this type directly, with * the exception of the 'link' and 'list' fields which may be used directly * for whatever purpose the client desires. */ struct dns_name { unsigned char * ndata; unsigned int length; unsigned int labels; unsigned int attributes; unsigned char * offsets; isc_buffer_t * buffer; ISC_LINK(dns_name_t) link; ISC_LIST(dns_rdataset_t) list; }; #define DNS_NAMEATTR_ABSOLUTE 0x00000001 #define DNS_NAMEATTR_READONLY 0x00000002 #define DNS_NAMEATTR_DYNAMIC 0x00000004 #define DNS_NAMEATTR_DYNOFFSETS 0x00000008 #define DNS_NAMEATTR_NOCOMPRESS 0x00000010 /* * Attributes below 0x0100 reserved for name.c usage. */ #define DNS_NAMEATTR_CACHE 0x00000100 /*%< Used by resolver. */ #define DNS_NAMEATTR_ANSWER 0x00000200 /*%< Used by resolver. */ #define DNS_NAMEATTR_NCACHE 0x00000400 /*%< Used by resolver. */ #define DNS_NAMEATTR_CHAINING 0x00000800 /*%< Used by resolver. */ #define DNS_NAMEATTR_CHASE 0x00001000 /*%< Used by resolver. */ #define DNS_NAMEATTR_WILDCARD 0x00002000 /*%< Used by server. */ #define DNS_NAMEATTR_PREREQUISITE 0x00004000 /*%< Used by client. */ #define DNS_NAMEATTR_UPDATE 0x00008000 /*%< Used by client. */ #define DNS_NAMEATTR_HASUPDATEREC 0x00010000 /*%< Used by client. */ /* * Various flags. */ #define DNS_NAME_DOWNCASE 0x0001 #define DNS_NAME_CHECKNAMES 0x0002 /*%< Used by rdata. */ #define DNS_NAME_CHECKNAMESFAIL 0x0004 /*%< Used by rdata. */ #define DNS_NAME_CHECKREVERSE 0x0008 /*%< Used by rdata. */ #define DNS_NAME_CHECKMX 0x0010 /*%< Used by rdata. */ #define DNS_NAME_CHECKMXFAIL 0x0020 /*%< Used by rdata. */ extern dns_name_t *dns_rootname; /*% * Standard size of a wire format name */ #define DNS_NAME_MAXWIRE 255 /*** *** Initialization ***/ void dns_name_init(dns_name_t *name, unsigned char *offsets); /*%< * Initialize 'name'. * * Notes: * \li 'offsets' is never required to be non-NULL, but specifying a * dns_offsets_t for 'offsets' will improve the performance of most * name operations if the name is used more than once. * * Requires: * \li 'name' is not NULL and points to a struct dns_name. * * \li offsets == NULL or offsets is a dns_offsets_t. * * Ensures: * \li 'name' is a valid name. * \li dns_name_countlabels(name) == 0 * \li dns_name_isabsolute(name) == 0 */ void dns_name_reset(dns_name_t *name); /*%< * Reinitialize 'name'. * * Notes: * \li This function distinguishes itself from dns_name_init() in two * key ways: * * \li + If any buffer is associated with 'name' (via dns_name_setbuffer() * or by being part of a dns_fixedname_t) the link to the buffer * is retained but the buffer itself is cleared. * * \li + Of the attributes associated with 'name', all are retained except * DNS_NAMEATTR_ABSOLUTE. * * Requires: * \li 'name' is a valid name. * * Ensures: * \li 'name' is a valid name. * \li dns_name_countlabels(name) == 0 * \li dns_name_isabsolute(name) == 0 */ void dns_name_invalidate(dns_name_t *name); /*%< * Make 'name' invalid. * * Requires: * \li 'name' is a valid name. * * Ensures: * \li If assertion checking is enabled, future attempts to use 'name' * without initializing it will cause an assertion failure. * * \li If the name had a dedicated buffer, that association is ended. */ /*** *** Dedicated Buffers ***/ void dns_name_setbuffer(dns_name_t *name, isc_buffer_t *buffer); /*%< * Dedicate a buffer for use with 'name'. * * Notes: * \li Specification of a target buffer in dns_name_fromwire(), * dns_name_fromtext(), and dns_name_concatenate() is optional if * 'name' has a dedicated buffer. * * \li The caller must not write to buffer until the name has been * invalidated or is otherwise known not to be in use. * * \li If buffer is NULL and the name previously had a dedicated buffer, * than that buffer is no longer dedicated to use with this name. * The caller is responsible for ensuring that the storage used by * the name remains valid. * * Requires: * \li 'name' is a valid name. * * \li 'buffer' is a valid binary buffer and 'name' doesn't have a * dedicated buffer already, or 'buffer' is NULL. */ /*** *** Properties ***/ int dns_name_isabsolute(const dns_name_t *name); /*%< * Does 'name' end in the root label? * * Requires: * \li 'name' is