blob: 32518ce3d9a22d2276d243b0e31f3a76688332e3 [file] [log] [blame]
* Copyright 2004 The WebRTC Project Authors. All rights reserved.
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
#include <string>
#include <memory>
#include <vector>
#include "webrtc/rtc_base/buffer.h"
#include "webrtc/rtc_base/opensslidentity.h"
#include "webrtc/rtc_base/sslstreamadapter.h"
typedef struct ssl_st SSL;
typedef struct ssl_ctx_st SSL_CTX;
typedef struct ssl_cipher_st SSL_CIPHER;
typedef struct x509_store_ctx_st X509_STORE_CTX;
namespace rtc {
// This class was written with OpenSSLAdapter (a socket adapter) as a
// starting point. It has similar structure and functionality, but uses a
// "peer-to-peer" mode, verifying the peer's certificate using a digest
// sent over a secure signaling channel.
// Static methods to initialize and deinit the SSL library are in
// OpenSSLAdapter. These should probably be moved out to a neutral class.
// In a few cases I have factored out some OpenSSLAdapter code into static
// methods so it can be reused from this class. Eventually that code should
// probably be moved to a common support class. Unfortunately there remain a
// few duplicated sections of code. I have not done more restructuring because
// I did not want to affect existing code that uses OpenSSLAdapter.
// This class does not support the SSL connection restart feature present in
// OpenSSLAdapter. I am not entirely sure how the feature is useful and I am
// not convinced that it works properly.
// This implementation is careful to disallow data exchange after an SSL error,
// and it has an explicit SSL_CLOSED state. It should not be possible to send
// any data in clear after one of the StartSSL methods has been called.
// Look in sslstreamadapter.h for documentation of the methods.
class OpenSSLIdentity;
class OpenSSLStreamAdapter : public SSLStreamAdapter {
explicit OpenSSLStreamAdapter(StreamInterface* stream);
~OpenSSLStreamAdapter() override;
void SetIdentity(SSLIdentity* identity) override;
// Default argument is for compatibility
void SetServerRole(SSLRole role = SSL_SERVER) override;
bool SetPeerCertificateDigest(
const std::string& digest_alg,
const unsigned char* digest_val,
size_t digest_len,
SSLPeerCertificateDigestError* error = nullptr) override;
std::unique_ptr<SSLCertificate> GetPeerCertificate() const override;
// Goes from state SSL_NONE to either SSL_CONNECTING or SSL_WAIT, depending
// on whether the underlying stream is already open or not.
int StartSSL() override;
void SetMode(SSLMode mode) override;
void SetMaxProtocolVersion(SSLProtocolVersion version) override;
void SetInitialRetransmissionTimeout(int timeout_ms) override;
StreamResult Read(void* data,
size_t data_len,
size_t* read,
int* error) override;
StreamResult Write(const void* data,
size_t data_len,
size_t* written,
int* error) override;
void Close() override;
StreamState GetState() const override;
// TODO(guoweis): Move this away from a static class method.
static std::string SslCipherSuiteToName(int crypto_suite);
bool GetSslCipherSuite(int* cipher) override;
int GetSslVersion() const override;
// Key Extractor interface
bool ExportKeyingMaterial(const std::string& label,
const uint8_t* context,
size_t context_len,
bool use_context,
uint8_t* result,
size_t result_len) override;
// DTLS-SRTP interface
bool SetDtlsSrtpCryptoSuites(const std::vector<int>& crypto_suites) override;
bool GetDtlsSrtpCryptoSuite(int* crypto_suite) override;
bool IsTlsConnected() override;
// Capabilities interfaces.
static bool IsBoringSsl();
static bool IsAcceptableCipher(int cipher, KeyType key_type);
static bool IsAcceptableCipher(const std::string& cipher, KeyType key_type);
// Use our timeutils.h source of timing in BoringSSL, allowing us to test
// using a fake clock.
static void enable_time_callback_for_testing();
void OnEvent(StreamInterface* stream, int events, int err) override;
enum SSLState {
// Before calling one of the StartSSL methods, data flows
// in clear text.
SSL_WAIT, // waiting for the stream to open to start SSL negotiation
SSL_CONNECTING, // SSL negotiation in progress
SSL_CONNECTED, // SSL stream successfully established
SSL_ERROR, // some SSL error occurred, stream is closed
SSL_CLOSED // Clean close
enum { MSG_TIMEOUT = MSG_MAX+1};
// The following three methods return 0 on success and a negative
// error code on failure. The error code may be from OpenSSL or -1
// on some other error cases, so it can't really be interpreted
// unfortunately.
// Prepare SSL library, state is SSL_CONNECTING.
int BeginSSL();
// Perform SSL negotiation steps.
int ContinueSSL();
// Error handler helper. signal is given as true for errors in
// asynchronous contexts (when an error method was not returned
// through some other method), and in that case an SE_CLOSE event is
// raised on the stream with the specified error.
// A 0 error means a graceful close, otherwise there is not really enough
// context to interpret the error code.
// |alert| indicates an alert description (one of the SSL_AD constants) to
// send to the remote endpoint when closing the association. If 0, a normal
// shutdown will be performed.
void Error(const char* context, int err, uint8_t alert, bool signal);
void Cleanup(uint8_t alert);
// Override MessageHandler
void OnMessage(Message* msg) override;
// Flush the input buffers by reading left bytes (for DTLS)
void FlushInput(unsigned int left);
// SSL library configuration
SSL_CTX* SetupSSLContext();
// Verify the peer certificate matches the signaled digest.
bool VerifyPeerCertificate();
// SSL certification verification error handler, called back from
// the openssl library. Returns an int interpreted as a boolean in
// the C style: zero means verification failure, non-zero means
// passed.
static int SSLVerifyCallback(int ok, X509_STORE_CTX* store);
bool waiting_to_verify_peer_certificate() const {
return client_auth_enabled() && !peer_certificate_verified_;
bool has_peer_certificate_digest() const {
return !peer_certificate_digest_algorithm_.empty() &&
SSLState state_;
SSLRole role_;
int ssl_error_code_; // valid when state_ == SSL_ERROR or SSL_CLOSED
// Whether the SSL negotiation is blocked on needing to read or
// write to the wrapped stream.
bool ssl_read_needs_write_;
bool ssl_write_needs_read_;
SSL* ssl_;
SSL_CTX* ssl_ctx_;
// Our key and certificate.
std::unique_ptr<OpenSSLIdentity> identity_;
// The certificate that the peer presented. Initially null, until the
// connection is established.
std::unique_ptr<OpenSSLCertificate> peer_certificate_;
bool peer_certificate_verified_ = false;
// The digest of the certificate that the peer must present.
Buffer peer_certificate_digest_value_;
std::string peer_certificate_digest_algorithm_;
// The DtlsSrtp ciphers
std::string srtp_ciphers_;
// Do DTLS or not
SSLMode ssl_mode_;
// Max. allowed protocol version
SSLProtocolVersion ssl_max_version_;
// A 50-ms initial timeout ensures rapid setup on fast connections, but may
// be too aggressive for low bandwidth links.
int dtls_handshake_timeout_ms_ = 50;
} // namespace rtc