diff options
| -rw-r--r-- | resolv/nss_dns/dns-canon.c | 156 |
1 files changed, 86 insertions, 70 deletions
diff --git a/resolv/nss_dns/dns-canon.c b/resolv/nss_dns/dns-canon.c index e5b38f5e7c..ae3f40ba0a 100644 --- a/resolv/nss_dns/dns-canon.c +++ b/resolv/nss_dns/dns-canon.c @@ -53,81 +53,97 @@ _nss_dns_getcanonname_r (const char *name, char *buffer, size_t buflen, unsigned char *ptr; } ansp = { .ptr = buf }; enum nss_status status; + int qtypes[] = { ns_t_a, ns_t_aaaa }; +#define nqtypes (sizeof (qtypes) / sizeof (qtypes[0])) - int r = __libc_res_nquery (&_res, name, ns_c_in, ns_t_cname, - buf, sizeof (buf), &ansp.ptr); - if (r > 0) + for (int i = 0; i < nqtypes; ++i) { - /* 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) - || ansp.buf->hdr.ancount == 0) - goto unavail; - - /* 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) - goto unavail; - - /* Skip over the name and the two 16-bit values containing type - and class. */ - ptr += s + 2 * sizeof (uint16_t); - - /* Now the reply. First again the name from the query, then - type, class, TTL, and the length of the RDATA. */ - s = __dn_skipname (ptr, endptr); - if (s < 0) - goto unavail; - - ptr += s; - - /* Check whether type and class match. */ - if (*(uint16_t *) ptr != htons (ns_t_cname)) - goto unavail; - - ptr += sizeof (uint16_t); - if (*(uint16_t *) ptr != htons (ns_c_in)) - goto unavail; - - /* Also skip over the TTL and rdata length. */ - ptr += sizeof (uint16_t) + sizeof (uint32_t) + sizeof (int16_t); - - /* Now the name we are looking for. */ - s = __dn_expand (ansp.buf->buf, endptr, ptr, buffer, buflen); - if (s < 0) + int r = __libc_res_nquery (&_res, name, ns_c_in, qtypes[i], + buf, sizeof (buf), &ansp.ptr); + if (r > 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; + /* 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 whether type and class match. */ + unsigned int type = ntohs (*(uint16_t *) 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; + + ptr += sizeof (uint16_t); + if (*(uint16_t *) ptr != htons (ns_c_in)) + goto unavail; + + /* Also skip over the TTL. */ + ptr += sizeof (uint16_t) + sizeof (uint32_t); + + /* Skip over the data length and data. */ + ptr += sizeof (uint16_t) + ntohs (*(uint16_t *) ptr); + } } } - else if (h_errno == TRY_AGAIN) - { - again: - status = NSS_STATUS_TRYAGAIN; - *errnop = errno; - } - else - { - unavail: - status = NSS_STATUS_UNAVAIL; - *errnop = errno; - } + + out: *h_errnop = h_errno; if (ansp.ptr != buf) |