Adding upstream version 3.7.9.upstream/3.7.9upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1066 insertions, 0 deletions

diff --git a/libdane/dane.c b/libdane/dane.c
new file mode 100644
index 0000000..c9cbe84
--- /dev/null
+++ b/libdane/dane.c
@@ -0,0 +1,1066 @@
+/*
+ * Copyright (C) 2012 KU Leuven
+ * Copyright (C) 2013 Christian Grothoff
+ * Copyright (C) 2013 Nikos Mavrogiannopoulos
+ *
+ * Author: Nikos Mavrogiannopoulos
+ *
+ * This file is part of libdane.
+ *
+ * The libdane 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.
+ *
+ * This 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 this program.  If not, see <https://www.gnu.org/licenses/>
+ *
+ */
+
+#include <config.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <arpa/inet.h>
+#include <unbound.h>
+#include <gnutls/dane.h>
+#include <gnutls/x509.h>
+#include <gnutls/abstract.h>
+#include <gnutls/crypto.h>
+#include "../lib/gnutls_int.h"
+
+#define MAX_DATA_ENTRIES 100
+
+#undef gnutls_assert
+#undef gnutls_assert_val
+
+#ifdef DEBUG
+#define gnutls_assert() fprintf(stderr, "ASSERT: %s: %d\n", __FILE__, __LINE__);
+#define gnutls_assert_val(x) gnutls_assert_val_int(x, __FILE__, __LINE__)
+static int gnutls_assert_val_int(int val, const char *file, int line)
+{
+	fprintf(stderr, "ASSERT: %s: %d\n", file, line);
+	return val;
+}
+#else
+#define gnutls_assert()
+#define gnutls_assert_val(x) (x)
+#endif
+
+struct dane_state_st {
+	struct ub_ctx *ctx;
+	unsigned int flags;
+};
+
+struct dane_query_st {
+	struct ub_result *result;
+	unsigned int data_entries;
+	dane_cert_usage_t usage[MAX_DATA_ENTRIES];
+	dane_cert_type_t type[MAX_DATA_ENTRIES];
+	dane_match_type_t match[MAX_DATA_ENTRIES];
+	gnutls_datum_t data[MAX_DATA_ENTRIES];
+	unsigned int flags;
+	dane_query_status_t status;
+};
+
+/**
+ * dane_query_status:
+ * @q: The query result structure
+ *
+ * This function will return the status of the query response.
+ * See %dane_query_status_t for the possible types.
+ *
+ * Returns: The status type.
+ **/
+dane_query_status_t dane_query_status(dane_query_t q)
+{
+	return q->status;
+}
+
+/**
+ * dane_query_entries:
+ * @q: The query result structure
+ *
+ * This function will return the number of entries in a query.
+ *
+ * Returns: The number of entries.
+ **/
+unsigned int dane_query_entries(dane_query_t q)
+{
+	return q->data_entries;
+}
+
+/**
+ * dane_query_data:
+ * @q: The query result structure
+ * @idx: The index of the query response.
+ * @usage: The certificate usage (see %dane_cert_usage_t)
+ * @type: The certificate type (see %dane_cert_type_t)
+ * @match: The DANE matching type (see %dane_match_type_t)
+ * @data: The DANE data.
+ *
+ * This function will provide the DANE data from the query
+ * response.
+ *
+ * Returns: On success, %DANE_E_SUCCESS (0) is returned, otherwise a
+ *   negative error value.
+ **/
+int
+dane_query_data(dane_query_t q, unsigned int idx,
+		unsigned int *usage, unsigned int *type,
+		unsigned int *match, gnutls_datum_t * data)
+{
+	if (idx >= q->data_entries)
+		return
+		    gnutls_assert_val(DANE_E_REQUESTED_DATA_NOT_AVAILABLE);
+
+	if (usage)
+		*usage = q->usage[idx];
+	if (type)
+		*type = q->type[idx];
+	if (match)
+		*match = q->match[idx];
+	if (data) {
+		data->data = q->data[idx].data;
+		data->size = q->data[idx].size;
+	}
+
+	return DANE_E_SUCCESS;
+}
+
+/**
+ * dane_query_to_raw_tlsa:
+ * @q: The query result structure
+ * @data_entries: Pointer set to the number of entries in the query
+ * @dane_data: Pointer to contain an array of DNS rdata items, terminated with a NULL pointer;
+ *             caller must guarantee that the referenced data remains
+ *             valid until dane_query_deinit() is called.
+ * @dane_data_len: Pointer to contain the length n bytes of the dane_data items
+ * @secure: Pointer set true if the result is validated securely, false if
+ *               validation failed or the domain queried has no security info
+ * @bogus: Pointer set true if the result was not secure due to a security failure
+ *
+ * This function will provide the DANE data from the query
+ * response.
