DtlsFactory.cxx

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#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
 
#ifdef USE_SSL
 
#include "rutil/ResipAssert.h"
#include <iostream>
#include <rutil/ssl/OpenSSLInit.hxx>
 
#include <openssl/e_os2.h>
#include <openssl/evp.h>
#include <openssl/hmac.h>
#include <openssl/rand.h>
#include <openssl/err.h>
#include <openssl/crypto.h>
#include <openssl/ssl.h>
 
#include "DtlsFactory.hxx"
#include "DtlsSocket.hxx"
 
#include <string>
#include <utility>
 
using namespace dtls;
const char* DtlsFactory::DefaultSrtpProfile = "SRTP_AES128_CM_SHA1_80:SRTP_AES128_CM_SHA1_32";
 
DtlsFactory::DtlsFactory(std::unique_ptr<DtlsTimerContext> tc,X509 *cert, EVP_PKEY *privkey):
   mTimerContext(std::move(tc)),
   mCert(cert)
{
   int r;
 
   mContext=SSL_CTX_new(DTLS_method());
   resip_assert(mContext);
 
   r=SSL_CTX_use_certificate(mContext, cert);
   resip_assert(r==1);
 
   r=SSL_CTX_use_PrivateKey(mContext, privkey);
   resip_assert(r==1);
 
   // Set SRTP profiles
   r=SSL_CTX_set_tlsext_use_srtp(mContext, DefaultSrtpProfile);
   resip_assert(r==0);
 
   // DTLS cookies, for DtlsListener
   r=RAND_bytes(mCookieSecret, sizeof(mCookieSecret));
   resip_assert(r==1);
   SSL_CTX_set_app_data(mContext, this);
   SSL_CTX_set_cookie_generate_cb(mContext, generateCookie);
   SSL_CTX_set_cookie_verify_cb(mContext, verifyCookie);
}
 
DtlsFactory::~DtlsFactory()
{
   SSL_CTX_free(mContext);
}
 
 
DtlsSocket*
DtlsFactory::createClient(std::unique_ptr<DtlsSocketContext> context)
{
   return new DtlsSocket(std::move(context), this, DtlsSocket::Client);
}
 
DtlsSocket*
DtlsFactory::createServer(std::unique_ptr<DtlsSocketContext> context)
{
   return new DtlsSocket(std::move(context), this, DtlsSocket::Server);
}
 
std::unique_ptr<DtlsListener>
DtlsFactory::createListener()
{
   return std::unique_ptr<DtlsListener>(new DtlsListener(this));
}
 
int
DtlsFactory::cookiePeerIndex()
{
   static const int index = SSL_get_ex_new_index(0, (void*)"dtls cookie peer", nullptr, nullptr, nullptr);
   return index;
}
 
bool
DtlsFactory::computeCookie(SSL* ssl, unsigned char* cookie, unsigned int* cookieLen)
{
   DtlsFactory* factory = static_cast<DtlsFactory*>(SSL_CTX_get_app_data(SSL_get_SSL_CTX(ssl)));
   const std::string* peer = static_cast<const std::string*>(SSL_get_ex_data(ssl, cookiePeerIndex()));
   if(!factory || !peer || peer->empty())
   {
      return false;
   }
   return HMAC(EVP_sha256(), factory->mCookieSecret, sizeof(factory->mCookieSecret),
               (const unsigned char*)peer->data(), peer->size(), cookie, cookieLen) != nullptr;
}
 
int
DtlsFactory::generateCookie(SSL* ssl, unsigned char* cookie, unsigned int* cookieLen)
{
   // cookie has room for DTLS1_COOKIE_LENGTH (255) bytes, the HMAC takes 32
   return computeCookie(ssl, cookie, cookieLen) ? 1 : 0;
}
 
int
DtlsFactory::verifyCookie(SSL* ssl, const unsigned char* cookie, unsigned int cookieLen)
{
   unsigned char expected[EVP_MAX_MD_SIZE];
   unsigned int expectedLen = 0;
   return computeCookie(ssl, expected, &expectedLen) &&
          cookieLen == expectedLen && CRYPTO_memcmp(cookie, expected, expectedLen) == 0 ? 1 : 0;
}
 
void
DtlsFactory::getMyCertFingerprint(char *fingerprint)
{
   DtlsSocket::computeFingerprint(mCert,fingerprint);
}
 
void
DtlsFactory::setSrtpProfiles(const char *str)
{
   int r;
 
   r=SSL_CTX_set_tlsext_use_srtp(mContext,str);
 
   resip_assert(r==0);
}
 
void
DtlsFactory::setCipherSuites(const char *str)
{
   int r;
 
   r=SSL_CTX_set_cipher_list(mContext,str);
   resip_assert(r==1);
}
 
DtlsFactory::PacketType
DtlsFactory::demuxPacket(const unsigned char *data, size_t len) 
{
   // By the first byte, as RFC 7983 section 7 sets out: 0-3 STUN, 20-63 DTLS, 128-191 RTP/RTCP.
   // Anything else (eg. 16-19 ZRTP, 64-79 TURN ChannelData) is unknown, as is an empty datagram,
   // which a peer can send.
   if(len == 0)
      return unknown;
 
   if(data[0]<=3)
      return stun;
   if((data[0]>=128) && (data[0]<=191))
      return rtp;
   if((data[0]>=20)  && (data[0]<=63))
      return dtls;
 
   return unknown;
}
 
#endif //USE_SSL
 
 
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