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Diffstat (limited to 'src/libknot/nameserver/chaos.c')
| -rw-r--r-- | src/libknot/nameserver/chaos.c | 139 |
1 files changed, 139 insertions, 0 deletions
diff --git a/src/libknot/nameserver/chaos.c b/src/libknot/nameserver/chaos.c new file mode 100644 index 0000000..e548482 --- /dev/null +++ b/src/libknot/nameserver/chaos.c @@ -0,0 +1,139 @@ +/* Copyright (C) 2011 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz> + + 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/>. + */ + +#include <config.h> +#include <strings.h> + +#include "chaos.h" +#include "common/descriptor.h" +#include "packet/packet.h" +#include "packet/response.h" + +/*! + * \brief Get a string result for a given TXT query. + */ +static const char *get_txt_response_string(const knot_nameserver_t *nameserver, + const knot_dname_t *qname) +{ + char *qname_str = knot_dname_to_str(qname); + const char *response = NULL; + + if (strcasecmp("id.server.", qname_str) == 0) { + response = nameserver->identity; + } else if (strcasecmp("version.server.", qname_str) == 0) { + response = nameserver->version; + } else if (strcasecmp("hostname.server.", qname_str) == 0) { + response = nameserver->hostname; + } + + free(qname_str); + + return response; +} + +/*! + * \brief Create TXT RR with a given string content. + * + * \param owner RR owner name. + * \param response String to be saved in RDATA. Truncated to 255 chars. + * + * \return Allocated RRset or NULL in case of error. + */ +static knot_rrset_t *create_txt_rrset(const knot_dname_t *owner, + const char *response) +{ + // truncate response to one TXT label + size_t response_len = strlen(response); + if (response_len > 255) + response_len = 255; + + knot_dname_t *rowner = knot_dname_deep_copy(owner); + if (!rowner) + return NULL; + + knot_rrset_t *rrset; + rrset = knot_rrset_new(rowner, KNOT_RRTYPE_TXT, KNOT_CLASS_CH, 0); + knot_dname_release(rowner); + if (!rrset) + return NULL; + + uint8_t *rdata = knot_rrset_create_rdata(rrset, response_len + 1); + if (!rdata) { + knot_rrset_deep_free(&rrset, 1, 0); + return NULL; + } + + rdata[0] = response_len; + memcpy(&rdata[1], response, response_len); + + return rrset; +} + +/*! + * \brief Create a response for a TXT CHAOS query. + * + * \param return KNOT_RCODE_NOERROR if the response was succesfully created, + * otherwise an RCODE representing the failure. + */ +static int answer_txt(knot_nameserver_t *nameserver, knot_packet_t *response, + uint8_t *response_wire, size_t *response_size) +{ + const knot_dname_t *qname = knot_packet_qname(response); + const char *response_str = get_txt_response_string(nameserver, qname); + if (response_str == NULL || response_str[0] == '\0') + return KNOT_RCODE_REFUSED; + + knot_rrset_t *rrset = create_txt_rrset(qname, response_str); + if (!rrset) + return KNOT_RCODE_SERVFAIL; + + int result = knot_response_add_rrset_answer(response, rrset, 1, 0, 0); + if (result != KNOT_EOK) { + knot_rrset_deep_free(&rrset, 1, 0); + return KNOT_RCODE_SERVFAIL; + } + + result = ns_response_to_wire(response, response_wire, response_size); + if (result != KNOT_EOK) { + knot_rrset_deep_free(&rrset, 1, 0); + return KNOT_RCODE_SERVFAIL; + } + + knot_rrset_deep_free(&rrset, 1, 0); + knot_response_set_rcode(response, KNOT_RCODE_NOERROR); + + return KNOT_RCODE_NOERROR; +} + +/*! + * \brief Create a response for a given query in the CHAOS class. + */ +int knot_ns_answer_chaos(knot_nameserver_t *nameserver, knot_packet_t *resp, + uint8_t *resp_wire, size_t *resp_size) +{ + int rcode = KNOT_RCODE_REFUSED; + + if (knot_packet_qtype(resp) == KNOT_RRTYPE_TXT) { + rcode = answer_txt(nameserver, resp, resp_wire, resp_size); + } + + if (rcode != KNOT_RCODE_NOERROR) { + knot_ns_error_response_full(nameserver, resp, rcode, + resp_wire, resp_size); + } + + return KNOT_EOK; +} |