+ *
+ * The pointers dane_data and dane_data_len are allocated with gnutls_malloc()
+ * to contain the data from the query result structure (individual
+ * @dane_data items simply point to the original data and are not allocated separately).
+ * The returned @dane_data are only valid during the lifetime of @q.
+ *
+ * Returns: On success, %DANE_E_SUCCESS (0) is returned, otherwise a
+ *   negative error value.
+ */
+int
+dane_query_to_raw_tlsa(dane_query_t q, unsigned int *data_entries,
+		char ***dane_data, int **dane_data_len, int *secure, int *bogus)
+{
+	size_t data_sz;
+	char *data_buf;
+	unsigned int idx;
+
+	*data_entries = 0;
+	*dane_data = NULL;
+	*dane_data_len = NULL;
+
+	if (secure) {
+		if (q->status & DANE_QUERY_DNSSEC_VERIFIED)
+			*secure = 1;
+		else
+			*secure = 0;
+	}
+
+	if (bogus) {
+		if (q->status & DANE_QUERY_BOGUS)
+			*bogus = 1;
+		else
+			*bogus = 0;
+	}
+
+	/* pack dane_data pointer list followed by dane_data contents */
+	data_sz = sizeof (**dane_data) * (q->data_entries + 1);
+	for (idx = 0; idx < q->data_entries; idx++)
+		data_sz += 3 + q->data[idx].size;
+
+	*dane_data = gnutls_calloc (1, data_sz);
+	if (*dane_data == NULL)
+		return DANE_E_MEMORY_ERROR;
+	data_buf = (char *)*dane_data;
+	data_buf += sizeof (**dane_data) * (q->data_entries + 1);
+
+	*dane_data_len = gnutls_calloc (q->data_entries + 1, sizeof (**dane_data_len));
+	if (*dane_data_len == NULL) {
+		free(*dane_data);
+		*dane_data = NULL;
+		return DANE_E_MEMORY_ERROR;
+	}
+
+	for (idx = 0; idx < q->data_entries; idx++) {
+		(*dane_data)[idx] = data_buf;
+		(*dane_data)[idx][0] = q->usage[idx];
+		(*dane_data)[idx][1] = q->type[idx];
+		(*dane_data)[idx][2] = q->match[idx];
+		memcpy(&(*dane_data)[idx][3], q->data[idx].data, q->data[idx].size);
+		(*dane_data_len)[idx] = 3 + q->data[idx].size;
+		data_buf += 3 + q->data[idx].size;
+	}
+	(*dane_data)[idx] = NULL;
+	(*dane_data_len)[idx] = 0;
+	*data_entries = q->data_entries;
+
+	return DANE_E_SUCCESS;
+}
+
+/**
+ * dane_state_init:
+ * @s: The structure to be initialized
+ * @flags: flags from the %dane_state_flags enumeration
+ *
+ * This function will initialize the backend resolver. It is
+ * intended to be used in scenarios where multiple resolvings
+ * occur, to optimize against multiple re-initializations.
+ *
+ * Returns: On success, %DANE_E_SUCCESS (0) is returned, otherwise a
+ *   negative error value.
+ **/
+int dane_state_init(dane_state_t * s, unsigned int flags)
+{
+	struct ub_ctx *ctx;
+	int ret;
+
+	*s = calloc(1, sizeof(struct dane_state_st));
+	if (*s == NULL)
+		return gnutls_assert_val(DANE_E_MEMORY_ERROR);
+
+	ctx = ub_ctx_create();
+	if (!ctx) {
+		gnutls_assert();
+		ret = DANE_E_INITIALIZATION_ERROR;
+		goto cleanup;
+	}
+	ub_ctx_debugout(ctx, stderr);
+
+	if (!(flags & DANE_F_IGNORE_LOCAL_RESOLVER)) {
+		if (ub_ctx_resolvconf(ctx, NULL) != 0) {
+			gnutls_assert();
+			ret = DANE_E_INITIALIZATION_ERROR;
+			goto cleanup;
+		}
+
+		if (ub_ctx_hosts(ctx, NULL) != 0) {
+			gnutls_assert();
+			ret = DANE_E_INITIALIZATION_ERROR;
+			goto cleanup;
+		}
+	}
+
+	/* read public keys for DNSSEC verification */
+	if (!(flags & DANE_F_IGNORE_DNSSEC)) {
+		if (ub_ctx_add_ta_file(ctx,
+				       (char *) UNBOUND_ROOT_KEY_FILE) !=
+		    0) {
+			gnutls_assert();
+			ret = DANE_E_INITIALIZATION_ERROR;
+			goto cleanup;
+		}
+	}
+
+	(*s)->ctx = ctx;
+	(*s)->flags = flags;
+
+	return DANE_E_SUCCESS;
+      cleanup:
+
+	if (ctx)
+		ub_ctx_delete(ctx);
+	free(*s);
+
+	return ret;
+}
+
+/**
+ * dane_state_deinit:
+ * @s: The structure to be deinitialized
+ *
+ * This function will deinitialize a DANE query structure.
