[thirdparty/systemd.git] / src / resolve / resolved-dnstls-openssl.c

/* SPDX-License-Identifier: LGPL-2.1+ */

#if !ENABLE_DNS_OVER_TLS || !DNS_OVER_TLS_USE_OPENSSL
#error This source file requires DNS-over-TLS to be enabled and OpenSSL to be available.
#endif

#include "resolved-dnstls.h"
#include "resolved-dns-stream.h"

#include <openssl/bio.h>
#include <openssl/err.h>

DEFINE_TRIVIAL_CLEANUP_FUNC(SSL*, SSL_free);
DEFINE_TRIVIAL_CLEANUP_FUNC(BIO*, BIO_free);

static int dnstls_flush_write_buffer(DnsStream *stream) {
        ssize_t ss;

        assert(stream);
        assert(stream->encrypted);

        if (stream->dnstls_data.write_buffer->length > 0) {
                assert(stream->dnstls_data.write_buffer->data);

                struct iovec iov[1];
                iov[0].iov_base = stream->dnstls_data.write_buffer->data;
                iov[0].iov_len = stream->dnstls_data.write_buffer->length;
                ss = dns_stream_writev(stream, iov, 1, DNS_STREAM_WRITE_TLS_DATA);
                if (ss < 0) {
                        if (ss == -EAGAIN)
                                stream->dnstls_events |= EPOLLOUT;

                        return ss;
                } else {
                        stream->dnstls_data.write_buffer->length -= ss;
                        stream->dnstls_data.write_buffer->data += ss;

                        if (stream->dnstls_data.write_buffer->length > 0) {
                                stream->dnstls_events |= EPOLLOUT;
                                return -EAGAIN;
                        }
                }
        }

        return 0;
}

int dnstls_stream_connect_tls(DnsStream *stream, DnsServer *server) {
        _cleanup_(BIO_freep) BIO *rb = NULL, *wb = NULL;
        _cleanup_(SSL_freep) SSL *s = NULL;
        int error, r;

        assert(stream);
        assert(server);

        rb = BIO_new_socket(stream->fd, 0);
        if (!rb)
                return -ENOMEM;

        wb = BIO_new(BIO_s_mem());
        if (!wb)
                return -ENOMEM;

        BIO_get_mem_ptr(wb, &stream->dnstls_data.write_buffer);

        s = SSL_new(server->dnstls_data.ctx);
        if (!s)
                return -ENOMEM;

        SSL_set_connect_state(s);
        SSL_set_session(s, server->dnstls_data.session);
        SSL_set_bio(s, TAKE_PTR(rb), TAKE_PTR(wb));

        ERR_clear_error();
        stream->dnstls_data.handshake = SSL_do_handshake(s);
        if (stream->dnstls_data.handshake <= 0) {
                error = SSL_get_error(s, stream->dnstls_data.handshake);
                if (!IN_SET(error, SSL_ERROR_WANT_READ, SSL_ERROR_WANT_WRITE)) {
                        char errbuf[256];

                        ERR_error_string_n(error, errbuf, sizeof(errbuf));
                        log_debug("Failed to invoke SSL_do_handshake: %s", errbuf);
                        return -ECONNREFUSED;
                }
        }

        stream->encrypted = true;

        r = dnstls_flush_write_buffer(stream);
        if (r < 0 && r != -EAGAIN)
                return r;

        stream->dnstls_data.ssl = TAKE_PTR(s);

        return 0;
}

void dnstls_stream_free(DnsStream *stream) {
        assert(stream);
        assert(stream->encrypted);

        if (stream->dnstls_data.ssl)
                SSL_free(stream->dnstls_data.ssl);
}

int dnstls_stream_on_io(DnsStream *stream, uint32_t revents) {
        int error, r;

        assert(stream);
        assert(stream->encrypted);
        assert(stream->dnstls_data.ssl);

