StdLib/BsdSocketLib/ns_name.c

/*
 * Copyright (c) 1996 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.
 */

/*
 * Portions copyright (c) 1999, 2000
 * Intel Corporation.
 * 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 Intel Corporation and
 *    its contributors.
 *
 * 4. Neither the name of Intel Corporation or its contributors may be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY INTEL CORPORATION 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 INTEL CORPORATION 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.
 *
 */

#ifndef lint
static char rcsid[] = "$Id: ns_name.c,v 1.1.1.1 2003/11/19 01:51:32 kyu3 Exp $";
#endif

#include <sys/types.h>

#include <netinet/in.h>
#include <arpa/nameser.h>

#include <errno.h>
#include <resolv.h>
#include <string.h>

/* Data. */

static char     digits[] = "0123456789";

/* Forward. */

static int      special(int);
static int      printable(int);
static int      dn_find(const u_char *, const u_char *,
                const u_char * const *,
                const u_char * const *);

/* Public. */

/*
 * 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
 */
int
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) {
            /* Some kind of compression pointer. */
            errno = EMSGSIZE;
            return (-1);
        }
        if (dn != dst) {
            if (dn >= eom) {
                errno = EMSGSIZE;
                return (-1);
            }
            *dn++ = '.';
        }
        if (dn + n >= eom) {
            errno = EMSGSIZE;
            return (-1);
        }
        for ((void)NULL; n > 0; n--) {
            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 ((int)(dn - dst));
}

/*
 * ns_name_pton(src, dst, dstsiz)
 *  Convert a ascii string into an encoded domain name as per RFC1035.
 * return:
 *  -1 if it fails
 *  1 if string was fully qualified
 *  0 is string was not fully qualified
 * notes:
 *  Enforces label and domain length limits.
 */

int
ns_name_pton(const char *src, u_char *dst, size_t dstsiz) {
    u_char *label, *bp, *eom;
    int c, n, escaped;
    char *cp;

    escaped = 0;
    bp = dst;
    eom = dst + dstsiz;
    label = bp++;

    while ((c = *src++) != 0) {
        if (escaped) {
            if ((cp = strchr(digits, c)) != NULL) {
                n = (int)(cp - digits) * 100;
                if ((c = *src++) == 0 ||
                    (cp = strchr(digits, c)) == NULL) {
                    errno = EMSGSIZE;
                    return (-1);
                }
                n += (int)(cp - digits) * 10;
                if ((c = *src++) == 0 ||
                    (cp = strchr(digits, c)) == NULL) {
                    errno = EMSGSIZE;
                    return (-1);
                }
                n += (int)(cp - digits);
                if (n > 255) {
                    errno = EMSGSIZE;
                    return (-1);
                }
                c = n;
            }
            escaped = 0;
        } else if (c == '\\') {
            escaped = 1;
            continue;
        } else if (c == '.') {
            c = ((int)(bp - label) - 1);
            if ((c & NS_CMPRSFLGS) != 0) {  /* Label too big. */
                errno = EMSGSIZE;
                return (-1);
            }
            if (label >= eom) {
                errno = EMSGSIZE;
                return (-1);
            }
            *label = (u_char)c;
            /* Fully qualified ? */
            if (*src == '\0') {
                if (c != 0) {
                    if (bp >= eom) {
                        errno = EMSGSIZE;
                        return (-1);
                    }
                    *bp++ = '\0';
                }
                if ((bp - dst) > MAXCDNAME) {
                    errno = EMSGSIZE;
                    return (-1);
                }
                return (1);
            }
            if (c == 0) {
                errno = EMSGSIZE;
                return (-1);
            }
            label = bp++;
            continue;
        }
        if (bp >= eom) {
            errno = EMSGSIZE;
            return (-1);
        }
        *bp++ = (u_char)c;
    }
    c = ((int)(bp - label) - 1);
    if ((c & NS_CMPRSFLGS) != 0) {      /* Label too big. */
        errno = EMSGSIZE;
        return (-1);
    }
    if (label >= eom) {
        errno = EMSGSIZE;
        return (-1);
    }
    *label = (u_char)c;
    if (c != 0) {
        if (bp >= eom) {
            errno = EMSGSIZE;
            return (-1);
        }
        *bp++ = 0;
    }
    if ((bp - dst) > MAXCDNAME) {   /* src too big */
        errno = EMSGSIZE;
        return (-1);
    }
    return (0);
}

/*
 * 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.
 */
int
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) {
        errno = EMSGSIZE;
        return (-1);
    }
    /* Fetch next label in domain name. */
    while ((n = *srcp++) != 0) {
        /* Check for indirection. */
        switch (n & NS_CMPRSFLGS) {
        case 0:
            /* Limit checks. */
            if (dstp + n + 1 >= dstlim || srcp + n >= eom) {
                errno = EMSGSIZE;
                return (-1);
            }
            checked += n + 1;
            *dstp++ = (u_char)n;
            memcpy(dstp, srcp, n);
            dstp += n;
            srcp += n;
            break;

        case NS_CMPRSFLGS:
            if (srcp >= eom) {
                errno = EMSGSIZE;
                return (-1);
            }
            if (len < 0)
                len = (int)(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 = (int)(srcp - src);
    return (len);
}

