Rework client certificates, add support for decoding a PEM object

src/SSLClient.h

@@ -22,6 +22,7 @@
 #include "SSLClientImpl.h"
 #include "SSLSession.h"
 #include "SSLClientParameters.h"
+#include "SSLObj.h"
 
 #ifndef SSLClient_H_
 #define SSLClient_H_
@@ -82,25 +83,6 @@ public:
         setTimeout(30 * 1000);
     }
 
-    /** 
-     * Same as SSLClient::SSLClient(const C &, const br_x509_trust_anchor*, const size_t, const int, const DebugLevel), 
-     * but can compile support for mutual authentication.
-     */
-    explicit SSLClient( const C& client, 
-                        const br_x509_trust_anchor *trust_anchors, 
-                        const size_t trust_anchors_num, 
-                        const int analog_pin, 
-                        const DebugLevel debug,
-                        const SSLClientParameters* mutual_auth_params)
-    : SSLClientImpl(trust_anchors, trust_anchors_num, analog_pin, debug, mutual_auth_params) 
-    , m_client(client)
-    , m_sessions{}
-    {
-        // set the timeout to a reasonable number (it can always be changes later)
-        // SSL Connections take a really long time so we don't want to time out a legitimate thing
-        setTimeout(30 * 1000);
-    }
-
     //========================================
     //= Functions implemented in SSLClientImpl
     //========================================
@@ -307,6 +289,13 @@ public:
     //= Functions Not in the Client Interface
     //========================================
 
+    /**
+     * @brief Add a client certificate and enable support for mutual auth
+     * 
+     * This function must be called BEFORE making an SSL connection.
+     */
+    void setMutualAuthParams(const SSLClientParameters* params) { return set_mutual_impl(params); }
+
     /**
      * @brief Gets a session reference corresponding to a host and IP, or a reference to a empty session if none exist
      * 

src/SSLClientImpl.cpp

@@ -69,23 +69,6 @@ SSLClientImpl::SSLClientImpl(const br_x509_trust_anchor *trust_anchors,
     br_ssl_engine_set_buffer(&m_sslctx.eng, m_iobuf, sizeof m_iobuf, duplex);
 }
 
-/* see SSLClientImpl.h */
-SSLClientImpl::SSLClientImpl(const br_x509_trust_anchor *trust_anchors, 
-    const size_t trust_anchors_num, const int analog_pin, 
-    const DebugLevel debug, const SSLClientParameters* mutual_auth_params)
-    : SSLClientImpl(trust_anchors, trust_anchors_num, analog_pin, debug) {
-    // if mutual authentication if needed, configure bearssl to support it.
-    if (mutual_auth_params != nullptr)
-        br_ssl_client_set_single_ec(    &m_sslctx, 
-                                        mutual_auth_params->client_cert_chain, 
-                                        mutual_auth_params->chain_len,
-                                        &mutual_auth_params->ec_key,
-                                        BR_KEYTYPE_KEYX | BR_KEYTYPE_SIGN,
-                                        BR_KEYTYPE_EC,
-                                        br_ssl_engine_get_ec(&m_sslctx.eng),
-                                        &br_ecdsa_i15_sign_asn1);
-    }
-
 /* see SSLClientImpl.h*/
 int SSLClientImpl::connect_impl(IPAddress ip, uint16_t port) {
     const char* func_name = __func__;
@@ -331,6 +314,20 @@ void SSLClientImpl::remove_session_impl(const char* host, const IPAddress& addr)
     }
 }
 
+/* see SSLClientImpl.h */
+void SSLClientImpl::set_mutual_impl(const SSLClientParameters* params) {
+    // if mutual authentication if needed, configure bearssl to support it.
+    if (params != nullptr)
+        br_ssl_client_set_single_ec(    &m_sslctx, 
+                                        params->client_cert_chain, 
+                                        params->chain_len,
+                                        &params->ec_key,
+                                        BR_KEYTYPE_KEYX | BR_KEYTYPE_SIGN,
+                                        BR_KEYTYPE_EC,
+                                        br_ssl_engine_get_ec(&m_sslctx.eng),
+                                        &br_ecdsa_i15_sign_asn1);
+}
+
 bool SSLClientImpl::m_soft_connected(const char* func_name) {
     // check if the socket is still open and such
     if (getWriteError()) {