        /* Flush write buffer when requested by OpenSSL */
        if ((revents & EPOLLOUT) && (stream->dnstls_events & EPOLLOUT)) {
                r = dnstls_flush_write_buffer(stream);
                if (r < 0)
                        return r;
        }

        if (stream->dnstls_data.shutdown) {
                ERR_clear_error();
                r = SSL_shutdown(stream->dnstls_data.ssl);
                if (r == 0) {
                        stream->dnstls_events = 0;

                        r = dnstls_flush_write_buffer(stream);
                        if (r < 0)
                                return r;

                        return -EAGAIN;
                } else if (r < 0) {
                        error = SSL_get_error(stream->dnstls_data.ssl, r);
                        if (IN_SET(error, SSL_ERROR_WANT_READ, SSL_ERROR_WANT_WRITE)) {
                                stream->dnstls_events = error == SSL_ERROR_WANT_READ ? EPOLLIN : EPOLLOUT;

                                r = dnstls_flush_write_buffer(stream);
                                if (r < 0)
                                        return r;

                                return -EAGAIN;
                        } else if (error == SSL_ERROR_SYSCALL) {
                                if (errno > 0)
                                        log_debug_errno(errno, "Failed to invoke SSL_shutdown, ignoring: %m");
                        } else {
                                char errbuf[256];

                                ERR_error_string_n(error, errbuf, sizeof(errbuf));
                                log_debug("Failed to invoke SSL_shutdown, ignoring: %s", errbuf);
                        }
                }

                stream->dnstls_events = 0;
                stream->dnstls_data.shutdown = false;

                r = dnstls_flush_write_buffer(stream);
                if (r < 0)
                        return r;

                dns_stream_unref(stream);
                return DNSTLS_STREAM_CLOSED;
        } else if (stream->dnstls_data.handshake <= 0) {
                ERR_clear_error();
                stream->dnstls_data.handshake = SSL_do_handshake(stream->dnstls_data.ssl);
                if (stream->dnstls_data.handshake <= 0) {
                        error = SSL_get_error(stream->dnstls_data.ssl, stream->dnstls_data.handshake);
                        if (IN_SET(error, SSL_ERROR_WANT_READ, SSL_ERROR_WANT_WRITE)) {
                                stream->dnstls_events = error == SSL_ERROR_WANT_READ ? EPOLLIN : EPOLLOUT;
                                r = dnstls_flush_write_buffer(stream);
                                if (r < 0)
                                        return r;

                                return -EAGAIN;
                        } else {
                                char errbuf[256];

                                ERR_error_string_n(error, errbuf, sizeof(errbuf));
                                log_debug("Failed to invoke SSL_do_handshake: %s", errbuf);
                                return -ECONNREFUSED;
                        }
                }

                stream->dnstls_events = 0;
                r = dnstls_flush_write_buffer(stream);
                if (r < 0)
                        return r;
        }

        return 0;
}

int dnstls_stream_shutdown(DnsStream *stream, int error) {
        int ssl_error, r;
        SSL_SESSION *s;

        assert(stream);
        assert(stream->encrypted);
        assert(stream->dnstls_data.ssl);

        if (stream->server) {
                s = SSL_get1_session(stream->dnstls_data.ssl);
                if (s) {
                        if (stream->server->dnstls_data.session)
                                SSL_SESSION_free(stream->server->dnstls_data.session);

                        stream->server->dnstls_data.session = s;
                }
        }

        if (error == ETIMEDOUT) {
                ERR_clear_error();
                r = SSL_shutdown(stream->dnstls_data.ssl);
                if (r == 0) {
                        if (!stream->dnstls_data.shutdown) {
                                stream->dnstls_data.shutdown = true;
                                dns_stream_ref(stream);
                        }

                        stream->dnstls_events = 0;

                        r = dnstls_flush_write_buffer(stream);
                        if (r < 0)
                                return r;

