1 files changed, 145 insertions, 0 deletions
diff --git a/src/knot/nameserver/chaos.c b/src/knot/nameserver/chaos.c
new file mode 100644
index 0000000..b83e2f5
--- /dev/null
+++ b/src/knot/nameserver/chaos.c
@@ -0,0 +1,145 @@
+/*  Copyright (C) 2018 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 <https://www.gnu.org/licenses/>.
+ */
+
+#include <strings.h>
+#include <stdlib.h>
+
+#include "knot/nameserver/chaos.h"
+#include "knot/conf/conf.h"
+#include "libknot/libknot.h"
+
+#define WISH "Knot DNS developers wish you "
+#define HOPE "Knot DNS developers hope you "
+
+static const char *wishes[] = {
+	HOPE "have all your important life questions answered without SERVFAIL.",
+	WISH "many wonderful people in your domain.",
+	WISH "non-empty lymph nodes.",
+	HOPE "resolve the . of your problems.",
+	WISH "long enough TTL.",
+	HOPE "become authoritative master in your domain.",
+	HOPE "always find useful PTR in CHAOS.",
+	"Canonical name is known to both DNS experts and Ubuntu users.",
+	HOPE "never forget both your name and address.",
+	"Don't fix broken CNAME chains with glue!",
+	WISH "no Additional section in your TODO list.",
+	HOPE "won't find surprising news in today's journal.",
+	HOPE "perform rollover often just when playing roulette.",
+	HOPE "get notified before your domain registration expires.",
+};
+
+#undef WISH
+#undef HOPE
+
+static const char *get_txt_response_string(knot_pkt_t *response)
+{
+	char qname[32];
+	if (knot_dname_to_str(qname, knot_pkt_qname(response), sizeof(qname)) == NULL) {
+		return NULL;
+	}
+
+	const char *response_str = NULL;
+
+	/* Allow hostname.bind. for compatibility. */
+	if (strcasecmp("id.server.",     qname) == 0 ||
+	    strcasecmp("hostname.bind.", qname) == 0) {
+		conf_val_t val = conf_get(conf(), C_SRV, C_IDENT);
+		if (val.code == KNOT_EOK) {
+			response_str = conf_str(&val); // Can be NULL!
+		} else {
+			response_str = conf()->hostname;
+		}
+	/* Allow version.bind. for compatibility. */
+	} else if (strcasecmp("version.server.", qname) == 0 ||
+	           strcasecmp("version.bind.",   qname) == 0) {
+		conf_val_t val = conf_get(conf(), C_SRV, C_VERSION);
+		if (val.code == KNOT_EOK) {
+			response_str = conf_str(&val); // Can be NULL!
+		} else {
+			response_str = "Knot DNS " PACKAGE_VERSION;
+		}
+	} else if (strcasecmp("fortune.", qname) == 0) {
+		conf_val_t val = conf_get(conf(), C_SRV, C_VERSION);
+		if (val.code != KNOT_EOK) {
+			uint16_t wishno = knot_wire_get_id(response->wire) %
+			                  (sizeof(wishes) / sizeof(wishes[0]));
+			response_str = wishes[wishno];
+		}
+	}
+
+	return response_str;
+}
+
+static int create_txt_rrset(knot_rrset_t *rrset, const knot_dname_t *owner,
+                            const char *response_str, knot_mm_t *mm)
+{
+	/* Truncate response to one TXT label. */
+	size_t response_len = strlen(response_str);
+	if (response_len > UINT8_MAX) {
+		response_len = UINT8_MAX;
+	}
+
+	knot_dname_t *rowner = knot_dname_copy(owner, mm);
+	if (rowner == NULL) {
+		return KNOT_ENOMEM;
+	}
+
+	knot_rrset_init(rrset, rowner, KNOT_RRTYPE_TXT, KNOT_CLASS_CH, 0);
+	uint8_t rdata[response_len + 1];
+
+	rdata[0] = response_len;
+	memcpy(&rdata[1], response_str, response_len);
+
+	int ret = knot_rrset_add_rdata(rrset, rdata, response_len + 1, mm);
+	if (ret != KNOT_EOK) {
+		knot_dname_free(rrset->owner, mm);
+		return ret;
+	}
+
+	return KNOT_EOK;
+}
+
+static int answer_txt(knot_pkt_t *response)
+{
+	const char *response_str = get_txt_response_string(response);
+	if (response_str == NULL || response_str[0] == '\0') {
+		return KNOT_RCODE_REFUSED;
+	}
+
+	knot_rrset_t rrset;
+	int ret = create_txt_rrset(&rrset, knot_pkt_qname(response),
+	                           response_str, &response->mm);
+	if (ret != KNOT_EOK) {
+		return KNOT_RCODE_SERVFAIL;
+	}
+
+	int result = knot_pkt_put(response, 0, &rrset, KNOT_PF_FREE);
+	if (result != KNOT_EOK) {
+		knot_rrset_clear(&rrset, &response->mm);
+		return KNOT_RCODE_SERVFAIL;
+	}
+
+	return KNOT_RCODE_NOERROR;
+}
+
+int knot_chaos_answer(knot_pkt_t *pkt)
+{
+	if (knot_pkt_qtype(pkt) != KNOT_RRTYPE_TXT) {
+		return KNOT_RCODE_REFUSED;
+	}
+
+	return answer_txt(pkt);
+}