Merge pull request #19413 from Faless/lws_3.0

Update libwebsockets to version 3.0

1 files changed, 694 insertions, 0 deletions

diff --git a/thirdparty/libwebsockets/tls/mbedtls/mbedtls-server.c b/thirdparty/libwebsockets/tls/mbedtls/mbedtls-server.c
new file mode 100644
index 0000000000..2de6d422e3
--- /dev/null
+++ b/thirdparty/libwebsockets/tls/mbedtls/mbedtls-server.c
@@ -0,0 +1,694 @@
+/*
+ * libwebsockets - mbedTLS-specific server functions
+ *
+ * Copyright (C) 2010-2017 Andy Green <andy@warmcat.com>
+ *
+ *  This 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:
+ *  version 2.1 of the License.
+ *
+ *  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 library; if not, write to the Free Software
+ *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+ *  MA  02110-1301  USA
+ */
+
+#include "core/private.h"
+#include <mbedtls/x509_csr.h>
+
+int
+lws_tls_server_client_cert_verify_config(struct lws_vhost *vh)
+{
+	int verify_options = SSL_VERIFY_PEER;
+
+	/* as a server, are we requiring clients to identify themselves? */
+	if (!lws_check_opt(vh->options,
+			  LWS_SERVER_OPTION_REQUIRE_VALID_OPENSSL_CLIENT_CERT)) {
+		lwsl_notice("no client cert required\n");
+		return 0;
+	}
+
+	/*
+	 * The wrapper has this messed-up mapping:
+	 *
+	 * 	   else if (ctx->verify_mode == SSL_VERIFY_FAIL_IF_NO_PEER_CERT)
+	 *     mode = MBEDTLS_SSL_VERIFY_OPTIONAL;
+	 *
+	 * ie the meaning is inverted.  So where we should test for ! we don't
+	 */
+	if (lws_check_opt(vh->options, LWS_SERVER_OPTION_PEER_CERT_NOT_REQUIRED))
+		verify_options = SSL_VERIFY_FAIL_IF_NO_PEER_CERT;
+
+	lwsl_notice("%s: vh %s requires client cert %d\n", __func__, vh->name,
+		    verify_options);
+
+	SSL_CTX_set_verify(vh->tls.ssl_ctx, verify_options, NULL);
+
+	return 0;
+}
+
+static int
+lws_mbedtls_sni_cb(void *arg, mbedtls_ssl_context *mbedtls_ctx,
+		   const unsigned char *servername, size_t len)
+{
+	SSL *ssl = SSL_SSL_from_mbedtls_ssl_context(mbedtls_ctx);
+	struct lws_context *context = (struct lws_context *)arg;
+	struct lws_vhost *vhost, *vh;
+
+	lwsl_notice("%s: %s\n", __func__, servername);
+
+	/*
+	 * We can only get ssl accepted connections by using a vhost's ssl_ctx
+	 * find out which listening one took us and only match vhosts on the
+	 * same port.
+	 */
+	vh = context->vhost_list;
+	while (vh) {
+		if (!vh->being_destroyed &&
+		    vh->tls.ssl_ctx == SSL_get_SSL_CTX(ssl))
+			break;
+		vh = vh->vhost_next;
+	}
+
+	if (!vh) {
+		assert(vh); /* can't match the incoming vh? */
+		return 0;
+	}
+
+	vhost = lws_select_vhost(context, vh->listen_port,
+				 (const char *)servername);
+	if (!vhost) {
+		lwsl_info("SNI: none: %s:%d\n", servername, vh->listen_port);
+
+		return 0;
+	}
+
+	lwsl_info("SNI: Found: %s:%d at vhost '%s'\n", servername,
+					vh->listen_port, vhost->name);
+
+	/* select the ssl ctx from the selected vhost for this conn */
+	SSL_set_SSL_CTX(ssl, vhost->tls.ssl_ctx);
+
+	return 0;
+}
+
+int
+lws_tls_server_certs_load(struct lws_vhost *vhost, struct lws *wsi,
+			  const char *cert, const char *private_key,
+			  const char *mem_cert, size_t len_mem_cert,
+			  const char *mem_privkey, size_t mem_privkey_len)
+{
+	int n, f = 0;
+	const char *filepath = private_key;
+	uint8_t *mem = NULL, *p = NULL;
+	size_t mem_len = 0;
+	lws_filepos_t flen;
+	long err;
+
+	if ((!cert || !private_key) && (!mem_cert || !mem_privkey)) {
+		lwsl_notice("%s: no usable input\n", __func__);
+		return 0;
+	}
+
+	n = lws_tls_generic_cert_checks(vhost, cert, private_key);
+
+	if (n == LWS_TLS_EXTANT_NO && (!mem_cert || !mem_privkey))
+		return 0;
+
+	/*
+	 * we can't read the root-privs files.  But if mem_cert is provided,
+	 * we should use that.