+ *
+ **/
+void dane_state_deinit(dane_state_t s)
+{
+	ub_ctx_delete(s->ctx);
+	free(s);
+}
+
+/**
+ * dane_state_set_dlv_file:
+ * @s: The structure to be deinitialized
+ * @file: The file holding the DLV keys.
+ *
+ * This function will set a file with trusted keys
+ * for DLV (DNSSEC Lookaside Validation).
+ *
+ **/
+int dane_state_set_dlv_file(dane_state_t s, const char *file)
+{
+	int ret;
+
+	ret =
+	    ub_ctx_set_option(s->ctx, (char *) "dlv-anchor-file:",
+			      (void *) file);
+	if (ret != 0)
+		return gnutls_assert_val(DANE_E_FILE_ERROR);
+
+	return 0;
+}
+
+/**
+ * dane_query_deinit:
+ * @q: The structure to be deinitialized
+ *
+ * This function will deinitialize a DANE query result structure.
+ *
+ **/
+void dane_query_deinit(dane_query_t q)
+{
+	if (q->result)
+		ub_resolve_free(q->result);
+	free(q);
+}
+
+
+/**
+ * dane_raw_tlsa:
+ * @s: The DANE state structure
+ * @r: A structure to place the result
+ * @dane_data: array of DNS rdata items, terminated with a NULL pointer;
+ *             caller must guarantee that the referenced data remains
+ *             valid until dane_query_deinit() is called.
+ * @dane_data_len: the length n bytes of the dane_data items
+ * @secure: true if the result is validated securely, false if
+ *               validation failed or the domain queried has no security info
+ * @bogus: if the result was not secure (secure = 0) due to a security failure,
+ *              and the result is due to a security failure, bogus is true.
+ *
+ * This function will fill in the TLSA (DANE) structure from
+ * the given raw DNS record data. The @dane_data must be valid
+ * during the lifetime of the query.
+ *
+ * Returns: On success, %DANE_E_SUCCESS (0) is returned, otherwise a
+ *   negative error value.
+ **/
+int
+dane_raw_tlsa(dane_state_t s, dane_query_t * r, char *const *dane_data,
+	      const int *dane_data_len, int secure, int bogus)
+{
+	int ret = DANE_E_SUCCESS;
+	unsigned int i;
+
+	*r = calloc(1, sizeof(struct dane_query_st));
+	if (*r == NULL)
+		return gnutls_assert_val(DANE_E_MEMORY_ERROR);
+
+	(*r)->data_entries = 0;
+
+	for (i = 0; i < MAX_DATA_ENTRIES; i++) {
+		if (dane_data[i] == NULL)
+			break;
+
+		if (dane_data_len[i] <= 3)
+			return
+			    gnutls_assert_val
+			    (DANE_E_RECEIVED_CORRUPT_DATA);
+
+		(*r)->usage[i] = dane_data[i][0];
+		(*r)->type[i] = dane_data[i][1];
+		(*r)->match[i] = dane_data[i][2];
+		(*r)->data[i].data = (void *) &dane_data[i][3];
+		(*r)->data[i].size = dane_data_len[i] - 3;
+		(*r)->data_entries++;
+	}
+
+	if (!(s->flags & DANE_F_INSECURE) && !secure) {
+		if (bogus)
+			ret = gnutls_assert_val(DANE_E_INVALID_DNSSEC_SIG);
+		else
+			ret = gnutls_assert_val(DANE_E_NO_DNSSEC_SIG);
+	}
+
+	/* show security status */
+	if (secure) {
+		(*r)->status = DANE_QUERY_DNSSEC_VERIFIED;
+	} else if (bogus) {
+		gnutls_assert();
+		(*r)->status = DANE_QUERY_BOGUS;
+	} else {
+		gnutls_assert();
+		(*r)->status = DANE_QUERY_NO_DNSSEC;
+	}
+
+	return ret;
+}
+
+
+/**
+ * dane_query_tlsa:
+ * @s: The DANE state structure
+ * @r: A structure to place the result
+ * @host: The host name to resolve.
+ * @proto: The protocol type (tcp, udp, etc.)