src/SSLClientImpl.h

@@ -107,7 +107,8 @@ public:
     SSLSession& get_session_impl(const char* host, const IPAddress& addr);
     /** @see SSLClient::removeSession */
     void remove_session_impl(const char* host, const IPAddress& addr);
-
+    /** @see SSLClient::setMutualAuthParams */
+    void set_mutual_impl(const SSLClientParameters* params);
     //============================================
     //= Functions implemented in SSLClient.h
     //============================================

src/SSLObj.cpp

@@ -0,0 +1,57 @@
+#include "SSLObj.h"
+
+struct ssl_pem_decode_state {
+    std::vector<unsigned char>* vect;
+    size_t index = 0;
+};
+
+static void ssl_pem_decode(void *dest_ctx, const void *src, size_t len) {
+    ssl_pem_decode_state* ctx = static_cast<ssl_pem_decode_state*>(dest_ctx);
+    // copy the recieved bytes into the vector, resizing if needed
+    if (ctx->vect->size() < len + ctx->index) {
+        Serial.println("Overflow!");
+        return;
+    }
+    for (size_t i = 0; i < len; i++) (*(ctx->vect))[i + ctx->index] = static_cast<const unsigned char*>(src)[i];
+    // update index
+    ctx->index += len;
+}
+
+const std::vector<unsigned char> SSLObj::make_vector_pem(const char* data, const size_t len) {
+    if (data == nullptr || len == 0) return { 0 };
+    // initialize the bearssl PEM context
+    br_pem_decoder_context pctx;
+    br_pem_decoder_init(&pctx);
+    // create a temporary vector
+    std::vector<unsigned char> temp(len * 3 / 4 + 5);
+    // initialize the DER storage context
+    ssl_pem_decode_state state;
+    state.vect = &temp;
+    state.index = 0;
+    // set the byte reciever
+    br_pem_decoder_setdest(&pctx, &ssl_pem_decode, &state);
+    // start decoding!
+    int br_state = 0;
+    size_t index = 0;
+    do {
+        index += br_pem_decoder_push(&pctx, static_cast<const void*>(&data[index]), len - index);
+        br_state = br_pem_decoder_event(&pctx);
+    } while (br_state != BR_PEM_ERROR && br_state != BR_PEM_END_OBJ);
+    // error check
+    if (br_state == BR_PEM_ERROR) {
+        // set data to error
+        temp.clear();
+    }
+    // else we're good!
+    return { temp };
+}
+
+const std::vector<unsigned char> SSLObj::make_vector_der(const char* data, const size_t len) {
+    if (data == nullptr || len == 0) return { 0 };
+    // create a temporary vector
+    std::vector<unsigned char> temp(len);
+    // copy the elements over
+    for (size_t i = 0; i < len; i++) temp[i] = data[i];
+    // return the new SSLObj
+    return { temp };
+}

src/SSLObj.h

@@ -0,0 +1,51 @@
+/* Copyright 2019 OSU OPEnS Lab
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of this
+ * software and associated documentation files (the "Software"), to deal in the Software
+ * without restriction, including without limitation the rights to use, copy, modify,
+ * merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to the following
+ * conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+ * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
+ * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+/**
+ * SSLObj.h
+ * 
+ * This file contains a utility class to take PEM input and store it as a DER object
+ * for later use by BearSSL.
+ */
+
+#include <vector>
+#include "bearssl_pem.h"
+#include "Arduino.h"
+
+#ifndef SSLObj_H_
+#define SSLObj_H_
+
+/**
+ * \brief This namespace works with raw DER byte arrays for use later with TLS mutual auth.
+ * 
+ * This namespace was created to store some of the values stored in ::SSLClientParameters, 
+ * which allow BearSSL use client certificates when creating a TLS connection. Since
+ * most certificates are transmitted over the internet in PEM format, a certificate can
+ * be provided in PEM or DER format, and will be converted internally to DER format for
+ * later use. A PEM file provided to this class MUST CONTAIN the `----BEGIN ... -----`
+ * header in order to be parsed correctly.
+ */
+
+namespace SSLObj {
+    const std::vector<unsigned char> make_vector_pem(const char* data, const size_t len);
+    const std::vector<unsigned char> make_vector_der(const char* data, const size_t len);
+}
+
+#endif