+	 */
+	if (n == LWS_TLS_EXTANT_NO)
+		n = LWS_TLS_EXTANT_ALTERNATIVE;
+
+	if (n == LWS_TLS_EXTANT_ALTERNATIVE && (!mem_cert || !mem_privkey))
+		return 1; /* no alternative */
+
+	if (n == LWS_TLS_EXTANT_ALTERNATIVE) {
+		/*
+		 * Although we have prepared update certs, we no longer have
+		 * the rights to read our own cert + key we saved.
+		 *
+		 * If we were passed copies in memory buffers, use those
+		 * instead.
+		 *
+		 * The passed memory-buffer cert image is in DER, and the
+		 * memory-buffer private key image is PEM.
+		 */
+		/* mem cert is already DER */
+		p = (uint8_t *)mem_cert;
+		flen = len_mem_cert;
+		/* mem private key is PEM, so go through the motions */
+		mem = (uint8_t *)mem_privkey;
+		mem_len = mem_privkey_len;
+		filepath = NULL;
+	} else {
+		if (lws_tls_alloc_pem_to_der_file(vhost->context, cert, NULL,
+						  0, &p, &flen)) {
+			lwsl_err("couldn't find cert file %s\n", cert);
+
+			return 1;
+		}
+		f = 1;
+	}
+	err = SSL_CTX_use_certificate_ASN1(vhost->tls.ssl_ctx, flen, p);
+	if (!err) {
+		free(p);
+		lwsl_err("Problem loading cert\n");
+		return 1;
+	}
+
+	if (f)
+		free(p);
+	p = NULL;
+
+	if (private_key || n == LWS_TLS_EXTANT_ALTERNATIVE) {
+		if (lws_tls_alloc_pem_to_der_file(vhost->context, filepath,
+						  (char *)mem, mem_len, &p,
+						  &flen)) {
+			lwsl_err("couldn't find private key file %s\n",
+					private_key);
+
+			return 1;
+		}
+		err = SSL_CTX_use_PrivateKey_ASN1(0, vhost->tls.ssl_ctx, p, flen);
+		if (!err) {
+			free(p);
+			lwsl_err("Problem loading key\n");
+
+			return 1;
+		}
+	}
+
+	if (p && !mem_privkey) {
+		free(p);
+		p = NULL;
+	}
+
+	if (!private_key && !mem_privkey &&
+	    vhost->protocols[0].callback(wsi,
+			LWS_CALLBACK_OPENSSL_CONTEXT_REQUIRES_PRIVATE_KEY,
+			vhost->tls.ssl_ctx, NULL, 0)) {
+		lwsl_err("ssl private key not set\n");
+
+		return 1;
+	}
+
+	vhost->tls.skipped_certs = 0;
+
+	return 0;
+}
+
+int
+lws_tls_server_vhost_backend_init(const struct lws_context_creation_info *info,
+				  struct lws_vhost *vhost, struct lws *wsi)
+{
+	const SSL_METHOD *method = TLS_server_method();
+	uint8_t *p;
+	lws_filepos_t flen;
+	int n;
+
+	vhost->tls.ssl_ctx = SSL_CTX_new(method);	/* create context */
+	if (!vhost->tls.ssl_ctx) {
+		lwsl_err("problem creating ssl context\n");
+		return 1;
+	}
+
+	if (!vhost->tls.use_ssl || !info->ssl_cert_filepath)
+		return 0;
+
+	if (info->ssl_ca_filepath) {
+		lwsl_notice("%s: vh %s: loading CA filepath %s\n", __func__,
+			    vhost->name, info->ssl_ca_filepath);
+		if (lws_tls_alloc_pem_to_der_file(vhost->context,
+				info->ssl_ca_filepath, NULL, 0, &p, &flen)) {
+			lwsl_err("couldn't find client CA file %s\n",
+					info->ssl_ca_filepath);
+
+			return 1;
+		}
+
+		if (SSL_CTX_add_client_CA_ASN1(vhost->tls.ssl_ctx, (int)flen, p) != 1) {