                        return -EAGAIN;
                } else if (r < 0) {
                        ssl_error = SSL_get_error(stream->dnstls_data.ssl, r);
                        if (IN_SET(ssl_error, SSL_ERROR_WANT_READ, SSL_ERROR_WANT_WRITE)) {
                                stream->dnstls_events = ssl_error == SSL_ERROR_WANT_READ ? EPOLLIN : EPOLLOUT;
                                r = dnstls_flush_write_buffer(stream);
                                if (r < 0 && r != -EAGAIN)
                                        return r;

                                if (!stream->dnstls_data.shutdown) {
                                        stream->dnstls_data.shutdown = true;
                                        dns_stream_ref(stream);
                                }
                                return -EAGAIN;
                        } else if (ssl_error == SSL_ERROR_SYSCALL) {
                                if (errno > 0)
                                        log_debug_errno(errno, "Failed to invoke SSL_shutdown, ignoring: %m");
                        } else {
                                char errbuf[256];

                                ERR_error_string_n(ssl_error, errbuf, sizeof(errbuf));
                                log_debug("Failed to invoke SSL_shutdown, ignoring: %s", errbuf);
                        }
                }

                stream->dnstls_events = 0;
                r = dnstls_flush_write_buffer(stream);
                if (r < 0)
                        return r;
        }

        return 0;
}

ssize_t dnstls_stream_write(DnsStream *stream, const char *buf, size_t count) {
        int error, r;
        ssize_t ss;

        assert(stream);
        assert(stream->encrypted);
        assert(stream->dnstls_data.ssl);
        assert(buf);

        ERR_clear_error();
        ss = r = SSL_write(stream->dnstls_data.ssl, buf, count);
        if (r <= 0) {
                error = SSL_get_error(stream->dnstls_data.ssl, ss);
                if (IN_SET(error, SSL_ERROR_WANT_READ, SSL_ERROR_WANT_WRITE)) {
                        stream->dnstls_events = error == SSL_ERROR_WANT_READ ? EPOLLIN : EPOLLOUT;
                        r = dnstls_flush_write_buffer(stream);
                        if (r < 0)
                                return r;

                        ss = -EAGAIN;
                } else {
                        char errbuf[256];

                        ERR_error_string_n(error, errbuf, sizeof(errbuf));
                        log_debug("Failed to invoke SSL_write: %s", errbuf);
                        ss = -EPIPE;
                }
        }

        stream->dnstls_events = 0;
        r = dnstls_flush_write_buffer(stream);
        if (r < 0)
                return r;

        return ss;
}

ssize_t dnstls_stream_read(DnsStream *stream, void *buf, size_t count) {
        int error, r;
        ssize_t ss;

        assert(stream);
        assert(stream->encrypted);
        assert(stream->dnstls_data.ssl);
        assert(buf);

        ERR_clear_error();
        ss = r = SSL_read(stream->dnstls_data.ssl, buf, count);
        if (r <= 0) {
                error = SSL_get_error(stream->dnstls_data.ssl, ss);
                if (IN_SET(error, SSL_ERROR_WANT_READ, SSL_ERROR_WANT_WRITE)) {
                        stream->dnstls_events = error == SSL_ERROR_WANT_READ ? EPOLLIN : EPOLLOUT;

                        /* flush write buffer in cache of renegotiation */
                        r = dnstls_flush_write_buffer(stream);
                        if (r < 0)
                                return r;

                        ss = -EAGAIN;
                } else {
                        char errbuf[256];

                        ERR_error_string_n(error, errbuf, sizeof(errbuf));
                        log_debug("Failed to invoke SSL_read: %s", errbuf);
                        ss = -EPIPE;
                }
        }

        stream->dnstls_events = 0;

