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esp8266/libraries/ESP8266WiFi/src/WiFiServerSecureBearSSL.cpp
Earle F. Philhower, III e3c970210f
Add BearSSL client and server, support true bidir, lower memory, modern SSL (#4273)
BearSSL (https://www.bearssl.org) is a TLS(SSL) library written by
Thomas Pornin that is optimized for lower-memory embedded systems
like the ESP8266. It supports a wide variety of modern ciphers and
is unique in that it doesn't perform any memory allocations during
operation (which is the unfortunate bane of the current axTLS).

BearSSL is also absolutely focused on security and by default performs
all its security checks on x.509 certificates during the connection
phase (but if you want to be insecure and dangerous, that's possible
too).

While it does support unidirectional SSL buffers, like axTLS,
as implemented the ESP8266 wrappers only support bidirectional
buffers. These bidirectional buffers avoid deadlocks in protocols
which don't have well separated receive and transmit periods.

This patch adds several classes which allow connecting to TLS servers
using this library in almost the same way as axTLS:
BearSSL::WiFiClientSecure - WiFiClient that supports TLS
BearSSL::WiFiServerSecure - WiFiServer supporting TLS and client certs

It also introduces objects for PEM/DER encoded keys and certificates:
BearSSLX509List - x.509 Certificate (list) for general use
BearSSLPrivateKey - RSA or EC private key
BearSSLPublicKey - RSA or EC public key (i.e. from a public website)

Finally, it adds a Certificate Authority store object which lets
BearSSL access a set of trusted CA certificates on SPIFFS to allow it
to verify the identity of any remote site on the Internet, without
requiring RAM except for the single matching certificate.
CertStoreSPIFFSBearSSL - Certificate store utility

Client certificates are supported for the BearSSL::WiFiClientSecure, and
what's more the BearSSL::WiFiServerSecure can also *require* remote clients
to have a trusted certificate signed by a specific CA (or yourself with
self-signing CAs).

Maximum Fragment Length Negotiation probing and usage are supported, but
be aware that most sites on the Internet don't support it yet.  When
available, you can reduce the memory footprint of the SSL client or server
dramatically (i.e. down to 2-8KB vs. the ~22KB required for a full 16K
receive fragment and 512b send fragment).  You can also manually set a
smaller fragment size and guarantee at your protocol level all data will
fit within it.

Examples are included to show the usage of these new features.

axTLS has been moved to its own namespace, "axtls".  A default "using"
clause allows existing apps to run using axTLS without any changes.

The BearSSL::WiFi{client,server}Secure implements the axTLS
client/server API which lets many end user applications take advantage
of BearSSL with few or no changes.

The BearSSL static library used presently is stored at
https://github.com/earlephilhower/bearssl-esp8266 and can be built
using the standard ESP8266 toolchain.
2018-05-14 20:46:47 -07:00

120 lines
3.9 KiB
C++

/*
WiFiServerBearSSL.cpp - SSL server for esp8266, mostly compatible
with Arduino WiFi shield library
Copyright (c) 2018 Earle F. Philhower, III
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; 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 library; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#define LWIP_INTERNAL
extern "C" {
#include "osapi.h"
#include "ets_sys.h"
}
#include "debug.h"
#include "ESP8266WiFi.h"
#include "WiFiClient.h"
#include "WiFiServer.h"
#include "lwip/opt.h"
#include "lwip/tcp.h"
#include "lwip/inet.h"
#include "include/ClientContext.h"
#include "WiFiServerSecureBearSSL.h"
namespace BearSSL {
// Only need to call the standard server constructor
WiFiServerSecure::WiFiServerSecure(IPAddress addr, uint16_t port) : WiFiServer(addr, port) {
}
// Only need to call the standard server constructor
WiFiServerSecure::WiFiServerSecure(uint16_t port) : WiFiServer(port) {
}
// Destructor only checks if we need to delete compatibilty cert/key
WiFiServerSecure::~WiFiServerSecure() {
if (_deleteChainAndKey) {
delete _chain;
delete _sk;
}
}
// Specify a RSA-signed certificate and key for the server. Only copies the pointer, the
// caller needs to preserve this chain and key for the life of the object.
void WiFiServerSecure::setRSACert(const BearSSLX509List *chain, const BearSSLPrivateKey *sk) {
_chain = chain;
_sk = sk;
}
// Specify a EC-signed certificate and key for the server. Only copies the pointer, the
// caller needs to preserve this chain and key for the life of the object.
void WiFiServerSecure::setECCert(const BearSSLX509List *chain, unsigned cert_issuer_key_type, const BearSSLPrivateKey *sk) {
_chain = chain;
_cert_issuer_key_type = cert_issuer_key_type;
_sk = sk;
}
// Return a client if there's an available connection waiting. If one is returned,
// then any validation (i.e. client cert checking) will have succeeded.
WiFiClientSecure WiFiServerSecure::available(uint8_t* status) {
(void) status; // Unused
if (_unclaimed) {
if (_sk && _sk->isRSA()) {
WiFiClientSecure result(_unclaimed, _chain, _sk, _iobuf_in_size, _iobuf_out_size, _client_CA_ta);
_unclaimed = _unclaimed->next();
result.setNoDelay(_noDelay);
DEBUGV("WS:av\r\n");
return result;
} else if (_sk && _sk->isEC()) {
WiFiClientSecure result(_unclaimed, _chain, _cert_issuer_key_type, _sk, _iobuf_in_size, _iobuf_out_size, _client_CA_ta);
_unclaimed = _unclaimed->next();
result.setNoDelay(_noDelay);
DEBUGV("WS:av\r\n");
return result;
} else {
// No key was defined, so we can't actually accept and attempt accept() and SSL handshake.
DEBUGV("WS:nokey\r\n");
}
}
// Something weird, return a no-op object
optimistic_yield(1000);
return WiFiClientSecure();
}
void WiFiServerSecure::setServerKeyAndCert(const uint8_t *key, int keyLen, const uint8_t *cert, int certLen) {
BearSSLX509List *chain = new BearSSLX509List(cert, certLen);
BearSSLPrivateKey *sk = new BearSSLPrivateKey(key, keyLen);
if (!chain || !key) {
// OOM, fail gracefully
delete chain;
delete sk;
return;
}
_deleteChainAndKey = true;
setRSACert(chain, sk);
}
void WiFiServerSecure::setServerKeyAndCert_P(const uint8_t *key, int keyLen, const uint8_t *cert, int certLen) {
setServerKeyAndCert(key, keyLen, cert, certLen);
}
};