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ircu2/ircd/ircd_reslib.c

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/*
* 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. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. 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.
*/
/*
* Portions 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.
*/
/* Original copyright ISC as above.
* Code modified specifically for ircd use from the following original files
* in bind ...
*
* res_comp.c
* ns_name.c
* ns_netint.c
* res_init.c
*
* - Dianora
*/
#include "ircd.h"
#include "res.h"
#include "ircd_reslib.h"
#include "ircd_defs.h"
#include "fileio.h"
#include "ircd_string.h"
#include <ctype.h>
#include <errno.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#define NS_TYPE_ELT 0x40 /**< EDNS0 extended label type */
#define DNS_LABELTYPE_BITSTRING 0x41 /**< Bitstring label */
#define MAXLINE 128 /**< Maximum line length for resolv.conf */
/** @file
* @brief DNS resolver library functions.
* @version $Id: ircd_reslib.c 1764 2007-02-25 15:41:49Z entrope $
*/
/** Array of nameserver addresses. */
struct irc_sockaddr irc_nsaddr_list[IRCD_MAXNS];
/** Number of nameservers in #irc_nsaddr_list. */
int irc_nscount;
/** Local domain to use as a search suffix. */
char irc_domain[HOSTLEN + 1];
/** Maps hex digits to their values, or -1 for other characters. */
static const char digitvalue[256] = {
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*16*/
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*32*/
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*48*/
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, -1, -1, -1, -1, -1, -1, /*64*/
-1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*80*/
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*96*/
-1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*112*/
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*128*/
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*256*/
};
static int parse_resvconf(void);
/** Array of decimal digits, indexed by value. */
static const char digits[] = "0123456789";
static int labellen(const unsigned char *lp);
static int special(int ch);
static int printable(int ch);
static int irc_decode_bitstring(const char **cpp, char *dn, const char *eom);
static int irc_ns_name_compress(const char *src, unsigned char *dst, size_t dstsiz,
const unsigned char **dnptrs, const unsigned char **lastdnptr);
static int irc_dn_find(const unsigned char *, const unsigned char *, const unsigned char * const *,
const unsigned char * const *);
static int irc_encode_bitsring(const char **, const char *, unsigned char **, unsigned char **,
const char *);
static int mklower(int ch);
/** Initialize the resolver library.
* @return Zero on success, non-zero on failure.
*/
int
irc_res_init(void)
{
return (irc_nscount == 0) ? parse_resvconf() : 0;
}
/** Read resolver configuration file for domain and nameserver lines.
* The "domain" line is used to overwrite #irc_domain.
* Addresses in "nameserver" lines are appended to #irc_nsaddr_list.
* @return Zero on success, non-zero on failure.
*/
static int
parse_resvconf(void)
{
char *p;
char *opt;
char *arg;
char input[MAXLINE];
FBFILE *file;
/* XXX "/etc/resolv.conf" should be from a define in setup.h perhaps
* for cygwin support etc. this hardcodes it to unix for now -db
*/
if ((file = fbopen("/etc/resolv.conf", "r")) == NULL)
return(-1);
while (fbgets(input, MAXLINE, file) != NULL)
{
/* blow away any newline */
if ((p = strpbrk(input, "\r\n")) != NULL)
*p = '\0';
/* Ignore comment lines immediately */
if (*input == '#')
continue;
p = input;
/* skip until something that's not a space is seen */
while (IsSpace(*p))
p++;
/* if at this point, have a '\0' then continue */
if (*p == '\0')
continue;
/* skip until a space is found */
opt = input;
while (!IsSpace(*p))
if (*p++ == '\0')
continue; /* no arguments?.. ignore this line */
/* blow away the space character */
*p++ = '\0';
/* skip these spaces that are before the argument */
while (IsSpace(*p))
p++;
/* Now arg should be right where p is pointing */
arg = p;
if ((p = strpbrk(arg, " \t")) != NULL)
*p = '\0'; /* take the first word */
if (strcasecmp(opt, "domain") == 0)
ircd_strncpy(irc_domain, arg, HOSTLEN + 1);
else if (strcasecmp(opt, "nameserver") == 0)
add_nameserver(arg);
}
fbclose(file);
return(0);
}
/** Add a resolver to #irc_nsaddr_list.
