diff options
Diffstat (limited to 'server/resolv/ares/ares_parse_srv_reply.c')
| -rw-r--r-- | server/resolv/ares/ares_parse_srv_reply.c | 173 |
1 files changed, 173 insertions, 0 deletions
diff --git a/server/resolv/ares/ares_parse_srv_reply.c b/server/resolv/ares/ares_parse_srv_reply.c new file mode 100644 index 000000000..9745fb07a --- /dev/null +++ b/server/resolv/ares/ares_parse_srv_reply.c @@ -0,0 +1,173 @@ +/* + SSSD + + Async resolver - SRV records parsing + + Authors: + Jakub Hrozek <jhrozek@redhat.com> + + Copyright (C) Red Hat, Inc 2009 + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 3 of the License, or + (at your option) any later version. + + This program 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 General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see <http://www.gnu.org/licenses/>. +*/ + +/* + * This code is based on other c-ares parsing licensed as follows: + + * Copyright 1998 by the Massachusetts Institute of Technology. + * + * Permission to use, copy, modify, and distribute this + * software and its documentation for any purpose and without + * fee is hereby granted, provided that the above copyright + * notice appear in all copies and that both that copyright + * notice and this permission notice appear in supporting + * documentation, and that the name of M.I.T. not be used in + * advertising or publicity pertaining to distribution of the + * software without specific, written prior permission. + * M.I.T. makes no representations about the suitability of + * this software for any purpose. It is provided "as is" + * without express or implied warranty. + */ + + +#include <sys/socket.h> +#include <netinet/in.h> +#include <arpa/inet.h> +#include <netdb.h> +#include <arpa/nameser.h> +#include <stdlib.h> +#include <string.h> +#include "ares.h" +/* this drags in some private macros c-ares uses */ +#include "ares_dns.h" + +#include "ares_parse_srv_reply.h" + +int _ares_parse_srv_reply (const unsigned char *abuf, int alen, + struct srv_reply **srv_out, int *nsrvreply) +{ + unsigned int qdcount, ancount; + const unsigned char *aptr; + int status, i, rr_type, rr_class, rr_len; + long len; + char *hostname = NULL, *rr_name = NULL; + struct srv_reply *srv = NULL; + + /* Set *srv_out to NULL for all failure cases. */ + if (srv_out) + *srv_out = NULL; + /* Same with *nsrvreply. */ + if (nsrvreply) + *nsrvreply = 0; + + /* Give up if abuf doesn't have room for a header. */ + if (alen < HFIXEDSZ) + return ARES_EBADRESP; + + /* Fetch the question and answer count from the header. */ + qdcount = DNS_HEADER_QDCOUNT (abuf); + ancount = DNS_HEADER_ANCOUNT (abuf); + if (qdcount != 1) + return ARES_EBADRESP; + if (ancount == 0) + return ARES_ENODATA; + + /* Expand the name from the question, and skip past the question. */ + aptr = abuf + HFIXEDSZ; + status = ares_expand_name (aptr, abuf, alen, &hostname, &len); + if (status != ARES_SUCCESS) + return status; + + if (aptr + len + QFIXEDSZ > abuf + alen) + { + free (hostname); + return ARES_EBADRESP; + } + aptr += len + QFIXEDSZ; + + /* Allocate srv_reply array; ancount gives an upper bound */ + srv = malloc ((ancount) * sizeof (struct srv_reply)); + if (!srv) + { + free (hostname); + return ARES_ENOMEM; + } + + /* Examine each answer resource record (RR) in turn. */ + for (i = 0; i < (int) ancount; i++) + { + /* Decode the RR up to the data field. */ + status = ares_expand_name (aptr, abuf, alen, &rr_name, &len); + if (status != ARES_SUCCESS) + { + break; + } + aptr += len; + if (aptr + RRFIXEDSZ > abuf + alen) + { + status = ARES_EBADRESP; + break; + } + rr_type = DNS_RR_TYPE (aptr); + rr_class = DNS_RR_CLASS (aptr); + rr_len = DNS_RR_LEN (aptr); + aptr += RRFIXEDSZ; + + /* Check if we are really looking at a SRV record */ + if (rr_class == C_IN && rr_type == T_SRV) + { + /* parse the SRV record itself */ + if (rr_len < 6) + { + status = ARES_EBADRESP; + break; + } + + srv[i].priority = ntohs (*((const uint16_t *)aptr)); + aptr += sizeof(uint16_t); + srv[i].weight = ntohs (*((const uint16_t *)aptr)); + aptr += sizeof(uint16_t); + srv[i].port = ntohs (*((const uint16_t *)aptr)); + aptr += sizeof(uint16_t); + + status = ares_expand_name (aptr, abuf, alen, &srv[i].host, &len); + if (status != ARES_SUCCESS) + break; + + /* Move on to the next record */ + aptr += len; + + /* Don't lose memory in the next iteration */ + free (rr_name); + rr_name = NULL; + } + } + + /* clean up on error */ + if (status != ARES_SUCCESS) + { + free (srv); + free (hostname); + free (rr_name); + return status; + } + + /* everything looks fine, return the data */ + *srv_out = srv; + *nsrvreply = ancount; + + free (hostname); + free (rr_name); + return status; +} |