+ * @port: The service port number (eg. 443).
+ *
+ * This function will query the DNS server for the TLSA (DANE)
+ * data for the given host.
+ *
+ * Returns: On success, %DANE_E_SUCCESS (0) is returned, otherwise a
+ *   negative error value.
+ **/
+int
+dane_query_tlsa(dane_state_t s, dane_query_t * r, const char *host,
+		const char *proto, unsigned int port)
+{
+	char ns[1024];
+	int ret;
+	struct ub_result *result;
+
+	snprintf(ns, sizeof(ns), "_%u._%s.%s", port, proto, host);
+
+	/* query for webserver */
+	ret = ub_resolve(s->ctx, ns, 52, 1, &result);
+	if (ret != 0) {
+		return gnutls_assert_val(DANE_E_RESOLVING_ERROR);
+	}
+
+/* show first result */
+	if (!result->havedata) {
+		ub_resolve_free(result);
+		return gnutls_assert_val(DANE_E_NO_DANE_DATA);
+	}
+
+	ret =
+	    dane_raw_tlsa(s, r, result->data, result->len, result->secure,
+			  result->bogus);
+	if (*r == NULL) {
+		ub_resolve_free(result);
+		return ret;
+	}
+	(*r)->result = result;
+	return ret;
+}
+
+
+static unsigned int
+matches(const gnutls_datum_t * raw1, const gnutls_datum_t * raw2,
+	dane_match_type_t match)
+{
+	uint8_t digest[64];
+	int ret;
+
+	if (match == DANE_MATCH_EXACT) {
+		if (raw1->size != raw2->size)
+			return gnutls_assert_val(0);
+
+		if (memcmp(raw1->data, raw2->data, raw1->size) != 0)
+			return gnutls_assert_val(0);
+
+		return 1;
+	} else if (match == DANE_MATCH_SHA2_256) {
+
+		if (raw2->size != 32)
+			return gnutls_assert_val(0);
+
+		ret =
+		    gnutls_hash_fast(GNUTLS_DIG_SHA256, raw1->data,
+				     raw1->size, digest);
+		if (ret < 0)
+			return gnutls_assert_val(0);
+
+		if (memcmp(digest, raw2->data, 32) != 0)
+			return gnutls_assert_val(0);
+
+		return 1;
+	} else if (match == DANE_MATCH_SHA2_512) {
+		if (raw2->size != 64)
+			return gnutls_assert_val(0);
+
+		ret =
+		    gnutls_hash_fast(GNUTLS_DIG_SHA512, raw1->data,
+				     raw1->size, digest);
+		if (ret < 0)
+			return gnutls_assert_val(0);
+
+		if (memcmp(digest, raw2->data, 64) != 0)
+			return gnutls_assert_val(0);
+
+		return 1;
+	}
+
+	return gnutls_assert_val(0);
+}
+
+static int
+crt_to_pubkey(const gnutls_datum_t * raw_crt, gnutls_datum_t * out)
+{
+	gnutls_pubkey_t pub = NULL;
+	gnutls_x509_crt_t crt = NULL;
+	int ret;
+
+	out->data = NULL;
+
+	ret = gnutls_x509_crt_init(&crt);
+	if (ret < 0)
+		return gnutls_assert_val(DANE_E_PUBKEY_ERROR);
+
+	ret = gnutls_pubkey_init(&pub);
+	if (ret < 0) {
+		gnutls_assert();
+		ret = DANE_E_PUBKEY_ERROR;
+		goto cleanup;
+	}
+
+	ret = gnutls_x509_crt_import(crt, raw_crt, GNUTLS_X509_FMT_DER);
+	if (ret < 0) {
+		gnutls_assert();
+		ret = DANE_E_PUBKEY_ERROR;
+		goto cleanup;
+	}
+
+	ret = gnutls_pubkey_import_x509(pub, crt, 0);
+	if (ret < 0) {
+		gnutls_assert();
+		ret = DANE_E_PUBKEY_ERROR;
+		goto cleanup;
+	}
+
+	ret = gnutls_pubkey_export2(pub, GNUTLS_X509_FMT_DER, out);
+	if (ret < 0) {
+		gnutls_assert();
+		ret = DANE_E_PUBKEY_ERROR;
+		goto cleanup;
+	}
+
+	ret = 0;
+	goto clean_certs;
+
+      cleanup:
+	free(out->data);
+	out->data = NULL;
+      clean_certs:
+	if (pub)
+		gnutls_pubkey_deinit(pub);
+	if (crt)
+		gnutls_x509_crt_deinit(crt);
+
+	return ret;
+}
+
+static int
+verify_ca(const gnutls_datum_t * raw_crt, unsigned raw_crt_size,
+	  gnutls_certificate_type_t crt_type,
+	  dane_cert_type_t ctype,
+	  dane_match_type_t match, gnutls_datum_t * data,
+	  unsigned int *verify)
+{