/*
 * ns_name_pack(src, dst, dstsiz, dnptrs, lastdnptr)
 *  Pack domain name 'domain' into 'comp_dn'.
 * return:
 *  Size of the compressed name, or -1.
 * notes:
 *  'dnptrs' is an array of pointers to previous compressed names.
 *  dnptrs[0] is a pointer to the beginning of the message. The array
 *  ends with NULL.
 *  'lastdnptr' is a pointer to the end of the array pointed to
 *  by 'dnptrs'.
 * Side effects:
 *  The list of pointers in dnptrs is updated 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
ns_name_pack(const u_char *src, u_char *dst, int dstsiz,
         const u_char **dnptrs, const u_char **lastdnptr)
{
    u_char *dstp;
    const u_char **cpp, **lpp, *eob, *msg;
    const u_char *srcp;
    int n, l;

    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 {
        n = *srcp;
        if ((n & NS_CMPRSFLGS) != 0) {
            errno = EMSGSIZE;
            return (-1);
        }
        l += n + 1;
        if (l > MAXCDNAME) {
            errno = EMSGSIZE;
            return (-1);
        }
        srcp += n + 1;
    } while (n != 0);

    srcp = src;
    do {
        /* Look to see if we can use pointers. */
        n = *srcp;
        if (n != 0 && msg != NULL) {
            l = dn_find(srcp, msg, (const u_char * const *)dnptrs,
                    (const u_char * const *)lpp);
            if (l >= 0) {
                if (dstp + 1 >= eob) {
                    errno = EMSGSIZE;
                    return (-1);
                }
                *dstp++ = (u_char)((l >> 8) | NS_CMPRSFLGS );
                *dstp++ = (u_char)( l % 256 );
                return ((int)(dstp - dst));
            }
            /* Not found, save it. */
            if (lastdnptr != NULL && cpp < lastdnptr - 1 &&
                (dstp - msg) < 0x4000) {
                *cpp++ = dstp;
                *cpp = NULL;
            }
        }
        /* copy label to buffer */
        if (n & NS_CMPRSFLGS) {     /* Should not happen. */
            errno = EMSGSIZE;
            return (-1);
        }
        if (dstp + 1 + n >= eob) {
            errno = EMSGSIZE;
            return (-1);
        }
        memcpy(dstp, srcp, n + 1);
        srcp += n + 1;
        dstp += n + 1;
    } while (n != 0);

    if (dstp > eob) {
        if (msg != NULL)
            *lpp = NULL;
        errno = EMSGSIZE;
        return (-1);
    }
    return ((int)(dstp - dst));
}

/*
 * 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
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 = ns_name_unpack(msg, eom, src, tmp, sizeof tmp)) == -1)
        return (-1);
    if (ns_name_ntop(tmp, dst, dstsiz) == -1)
        return (-1);
    return (n);
}

/*
 * ns_name_compress(src, dst, dstsiz, dnptrs, lastdnptr)
 *  Compress a domain name into wire format, using compression pointers.
 * return:
 *  Number of bytes consumed in `dst' or -1 (with errno set).
 * notes:
 *  'dnptrs' is an array 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
ns_name_compress(const char *src, u_char *dst, size_t dstsiz,
         const u_char **dnptrs, const u_char **lastdnptr)
{
    u_char tmp[NS_MAXCDNAME];

    if (ns_name_pton(src, tmp, sizeof tmp) == -1)
        return (-1);
    return (ns_name_pack(tmp, dst, (int)dstsiz, dnptrs, lastdnptr));
}

/*
 * 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
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 */
            errno = EMSGSIZE;
            return (-1);
        }
        break;
    }
    if (cp > eom) {
        errno = EMSGSIZE;
        return (-1);
    }
    *ptrptr = cp;
    return (0);
}

/* Private. */

/*
 * special(ch)
 *  Thinking in noninternationalized USASCII (per the DNS spec),
 *  is this characted 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);
}

/*
 *  Thinking in noninternationalized USASCII (per the DNS spec),
 *  convert this character to lower case if it's upper case.
 */
static int
mklower(int ch) {
    if (ch >= 0x41 && ch <= 0x5A)
        return (ch + 0x20);
    return (ch);
}

/*
 * dn_find(domain, msg, dnptrs, lastdnptr)
 *  Search for the counted-label name in an array of compressed names.
 * return:
 *  offset from msg if found, or -1.
 * notes:
 *  dnptrs is the pointer to the first name on the list,
 *  not the pointer to the start of the message.
 */
static int
dn_find(const u_char *domain, const u_char *msg,
    const u_char * const *dnptrs,
    const u_char * const *lastdnptr)
{
    const u_char *dn, *cp, *sp;
    const u_char * const *cpp;
    u_int n;

    for (cpp = dnptrs; cpp < lastdnptr; cpp++) {
        dn = domain;
        sp = cp = *cpp;
        while ((n = *cp++) != 0) {
            /*
             * check for indirection
             */
            switch (n & NS_CMPRSFLGS) {
            case 0:         /* normal case, n == len */
                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 ((int)(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: ;
    }
    errno = ENOENT;
    return (-1);
}