/* $OpenBSD: res_comp.c,v 1.23 2023/03/15 22:12:00 millert Exp $ */ /* * ++Copyright++ 1985, 1993 * - * Copyright (c) 1985, 1993 * The Regents of the University of California. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. 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. * 3. Neither the name of the University 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 REGENTS 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 REGENTS 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. * - * Portions Copyright (c) 1993 by Digital Equipment Corporation. * * Permission to use, copy, modify, and 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, and that * the name of Digital Equipment Corporation not be used in advertising or * publicity pertaining to distribution of the document or software without * specific, written prior permission. * * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL DIGITAL EQUIPMENT * CORPORATION 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. * - * --Copyright-- */ #include <sys/types.h> #include <netinet/in.h> #include <arpa/nameser.h> #include <stdio.h> #include <resolv.h> #include <ctype.h> #include <unistd.h> #include <limits.h> #include <string.h> static int dn_find(u_char *, u_char *, u_char **, u_char **); /* * Expand compressed domain name 'comp_dn' to full domain name. * 'msg' is a pointer to the beginning of the message, * 'eomorig' points to the first location after the message, * 'exp_dn' is a pointer to a buffer of size 'length' for the result. * Return size of compressed name or -1 if there was an error. */ int dn_expand(const u_char *msg, const u_char *eomorig, const u_char *comp_dn, char *exp_dn, int length) { const u_char *cp; char *dn; int n, c; char *eom; int len = -1, checked = 0; if (comp_dn < msg || comp_dn >= eomorig) return (-1); dn = exp_dn; cp = comp_dn; if (length > HOST_NAME_MAX) length = HOST_NAME_MAX; eom = exp_dn + length; /* * fetch next label in domain name */ while ((n = *cp++)) { if (cp >= eomorig) /* out of range */ return (-1); /* * Check for indirection */ switch (n & INDIR_MASK) { case 0: if (dn != exp_dn) { if (dn >= eom) return (-1); *dn++ = '.'; } if (dn+n >= eom) return (-1); checked += n + 1; while (--n >= 0) { if (((c = *cp++) == '.') || (c == '\\')) { if (dn + n + 2 >= eom) return (-1); *dn++ = '\\'; } *dn++ = c; if (cp >= eomorig) /* out of range */ return (-1); } break; case INDIR_MASK: if (len < 0) len = cp - comp_dn + 1; cp = msg + (((n & 0x3f) << 8) | (*cp & 0xff)); if (cp < msg || cp >= eomorig) /* out of range */ return (-1); checked += 2; /* * Check for loops in the compressed name; * if we've looked at the whole message, * there must be a loop. */ if (checked >= eomorig - msg) return (-1); break; default: return (-1); /* flag error */ } } *dn = '\0'; if (len < 0) len = cp - comp_dn; return (len); } DEF_WEAK(dn_expand); /* * Compress domain name 'exp_dn' into 'comp_dn'. * Return the size of the compressed name or -1. * 'length' is the size of the array pointed to by 'comp_dn'. * 'dnptrs' is a list of pointers to previous compressed names. dnptrs[0] * is a pointer to the beginning of the message. The list ends with NULL. * 'lastdnptr' is a pointer to the end of the array pointed to * by 'dnptrs'. Side effect is to update the list of pointers for * labels inserted into the message as we compress the name. * If 'dnptr' is NULL, we don't try to compress names. If 'lastdnptr' * is NULL, we don't update the list. */ int dn_comp(const char *exp_dn, u_char *comp_dn, int length, u_char **dnptrs, u_char **lastdnptr) { u_char *cp, *dn; int c, l; u_char **cpp, **lpp, *sp, *eob; u_char *msg; dn = (u_char *)exp_dn; cp = comp_dn; eob = cp + length; lpp = cpp = NULL; if (dnptrs != NULL) { if ((msg = *dnptrs++) != NULL) { for (cpp = dnptrs; *cpp != NULL; cpp++) ; lpp = cpp; /* end of list to search */ } } else msg = NULL; for (c = *dn++; c != '\0'; ) { /* look to see if we can use pointers */ if (msg != NULL) { if ((l = dn_find(dn-1, msg, dnptrs, lpp)) >= 0) { if (cp+1 >= eob) return (-1); *cp++ = (l >> 8) | INDIR_MASK; *cp++ = l % 256; return (cp - comp_dn); } /* not found, save it */ if (lastdnptr != NULL && cpp < lastdnptr-1) { *cpp++ = cp; *cpp = NULL; } } sp = cp++; /* save ptr to length byte */ do { if (c == '.') { c = *dn++; break; } if (c == '\\') { if ((c = *dn++) == '\0') break; } if (cp >= eob) { if (msg != NULL) *lpp = NULL; return (-1); } *cp++ = c; } while ((c = *dn++) != '\0'); /* catch trailing '.'s but not '..' */ if ((l = cp - sp - 1) == 0 && c == '\0') { cp--; break; } if (l <= 0 || l > MAXLABEL) { if (msg != NULL) *lpp = NULL; return (-1); } *sp = l; } if (cp >= eob) { if (msg != NULL) *lpp = NULL; return (-1); } *cp++ = '\0'; return (cp - comp_dn); } /* * Skip over a compressed domain name. Return the size or -1. */ int __dn_skipname(const u_char *comp_dn, const u_char *eom) { const u_char *cp; int n; cp = comp_dn; while (cp < eom && (n = *cp++)) { /* * check for indirection */ switch (n & INDIR_MASK) { case 0: /* normal case, n == len */ cp += n; continue; case INDIR_MASK: /* indirection */ cp++; break; default: /* illegal type */ return (-1); } break; } if (cp > eom) return (-1); return (cp - comp_dn); } /* * Search for expanded name from a list of previously compressed names. * Return the offset from msg if found or -1. * dnptrs is the pointer to the first name on the list, * not the pointer to the start of the message. */ static int dn_find(u_char *exp_dn, u_char *msg, u_char **dnptrs, u_char **lastdnptr) { u_char *dn, *cp, **cpp; int n; u_char *sp; for (cpp = dnptrs; cpp < lastdnptr; cpp++) { dn = exp_dn; sp = cp = *cpp; while ((n = *cp++)) { /* * check for indirection */ switch (n & INDIR_MASK) { case 0: /* normal case, n == len */ while (--n >= 0) { if (*dn == '.') goto next; if (*dn == '\\') dn++; if (tolower((unsigned char)*dn++) != tolower((unsigned char)*cp++)) goto next; } if ((n = *dn++) == '\0' && *cp == '\0') return (sp - msg); if (n == '.') continue; goto next; case INDIR_MASK: /* indirection */ cp = msg + (((n & 0x3f) << 8) | *cp); break; default: /* illegal type */ return (-1); } } if (*dn == '\0') return (sp - msg); next: ; } return (-1); } /* * Verify that a domain name uses an acceptable character set. */ /* * Note the conspicuous absence of ctype macros in these definitions. On * non-ASCII hosts, we can't depend on string literals or ctype macros to * tell us anything about network-format data. The rest of the BIND system * is not careful about this, but for some reason, we're doing it right here. */ #define PERIOD 0x2e #define hyphenchar(c) ((c) == 0x2d) #define bslashchar(c) ((c) == 0x5c) #define underscorechar(c) ((c) == 0x5f) #define periodchar(c) ((c) == PERIOD) #define asterchar(c) ((c) == 0x2a) #define alphachar(c) (((c) >= 0x41 && (c) <= 0x5a) \ || ((c) >= 0x61 && (c) <= 0x7a)) #define digitchar(c) ((c) >= 0x30 && (c) <= 0x39) #define borderchar(c) (alphachar(c) || digitchar(c)) #define middlechar(c) (borderchar(c) || hyphenchar(c) || underscorechar(c)) #define domainchar(c) ((c) > 0x20 && (c) < 0x7f) int __res_hnok(const char *dn) { int pch = PERIOD, ch = *dn++; while (ch != '\0') { int nch = *dn++; if (periodchar(ch)) { ; } else if (periodchar(pch)) { if (!borderchar(ch)) return (0); } else if (periodchar(nch) || nch == '\0') { if (!borderchar(ch)) return (0); } else { if (!middlechar(ch)) return (0); } pch = ch, ch = nch; } return (1); } DEF_STRONG(__res_hnok); /* * hostname-like (A, MX, WKS) owners can have "*" as their first label * but must otherwise be as a host name. */ int res_ownok(const char *dn) { if (asterchar(dn[0])) { if (periodchar(dn[1])) return (res_hnok(dn+2)); if (dn[1] == '\0') return (1); } return (res_hnok(dn)); } /* * SOA RNAMEs and RP RNAMEs can have any printable character in their first * label, but the rest of the name has to look like a host name. */ int res_mailok(const char *dn) { int ch, escaped = 0; /* "." is a valid missing representation */ if (*dn == '\0') return(1); /* otherwise <label>.<hostname> */ while ((ch = *dn++) != '\0') { if (!domainchar(ch)) return (0); if (!escaped && periodchar(ch)) break; if (escaped) escaped = 0; else if (bslashchar(ch)) escaped = 1; } if (periodchar(ch)) return (res_hnok(dn)); return(0); } /* * This function is quite liberal, since RFC 1034's character sets are only * recommendations. */ int res_dnok(const char *dn) { int ch; while ((ch = *dn++) != '\0') if (!domainchar(ch)) return (0); return (1); } /* * Routines to insert/extract short/long's. */ u_int16_t _getshort(const u_char *msgp) { u_int16_t u; GETSHORT(u, msgp); return (u); } DEF_STRONG(_getshort); u_int32_t _getlong(const u_char *msgp) { u_int32_t u; GETLONG(u, msgp); return (u); } DEF_STRONG(_getlong); void __putshort(u_int16_t s, u_char *msgp) { PUTSHORT(s, msgp); } void __putlong(u_int32_t l, u_char *msgp) { PUTLONG(l, msgp); }