+	gnutls_datum_t pubkey = { NULL, 0 };
+	int ret, i;
+	unsigned int vstatus = 0;
+	gnutls_x509_crt_t crt = NULL, ca = NULL;
+	unsigned is_ok = 0;
+
+	if (raw_crt_size < 2) /* we cannot verify the CA */
+		return gnutls_assert_val(DANE_E_UNKNOWN_DANE_DATA);
+
+	if (ctype == DANE_CERT_X509 && crt_type == GNUTLS_CRT_X509) {
+		is_ok = 0;
+		for (i=raw_crt_size-1;i>=1;i--) {
+			if (matches(&raw_crt[i], data, match)) {
+				is_ok = 1;
+				break;
+			}
+		}
+
+		if (is_ok == 0) {
+			gnutls_assert();
+			*verify |= DANE_VERIFY_CA_CONSTRAINTS_VIOLATED;
+		}
+
+	} else if (ctype == DANE_CERT_PK && crt_type == GNUTLS_CRT_X509) {
+		is_ok = 0;
+
+		for (i=raw_crt_size-1;i>=1;i--) {
+			ret = crt_to_pubkey(&raw_crt[i], &pubkey);
+			if (ret < 0) {
+				gnutls_assert();
+				goto cleanup;
+			}
+
+			if (matches(&pubkey, data, match)) {
+				is_ok = 1;
+				break;
+			}
+
+			free(pubkey.data);
+			pubkey.data = NULL;
+		}
+
+		if (is_ok == 0) {
+			gnutls_assert();
+			*verify |= DANE_VERIFY_CA_CONSTRAINTS_VIOLATED;
+		}
+	} else {
+		ret = gnutls_assert_val(DANE_E_UNKNOWN_DANE_DATA);
+		goto cleanup;
+	}
+
+	/* check if the certificate chain is actually a chain */
+	ret = gnutls_x509_crt_init(&crt);
+	if (ret < 0) {
+		ret = gnutls_assert_val(DANE_E_CERT_ERROR);
+		goto cleanup;
+	}
+
+	ret =
+	    gnutls_x509_crt_import(crt, &raw_crt[0], GNUTLS_X509_FMT_DER);
+	if (ret < 0) {
+		ret = gnutls_assert_val(DANE_E_CERT_ERROR);
+		goto cleanup;
+	}
+
+	for (i=raw_crt_size-1;i>=1;i--) {
+		ret = gnutls_x509_crt_init(&ca);
+		if (ret < 0) {
+			ret = gnutls_assert_val(DANE_E_CERT_ERROR);
+			goto cleanup;
+		}
+
+		ret = gnutls_x509_crt_import(ca, &raw_crt[i], GNUTLS_X509_FMT_DER);
+		if (ret < 0) {
+			ret = gnutls_assert_val(DANE_E_CERT_ERROR);
+			goto cleanup;
+		}
+
+		ret = gnutls_x509_crt_check_issuer(crt, ca);
+		if (ret != 0)
+			break;
+
+		gnutls_x509_crt_deinit(ca);
+		ca = NULL;
+	}
+
+	if (ca == NULL) {
+		gnutls_assert();
+		*verify |= DANE_VERIFY_CA_CONSTRAINTS_VIOLATED;
+	} else {
+		ret = gnutls_x509_crt_verify(crt, &ca, 1, 0, &vstatus);
+		if (ret < 0) {
+			ret = gnutls_assert_val(DANE_E_CERT_ERROR);
+			goto cleanup;
+		}
+
+		if (vstatus != 0)
+			*verify |= DANE_VERIFY_CA_CONSTRAINTS_VIOLATED;
+	}
+
+	ret = 0;
+      cleanup:
+	free(pubkey.data);
+	if (crt != NULL)
+		gnutls_x509_crt_deinit(crt);
+	if (ca != NULL)
+		gnutls_x509_crt_deinit(ca);
+	return ret;
+}
+
+static int
+verify_ee(const gnutls_datum_t * raw_crt,
+	  gnutls_certificate_type_t crt_type, dane_cert_type_t ctype,
+	  dane_match_type_t match, gnutls_datum_t * data,
+	  unsigned int *verify)
+{
+	gnutls_datum_t pubkey = { NULL, 0 };
+	int ret;
+
+	if (ctype == DANE_CERT_X509 && crt_type == GNUTLS_CRT_X509) {
+
+		if (!matches(raw_crt, data, match)) {
+			gnutls_assert();
+			*verify |= DANE_VERIFY_CERT_DIFFERS;
+		}
+
+	} else if (ctype == DANE_CERT_PK && crt_type == GNUTLS_CRT_X509) {
+
+		ret = crt_to_pubkey(raw_crt, &pubkey);
+		if (ret < 0) {
+			gnutls_assert();
+			goto cleanup;
+		}
+
+		if (!matches(&pubkey, data, match)) {
+			gnutls_assert();
+			*verify |= DANE_VERIFY_CERT_DIFFERS;
+		}
+	} else {
+		ret = gnutls_assert_val(DANE_E_UNKNOWN_DANE_DATA);
+		goto cleanup;
+	}
+
+	ret = 0;
+      cleanup:
+	free(pubkey.data);
+	return ret;
+}
+
+#define CHECK_VRET(ret, checked, record_status, status) \
+			if (ret == DANE_E_UNKNOWN_DANE_DATA) { \
