ssl.cpp

/*****************************************************************************

$Id$

File:     ssl.cpp
Date:     30Apr06

Copyright (C) 2006-07 by Francis Cianfrocca. All Rights Reserved.
Gmail: blackhedd

This program is free software; you can redistribute it and/or modify
it under the terms of either: 1) the GNU General Public License
as published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version; or 2) Ruby's License.

See the file COPYING for complete licensing information.

*****************************************************************************/


#ifdef WITH_SSL

#include "project.h"


bool SslContext_t::bLibraryInitialized = false;



static void InitializeDefaultCredentials();
static EVP_PKEY *DefaultPrivateKey = NULL;
static X509 *DefaultCertificate = NULL;

static char PrivateMaterials[] = {
"-----BEGIN RSA PRIVATE KEY-----\n"
"MIICXAIBAAKBgQDCYYhcw6cGRbhBVShKmbWm7UVsEoBnUf0cCh8AX+MKhMxwVDWV\n"
"Igdskntn3cSJjRtmgVJHIK0lpb/FYHQB93Ohpd9/Z18pDmovfFF9nDbFF0t39hJ/\n"
"AqSzFB3GiVPoFFZJEE1vJqh+3jzsSF5K56bZ6azz38VlZgXeSozNW5bXkQIDAQAB\n"
"AoGALA89gIFcr6BIBo8N5fL3aNHpZXjAICtGav+kTUpuxSiaym9cAeTHuAVv8Xgk\n"
"H2Wbq11uz+6JMLpkQJH/WZ7EV59DPOicXrp0Imr73F3EXBfR7t2EQDYHPMthOA1D\n"
"I9EtCzvV608Ze90hiJ7E3guGrGppZfJ+eUWCPgy8CZH1vRECQQDv67rwV/oU1aDo\n"
"6/+d5nqjeW6mWkGqTnUU96jXap8EIw6B+0cUKskwx6mHJv+tEMM2748ZY7b0yBlg\n"
"w4KDghbFAkEAz2h8PjSJG55LwqmXih1RONSgdN9hjB12LwXL1CaDh7/lkEhq0PlK\n"
"PCAUwQSdM17Sl0Xxm2CZiekTSlwmHrtqXQJAF3+8QJwtV2sRJp8u2zVe37IeH1cJ\n"
"xXeHyjTzqZ2803fnjN2iuZvzNr7noOA1/Kp+pFvUZUU5/0G2Ep8zolPUjQJAFA7k\n"
"xRdLkzIx3XeNQjwnmLlncyYPRv+qaE3FMpUu7zftuZBnVCJnvXzUxP3vPgKTlzGa\n"