+			lwsl_err("%s: SSL_CTX_add_client_CA_ASN1 unhappy\n",
+				 __func__);
+			free(p);
+			return 1;
+		}
+		free(p);
+	}
+
+	n = lws_tls_server_certs_load(vhost, wsi, info->ssl_cert_filepath,
+				      info->ssl_private_key_filepath, NULL,
+				      0, NULL, 0);
+	if (n)
+		return n;
+
+	return 0;
+}
+
+int
+lws_tls_server_new_nonblocking(struct lws *wsi, lws_sockfd_type accept_fd)
+{
+	errno = 0;
+	wsi->tls.ssl = SSL_new(wsi->vhost->tls.ssl_ctx);
+	if (wsi->tls.ssl == NULL) {
+		lwsl_err("SSL_new failed: errno %d\n", errno);
+
+		lws_ssl_elaborate_error();
+		return 1;
+	}
+
+	SSL_set_fd(wsi->tls.ssl, accept_fd);
+
+	if (wsi->vhost->tls.ssl_info_event_mask)
+		SSL_set_info_callback(wsi->tls.ssl, lws_ssl_info_callback);
+
+	SSL_set_sni_callback(wsi->tls.ssl, lws_mbedtls_sni_cb, wsi->context);
+
+	return 0;
+}
+
+int
+lws_tls_server_abort_connection(struct lws *wsi)
+{
+	__lws_tls_shutdown(wsi);
+	SSL_free(wsi->tls.ssl);
+
+	return 0;
+}
+
+enum lws_ssl_capable_status
+lws_tls_server_accept(struct lws *wsi)
+{
+	union lws_tls_cert_info_results ir;
+	int m, n;
+
+	n = SSL_accept(wsi->tls.ssl);
+	if (n == 1) {
+
+		if (strstr(wsi->vhost->name, ".invalid")) {
+			lwsl_notice("%s: vhost has .invalid, rejecting accept\n", __func__);
+
+			return LWS_SSL_CAPABLE_ERROR;
+		}
+
+		n = lws_tls_peer_cert_info(wsi, LWS_TLS_CERT_INFO_COMMON_NAME, &ir,
+					   sizeof(ir.ns.name));
+		if (!n)
+			lwsl_notice("%s: client cert CN '%s'\n",
+				    __func__, ir.ns.name);
+		else
+			lwsl_info("%s: couldn't get client cert CN\n", __func__);
+		return LWS_SSL_CAPABLE_DONE;
+	}
+
+	m = SSL_get_error(wsi->tls.ssl, n);
+	lwsl_debug("%s: %p: accept SSL_get_error %d errno %d\n", __func__,
+		   wsi, m, errno);
+
+	// mbedtls wrapper only
+	if (m == SSL_ERROR_SYSCALL && errno == 11)
+		return LWS_SSL_CAPABLE_MORE_SERVICE_READ;
+
+	if (m == SSL_ERROR_SYSCALL || m == SSL_ERROR_SSL)
+		return LWS_SSL_CAPABLE_ERROR;
+
+	if (m == SSL_ERROR_WANT_READ || SSL_want_read(wsi->tls.ssl)) {
+		if (lws_change_pollfd(wsi, 0, LWS_POLLIN)) {
+			lwsl_info("%s: WANT_READ change_pollfd failed\n", __func__);
+			return LWS_SSL_CAPABLE_ERROR;
+		}
+
+		lwsl_info("SSL_ERROR_WANT_READ\n");
+		return LWS_SSL_CAPABLE_MORE_SERVICE_READ;
+	}
+	if (m == SSL_ERROR_WANT_WRITE || SSL_want_write(wsi->tls.ssl)) {
+		lwsl_debug("%s: WANT_WRITE\n", __func__);
+
+		if (lws_change_pollfd(wsi, 0, LWS_POLLOUT)) {
+			lwsl_info("%s: WANT_WRITE change_pollfd failed\n", __func__);
+			return LWS_SSL_CAPABLE_ERROR;
+		}
+		return LWS_SSL_CAPABLE_MORE_SERVICE_WRITE;
+	}
+
+	return LWS_SSL_CAPABLE_ERROR;
+}
+
+#if defined(LWS_WITH_ACME)
+/*
+ * mbedtls doesn't support SAN for cert creation.  So we use a known-good
+ * tls-sni-01 cert from OpenSSL that worked on Let's Encrypt, and just replace
+ * the pubkey n part and the signature part.
