diff options
Diffstat (limited to 'REORG.TODO/resolv/nss_dns/dns-canon.c')
| -rw-r--r-- | REORG.TODO/resolv/nss_dns/dns-canon.c | 173 |
1 files changed, 173 insertions, 0 deletions
diff --git a/REORG.TODO/resolv/nss_dns/dns-canon.c b/REORG.TODO/resolv/nss_dns/dns-canon.c new file mode 100644 index 0000000000..4276eb6542 --- /dev/null +++ b/REORG.TODO/resolv/nss_dns/dns-canon.c @@ -0,0 +1,173 @@ +/* Copyright (C) 2004-2017 Free Software Foundation, Inc. + This file is part of the GNU C Library. + Contributed by Ulrich Drepper <drepper@redhat.com>, 2004. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <http://www.gnu.org/licenses/>. */ + +#include <errno.h> +#include <netdb.h> +#include <resolv.h> +#include <stdlib.h> +#include <stdint.h> +#include <arpa/nameser.h> +#include <nsswitch.h> + + +#if PACKETSZ > 65536 +# define MAXPACKET PACKETSZ +#else +# define MAXPACKET 65536 +#endif + + +/* We need this time later. */ +typedef union querybuf +{ + HEADER hdr; + unsigned char buf[MAXPACKET]; +} querybuf; + + +static const short int qtypes[] = { ns_t_a, ns_t_aaaa }; +#define nqtypes (sizeof (qtypes) / sizeof (qtypes[0])) + + +enum nss_status +_nss_dns_getcanonname_r (const char *name, char *buffer, size_t buflen, + char **result,int *errnop, int *h_errnop) +{ + /* Just an alibi buffer, res_nquery will allocate a real buffer for + us. */ + unsigned char buf[20]; + union + { + querybuf *buf; + unsigned char *ptr; + } ansp = { .ptr = buf }; + enum nss_status status = NSS_STATUS_UNAVAIL; + + for (int i = 0; i < nqtypes; ++i) + { + int r = __libc_res_nquery (&_res, name, ns_c_in, qtypes[i], + buf, sizeof (buf), &ansp.ptr, NULL, NULL, + NULL, NULL); + if (r > 0) + { + /* We need to decode the response. Just one question record. + And if we got no answers we bail out, too. */ + if (ansp.buf->hdr.qdcount != htons (1)) + continue; + + /* Number of answers. */ + unsigned int ancount = ntohs (ansp.buf->hdr.ancount); + + /* Beginning and end of the buffer with query, answer, and the + rest. */ + unsigned char *ptr = &ansp.buf->buf[sizeof (HEADER)]; + unsigned char *endptr = ansp.ptr + r; + + /* Skip over the query. This is the name, type, and class. */ + int s = __dn_skipname (ptr, endptr); + if (s < 0) + { + unavail: + status = NSS_STATUS_UNAVAIL; + break; + } + + /* Skip over the name and the two 16-bit values containing type + and class. */ + ptr += s + 2 * sizeof (uint16_t); + + while (ancount-- > 0) + { + /* Now the reply. First again the name from the query, + then type, class, TTL, and the length of the RDATA. + We remember the name start. */ + unsigned char *namestart = ptr; + s = __dn_skipname (ptr, endptr); + if (s < 0) + goto unavail; + + ptr += s; + + /* Check that there are enough bytes for the RR + metadata. */ + if (endptr - ptr < 10) + goto unavail; + + /* Check whether type and class match. */ + uint_fast16_t type; + NS_GET16 (type, ptr); + if (type == qtypes[i]) + { + /* We found the record. */ + s = __dn_expand (ansp.buf->buf, endptr, namestart, + buffer, buflen); + if (s < 0) + { + if (errno != EMSGSIZE) + goto unavail; + + /* The buffer is too small. */ + *errnop = ERANGE; + status = NSS_STATUS_TRYAGAIN; + h_errno = NETDB_INTERNAL; + } + else + { + /* Success. */ + *result = buffer; + status = NSS_STATUS_SUCCESS; + } + + goto out; + } + + if (type != ns_t_cname) + goto unavail; + + if (__ns_get16 (ptr) != ns_c_in) + goto unavail; + + /* Also skip over class and TTL. */ + ptr += sizeof (uint16_t) + sizeof (uint32_t); + + /* Skip over RDATA length and RDATA itself. */ + uint16_t rdatalen = __ns_get16 (ptr); + ptr += sizeof (uint16_t); + /* Not enough room for RDATA. */ + if (endptr - ptr < rdatalen) + goto unavail; + ptr += rdatalen; + } + } + + /* Restore original buffer before retry. */ + if (ansp.ptr != buf) + { + free (ansp.ptr); + ansp.ptr = buf; + } + } + + out: + *h_errnop = h_errno; + + if (ansp.ptr != buf) + free (ansp.ptr); + + return status; +} |