        /* flush write buffer in cache of renegotiation */
        r = dnstls_flush_write_buffer(stream);
        if (r < 0)
                return r;

        return ss;
}

void dnstls_server_init(DnsServer *server) {
        assert(server);

        server->dnstls_data.ctx = SSL_CTX_new(TLS_client_method());
        if (server->dnstls_data.ctx) {
                SSL_CTX_set_min_proto_version(server->dnstls_data.ctx, TLS1_2_VERSION);
                SSL_CTX_set_options(server->dnstls_data.ctx, SSL_OP_NO_COMPRESSION);
        }
}

void dnstls_server_free(DnsServer *server) {
        assert(server);

        if (server->dnstls_data.ctx)
                SSL_CTX_free(server->dnstls_data.ctx);

        if (server->dnstls_data.session)
                SSL_SESSION_free(server->dnstls_data.session);
}
Commit	Line	Data
096cbdce IT	1	/* SPDX-License-Identifier: LGPL-2.1+ */
	2
	3	#if !ENABLE_DNS_OVER_TLS \|\| !DNS_OVER_TLS_USE_OPENSSL
	4	#error This source file requires DNS-over-TLS to be enabled and OpenSSL to be available.
	5	#endif
	6
	7	#include "resolved-dnstls.h"
	8	#include "resolved-dns-stream.h"
	9
	10	#include <openssl/bio.h>
	11	#include <openssl/err.h>
	12
	13	DEFINE_TRIVIAL_CLEANUP_FUNC(SSL*, SSL_free);
	14	DEFINE_TRIVIAL_CLEANUP_FUNC(BIO*, BIO_free);
	15
04c4d919 IT	16	static int dnstls_flush_write_buffer(DnsStream *stream) {
	17	ssize_t ss;
	18
	19	assert(stream);
	20	assert(stream->encrypted);
	21
	22	if (stream->dnstls_data.write_buffer->length > 0) {
	23	assert(stream->dnstls_data.write_buffer->data);
	24
	25	struct iovec iov[1];
	26	iov[0].iov_base = stream->dnstls_data.write_buffer->data;
	27	iov[0].iov_len = stream->dnstls_data.write_buffer->length;
	28	ss = dns_stream_writev(stream, iov, 1, DNS_STREAM_WRITE_TLS_DATA);
	29	if (ss < 0) {
	30	if (ss == -EAGAIN)
	31	stream->dnstls_events \|= EPOLLOUT;
	32
	33	return ss;
	34	} else {
	35	stream->dnstls_data.write_buffer->length -= ss;
	36	stream->dnstls_data.write_buffer->data += ss;
	37
	38	if (stream->dnstls_data.write_buffer->length > 0) {
	39	stream->dnstls_events \|= EPOLLOUT;
	40	return -EAGAIN;
	41	}
	42	}
	43	}
	44
	45	return 0;
	46	}
	47
096cbdce	48	int dnstls_stream_connect_tls(DnsStream stream, DnsServer server) {
36f1946c	49	_cleanup_(BIO_freep) BIO rb = NULL, wb = NULL;
096cbdce	50	_cleanup_(SSL_freep) SSL *s = NULL;
36f1946c	51	int error, r;
096cbdce IT	52
	53	assert(stream);
	54	assert(server);
	55
04c4d919 IT	56	rb = BIO_new_socket(stream->fd, 0);
	57	if (!rb)
	58	return -ENOMEM;
	59
	60	wb = BIO_new(BIO_s_mem());
	61	if (!wb)
096cbdce IT	62	return -ENOMEM;
096cbdce IT	63
04c4d919 IT	64	BIO_get_mem_ptr(wb, &stream->dnstls_data.write_buffer);
04c4d919 IT	65
096cbdce IT	66	s = SSL_new(server->dnstls_data.ctx);
	67	if (!s)
	68	return -ENOMEM;
	69
	70	SSL_set_connect_state(s);
04c4d919 IT	71	SSL_set_session(s, server->dnstls_data.session);