* @param[in] arg Dotted quad or IPv6 text form of nameserver address.
*/
void
add_nameserver(const char *arg)
{
struct irc_sockaddr res;
/* Done max number of nameservers? */
if (irc_nscount >= IRCD_MAXNS)
return;
/* Failure converting from numeric string? */
if (!ircd_aton(&res.addr, arg))
return;
res.port = 53;
memcpy(&irc_nsaddr_list[irc_nscount], &res, sizeof(irc_nsaddr_list[irc_nscount]));
irc_nscount++;
}
/**
* Expand compressed domain name to full domain name.
* Like irc_ns_name_uncompress(), but checks for a well-formed result.
* @param[in] msg Pointer to the beginning of the message.
* @param[in] eom First location after the message.
* @param[in] src Pointer to where to starting decoding.
* @param[out] dst Output buffer.
* @param[in] dstsiz Number of bytes that can be written to \a dst.
* @return Number of bytes written to \a dst.
*/
int
irc_dn_expand(const unsigned char *msg, const unsigned char *eom,
const unsigned char *src, char *dst, int dstsiz)
{
int n = irc_ns_name_uncompress(msg, eom, src, dst, (size_t)dstsiz);
if (n > 0 && dst[0] == '.')
dst[0] = '\0';
return(n);
}
/**
* Expand compressed domain name to full domain name.
* @param[in] msg Pointer to the beginning of the message.
* @param[in] eom First location after the message.
* @param[in] src Pointer to where to starting decoding.
* @param[out] dst Output buffer.
* @param[in] dstsiz Number of bytes that can be written to \a dst.
* @return Number of bytes written to \a dst.
*/
int
irc_ns_name_uncompress(const unsigned char *msg, const unsigned char *eom,
const unsigned char *src, char *dst, size_t dstsiz)
{
unsigned char tmp[NS_MAXCDNAME];
int n;
if ((n = irc_ns_name_unpack(msg, eom, src, tmp, sizeof tmp)) == -1)
return(-1);
if (irc_ns_name_ntop((char*)tmp, (char*)dst, dstsiz) == -1)
return(-1);
return(n);
}
/**
* Unpack compressed domain name to uncompressed form.
* @param[in] msg Pointer to the beginning of the message.
* @param[in] eom First location after the message.
* @param[in] src Pointer to where to starting decoding.
* @param[out] dst Output buffer.
* @param[in] dstsiz Number of bytes that can be written to \a dst.
* @return Number of bytes written to \a dst.
*/
int
irc_ns_name_unpack(const unsigned char *msg, const unsigned char *eom,
const unsigned char *src, unsigned char *dst,
size_t dstsiz)
{
const unsigned char *srcp, *dstlim;
unsigned char *dstp;
int n, len, checked, l;
len = -1;
checked = 0;
dstp = dst;
srcp = src;
dstlim = dst + dstsiz;
if (srcp < msg || srcp >= eom) {
errno = EMSGSIZE;
return (-1);
}
/* Fetch next label in domain name. */
while ((n = *srcp++) != 0) {
/* Check for indirection. */
switch (n & NS_CMPRSFLGS) {
case 0:
case NS_TYPE_ELT:
/* Limit checks. */
if ((l = labellen(srcp - 1)) < 0) {
errno = EMSGSIZE;
return(-1);
}
if (dstp + l + 1 >= dstlim || srcp + l >= eom) {
errno = EMSGSIZE;
return (-1);
}
checked += l + 1;
*dstp++ = n;
memcpy(dstp, srcp, l);
dstp += l;
srcp += l;
break;
case NS_CMPRSFLGS:
if (srcp >= eom) {
errno = EMSGSIZE;
return (-1);
}
if (len < 0)
len = srcp - src + 1;
srcp = msg + (((n & 0x3f) << 8) | (*srcp & 0xff));
if (srcp < msg || srcp >= eom) { /* Out of range. */
errno = EMSGSIZE;
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) {
errno = EMSGSIZE;
return (-1);
}
break;
default:
errno = EMSGSIZE;
return (-1); /* flag error */
}
}
*dstp = '\0';
if (len < 0)
len = srcp - src;
return (len);
}
/**
* Convert RFC1035 length-prefixed tag sequence to printable ASCII.
* @param[in] src Input tag sequence (effectively NUL terminated).