a valid name * * Returns: * \li TRUE The last label in 'name' is the root label. * \li FALSE The last label in 'name' is not the root label. */ unsigned int dns_name_hash(dns_name_t *name, int case_sensitive); /*%< * Provide a hash value for 'name'. * * Note: if 'case_sensitive' is 0, then names which differ only in * case will have the same hash value. * * Requires: * \li 'name' is a valid name * * Returns: * \li A hash value */ /* *** Comparisons ***/ dns_namereln_t dns_name_fullcompare(const dns_name_t *name1, const dns_name_t *name2, int *orderp, unsigned int *nlabelsp); /*%< * Determine the relative ordering under the DNSSEC order relation of * 'name1' and 'name2', and also determine the hierarchical * relationship of the names. * * Note: It makes no sense for one of the names to be relative and the * other absolute. If both names are relative, then to be meaningfully * compared the caller must ensure that they are both relative to the * same domain. * * Requires: *\li 'name1' is a valid name * *\li dns_name_countlabels(name1) > 0 * *\li 'name2' is a valid name * *\li dns_name_countlabels(name2) > 0 * *\li orderp and nlabelsp are valid pointers. * *\li Either name1 is absolute and name2 is absolute, or neither is. * * Ensures: * *\li *orderp is < 0 if name1 < name2, 0 if name1 = name2, > 0 if * name1 > name2. * *\li *nlabelsp is the number of common significant labels. * * Returns: *\li dns_namereln_none There's no hierarchical relationship * between name1 and name2. *\li dns_namereln_contains name1 properly contains name2; i.e. * name2 is a proper subdomain of name1. *\li dns_namereln_subdomain name1 is a proper subdomain of name2. *\li dns_namereln_equal name1 and name2 are equal. *\li dns_namereln_commonancestor name1 and name2 share a common * ancestor. */ int dns_name_compare(const dns_name_t *name1, const dns_name_t *name2); /*%< * Determine the relative ordering under the DNSSEC order relation of * 'name1' and 'name2'. * * Note: It makes no sense for one of the names to be relative and the * other absolute. If both names are relative, then to be meaningfully * compared the caller must ensure that they are both relative to the * same domain. * * Requires: * \li 'name1' is a valid name * * \li 'name2' is a valid name * * \li Either name1 is absolute and name2 is absolute, or neither is. * * Returns: * \li < 0 'name1' is less than 'name2' * \li 0 'name1' is equal to 'name2' * \li > 0 'name1' is greater than 'name2' */ int dns_name_equal(const dns_name_t *name1, const dns_name_t *name2); /*%< * Are 'name1' and 'name2' equal? * * Notes: * \li Because it only needs to test for equality, dns_name_equal() can be * significantly faster than dns_name_fullcompare() or dns_name_compare(). * * \li Offset tables are not used in the comparison. * * \li It makes no sense for one of the names to be relative and the * other absolute. If both names are relative, then to be meaningfully * compared the caller must ensure that they are both relative to the * same domain. * * Requires: * \li 'name1' is a valid name * * \li 'name2' is a valid name * * \li Either name1 is absolute and name2 is absolute, or neither is. * * Returns: * \li 1 'name1' and 'name2' are equal * \li 0 'name1' and 'name2' are not equal */ int dns_name_caseequal(const dns_name_t *name1, const dns_name_t *name2); /*%< * Case sensitive version of dns_name_equal(). */ int dns_name_issubdomain(const dns_name_t *name1, const dns_name_t *name2); /*%< * Is 'name1' a subdomain of 'name2'? * * Notes: * \li name1 is a subdomain of name2 if name1 is contained in name2, or * name1 equals name2. * * \li It makes no sense for one of the names to be relative and the * other absolute. If both names are relative, then to be meaningfully * compared the caller must ensure that they are both relative to the * same domain. * * Requires: * \li 'name1' is a valid name * * \li 'name2' is a valid name * * \li Either name1 is absolute and name2 is absolute, or neither is. * * Returns: * \li TRUE 'name1' is a subdomain of 'name2' * \li FALSE 'name1' is not a subdomain of 'name2' */ /*** *** Labels ***/ unsigned int dns_name_countlabels(const dns_name_t *name); /*%< * How many labels does 'name' have? * * Notes: * \li In this case, as in other places, a 'label' is an ordinary label. * * Requires: * \li 'name' is a valid name * * Ensures: * \li The result is <= 128. * * Returns: * \li The number of labels in 'name'. */ void dns_name_getlabel(const dns_name_t *name, unsigned int n, dns_label_t *label); /*%< * Make 'label' refer to the 'n'th least significant label of 'name'. * * Notes: * \li Numbering starts at 0. * * \li Given "rc.vix.com.", the label 0 is "rc", and label 3 is the * root label. * * \li 'label' refers to the same memory as 'name', so 'name' must not * be changed while 'label' is still in use. * * Requires: * \li n < dns_name_countlabels(name) */ void dns_name_getlabelsequence(const dns_name_t *source, unsigned int first, unsigned int n, dns_name_t *target); /*%< * Make 'target' refer to the 'n' labels including and following 'first' * in 'source'. * * Notes: * \li Numbering starts at 0. * * \li Given "rc.vix.com.", the label 0 is "rc", and label 3 is the * root label. * * \li 'target' refers to the same memory as 'source', so 'source' * must not be changed while 'target' is still in use. * * Requires: * \li 'source' and 'target' are valid names. * * \li first < dns_name_countlabels(name) * * \li first + n <= dns_name_countlabels(name) */ void dns_name_clone(const dns_name_t *source, dns_name_t *target); /*%< * Make 'target' refer to the same name as 'source'. * * Notes: * * \li 'target' refers to the same memory as 'source', so 'source' * must not be changed while 'target' is still in use. * * \li This call is functionally equivalent to: * * \code * dns_name_getlabelsequence(source, 0, * dns_name_countlabels(source), * target); * \endcode * * but is more efficient. Also, dns_name_clone() works even if 'source' * is empty. * * Requires: * * \li 'source' is a valid name. * * \li 'target' is a valid name that is not read-only. */ /*** *** Conversions ***/ void dns_name_fromregion(dns_name_t *name, const isc_region_t *r); /*%< * Make 'name' refer to region 'r'. * * Note: * \li If the conversion encounters a root label before the end of the * region the conversion stops and the length is set to the length * so far converted. A maximum of 255 bytes is converted. * * Requires: * \li The data in 'r' is a sequence of one or more type 00 or type 01000001 * labels. */ void dns_name_toregion(dns_name_t *name, isc_region_t *r); /*%< * Make 'r' refer to 'name'. * * Requires: * * \li 'name' is a valid name. * * \li 'r' is a valid region. */ isc_result_t dns_name_fromwire(dns_name_t *name, isc_buffer_t *source, dns_decompress_t *dctx, unsigned int options, isc_buffer_t *target); /*%< * Copy the possibly-compressed name at source (active region) into target, * decompressing it. * * Notes: * \li Decompression policy is controlled by 'dctx'. * * \li If DNS_NAME_DOWNCASE is set, any uppercase letters in 'source' will be * downcased when they are copied into 'target'. * * Security: * * \li *** WARNING *** * * \li This routine will often be used when 'source' contains raw network * data. A programming error in this routine could result in a denial * of service, or in the hijacking of the server. * * Requires: * * \li 'name' is a valid name. * * \li 'source' is a valid buffer and the first byte of the active * region should be the first byte of a DNS wire format domain name. * * \li 'target' is a valid buffer or 'target' is NULL and 'name' has * a dedicated buffer. * * \li 'dctx' is a valid decompression context. * * Ensures: * * If result is success: * \li If 'target' is not NULL, 'name' is attached to it. * * \li Uppercase letters are downcased in the copy iff * DNS_NAME_DOWNCASE is set in options. * * \li The current location in source is advanced, and the used space * in target is updated. * * Result: * \li Success * \li Bad Form: Label Length * \li Bad Form: Unknown Label Type * \li Bad Form: Name Length * \li Bad Form: Compression type not allowed * \li Bad Form: Bad compression pointer * \li Bad Form: Input too short * \li Resource Limit: Too many compression pointers * \li Resource Limit: Not enough space in buffer */ isc_result_t