+ *
+ * This will need redoing for tls-sni-02...
+ */
+
+static uint8_t ss_cert_leadin[] = {
+	0x30, 0x82,
+	  0x05, 0x56, /* total length: LEN1 (+2 / +3) (correct for 513 + 512)*/
+
+	0x30, 0x82, /* length: LEN2  (+6 / +7) (correct for 513) */
+		0x03, 0x3e,
+
+	/* addition: v3 cert (+5 bytes)*/
+	0xa0, 0x03,
+		0x02, 0x01, 0x02,
+
+	0x02, 0x01, 0x01,
+	0x30, 0x0d, 0x06, 0x09, 0x2a,
+	0x86, 0x48, 0x86, 0xf7, 0x0d, 0x01, 0x01, 0x0b, 0x05, 0x00, 0x30, 0x3f,
+	0x31, 0x0b, 0x30, 0x09, 0x06, 0x03, 0x55, 0x04, 0x06, 0x13, 0x02, 0x47,
+	0x42, 0x31, 0x14, 0x30, 0x12, 0x06, 0x03, 0x55, 0x04, 0x0a, 0x0c, 0x0b,
+	0x73, 0x6f, 0x6d, 0x65, 0x63, 0x6f, 0x6d, 0x70, 0x61, 0x6e, 0x79, 0x31,
+	0x1a, 0x30, 0x18, 0x06, 0x03, 0x55, 0x04, 0x03, 0x0c, 0x11, 0x74, 0x65,
+	0x6d, 0x70, 0x2e, 0x61, 0x63, 0x6d, 0x65, 0x2e, 0x69, 0x6e, 0x76, 0x61,
+	0x6c, 0x69, 0x64, 0x30, 0x1e, 0x17, 0x0d,
+
+	/* from 2017-10-29 ... */
+	0x31, 0x37, 0x31, 0x30, 0x32, 0x39, 0x31, 0x31, 0x34, 0x39, 0x34, 0x35,
+	0x5a, 0x17, 0x0d,
+
+	/* thru 2049-10-29 we immediately discard the private key, no worries */
+	0x34, 0x39, 0x31, 0x30, 0x32, 0x39, 0x31, 0x32, 0x34, 0x39, 0x34, 0x35,
+	0x5a,
+
+	0x30, 0x3f, 0x31, 0x0b, 0x30, 0x09, 0x06, 0x03, 0x55, 0x04, 0x06, 0x13,
+	0x02, 0x47, 0x42, 0x31, 0x14, 0x30, 0x12, 0x06, 0x03, 0x55, 0x04, 0x0a,
+	0x0c, 0x0b, 0x73, 0x6f, 0x6d, 0x65, 0x63, 0x6f, 0x6d, 0x70, 0x61, 0x6e,
+	0x79, 0x31, 0x1a, 0x30, 0x18, 0x06, 0x03, 0x55, 0x04, 0x03, 0x0c, 0x11,
+	0x74, 0x65, 0x6d, 0x70, 0x2e, 0x61, 0x63, 0x6d, 0x65, 0x2e, 0x69, 0x6e,
+	0x76, 0x61, 0x6c, 0x69, 0x64, 0x30,
+
+	0x82,
+		0x02, 0x22, /* LEN3 (+C3 / C4) */
+	0x30, 0x0d, 0x06,
+	0x09, 0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x01, 0x01, 0x01, 0x05, 0x00,
+	0x03,
+
+	0x82,
+		0x02, 0x0f, /* LEN4 (+D6 / D7) */
+
+	0x00, 0x30, 0x82,
+
+		0x02, 0x0a, /* LEN5 (+ DB / DC) */
+
+	0x02, 0x82,
+
+	//0x02, 0x01, /* length of n in bytes (including leading 00 if any) */
+	},
+
+	/* 1 + (keybits / 8) bytes N */
+
+	ss_cert_san_leadin[] = {
+		/* e - fixed */
+		0x02, 0x03, 0x01, 0x00, 0x01,
+
+		0xa3, 0x5d, 0x30, 0x5b, 0x30, 0x59, 0x06, 0x03, 0x55, 0x1d,
+		0x11, 0x04, 0x52, 0x30, 0x50, /* <-- SAN length + 2 */
+
+		0x82, 0x4e, /* <-- SAN length */
+	},
+
+	/* 78 bytes of SAN (tls-sni-01)