* @param[out] dst Buffer for uncompressed output.
* @param[in] dstsiz Number of bytes that can be written to \a dst.
* @return Number of bytes written to \a dst.
*/
int
irc_ns_name_ntop(const char *src, char *dst, size_t dstsiz)
{
const char *cp;
char *dn, *eom;
unsigned char c;
unsigned int n;
int l;
cp = src;
dn = dst;
eom = dst + dstsiz;
while ((n = *cp++) != 0) {
if ((n & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
/* Some kind of compression pointer. */
errno = EMSGSIZE;
return (-1);
}
if (dn != dst) {
if (dn >= eom) {
errno = EMSGSIZE;
return (-1);
}
*dn++ = '.';
}
if ((l = labellen((const unsigned char*)(cp - 1))) < 0) {
errno = EMSGSIZE; /* XXX */
return(-1);
}
if (dn + l >= eom) {
errno = EMSGSIZE;
return (-1);
}
if ((n & NS_CMPRSFLGS) == NS_TYPE_ELT) {
int m;
if (n != DNS_LABELTYPE_BITSTRING) {
/* XXX: labellen should reject this case */
errno = EINVAL;
return(-1);
}
if ((m = irc_decode_bitstring(&cp, dn, eom)) < 0)
{
errno = EMSGSIZE;
return(-1);
}
dn += m;
continue;
}
for ((void)NULL; l > 0; l--) {
c = *cp++;
if (special(c)) {
if (dn + 1 >= eom) {
errno = EMSGSIZE;
return (-1);
}
*dn++ = '\\';
*dn++ = (char)c;
} else if (!printable(c)) {
if (dn + 3 >= eom) {
errno = EMSGSIZE;
return (-1);
}
*dn++ = '\\';
*dn++ = digits[c / 100];
*dn++ = digits[(c % 100) / 10];
*dn++ = digits[c % 10];
} else {
if (dn >= eom) {
errno = EMSGSIZE;
return (-1);
}
*dn++ = (char)c;
}
}
}
if (dn == dst) {
if (dn >= eom) {
errno = EMSGSIZE;
return (-1);
}
*dn++ = '.';
}
if (dn >= eom) {
errno = EMSGSIZE;
return (-1);
}
*dn++ = '\0';
return (dn - dst);
}
/** Pack domain name from presentation form into compressed format.
* @param[in] src Presentation form of name.
* @param[out] dst Output buffer.
* @param[in] dstsiz Number of bytes that can be written to \a dst.
* @param[in,out] dnptrs Array of previously seen labels.
* @param[in] lastdnptr End of \a dnptrs array.
* @return Number of bytes written to \a dst.
*/
int
irc_dn_comp(const char *src, unsigned char *dst, int dstsiz,
unsigned char **dnptrs, unsigned char **lastdnptr)
{
return(irc_ns_name_compress(src, dst, (size_t)dstsiz,
(const unsigned char **)dnptrs,
(const unsigned char **)lastdnptr));
}
/** Skip over a compressed domain name.
* @param[in] ptr Start of compressed name.
* @param[in] eom End of message.
* @return Length of the compressed name, or -1 on error.
*/
int
irc_dn_skipname(const unsigned char *ptr, const unsigned char *eom) {
const unsigned char *saveptr = ptr;
if (irc_ns_name_skip(&ptr, eom) == -1)
return(-1);
return(ptr - saveptr);
}
/** Advance \a ptrptr to skip over the compressed name it points at.
* @param[in,out] ptrptr Pointer to the compressed name.
* @param[in] eom End of message.
* @return Zero on success; non-zero (with errno set) on failure.
*/
int
irc_ns_name_skip(const unsigned char **ptrptr, const unsigned char *eom)
{
const unsigned char *cp;
unsigned int n;
int l;
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_TYPE_ELT: /* EDNS0 extended label */
if ((l = labellen(cp - 1)) < 0)
{
errno = EMSGSIZE; /* XXX */
return(-1);
}
cp += l;
continue;
case NS_CMPRSFLGS: /* indirection */
cp++;
break;
default: /* illegal type */
errno = EMSGSIZE;
return(-1);
}
break;
}
if (cp > eom)
{
errno = EMSGSIZE;
return (-1);
}
*ptrptr = cp;
return(0);
}
/** Read a 16-bit network-endian value from \a src.
