diff options
Diffstat (limited to 'resolv/ns_name_pack.c')
| -rw-r--r-- | resolv/ns_name_pack.c | 202 |
1 files changed, 202 insertions, 0 deletions
diff --git a/resolv/ns_name_pack.c b/resolv/ns_name_pack.c new file mode 100644 index 0000000..3200b78 --- /dev/null +++ b/resolv/ns_name_pack.c @@ -0,0 +1,202 @@ +/* Compression of DNS domain names. + * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC") + * 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 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. + */ + +#include <arpa/nameser.h> +#include <errno.h> +#include <string.h> +#include <shlib-compat.h> + +/* 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 >= 'A' && ch <= 'Z') + return ch - 'A' + 'a'; + return ch; +} + +/* Search for the counted-label name in an array of compressed names. + Returns 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 (const unsigned char *domain, const unsigned char *msg, + const unsigned char **dnptrs, + const unsigned char **lastdnptr) +{ + const unsigned char *dn, *cp, *sp; + const unsigned char **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. */ + if (n != *dn++) + goto next; + + for (; 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. */ + __set_errno (EMSGSIZE); + return -1; + } + } + next: ; + sp += *sp + 1; + } + } + __set_errno (ENOENT); + return -1; +} + +/* Packs domain name SRC into DST. Returns size of the compressed + name, or -1. + + 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'. + + The list of pointers in DNPTRS is updated for labels inserted into + the message as we compress the name. If DNPTRS is NULL, we don't + try to compress names. If LASTDNPTR is NULL, we don't update the + list. */ +int +___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++) + ; + 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 >= 64) + { + __set_errno (EMSGSIZE); + return -1; + } + l += n + 1; + if (l > MAXCDNAME) + { + __set_errno (EMSGSIZE); + return -1; + } + srcp += n + 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 = dn_find (srcp, msg, dnptrs, lpp); + if (l >= 0) + { + if (eob - dstp <= 1) + 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 >= 64) + /* Should not happen. */ + goto cleanup; + if (n + 1 > eob - dstp) + 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; + __set_errno (EMSGSIZE); + return -1; + } + return dstp - dst; +} +versioned_symbol (libc, ___ns_name_pack, ns_name_pack, GLIBC_2_34); +versioned_symbol (libc, ___ns_name_pack, __ns_name_pack, GLIBC_PRIVATE); +libc_hidden_ver (___ns_name_pack, __ns_name_pack) + +#if OTHER_SHLIB_COMPAT (libresolv, GLIBC_2_9, GLIBC_2_34) +compat_symbol (libresolv, ___ns_name_pack, ns_name_pack, GLIBC_2_9); +#endif |