"dg5XivDRfsV+okY5uQJBAMV4FesUuLQVEKb6lMs7rzZwpeGQhFDRfywJzfom2TLn\n"
"2RdJQQ3dcgnhdVDgt5o1qkmsqQh8uJrJ9SdyLIaZQIc=\n"
"-----END RSA PRIVATE KEY-----\n"
"-----BEGIN CERTIFICATE-----\n"
"MIID6TCCA1KgAwIBAgIJANm4W/Tzs+s+MA0GCSqGSIb3DQEBBQUAMIGqMQswCQYD\n"
"VQQGEwJVUzERMA8GA1UECBMITmV3IFlvcmsxETAPBgNVBAcTCE5ldyBZb3JrMRYw\n"
"FAYDVQQKEw1TdGVhbWhlYXQubmV0MRQwEgYDVQQLEwtFbmdpbmVlcmluZzEdMBsG\n"
"A1UEAxMUb3BlbmNhLnN0ZWFtaGVhdC5uZXQxKDAmBgkqhkiG9w0BCQEWGWVuZ2lu\n"
"ZWVyaW5nQHN0ZWFtaGVhdC5uZXQwHhcNMDYwNTA1MTcwNjAzWhcNMjQwMjIwMTcw\n"
"NjAzWjCBqjELMAkGA1UEBhMCVVMxETAPBgNVBAgTCE5ldyBZb3JrMREwDwYDVQQH\n"
"EwhOZXcgWW9yazEWMBQGA1UEChMNU3RlYW1oZWF0Lm5ldDEUMBIGA1UECxMLRW5n\n"
"aW5lZXJpbmcxHTAbBgNVBAMTFG9wZW5jYS5zdGVhbWhlYXQubmV0MSgwJgYJKoZI\n"
"hvcNAQkBFhllbmdpbmVlcmluZ0BzdGVhbWhlYXQubmV0MIGfMA0GCSqGSIb3DQEB\n"
"AQUAA4GNADCBiQKBgQDCYYhcw6cGRbhBVShKmbWm7UVsEoBnUf0cCh8AX+MKhMxw\n"
"VDWVIgdskntn3cSJjRtmgVJHIK0lpb/FYHQB93Ohpd9/Z18pDmovfFF9nDbFF0t3\n"
"9hJ/AqSzFB3GiVPoFFZJEE1vJqh+3jzsSF5K56bZ6azz38VlZgXeSozNW5bXkQID\n"
"AQABo4IBEzCCAQ8wHQYDVR0OBBYEFPJvPd1Fcmd8o/Tm88r+NjYPICCkMIHfBgNV\n"
"HSMEgdcwgdSAFPJvPd1Fcmd8o/Tm88r+NjYPICCkoYGwpIGtMIGqMQswCQYDVQQG\n"
"EwJVUzERMA8GA1UECBMITmV3IFlvcmsxETAPBgNVBAcTCE5ldyBZb3JrMRYwFAYD\n"
"VQQKEw1TdGVhbWhlYXQubmV0MRQwEgYDVQQLEwtFbmdpbmVlcmluZzEdMBsGA1UE\n"
"AxMUb3BlbmNhLnN0ZWFtaGVhdC5uZXQxKDAmBgkqhkiG9w0BCQEWGWVuZ2luZWVy\n"
"aW5nQHN0ZWFtaGVhdC5uZXSCCQDZuFv087PrPjAMBgNVHRMEBTADAQH/MA0GCSqG\n"
"SIb3DQEBBQUAA4GBAC1CXey/4UoLgJiwcEMDxOvW74plks23090iziFIlGgcIhk0\n"
"Df6hTAs7H3MWww62ddvR8l07AWfSzSP5L6mDsbvq7EmQsmPODwb6C+i2aF3EDL8j\n"
"uw73m4YIGI0Zw2XdBpiOGkx2H56Kya6mJJe/5XORZedh1wpI7zki01tHYbcy\n"
"-----END CERTIFICATE-----\n"};