* @param[in] src Input data buffer.
* @return Value retrieved from buffer.
*/
unsigned int
irc_ns_get16(const unsigned char *src)
{
unsigned int dst;
IRC_NS_GET16(dst, src);
return(dst);
}
/** Read a 32-bit network-endian value from \a src.
* @param[in] src Input data buffer.
* @return Value retrieved from buffer.
*/
unsigned long
irc_ns_get32(const unsigned char *src)
{
unsigned long dst;
IRC_NS_GET32(dst, src);
return(dst);
}
/** Write a 16-bit network-endian value to \a dst.
* @param[in] src Value to write.
* @param[out] dst Output buffer.
*/
void
irc_ns_put16(unsigned int src, unsigned char *dst)
{
IRC_NS_PUT16(src, dst);
}
/** Write a 32-bit network-endian value to \a dst.
* @param[in] src Value to write.
* @param[out] dst Output buffer.
*/
void
irc_ns_put32(unsigned long src, unsigned char *dst)
{
IRC_NS_PUT32(src, dst);
}
/* From ns_name.c */
/** Indicate whether a character needs quoting.
* (What RFC does this come from?)
* @param[in] ch Character to check for specialness.
* @return Non-zero if the character should be quoted.
*/
static int
special(int ch)
{
switch (ch)
{
case 0x22: /* '"' */
case 0x2E: /* '.' */
case 0x3B: /* ';' */
case 0x5C: /* '\\' */
case 0x28: /* '(' */
case 0x29: /* ')' */
/* Special modifiers in zone files. */
case 0x40: /* '@' */
case 0x24: /* '$' */
return(1);
default:
return(0);
}
}
/** Calculate the length of a particular DNS label.
* @param[in] lp Start of label.
* @return Length of label, or -1 on error.
*/
static int
labellen(const unsigned char *lp)
{
int bitlen;
unsigned char l = *lp;
if ((l & NS_CMPRSFLGS) == NS_CMPRSFLGS)
{
/* should be avoided by the caller */
return(-1);
}
if ((l & NS_CMPRSFLGS) == NS_TYPE_ELT)
{
if (l == DNS_LABELTYPE_BITSTRING)
{
if ((bitlen = *(lp + 1)) == 0)
bitlen = 256;
return((bitlen + 7 ) / 8 + 1);
}
return(-1); /* unknown ELT */
}
return(l);
}
/** Indicate whether a character is printable.
* @param[in] ch Character to check for printability.
* @return Non-zero if the character is printable; zero if it is not.
*/
static int
printable(int ch)
{
return(ch > 0x20 && ch < 0x7f);
}
/** Decode a bitstring label from DNS.
* @param[in,out] cpp Pointer to start of label.
* @param[in,out] dn Output buffer.
* @param[in] eom End of message.
*/
static int
irc_decode_bitstring(const char **cpp, char *dn, const char *eom)
{
const char *cp = *cpp;
char *beg = dn, tc;
int b, blen, plen;
if ((blen = (*cp & 0xff)) == 0)
blen = 256;
plen = (blen + 3) / 4;
plen += sizeof("\\[x/]") + (blen > 99 ? 3 : (blen > 9) ? 2 : 1);
if (dn + plen >= eom)
return(-1);
cp++;
dn += sprintf(dn, "\\[x");
for (b = blen; b > 7; b -= 8, cp++)
dn += sprintf(dn, "%02x", *cp & 0xff);
if (b > 4) {
tc = *cp++;
dn += sprintf(dn, "%02x", tc & (0xff << (8 - b)));
} else if (b > 0) {
tc = *cp++;
dn += sprintf(dn, "%1x",
((tc >> 4) & 0x0f) & (0x0f << (4 - b)));
}
dn += sprintf(dn, "/%d]", blen);
*cpp = cp;
return(dn - beg);
}
/** Convert an ASCII name string into an encoded domain name.
* This function enforces per-label and total name lengths.
* @param[in] src ASCII name string.
* @param[out] dst Destination buffer.
* @param[in] dstsiz Number of bytes that can be written to \a dst.
* @return -1 on failure, 0 if \a src was not fully qualified, 1 if \a
* src was fully qualified.