+				/* skip that entry */ \
+				continue; \
+			} else if (ret < 0) { \
+				gnutls_assert(); \
+				goto cleanup; \
+			} \
+			checked = 1; \
+			if (record_status == 0) { \
+				status = 0; \
+				break; \
+			} else { \
+				status |= record_status; \
+			}
+
+/**
+ * dane_verify_crt_raw:
+ * @s: A DANE state structure (may be NULL)
+ * @chain: A certificate chain
+ * @chain_size: The size of the chain
+ * @chain_type: The type of the certificate chain
+ * @r: DANE data to check against
+ * @sflags: Flags for the initialization of @s (if NULL)
+ * @vflags: Verification flags; an OR'ed list of %dane_verify_flags_t.
+ * @verify: An OR'ed list of %dane_verify_status_t.
+ *
+ * This is the low-level function of dane_verify_crt(). See the
+ * high level function for documentation.
+ *
+ * This function does not perform any resolving, it utilizes
+ * cached entries from @r.
+ *
+ * Returns: a negative error code on error and %DANE_E_SUCCESS (0)
+ * when the DANE entries were successfully parsed, irrespective of
+ * whether they were verified (see @verify for that information). If
+ * no usable entries were encountered %DANE_E_REQUESTED_DATA_NOT_AVAILABLE
+ * will be returned.
+ *
+ **/
+int
+dane_verify_crt_raw(dane_state_t s,
+		    const gnutls_datum_t * chain, unsigned chain_size,
+		    gnutls_certificate_type_t chain_type,
+		    dane_query_t r,
+		    unsigned int sflags, unsigned int vflags,
+		    unsigned int *verify)
+{
+	int ret;
+	unsigned checked = 0;
+	unsigned int usage, type, match, idx;
+	gnutls_datum_t data;
+
+	if (chain_type != GNUTLS_CRT_X509)
+		return gnutls_assert_val(DANE_E_INVALID_REQUEST);
+
+	if (chain_size == 0)
+		return gnutls_assert_val(DANE_E_NO_CERT);
+
+	*verify = 0;
+	idx = 0;
+	do {
+		unsigned int record_verify = 0;
+
+		ret =
+		    dane_query_data(r, idx++, &usage, &type, &match,
+				    &data);
+		if (ret == DANE_E_REQUESTED_DATA_NOT_AVAILABLE)
+			break;
+
+		if (ret < 0) {
+			gnutls_assert();
+			goto cleanup;
+		}
+
+		if (!(vflags & DANE_VFLAG_ONLY_CHECK_EE_USAGE)
+		    && (usage == DANE_CERT_USAGE_LOCAL_CA
+			|| usage == DANE_CERT_USAGE_CA)) {
+			ret =
+			    verify_ca(chain, chain_size, chain_type, type,
+				      match, &data, &record_verify);
+			CHECK_VRET(ret, checked, record_verify, *verify);
+
+		} else if (!(vflags & DANE_VFLAG_ONLY_CHECK_CA_USAGE)
+			   && (usage == DANE_CERT_USAGE_LOCAL_EE
+			       || usage == DANE_CERT_USAGE_EE)) {
+			ret =
+			    verify_ee(&chain[0], chain_type, type, match,
+				      &data, &record_verify);
+			CHECK_VRET(ret, checked, record_verify, *verify);
+		}
+	}
+	while (1);
+
+	if ((vflags & DANE_VFLAG_FAIL_IF_NOT_CHECKED) && checked == 0) {
+		ret =
+		    gnutls_assert_val(DANE_E_REQUESTED_DATA_NOT_AVAILABLE);
+	} else if (checked == 0) {
+		*verify |= DANE_VERIFY_UNKNOWN_DANE_INFO;
+	} else {
+		ret = 0;
+	}
+
+      cleanup:
+	return ret;
+}
+
+
+/**
+ * dane_verify_crt:
+ * @s: A DANE state structure (may be NULL)
+ * @chain: A certificate chain
+ * @chain_size: The size of the chain
+ * @chain_type: The type of the certificate chain
+ * @hostname: The hostname associated with the chain
+ * @proto: The protocol of the service connecting (e.g. tcp)
+ * @port: The port of the service connecting (e.g. 443)
+ * @sflags: Flags for the initialization of @s (if NULL)
+ * @vflags: Verification flags; an OR'ed list of %dane_verify_flags_t.