+	0x61, 0x64, 0x34, 0x31, 0x61, 0x66, 0x62, 0x65, 0x30, 0x63, 0x61, 0x34,
+	0x36, 0x34, 0x32, 0x66, 0x30, 0x61, 0x34, 0x34, 0x39, 0x64, 0x39, 0x63,
+	0x61, 0x37, 0x36, 0x65, 0x62, 0x61, 0x61, 0x62, 0x2e, 0x32, 0x38, 0x39,
+	0x34, 0x64, 0x34, 0x31, 0x36, 0x63, 0x39, 0x38, 0x33, 0x66, 0x31, 0x32,
+	0x65, 0x64, 0x37, 0x33, 0x31, 0x61, 0x33, 0x30, 0x66, 0x35, 0x63, 0x34,
+	0x34, 0x37, 0x37, 0x66, 0x65, 0x2e, 0x61, 0x63, 0x6d, 0x65, 0x2e, 0x69,
+	0x6e, 0x76, 0x61, 0x6c, 0x69, 0x64, */
+
+	/* end of LEN2 area */
+
+	ss_cert_sig_leadin[] = {
+		/* it's saying that the signature is SHA256 + RSA */
+		0x30, 0x0d, 0x06, 0x09, 0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d,
+		0x01, 0x01, 0x0b, 0x05, 0x00, 0x03,
+
+		0x82,
+			0x02, 0x01,
+		0x00,
+	};
+
+	/* (keybits / 8) bytes signature to end of LEN1 area */
+
+#define SAN_A_LENGTH 78
+
+LWS_VISIBLE int
+lws_tls_acme_sni_cert_create(struct lws_vhost *vhost, const char *san_a,
+			     const char *san_b)
+{
+	int buflen = 0x560;
+	uint8_t *buf = lws_malloc(buflen, "tmp cert buf"), *p = buf, *pkey_asn1;
+	struct lws_genrsa_ctx ctx;
+	struct lws_genrsa_elements el;
+	uint8_t digest[32];
+	struct lws_genhash_ctx hash_ctx;
+	int pkey_asn1_len = 3 * 1024;
+	int n, m, keybits = lws_plat_recommended_rsa_bits(), adj;
+
+	if (!buf)
+		return 1;
+
+	n = lws_genrsa_new_keypair(vhost->context, &ctx, &el, keybits);
+	if (n < 0) {
+		lws_jwk_destroy_genrsa_elements(&el);
+		goto bail1;
+	}
+
+	n = sizeof(ss_cert_leadin);
+	memcpy(p, ss_cert_leadin, n);
+	p += n;
+
+	adj = (0x0556 - 0x401) + (keybits / 4) + 1;
+	buf[2] = adj >> 8;
+	buf[3] = adj & 0xff;
+
+	adj = (0x033e - 0x201) + (keybits / 8) + 1;
+	buf[6] = adj >> 8;
+	buf[7] = adj & 0xff;
+
+	adj = (0x0222 - 0x201) + (keybits / 8) + 1;
+	buf[0xc3] = adj >> 8;
+	buf[0xc4] = adj & 0xff;
+
+	adj = (0x020f - 0x201) + (keybits / 8) + 1;
+	buf[0xd6] = adj >> 8;
+	buf[0xd7] = adj & 0xff;
+
+	adj = (0x020a - 0x201) + (keybits / 8) + 1;
+	buf[0xdb] = adj >> 8;
+	buf[0xdc] = adj & 0xff;
+
+	*p++ = ((keybits / 8) + 1) >> 8;
+	*p++ = ((keybits / 8) + 1) & 0xff;
+
+	/* we need to drop 1 + (keybits / 8) bytes of n in here, 00 + key */
+
+	*p++ = 0x00;
+	memcpy(p, el.e[JWK_KEY_N].buf, el.e[JWK_KEY_N].len);
+	p += el.e[JWK_KEY_N].len;
+
+	memcpy(p, ss_cert_san_leadin, sizeof(ss_cert_san_leadin));