dns_name_towire(const dns_name_t *name, dns_compress_t *cctx, isc_buffer_t *target); /*%< * Convert 'name' into wire format, compressing it as specified by the * compression context 'cctx', and storing the result in 'target'. * * Notes: * \li If the compression context allows global compression, then the * global compression table may be updated. * * Requires: * \li 'name' is a valid name * * \li dns_name_countlabels(name) > 0 * * \li dns_name_isabsolute(name) == TRUE * * \li target is a valid buffer. * * \li Any offsets specified in a global compression table are valid * for buffer. * * Ensures: * * If the result is success: * * \li The used space in target is updated. * * Returns: * \li Success * \li Resource Limit: Not enough space in buffer */ isc_result_t dns_name_fromtext(dns_name_t *name, isc_buffer_t *source, const dns_name_t *origin, unsigned int options, isc_buffer_t *target); /*%< * Convert the textual representation of a DNS name at source * into uncompressed wire form stored in target. * * Notes: * \li Relative domain names will have 'origin' appended to them * unless 'origin' is NULL, in which case relative domain names * will remain relative. * * \li If DNS_NAME_DOWNCASE is set in 'options', any uppercase letters * in 'source' will be downcased when they are copied into 'target'. * * Requires: * * \li 'name' is a valid name. * * \li 'source' is a valid buffer. * * \li 'target' is a valid buffer or 'target' is NULL and 'name' has * a dedicated buffer. * * Ensures: * * If result is success: * \li If 'target' is not NULL, 'name' is attached to it. * * \li Uppercase letters are downcased in the copy iff * DNS_NAME_DOWNCASE is set in 'options'. * * \li The current location in source is advanced, and the used space * in target is updated. * * Result: *\li #ISC_R_SUCCESS *\li #DNS_R_EMPTYLABEL *\li #DNS_R_LABELTOOLONG *\li #DNS_R_BADESCAPE *\li #DNS_R_BADDOTTEDQUAD *\li #ISC_R_NOSPACE *\li #ISC_R_UNEXPECTEDEND */ #define DNS_NAME_OMITFINALDOT 0x01U #define DNS_NAME_MASTERFILE 0x02U /* escape $ and @ */ isc_result_t dns_name_totext(dns_name_t *name, int omit_final_dot, isc_buffer_t *target); isc_result_t dns_name_totext2(dns_name_t *name, unsigned int options, isc_buffer_t *target); /*%< * Convert 'name' into text format, storing the result in 'target'. * * Notes: *\li If 'omit_final_dot' is true, then the final '.' in absolute * names other than the root name will be omitted. * *\li If DNS_NAME_OMITFINALDOT is set in options, then the final '.' * in absolute names other than the root name will be omitted. * *\li If DNS_NAME_MASTERFILE is set in options, '$' and '@' will also * be escaped. * *\li If dns_name_countlabels == 0, the name will be "@", representing the * current origin as described by RFC1035. * *\li The name is not NUL terminated. * * Requires: * *\li 'name' is a valid name * *\li 'target' is a valid buffer. * *\li if dns_name_isabsolute == FALSE, then omit_final_dot == FALSE * * Ensures: * *\li If the result is success: * the used space in target is updated. * * Returns: *\li #ISC_R_SUCCESS *\li #ISC_R_NOSPACE */ #define DNS_NAME_MAXTEXT 1023 /*%< * The maximum length of the text representation of a domain * name as generated by dns_name_totext(). This does not * include space for a terminating NULL. * * This definition is conservative - the actual maximum * is 1004, derived as follows: * * A backslash-decimal escaped character takes 4 bytes. * A wire-encoded name can be up to 255 bytes and each * label is one length byte + at most 63 bytes of data. * Maximizing the label lengths gives us a name of * three 63-octet labels, one 61-octet label, and the * root label: * * 1 + 63 + 1 + 63 + 1 + 63 + 1 + 61 + 1 = 255 * * When printed, this is (3 * 63 + 61) * 4 * bytes for the escaped label data + 4 bytes for the * dot terminating each label = 1004 bytes total. */ isc_result_t dns_name_downcase(dns_name_t *source, dns_name_t *name, isc_buffer_t *target); /*%< * Downcase 'source'. * * Requires: * *\li 'source' and 'name' are valid names. * *\li If source == name, then * 'source' must not be read-only * *\li Otherwise, * 'target' is a valid buffer or 'target' is NULL and * 'name' has