+ * @verify: An OR'ed list of %dane_verify_status_t.
+ *
+ * This function will verify the given certificate chain against the
+ * CA constrains and/or the certificate available via DANE.
+ * If no information via DANE can be obtained the flag %DANE_VERIFY_NO_DANE_INFO
+ * is set. If a DNSSEC signature is not available for the DANE
+ * record then the verify flag %DANE_VERIFY_NO_DNSSEC_DATA is set.
+ *
+ * Due to the many possible options of DANE, there is no single threat
+ * model countered. When notifying the user about DANE verification results
+ * it may be better to mention: DANE verification did not reject the certificate,
+ * rather than mentioning a successful DANE verication.
+ *
+ * Note that this function is designed to be run in addition to
+ * PKIX - certificate chain - verification. To be run independently
+ * the %DANE_VFLAG_ONLY_CHECK_EE_USAGE flag should be specified;
+ * then the function will check whether the key of the peer matches the
+ * key advertized in the DANE entry.
+ *
+ * Returns: a negative error code on error and %DANE_E_SUCCESS (0)
+ * when the DANE entries were successfully parsed, irrespective of
+ * whether they were verified (see @verify for that information). If
+ * no usable entries were encountered %DANE_E_REQUESTED_DATA_NOT_AVAILABLE
+ * will be returned.
+ *
+ **/
+int
+dane_verify_crt(dane_state_t s,
+		const gnutls_datum_t * chain, unsigned chain_size,
+		gnutls_certificate_type_t chain_type,
+		const char *hostname, const char *proto, unsigned int port,
+		unsigned int sflags, unsigned int vflags,
+		unsigned int *verify)
+{
+	dane_state_t state = NULL;
+	dane_query_t r = NULL;
+	int ret;
+
+	*verify = 0;
+	if (s == NULL) {
+		ret = dane_state_init(&state, sflags);
+		if (ret < 0) {
+			gnutls_assert();
+			return ret;
+		}
+	} else
+		state = s;
+
+	ret = dane_query_tlsa(state, &r, hostname, proto, port);
+	if (ret < 0) {
+		gnutls_assert();
+		goto cleanup;
+	}
+	ret = dane_verify_crt_raw(state, chain, chain_size, chain_type,
+				  r, sflags, vflags, verify);
+      cleanup:
+	if (state != s)
+		dane_state_deinit(state);
+	if (r != NULL)
+		dane_query_deinit(r);
+	return ret;
+}
+
+/**
+ * dane_verify_session_crt:
+ * @s: A DANE state structure (may be NULL)
+ * @session: A gnutls session
+ * @hostname: The hostname associated with the chain
+ * @proto: The protocol of the service connecting (e.g. tcp)
+ * @port: The port of the service connecting (e.g. 443)
+ * @sflags: Flags for the initialization of @s (if NULL)
+ * @vflags: Verification flags; an OR'ed list of %dane_verify_flags_t.
+ * @verify: An OR'ed list of %dane_verify_status_t.
+ *
+ * This function will verify session's certificate chain against the
+ * CA constrains and/or the certificate available via DANE.
+ * See dane_verify_crt() for more information.
+ *
+ * This will not verify the chain for validity; unless the DANE
+ * verification is restricted to end certificates, this must be
+ * be performed separately using gnutls_certificate_verify_peers3().
+ *
+ * Returns: a negative error code on error and %DANE_E_SUCCESS (0)
+ * when the DANE entries were successfully parsed, irrespective of
+ * whether they were verified (see @verify for that information). If
+ * no usable entries were encountered %DANE_E_REQUESTED_DATA_NOT_AVAILABLE
+ * will be returned.