	72	SSL_set_bio(s, TAKE_PTR(rb), TAKE_PTR(wb));
	73
59c3fee2	74	ERR_clear_error();
04c4d919 IT	75	stream->dnstls_data.handshake = SSL_do_handshake(s);
	76	if (stream->dnstls_data.handshake <= 0) {
	77	error = SSL_get_error(s, stream->dnstls_data.handshake);
	78	if (!IN_SET(error, SSL_ERROR_WANT_READ, SSL_ERROR_WANT_WRITE)) {
	79	char errbuf[256];
096cbdce	80
04c4d919 IT	81	ERR_error_string_n(error, errbuf, sizeof(errbuf));
	82	log_debug("Failed to invoke SSL_do_handshake: %s", errbuf);
	83	return -ECONNREFUSED;
	84	}
	85	}
096cbdce IT	86
096cbdce IT	87	stream->encrypted = true;
04c4d919 IT	88
	89	r = dnstls_flush_write_buffer(stream);
	90	if (r < 0 && r != -EAGAIN)
	91	return r;
	92
096cbdce IT	93	stream->dnstls_data.ssl = TAKE_PTR(s);
	94
	95	return 0;
	96	}
	97
	98	void dnstls_stream_free(DnsStream *stream) {
	99	assert(stream);
	100	assert(stream->encrypted);
	101
	102	if (stream->dnstls_data.ssl)
	103	SSL_free(stream->dnstls_data.ssl);
	104	}
	105
04c4d919	106	int dnstls_stream_on_io(DnsStream *stream, uint32_t revents) {
36f1946c	107	int error, r;
096cbdce IT	108
	109	assert(stream);
	110	assert(stream->encrypted);
	111	assert(stream->dnstls_data.ssl);
	112
36f1946c	113	/* Flush write buffer when requested by OpenSSL */
04c4d919 IT	114	if ((revents & EPOLLOUT) && (stream->dnstls_events & EPOLLOUT)) {
	115	r = dnstls_flush_write_buffer(stream);
	116	if (r < 0)
	117	return r;
	118	}
	119
096cbdce	120	if (stream->dnstls_data.shutdown) {
59c3fee2	121	ERR_clear_error();
096cbdce	122	r = SSL_shutdown(stream->dnstls_data.ssl);
8eadd291 YW	123	if (r == 0) {
	124	stream->dnstls_events = 0;
	125
	126	r = dnstls_flush_write_buffer(stream);
	127	if (r < 0)
	128	return r;
	129
	130	return -EAGAIN;
	131	} else if (r < 0) {
096cbdce	132	error = SSL_get_error(stream->dnstls_data.ssl, r);
8eadd291 YW	133	if (IN_SET(error, SSL_ERROR_WANT_READ, SSL_ERROR_WANT_WRITE)) {
8eadd291 YW	134	stream->dnstls_events = error == SSL_ERROR_WANT_READ ? EPOLLIN : EPOLLOUT;
04c4d919 IT	135
	136	r = dnstls_flush_write_buffer(stream);
	137	if (r < 0)
	138	return r;
	139
096cbdce	140	return -EAGAIN;
8eadd291 YW	141	} else if (error == SSL_ERROR_SYSCALL) {
	142	if (errno > 0)
	143	log_debug_errno(errno, "Failed to invoke SSL_shutdown, ignoring: %m");
096cbdce IT	144	} else {
	145	char errbuf[256];
	146
	147	ERR_error_string_n(error, errbuf, sizeof(errbuf));
8eadd291	148	log_debug("Failed to invoke SSL_shutdown, ignoring: %s", errbuf);
096cbdce IT	149	}
	150	}
	151
8eadd291 YW	152	stream->dnstls_events = 0;
	153	stream->dnstls_data.shutdown = false;
	154
04c4d919 IT	155	r = dnstls_flush_write_buffer(stream);
	156	if (r < 0)
	157	return r;
	158
096cbdce IT	159	dns_stream_unref(stream);
	160	return DNSTLS_STREAM_CLOSED;
	161	} else if (stream->dnstls_data.handshake <= 0) {
59c3fee2	162	ERR_clear_error();
096cbdce IT	163	stream->dnstls_data.handshake = SSL_do_handshake(stream->dnstls_data.ssl);