*/
int
irc_ns_name_pton(const char *src, unsigned char *dst, size_t dstsiz)
{
unsigned char *label, *bp, *eom;
char *cp;
int c, n, escaped, e = 0;
escaped = 0;
bp = dst;
eom = dst + dstsiz;
label = bp++;
while ((c = *src++) != 0) {
if (escaped) {
if (c == '[') { /* start a bit string label */
if ((cp = strchr(src, ']')) == NULL) {
errno = EINVAL; /* ??? */
return(-1);
}
if ((e = irc_encode_bitsring(&src,
cp + 2,
&label,
&bp,
(const char *)eom))
!= 0) {
errno = e;
return(-1);
}
escaped = 0;
label = bp++;
if ((c = *src++) == 0)
goto done;
else if (c != '.') {
errno = EINVAL;
return(-1);
}
continue;
}
else if ((cp = strchr(digits, c)) != NULL) {
n = (cp - digits) * 100;
if ((c = *src++) == 0 ||
(cp = strchr(digits, c)) == NULL) {
errno = EMSGSIZE;
return (-1);
}
n += (cp - digits) * 10;
if ((c = *src++) == 0 ||
(cp = strchr(digits, c)) == NULL) {
errno = EMSGSIZE;
return (-1);
}
n += (cp - digits);
if (n > 255) {
errno = EMSGSIZE;
return (-1);
}
c = n;
}
escaped = 0;
} else if (c == '\\') {
escaped = 1;
continue;
} else if (c == '.') {
c = (bp - label - 1);
if ((c & NS_CMPRSFLGS) != 0) { /* Label too big. */
errno = EMSGSIZE;
return (-1);
}
if (label >= eom) {
errno = EMSGSIZE;
return (-1);
}
*label = c;
/* Fully qualified ? */
if (*src == '\0') {
if (c != 0) {
if (bp >= eom) {
errno = EMSGSIZE;
return (-1);
}
*bp++ = '\0';
}
if ((bp - dst) > NS_MAXCDNAME) {
errno = EMSGSIZE;
return (-1);
}
return (1);
}
if (c == 0 || *src == '.') {
errno = EMSGSIZE;
return (-1);
}
label = bp++;
continue;
}
if (bp >= eom) {
errno = EMSGSIZE;
return (-1);
}
*bp++ = (unsigned char)c;
}
c = (bp - label - 1);
if ((c & NS_CMPRSFLGS) != 0) { /* Label too big. */
errno = EMSGSIZE;
return (-1);
}
done:
if (label >= eom) {
errno = EMSGSIZE;
return (-1);
}
*label = c;
if (c != 0) {
if (bp >= eom) {
errno = EMSGSIZE;
return (-1);
}
*bp++ = 0;
}
if ((bp - dst) > NS_MAXCDNAME)
{ /* src too big */
errno = EMSGSIZE;
return (-1);
}
return (0);
}
/** Compress a domain name.
* @param[in] src List of length-prefixed labels.
* @param[out] dst Output buffer.
* @param[in] dstsiz Number of bytes that can be written to \a dst.
* @param[in,out] dnptrs Array of pointers to previously compressed names.
* @param[in] lastdnptr End of \a dnptrs array.
* @return Number of bytes written to \a dst.