+	p += sizeof(ss_cert_san_leadin);
+
+	/* drop in 78 bytes of san_a */
+
+	memcpy(p, san_a, SAN_A_LENGTH);
+	p += SAN_A_LENGTH;
+	memcpy(p, ss_cert_sig_leadin, sizeof(ss_cert_sig_leadin));
+
+	p[17] = ((keybits / 8) + 1) >> 8;
+	p[18] = ((keybits / 8) + 1) & 0xff;
+
+	p += sizeof(ss_cert_sig_leadin);
+
+	/* hash the cert plaintext */
+
+	if (lws_genhash_init(&hash_ctx, LWS_GENHASH_TYPE_SHA256))
+		goto bail2;
+
+	if (lws_genhash_update(&hash_ctx, buf, lws_ptr_diff(p, buf))) {
+		lws_genhash_destroy(&hash_ctx, NULL);
+
+		goto bail2;
+	}
+	if (lws_genhash_destroy(&hash_ctx, digest))
+		goto bail2;
+
+	/* sign the hash */
+
+	n = lws_genrsa_public_sign(&ctx, digest, LWS_GENHASH_TYPE_SHA256, p,
+				 buflen - lws_ptr_diff(p, buf));
+	if (n < 0)
+		goto bail2;
+	p += n;
+
+	pkey_asn1 = lws_malloc(pkey_asn1_len, "mbed crt tmp");
+	if (!pkey_asn1)
+		goto bail2;
+
+	m = lws_genrsa_render_pkey_asn1(&ctx, 1, pkey_asn1, pkey_asn1_len);
+	if (m < 0) {
+		lws_free(pkey_asn1);
+		goto bail2;
+	}
+
+//	lwsl_hexdump_level(LLL_DEBUG, buf, lws_ptr_diff(p, buf));
+	n = SSL_CTX_use_certificate_ASN1(vhost->tls.ssl_ctx,
+				 lws_ptr_diff(p, buf), buf);
+	if (n != 1) {
+		lws_free(pkey_asn1);
+		lwsl_err("%s: generated cert failed to load 0x%x\n",
+				__func__, -n);
+	} else {
+		//lwsl_debug("private key\n");
+		//lwsl_hexdump_level(LLL_DEBUG, pkey_asn1, n);
+
+		/* and to use our generated private key */
+		n = SSL_CTX_use_PrivateKey_ASN1(0, vhost->tls.ssl_ctx, pkey_asn1, m);
+		lws_free(pkey_asn1);
+		if (n != 1) {
+			lwsl_err("%s: SSL_CTX_use_PrivateKey_ASN1 failed\n",
+				    __func__);
+		}
+	}
+
+	lws_genrsa_destroy(&ctx);
+	lws_jwk_destroy_genrsa_elements(&el);
+
+	lws_free(buf);
+
+	return n != 1;
+
+bail2:
+	lws_genrsa_destroy(&ctx);
+	lws_jwk_destroy_genrsa_elements(&el);
+bail1:
+	lws_free(buf);
+
+	return -1;
+}
+
+void
+lws_tls_acme_sni_cert_destroy(struct lws_vhost *vhost)
+{
+}
+
+#if defined(LWS_WITH_JWS)
+static int
+_rngf(void *context, unsigned char *buf, size_t len)
+{
+	if ((size_t)lws_get_random(context, buf, len) == len)
+		return 0;
+
+	return -1;
+}
+
+static const char *x5[] = { "C", "ST", "L", "O", "CN" };
+
+/*
+ * CSR is output formatted as b64url(DER)
+ * Private key is output as a PEM in memory
+ */
+LWS_VISIBLE LWS_EXTERN int