	164	if (stream->dnstls_data.handshake <= 0) {
	165	error = SSL_get_error(stream->dnstls_data.ssl, stream->dnstls_data.handshake);
	166	if (IN_SET(error, SSL_ERROR_WANT_READ, SSL_ERROR_WANT_WRITE)) {
	167	stream->dnstls_events = error == SSL_ERROR_WANT_READ ? EPOLLIN : EPOLLOUT;
04c4d919 IT	168	r = dnstls_flush_write_buffer(stream);
	169	if (r < 0)
	170	return r;
	171
096cbdce IT	172	return -EAGAIN;
	173	} else {
	174	char errbuf[256];
	175
	176	ERR_error_string_n(error, errbuf, sizeof(errbuf));
	177	log_debug("Failed to invoke SSL_do_handshake: %s", errbuf);
	178	return -ECONNREFUSED;
	179	}
	180	}
	181
	182	stream->dnstls_events = 0;
04c4d919 IT	183	r = dnstls_flush_write_buffer(stream);
	184	if (r < 0)
	185	return r;
096cbdce IT	186	}
	187
	188	return 0;
	189	}
	190
	191	int dnstls_stream_shutdown(DnsStream *stream, int error) {
36f1946c	192	int ssl_error, r;
096cbdce IT	193	SSL_SESSION *s;
	194
	195	assert(stream);
	196	assert(stream->encrypted);
	197	assert(stream->dnstls_data.ssl);
	198
04c4d919 IT	199	if (stream->server) {
	200	s = SSL_get1_session(stream->dnstls_data.ssl);
	201	if (s) {
	202	if (stream->server->dnstls_data.session)
	203	SSL_SESSION_free(stream->server->dnstls_data.session);
	204
	205	stream->server->dnstls_data.session = s;
	206	}
	207	}
	208
096cbdce	209	if (error == ETIMEDOUT) {
59c3fee2	210	ERR_clear_error();
096cbdce IT	211	r = SSL_shutdown(stream->dnstls_data.ssl);
	212	if (r == 0) {
	213	if (!stream->dnstls_data.shutdown) {
	214	stream->dnstls_data.shutdown = true;
	215	dns_stream_ref(stream);
	216	}
04c4d919	217
8eadd291 YW	218	stream->dnstls_events = 0;
8eadd291 YW	219
04c4d919 IT	220	r = dnstls_flush_write_buffer(stream);
	221	if (r < 0)
	222	return r;
	223
096cbdce IT	224	return -EAGAIN;
	225	} else if (r < 0) {
	226	ssl_error = SSL_get_error(stream->dnstls_data.ssl, r);
	227	if (IN_SET(ssl_error, SSL_ERROR_WANT_READ, SSL_ERROR_WANT_WRITE)) {
	228	stream->dnstls_events = ssl_error == SSL_ERROR_WANT_READ ? EPOLLIN : EPOLLOUT;
04c4d919 IT	229	r = dnstls_flush_write_buffer(stream);
	230	if (r < 0 && r != -EAGAIN)
	231	return r;
	232
096cbdce IT	233	if (!stream->dnstls_data.shutdown) {
	234	stream->dnstls_data.shutdown = true;
	235	dns_stream_ref(stream);
	236	}
	237	return -EAGAIN;
8eadd291 YW	238	} else if (ssl_error == SSL_ERROR_SYSCALL) {
	239	if (errno > 0)
	240	log_debug_errno(errno, "Failed to invoke SSL_shutdown, ignoring: %m");
096cbdce IT	241	} else {
	242	char errbuf[256];
	243
	244	ERR_error_string_n(ssl_error, errbuf, sizeof(errbuf));
8eadd291	245	log_debug("Failed to invoke SSL_shutdown, ignoring: %s", errbuf);
096cbdce IT	246	}
096cbdce IT	247	}
04c4d919 IT	248
	249	stream->dnstls_events = 0;
	250	r = dnstls_flush_write_buffer(stream);
	251	if (r < 0)
	252	return r;
096cbdce IT	253	}
	254
	255	return 0;
	256	}
	257
