/* * Copyright (c) 1996,1999 by Internet Software Consortium. * * 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. * * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE * CONSORTIUM 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. */ #include "config.h" #ifdef HAVE_RESOLV #include <sys/types.h> #ifdef HAVE_NETINET_IN_H # include <netinet/in.h> #endif #ifdef HAVE_ARPA_NAMESER_H # include <arpa/nameser.h> #endif #include <ctype.h> #include <errno.h> #ifdef HAVE_RESOLV_H # include <resolv.h> #endif #include <string.h> /* Data. */ static const char digits[] = "0123456789"; /* Private. */ /* * special(ch) * Thinking in noninternationalized USASCII (per the DNS spec), * is this character special ("in need of quoting") ? * return: * boolean. */ static int special(int ch) { switch (ch) { case 0x22: /* '"' */ case 0x2E: /* '.' */ case 0x3B: /* ';' */ case 0x5C: /* '\\' */ /* Special modifiers in zone files. */ case 0x40: /* '@' */ case 0x24: /* '$' */ return (1); default: return (0); } } /* * printable(ch) * Thinking in noninternationalized USASCII (per the DNS spec), * is this character visible and not a space when printed ? * return: * boolean. */ static int printable(int ch) { return (ch > 0x20 && ch < 0x7f); } /* Public. */ /* * dns_ns_name_ntop(src, dst, dstsiz) * Convert an encoded domain name to printable ascii as per RFC1035. * return: * Number of bytes written to buffer, or -1 (with errno set) * notes: * The root is returned as "." * All other domains are returned in non absolute form */ static int dns_ns_name_ntop(const u_char *src, char *dst, size_t dstsiz) { const u_char *cp; char *dn, *eom; u_char c; u_int n; cp = src; dn = dst; eom = dst + dstsiz; while ((n = *cp++) != 0) { if ((n & NS_CMPRSFLGS) != 0 && n != 0x41) { /* Some kind of compression pointer. */ return (-1); } if (dn != dst) { if (dn >= eom) { return (-1); } *dn++ = '.'; } if (n == 0x41) { n = *cp++ / 8; if (dn + n * 2 + 4 >= eom) { return (-1); } *dn++ = '\\'; *dn++ = '['; *dn++ = 'x'; while (n-- > 0) { unsigned u; c = *cp++; u = c >> 4; *dn++ = u > 9 ? 'a' + u - 10 : '0' + u; u = c & 0xf; *dn++ = u > 9 ? 'a' + u - 10 : '0' + u; } *dn++ = ']'; continue; } if (dn + n >= eom) { return (-1); } while (n-- > 0) { c = *cp++; if (special(c)) { if (dn + 1 >= eom) { return (-1); } *dn++ = '\\'; *dn++ = (char)c; } else if (!printable(c)) { if (dn + 3 >= eom) { return (-1); } *dn++ = '\\'; *dn++ = digits[c / 100]; *dn++ = digits[(c % 100) / 10]; *dn++ = digits[c % 10]; } else { if (dn >= eom) { return (-1); } *dn++ = (char)c; } } } if (dn == dst) { if (dn >= eom) { return (-1); } *dn++ = '.'; } if (dn >= eom) { return (-1); } *dn++ = '\0'; return (dn - dst); } /* * dns_ns_name_unpack(msg, eom, src, dst, dstsiz) * Unpack a domain name from a message, source may be compressed. * return: * -1 if it fails, or consumed octets if it succeeds. */ static int dns_ns_name_unpack(const u_char *msg, const u_char *eom, const u_char *src, u_char *dst, size_t dstsiz) { const u_char *srcp, *dstlim; u_char *dstp; int n, len, checked; len = -1; checked = 0; dstp = dst; srcp = src; dstlim = dst + dstsiz; if (srcp < msg || srcp >= eom) { return (-1); } /* Fetch next label in domain name. */ while ((n = *srcp++) != 0) { /* Check for indirection. */ switch (n & NS_CMPRSFLGS) { case 0x40: if (n == 0x41) { if (dstp + 1 >= dstlim) { return (-1); } *dstp++ = 0x41; n = *srcp++ / 8; ++checked; } else { return (-1); /* flag error */ } /* FALLTHROUGH */ case 0: /* Limit checks. */ if (dstp + n + 1 >= dstlim || srcp + n >= eom) { return (-1); } checked += n + 1; dstp = memcpy(dstp, srcp - 1, n + 1); dstp += n + 1; srcp += n; break; case NS_CMPRSFLGS: if (srcp >= eom) { return (-1); } if (len < 0) len = srcp - src + 1; srcp = msg + (((n & 0x3f) << 8) | (*srcp & 0xff)); if (srcp < msg || srcp >= eom) { /* 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 >= eom - msg) { return (-1); } break; default: return (-1); /* flag error */ } } *dstp = '\0'; if (len < 0) len = srcp - src; return (len); } /* * dns_ns_name_uncompress(msg, eom, src, dst, dstsiz) * Expand compressed domain name to presentation format. * return: * Number of bytes read out of `src', or -1 (with errno set). * note: * Root domain returns as "." not "". */ int dns_ns_name_uncompress(const u_char *msg, const u_char *eom, const u_char *src, char *dst, size_t dstsiz) { u_char tmp[NS_MAXCDNAME]; int n; if ((n = dns_ns_name_unpack(msg, eom, src, tmp, sizeof tmp)) == -1) return (-1); if (dns_ns_name_ntop(tmp, dst, dstsiz) == -1) return (-1); return (n); } /* * dns_ns_name_skip(ptrptr, eom) * Advance *ptrptr to skip over the compressed name it points at. * return: * 0 on success, -1 (with errno set) on failure. */ int dns_ns_name_skip(const u_char **ptrptr, const u_char *eom) { const u_char *cp; u_int n; cp = *ptrptr; while (cp < eom && (n = *cp++) != 0) { /* Check for indirection. */ switch (n & NS_CMPRSFLGS) { case 0: /* normal case, n == len */ cp += n; continue; case NS_CMPRSFLGS: /* indirection */ cp++; break; default: /* illegal type */ return (-1); } break; } if (cp > eom) { return (-1); } *ptrptr = cp; return (0); } #endif /* HAVE_RESOLV */