+ *
+ **/
+int
+dane_verify_session_crt(dane_state_t s,
+			gnutls_session_t session,
+			const char *hostname, const char *proto,
+			unsigned int port, unsigned int sflags,
+			unsigned int vflags, unsigned int *verify)
+{
+	const gnutls_datum_t *cert_list;
+	unsigned int cert_list_size = 0;
+	unsigned int type;
+	gnutls_x509_crt_t crt, ca;
+	gnutls_certificate_credentials_t sc;
+	int ret;
+
+	cert_list = gnutls_certificate_get_peers(session, &cert_list_size);
+	if (cert_list_size == 0) {
+		return gnutls_assert_val(DANE_E_NO_CERT);
+	}
+
+	type = gnutls_certificate_type_get(session);
+
+	/* this list may be incomplete, try to get the self-signed CA if any */
+	ret = gnutls_x509_crt_init(&crt);
+	if (ret < 0) {
+		gnutls_assert();
+		goto failsafe;
+	}
+
+	ret = gnutls_x509_crt_import(crt, &cert_list[cert_list_size-1], GNUTLS_X509_FMT_DER);
+	if (ret < 0) {
+		gnutls_assert();
+		gnutls_x509_crt_deinit(crt);
+		goto failsafe;
+	}
+
+	/* if it is already self signed continue normally */
+	ret = gnutls_x509_crt_check_issuer(crt, crt);
+	if (ret != 0) {
+		gnutls_assert();
+		gnutls_x509_crt_deinit(crt);
+		goto failsafe;
+	}
+
+	/* chain does not finish in a self signed cert, try to obtain the issuer */
+	ret = gnutls_credentials_get(session, GNUTLS_CRD_CERTIFICATE, (void**)&sc);
+	if (ret < 0) {
+		gnutls_assert();
+		gnutls_x509_crt_deinit(crt);
+		goto failsafe;
+	}
+
+	ret = gnutls_certificate_get_issuer(sc, crt, &ca, 0);
+	if (ret < 0) {
+		gnutls_assert();
+		gnutls_x509_crt_deinit(crt);
+		goto failsafe;
+	}
+
+	/* make the new list */
+	gnutls_datum_t *new_cert_list;
+
+	new_cert_list = gnutls_malloc((cert_list_size + 1) * sizeof(gnutls_datum_t));
+	if (new_cert_list == NULL) {
+		gnutls_assert();
+		gnutls_x509_crt_deinit(crt);
+		goto failsafe;
+	}
+
+	memcpy(new_cert_list, cert_list, cert_list_size*sizeof(gnutls_datum_t));
+
+	ret = gnutls_x509_crt_export2(ca, GNUTLS_X509_FMT_DER, &new_cert_list[cert_list_size]);
+	if (ret < 0) {
+		gnutls_assert();
+		free(new_cert_list);
+		gnutls_x509_crt_deinit(crt);
+		goto failsafe;
+	}
+
+	ret = dane_verify_crt(s, new_cert_list, cert_list_size+1, type,
+			      hostname, proto, port, sflags, vflags,
+			      verify);
+	if (ret < 0) {
+		gnutls_assert();
+	}
+	gnutls_free(new_cert_list[cert_list_size].data);
+	free(new_cert_list);
+	return ret;
+
+ failsafe:
+	return dane_verify_crt(s, cert_list, cert_list_size, type,
+			       hostname, proto, port, sflags, vflags,
+			       verify);
+}
+
+/**
+ * dane_verification_status_print:
+ * @status: The status flags to be printed
+ * @type: The certificate type
+ * @out: Newly allocated datum with (0) terminated string.
+ * @flags: should be zero
+ *
+ * This function will pretty print the status of a verification
+ * process -- eg. the one obtained by dane_verify_crt().
+ *
+ * The output @out needs to be deallocated using gnutls_free().
+ *
+ * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise a
+ *   negative error value.
+ **/
+int
+dane_verification_status_print(unsigned int status,
+			       gnutls_datum_t * out, unsigned int flags)
+{
+	gnutls_buffer_st str;
+
+	_gnutls_buffer_init(&str);
+
+	if (status == 0)
+		_gnutls_buffer_append_str(&str,
+					  _("Certificate matches. "));
+	else
+		_gnutls_buffer_append_str(&str,
+					  _("Verification failed. "));
+
+	if (status & DANE_VERIFY_CA_CONSTRAINTS_VIOLATED)
+		_gnutls_buffer_append_str(&str,
+					  _
+					  ("CA constrains were violated. "));
+
+	if (status & DANE_VERIFY_CERT_DIFFERS)
+		_gnutls_buffer_append_str(&str,
+					  _("The certificate differs. "));
+
+	if (status & DANE_VERIFY_NO_DANE_INFO)
+		_gnutls_buffer_append_str(&str,
+					  _
+					  ("There were no DANE information. "));
+
+	return _gnutls_buffer_to_datum(&str, out, 1);
+}