a dedicated buffer. * * Returns: *\li #ISC_R_SUCCESS *\li #ISC_R_NOSPACE * * Note: if source == name, then the result will always be ISC_R_SUCCESS. */ isc_result_t dns_name_concatenate(dns_name_t *prefix, dns_name_t *suffix, dns_name_t *name, isc_buffer_t *target); /*%< * Concatenate 'prefix' and 'suffix'. * * Requires: * *\li 'prefix' is a valid name or NULL. * *\li 'suffix' is a valid name or NULL. * *\li 'name' is a valid name or NULL. * *\li 'target' is a valid buffer or 'target' is NULL and 'name' has * a dedicated buffer. * *\li If 'prefix' is absolute, 'suffix' must be NULL or the empty name. * * Ensures: * *\li On success, * If 'target' is not NULL and 'name' is not NULL, then 'name' * is attached to it. * The used space in target is updated. * * Returns: *\li #ISC_R_SUCCESS *\li #ISC_R_NOSPACE *\li #DNS_R_NAMETOOLONG */ isc_result_t dns_name_dup(const dns_name_t *source, dns_name_t *target); /*%< * Make 'target' a dynamically allocated copy of 'source'. * * Requires: * *\li 'source' is a valid non-empty name. * *\li 'target' is a valid name that is not read-only. * *\li 'mctx' is a valid memory context. */ isc_result_t dns_name_dupwithoffsets(dns_name_t *source, dns_name_t *target); /*%< * Make 'target' a read-only dynamically allocated copy of 'source'. * 'target' will also have a dynamically allocated offsets table. * * Requires: * *\li 'source' is a valid non-empty name. * *\li 'target' is a valid name that is not read-only. * *\li 'target' has no offsets table. * *\li 'mctx' is a valid memory context. */ void dns_name_free(dns_name_t *name); /*%< * Free 'name'. * * Requires: * *\li 'name' is a valid name created previously in 'mctx' by dns_name_dup(). * *\li 'mctx' is a valid memory context. * * Ensures: * *\li All dynamic resources used by 'name' are freed and the name is * invalidated. */ int dns_name_dynamic(dns_name_t *name); /*%< * Returns whether there is dynamic memory associated with this name. * * Requires: * *\li 'name' is a valid name. * * Returns: * *\li '1' if the name is dynamic otherwise '0'. */ void dns_name_format(dns_name_t *name, char *cp, unsigned int size); /*%< * Format 'name' as text appropriate for use in log messages. * * Store the formatted name at 'cp', writing no more than * 'size' bytes. The resulting string is guaranteed to be * null terminated. * * The formatted name will have a terminating dot only if it is * the root. * * This function cannot fail, instead any errors are indicated * in the returned text. * * Requires: * *\li 'name' is a valid name. * *\li 'cp' points a valid character array of size 'size'. * *\li 'size' > 0. * */ isc_result_t dns_name_fromstring2(dns_name_t *target, const char *src, const dns_name_t *origin, unsigned int options); /*%< * Convert a string to a name and place it in target, allocating memory * as necessary. 'options' has the same semantics as that of * dns_name_fromtext(). * * If 'target' has a buffer then the name will be copied into it rather than * memory being allocated. * * Requires: * * \li 'target' is a valid name that is not read-only. * \li 'src' is not NULL. * * Returns: * *\li #ISC_R_SUCCESS * *\li Any error that dns_name_fromtext() can return. * *\li Any error that dns_name_dup() can return. */ #define DNS_NAME_FORMATSIZE (DNS_NAME_MAXTEXT + 1) /*%< * Suggested size of buffer passed to dns_name_format(). * Includes space for the terminating NULL. */ isc_result_t dns_name_copy(dns_name_t *source, dns_name_t *dest, isc_buffer_t *target); /*%< * Makes 'dest' refer to a copy of the name in 'source'. The data are * either copied to 'target' or the dedicated buffer in 'dest'. * * Requires: * \li 'source' is a valid name. * * \li 'dest' is an initialized name with a dedicated buffer. * * \li 'target' is NULL or an initialized buffer. * * \li Either dest has a dedicated buffer or target != NULL. * * Ensures: * *\li On success, the used space in target is updated. * * Returns: *\li #ISC_R_SUCCESS *\li #ISC_R_NOSPACE */ #define DNS_NAME_INITABSOLUTE(A,B) { \ A, sizeof(A), sizeof(B), \ DNS_NAMEATTR_READONLY | DNS_NAMEATTR_ABSOLUTE, \ B, NULL, { (void *)-1, (void *)-1}, \ {NULL, NULL} \ } #endif /* DNS_NAME_H */