+lws_tls_acme_sni_csr_create(struct lws_context *context, const char *elements[],
+			    uint8_t *dcsr, size_t csr_len, char **privkey_pem,
+			    size_t *privkey_len)
+{
+	mbedtls_x509write_csr csr;
+	mbedtls_pk_context mpk;
+	int buf_size = 4096, n;
+	char subject[200], *p = subject, *end = p + sizeof(subject) - 1;
+	uint8_t *buf = malloc(buf_size); /* malloc because given to user code */
+
+	if (!buf)
+		return -1;
+
+	mbedtls_x509write_csr_init(&csr);
+
+	mbedtls_pk_init(&mpk);
+	if (mbedtls_pk_setup(&mpk, mbedtls_pk_info_from_type(MBEDTLS_PK_RSA))) {
+		lwsl_notice("%s: pk_setup failed\n", __func__);
+		goto fail;
+	}
+
+	n = mbedtls_rsa_gen_key(mbedtls_pk_rsa(mpk), _rngf, context,
+				lws_plat_recommended_rsa_bits(), 65537);
+	if (n) {
+		lwsl_notice("%s: failed to generate keys\n", __func__);
+
+		goto fail1;
+	}
+
+	/* subject must be formatted like "C=TW,O=warmcat,CN=myserver" */
+
+	for (n = 0; n < (int)ARRAY_SIZE(x5); n++) {
+		if (p != subject)
+			*p++ = ',';
+		if (elements[n])
+			p += lws_snprintf(p, end - p, "%s=%s", x5[n],
+					  elements[n]);
+	}
+
+	if (mbedtls_x509write_csr_set_subject_name(&csr, subject))
+		goto fail1;
+
+	mbedtls_x509write_csr_set_key(&csr, &mpk);
+	mbedtls_x509write_csr_set_md_alg(&csr, MBEDTLS_MD_SHA256);
+
+	/*
+	 * data is written at the end of the buffer! Use the
+	 * return value to determine where you should start
+	 * using the buffer
+	 */
+	n = mbedtls_x509write_csr_der(&csr, buf, buf_size, _rngf, context);
+	if (n < 0) {
+		lwsl_notice("%s: write csr der failed\n", __func__);
+		goto fail1;
+	}
+
+	/* we have it in DER, we need it in b64URL */
+
+	n = lws_jws_base64_enc((char *)(buf + buf_size) - n, n,
+			       (char *)dcsr, csr_len);
+	if (n < 0)
+		goto fail1;
+
+	/*
+	 * okay, the CSR is done, last we need the private key in PEM
+	 * re-use the DER CSR buf as the result buffer since we cn do it in
+	 * one step
+	 */
+
+	if (mbedtls_pk_write_key_pem(&mpk, buf, buf_size)) {
+		lwsl_notice("write key pem failed\n");
+		goto fail1;
+	}
+
+	*privkey_pem = (char *)buf;
+	*privkey_len = strlen((const char *)buf);
+
+	mbedtls_pk_free(&mpk);
+	mbedtls_x509write_csr_free(&csr);
+
+	return n;
+
+fail1:
+	mbedtls_pk_free(&mpk);
+fail:
+	mbedtls_x509write_csr_free(&csr);
+	free(buf);
+
+	return -1;
+}
+#endif
+#endif