*/
int
irc_ns_name_pack(const unsigned char *src, unsigned char *dst, int dstsiz,
const unsigned char **dnptrs, const unsigned char **lastdnptr)
{
unsigned char *dstp;
const unsigned char **cpp, **lpp, *eob, *msg;
const unsigned char *srcp;
int n, l, first = 1;
srcp = src;
dstp = dst;
eob = dstp + dstsiz;
lpp = cpp = NULL;
if (dnptrs != NULL) {
if ((msg = *dnptrs++) != NULL) {
for (cpp = dnptrs; *cpp != NULL; cpp++)
(void)NULL;
lpp = cpp; /* end of list to search */
}
} else
msg = NULL;
/* make sure the domain we are about to add is legal */
l = 0;
do {
int l0;
n = *srcp;
if ((n & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
errno = EMSGSIZE;
return (-1);
}
if ((l0 = labellen(srcp)) < 0) {
errno = EINVAL;
return(-1);
}
l += l0 + 1;
if (l > NS_MAXCDNAME) {
errno = EMSGSIZE;
return (-1);
}
srcp += l0 + 1;
} while (n != 0);
/* from here on we need to reset compression pointer array on error */
srcp = src;
do {
/* Look to see if we can use pointers. */
n = *srcp;
if (n != 0 && msg != NULL) {
l = irc_dn_find(srcp, msg, (const unsigned char * const *)dnptrs,
(const unsigned char * const *)lpp);
if (l >= 0) {
if (dstp + 1 >= eob) {
goto cleanup;
}
*dstp++ = (l >> 8) | NS_CMPRSFLGS;
*dstp++ = l % 256;
return (dstp - dst);
}
/* Not found, save it. */
if (lastdnptr != NULL && cpp < lastdnptr - 1 &&
(dstp - msg) < 0x4000 && first) {
*cpp++ = dstp;
*cpp = NULL;
first = 0;
}
}
/* copy label to buffer */
if ((n & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
/* Should not happen. */
goto cleanup;
}
n = labellen(srcp);
if (dstp + 1 + n >= eob) {
goto cleanup;
}
memcpy(dstp, srcp, n + 1);
srcp += n + 1;
dstp += n + 1;
} while (n != 0);
if (dstp > eob) {
cleanup:
if (msg != NULL)
*lpp = NULL;
errno = EMSGSIZE;
return (-1);
}
return(dstp - dst);
}
/** Encode and compress an ASCII domain name.
* @param[in] src ASCII domain name.
* @param[out] dst Output buffer.
* @param[in] dstsiz Number of bytes that can be written to \a dst.
* @param[in] dnptrs Array of previously compressed names.
* @param[in] lastdnptr End of \a dnptrs array.
*/
static int
irc_ns_name_compress(const char *src, unsigned char *dst, size_t dstsiz,
const unsigned char **dnptrs, const unsigned char **lastdnptr)
{
unsigned char tmp[NS_MAXCDNAME];
if (irc_ns_name_pton(src, tmp, sizeof tmp) == -1)
return(-1);
return(irc_ns_name_pack(tmp, dst, dstsiz, dnptrs, lastdnptr));
}
/** Encode a bitstring label.
* @param[in,out] bp Input buffer pointer.
* @param[in] end End of input buffer.
* @param[out] labelp Pointer to output label.
* @param[out] dst Output buffer.
* @param[out] eom End of output buffer.
*/
static int
irc_encode_bitsring(const char **bp, const char *end, unsigned char **labelp,
unsigned char **dst, const char *eom)
{
int afterslash = 0;
const char *cp = *bp;
char *tp, c;
const char *beg_blen;
char *end_blen = NULL;
int value = 0, count = 0, tbcount = 0, blen = 0;
beg_blen = end_blen = NULL;
/* a bitstring must contain at least 2 characters */
if (end - cp < 2)
return(EINVAL);
/* XXX: currently, only hex strings are supported */
if (*cp++ != 'x')
return(EINVAL);
if (!isxdigit((*cp) & 0xff)) /* reject '\[x/BLEN]' */
return(EINVAL);
for (tp = (char*)(*dst + 1); cp < end && tp < eom; cp++) {
switch((c = *cp)) {
case ']': /* end of the bitstring */
if (afterslash) {
if (beg_blen == NULL)
return(EINVAL);
blen = (int)strtol(beg_blen, &end_blen, 10);
if (*end_blen != ']')
return(EINVAL);
}
if (count)
*tp++ = ((value << 4) & 0xff);
cp++; /* skip ']' */
goto done;
case '/':
afterslash = 1;
break;
default:
if (afterslash) {
if (!isdigit(c&0xff))
return(EINVAL);
if (beg_blen == NULL) {
if (c == '0') {
/* blen never begins with 0 */
return(EINVAL);
}
beg_blen = cp;
}
} else {
if (!isxdigit(c&0xff))
return(EINVAL);
value <<= 4;
value += digitvalue[(int)c];
count += 4;
tbcount += 4;
if (tbcount > 256)
return(EINVAL);
if (count == 8) {
*tp++ = value;
count = 0;
}
}
break;
}
}
done:
if (cp >= end || tp >= eom)
return(EMSGSIZE);
/*
* bit length validation:
* If a <length> is present, the number of digits in the <bit-data>
* MUST be just sufficient to contain the number of bits specified
* by the <length>. If there are insignificant bits in a final
* hexadecimal or octal digit, they MUST be zero.