/* These private materials were made with:
 * openssl req -new -x509 -keyout cakey.pem -out cacert.pem -nodes -days 6500
 * TODO: We need a full-blown capability to work with user-supplied
 * keypairs and properly-signed certificates.
 */


/*****************
builtin_passwd_cb
*****************/

extern "C" int builtin_passwd_cb (char *buf, int bufsize, int rwflag, void *userdata)
{
	strcpy (buf, "kittycat");
	return 8;
}

/****************************
InitializeDefaultCredentials
****************************/

static void InitializeDefaultCredentials()
{
	BIO *bio = BIO_new_mem_buf (PrivateMaterials, -1);
	assert (bio);

	if (DefaultPrivateKey) {
		// we may come here in a restart.
		EVP_PKEY_free (DefaultPrivateKey);
		DefaultPrivateKey = NULL;
	}
	PEM_read_bio_PrivateKey (bio, &DefaultPrivateKey, builtin_passwd_cb, 0);

	if (DefaultCertificate) {
		// we may come here in a restart.
		X509_free (DefaultCertificate);
		DefaultCertificate = NULL;
	}
	PEM_read_bio_X509 (bio, &DefaultCertificate, NULL, 0);

	BIO_free (bio);
}



/**************************
SslContext_t::SslContext_t
**************************/

SslContext_t::SslContext_t (bool is_server, const string &privkeyfile, const string &certchainfile):
	pCtx (NULL),
	PrivateKey (NULL),
	Certificate (NULL)
{
	/* TODO: the usage of the specified private-key and cert-chain filenames only applies to
	 * client-side connections at this point. Server connections currently use the default materials.
	 * That needs to be fixed asap.
	 * Also, in this implementation, server-side connections use statically defined X-509 defaults.
	 * One thing I'm really not clear on is whether or not you have to explicitly free X509 and EVP_PKEY
	 * objects when we call our destructor, or whether just calling SSL_CTX_free is enough.
	 */

	if (!bLibraryInitialized) {
		bLibraryInitialized = true;
		SSL_library_init();
		OpenSSL_add_ssl_algorithms();
		OpenSSL_add_all_algorithms();
		SSL_load_error_strings();
		ERR_load_crypto_strings();

		InitializeDefaultCredentials();
	}

	bIsServer = is_server;
	pCtx = SSL_CTX_new (is_server ? SSLv23_server_method() : SSLv23_client_method());
	if (!pCtx)
		throw std::runtime_error ("no SSL context");

	SSL_CTX_set_options (pCtx, SSL_OP_ALL);
	//SSL_CTX_set_options (pCtx, (SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3));
#ifdef SSL_MODE_RELEASE_BUFFERS
	SSL_CTX_set_mode (pCtx, SSL_MODE_RELEASE_BUFFERS);
#endif

	if (is_server) {
		// The SSL_CTX calls here do NOT allocate memory.
		int e;
		if (privkeyfile.length() > 0)
			e = SSL_CTX_use_PrivateKey_file (pCtx, privkeyfile.c_str(), SSL_FILETYPE_PEM);
		else
			e = SSL_CTX_use_PrivateKey (pCtx, DefaultPrivateKey);
		if (e <= 0) ERR_print_errors_fp(stderr);
		assert (e > 0);

		if (certchainfile.length() > 0)
			e = SSL_CTX_use_certificate_chain_file (pCtx, certchainfile.c_str());
		else
			e = SSL_CTX_use_certificate (pCtx, DefaultCertificate);
		if (e <= 0) ERR_print_errors_fp(stderr);
		assert (e > 0);
	}

	SSL_CTX_set_cipher_list (pCtx, "ALL:!ADH:!LOW:!EXP:!DES-CBC3-SHA:@STRENGTH");

	if (is_server) {
		SSL_CTX_sess_set_cache_size (pCtx, 128);
		SSL_CTX_set_session_id_context (pCtx, (unsigned char*)"eventmachine", 12);
	}
	else {
		int e;
		if (privkeyfile.length() > 0) {
			e = SSL_CTX_use_PrivateKey_file (pCtx, privkeyfile.c_str(), SSL_FILETYPE_PEM);
			if (e <= 0) ERR_print_errors_fp(stderr);
			assert (e > 0);
		}
		if (certchainfile.length() > 0) {
			e = SSL_CTX_use_certificate_chain_file (pCtx, certchainfile.c_str());
			if (e <= 0) ERR_print_errors_fp(stderr);
			assert (e > 0);
		}
	}
}



/***************************
SslContext_t::~SslContext_t
***************************/

SslContext_t::~SslContext_t()
{
	if (pCtx)
		SSL_CTX_free (pCtx);
	if (PrivateKey)
		EVP_PKEY_free (PrivateKey);
	if (Certificate)
		X509_free (Certificate);
}



/******************
SslBox_t::SslBox_t
******************/

SslBox_t::SslBox_t (bool is_server, const string &privkeyfile, const string &certchainfile, bool verify_peer, const unsigned long binding):
	bIsServer (is_server),
	bHandshakeCompleted (false),
	bVerifyPeer (verify_peer),
	pSSL (NULL),
	pbioRead (NULL),
	pbioWrite (NULL)
{
	/* TODO someday: make it possible to re-use SSL contexts so we don't have to create
	 * a new one every time we come here.
	 */