	258	ssize_t dnstls_stream_write(DnsStream stream, const char buf, size_t count) {
36f1946c	259	int error, r;
096cbdce IT	260	ssize_t ss;
	261
	262	assert(stream);
	263	assert(stream->encrypted);
	264	assert(stream->dnstls_data.ssl);
	265	assert(buf);
	266
59c3fee2	267	ERR_clear_error();
096cbdce IT	268	ss = r = SSL_write(stream->dnstls_data.ssl, buf, count);
	269	if (r <= 0) {
	270	error = SSL_get_error(stream->dnstls_data.ssl, ss);
	271	if (IN_SET(error, SSL_ERROR_WANT_READ, SSL_ERROR_WANT_WRITE)) {
	272	stream->dnstls_events = error == SSL_ERROR_WANT_READ ? EPOLLIN : EPOLLOUT;
04c4d919 IT	273	r = dnstls_flush_write_buffer(stream);
	274	if (r < 0)
	275	return r;
	276
096cbdce IT	277	ss = -EAGAIN;
	278	} else {
	279	char errbuf[256];
	280
	281	ERR_error_string_n(error, errbuf, sizeof(errbuf));
36f1946c	282	log_debug("Failed to invoke SSL_write: %s", errbuf);
096cbdce IT	283	ss = -EPIPE;
	284	}
	285	}
	286
	287	stream->dnstls_events = 0;
04c4d919 IT	288	r = dnstls_flush_write_buffer(stream);
	289	if (r < 0)
	290	return r;
	291
096cbdce IT	292	return ss;
	293	}
	294
	295	ssize_t dnstls_stream_read(DnsStream stream, void buf, size_t count) {
36f1946c	296	int error, r;
096cbdce IT	297	ssize_t ss;
	298
	299	assert(stream);
	300	assert(stream->encrypted);
	301	assert(stream->dnstls_data.ssl);
	302	assert(buf);
	303
59c3fee2	304	ERR_clear_error();
096cbdce IT	305	ss = r = SSL_read(stream->dnstls_data.ssl, buf, count);
	306	if (r <= 0) {
	307	error = SSL_get_error(stream->dnstls_data.ssl, ss);
	308	if (IN_SET(error, SSL_ERROR_WANT_READ, SSL_ERROR_WANT_WRITE)) {
	309	stream->dnstls_events = error == SSL_ERROR_WANT_READ ? EPOLLIN : EPOLLOUT;
04c4d919 IT	310
	311	/* flush write buffer in cache of renegotiation */
	312	r = dnstls_flush_write_buffer(stream);
	313	if (r < 0)
	314	return r;
	315
096cbdce IT	316	ss = -EAGAIN;
	317	} else {
	318	char errbuf[256];
	319
	320	ERR_error_string_n(error, errbuf, sizeof(errbuf));
	321	log_debug("Failed to invoke SSL_read: %s", errbuf);
	322	ss = -EPIPE;
	323	}
	324	}
	325
	326	stream->dnstls_events = 0;
04c4d919 IT	327
	328	/* flush write buffer in cache of renegotiation */
	329	r = dnstls_flush_write_buffer(stream);
	330	if (r < 0)
	331	return r;
	332
096cbdce IT	333	return ss;
	334	}
	335
	336	void dnstls_server_init(DnsServer *server) {
	337	assert(server);
	338
	339	server->dnstls_data.ctx = SSL_CTX_new(TLS_client_method());
	340	if (server->dnstls_data.ctx) {
	341	SSL_CTX_set_min_proto_version(server->dnstls_data.ctx, TLS1_2_VERSION);
	342	SSL_CTX_set_options(server->dnstls_data.ctx, SSL_OP_NO_COMPRESSION);
	343	}
	344	}
	345
	346	void dnstls_server_free(DnsServer *server) {
	347	assert(server);
	348
	349	if (server->dnstls_data.ctx)
	350	SSL_CTX_free(server->dnstls_data.ctx);
04c4d919 IT	351
	352	if (server->dnstls_data.session)
	353	SSL_SESSION_free(server->dnstls_data.session);
096cbdce	354	}