* RFC 2673, Section 3.2.
*/
if (blen > 0) {
int traillen;
if (((blen + 3) & ~3) != tbcount)
return(EINVAL);
traillen = tbcount - blen; /* between 0 and 3 */
if (((value << (8 - traillen)) & 0xff) != 0)
return(EINVAL);
}
else
blen = tbcount;
if (blen == 256)
blen = 0;
/* encode the type and the significant bit fields */
**labelp = DNS_LABELTYPE_BITSTRING;
**dst = blen;
*bp = cp;
*dst = (unsigned char*)tp;
return(0);
}
/** Find a name in an array of compressed name.
* @param[in] domain Name to search for.
* @param[in] msg Start of DNS message.
* @param[in] dnptrs Start of compressed name array.
* @param[in] lastdnptr End of compressed name array.
* @return Non-negative offset from \a msg, or -1 if not found.
*/
static int
irc_dn_find(const unsigned char *domain, const unsigned char *msg,
const unsigned char * const *dnptrs,
const unsigned char * const *lastdnptr)
{
const unsigned char *dn, *cp, *sp;
const unsigned char * const *cpp;
unsigned int n;
for (cpp = dnptrs; cpp < lastdnptr; cpp++)
{
sp = *cpp;
/*
* terminate search on:
* root label
* compression pointer
* unusable offset
*/
while (*sp != 0 && (*sp & NS_CMPRSFLGS) == 0 &&
(sp - msg) < 0x4000) {
dn = domain;
cp = sp;
while ((n = *cp++) != 0) {
/*
* check for indirection
*/
switch (n & NS_CMPRSFLGS) {
case 0: /* normal case, n == len */
n = labellen(cp - 1); /* XXX */
if (n != *dn++)
goto next;
for ((void)NULL; n > 0; n--)
if (mklower(*dn++) !=
mklower(*cp++))
goto next;
/* Is next root for both ? */
if (*dn == '\0' && *cp == '\0')
return (sp - msg);
if (*dn)
continue;
goto next;
case NS_CMPRSFLGS: /* indirection */
cp = msg + (((n & 0x3f) << 8) | *cp);
break;
default: /* illegal type */
errno = EMSGSIZE;
return (-1);
}
}
next: ;
sp += *sp + 1;
}
}
errno = ENOENT;
return (-1);
}
/** Convert a character to lowercase, assuming ASCII encoded English.
* @param[in] ch Character to convert.
* @return Lower-case version of \a ch.
*/
static int
mklower(int ch)
{
if (ch >= 0x41 && ch <= 0x5A)
return(ch + 0x20);
return(ch);
}
/* From resolv/mkquery.c */
/** Form a query for \a dname in \a buf.
* @param[in] dname Domain name to look up.
* @param[in] class Query class to set in header.
* @param[in] type Query type to set in header.
* @param[out] buf Output buffer for query.
* @param[in] buflen Number of bytes that can be written to \a buf.
* @return Length of message written to \a buf, or -1 on error.
*/
int
irc_res_mkquery(
const char *dname, /* domain name */
int class, int type, /* class and type of query */
unsigned char *buf, /* buffer to put query */
int buflen) /* size of buffer */
{
HEADER *hp;
unsigned char *cp;
int n;
unsigned char *dnptrs[20], **dpp, **lastdnptr;
/*
* Initialize header fields.
*/
if ((buf == NULL) || (buflen < HFIXEDSZ))
return (-1);
memset(buf, 0, HFIXEDSZ);
hp = (HEADER *) buf;
hp->id = 0;
hp->opcode = QUERY;
hp->rd = 1; /* recurse */
hp->rcode = NO_ERRORS;
cp = buf + HFIXEDSZ;
buflen -= HFIXEDSZ;
dpp = dnptrs;
*dpp++ = buf;
*dpp++ = NULL;
lastdnptr = dnptrs + sizeof dnptrs / sizeof dnptrs[0];
if ((buflen -= QFIXEDSZ) < 0)
return (-1);
if ((n = irc_dn_comp(dname, cp, buflen, dnptrs, lastdnptr)) < 0)
return (-1);
cp += n;
buflen -= n;
IRC_NS_PUT16(type, cp);
IRC_NS_PUT16(class, cp);
hp->qdcount = htons(1);
return (cp - buf);
}
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