	Context = new SslContext_t (bIsServer, privkeyfile, certchainfile);
	assert (Context);

	pbioRead = BIO_new (BIO_s_mem());
	assert (pbioRead);

	pbioWrite = BIO_new (BIO_s_mem());
	assert (pbioWrite);

	pSSL = SSL_new (Context->pCtx);
	assert (pSSL);
	SSL_set_bio (pSSL, pbioRead, pbioWrite);

	// Store a pointer to the binding signature in the SSL object so we can retrieve it later
	SSL_set_ex_data(pSSL, 0, (void*) binding);

	if (bVerifyPeer)
		SSL_set_verify(pSSL, SSL_VERIFY_PEER | SSL_VERIFY_CLIENT_ONCE, ssl_verify_wrapper);

	if (!bIsServer)
		SSL_connect (pSSL);
}



/*******************
SslBox_t::~SslBox_t
*******************/

SslBox_t::~SslBox_t()
{
	// Freeing pSSL will also free the associated BIOs, so DON'T free them separately.
	if (pSSL) {
		if (SSL_get_shutdown (pSSL) & SSL_RECEIVED_SHUTDOWN)
			SSL_shutdown (pSSL);
		else
			SSL_clear (pSSL);
		SSL_free (pSSL);
	}

	delete Context;
}



/***********************
SslBox_t::PutCiphertext
***********************/

bool SslBox_t::PutCiphertext (const char *buf, int bufsize)
{
	assert (buf && (bufsize > 0));

	assert (pbioRead);
	int n = BIO_write (pbioRead, buf, bufsize);

	return (n == bufsize) ? true : false;
}


/**********************
SslBox_t::GetPlaintext
**********************/

int SslBox_t::GetPlaintext (char *buf, int bufsize)
{
	if (!SSL_is_init_finished (pSSL)) {
		int e = bIsServer ? SSL_accept (pSSL) : SSL_connect (pSSL);
		if (e < 0) {
			int er = SSL_get_error (pSSL, e);
			if (er != SSL_ERROR_WANT_READ) {
				// Return -1 for a nonfatal error, -2 for an error that should force the connection down.
				return (er == SSL_ERROR_SSL) ? (-2) : (-1);
			}
			else
				return 0;
		}
		bHandshakeCompleted = true;
		// If handshake finished, FALL THROUGH and return the available plaintext.
	}

	if (!SSL_is_init_finished (pSSL)) {
		// We can get here if a browser abandons a handshake.
		// The user can see a warning dialog and abort the connection.
		cerr << "<SSL_incomp>";
		return 0;
	}

	//cerr << "CIPH: " << SSL_get_cipher (pSSL) << endl;

	int n = SSL_read (pSSL, buf, bufsize);
	if (n >= 0) {
		return n;
	}
	else {
		if (SSL_get_error (pSSL, n) == SSL_ERROR_WANT_READ) {
			return 0;
		}
		else {
			return -1;
		}
	}

	return 0;
}



/**************************
SslBox_t::CanGetCiphertext
**************************/

bool SslBox_t::CanGetCiphertext()
{
	assert (pbioWrite);
	return BIO_pending (pbioWrite) ? true : false;
}



/***********************
SslBox_t::GetCiphertext
***********************/

int SslBox_t::GetCiphertext (char *buf, int bufsize)
{
	assert (pbioWrite);
	assert (buf && (bufsize > 0));

	return BIO_read (pbioWrite, buf, bufsize);
}



/**********************
SslBox_t::PutPlaintext
**********************/

int SslBox_t::PutPlaintext (const char *buf, int bufsize)
{
	// The caller will interpret the return value as the number of bytes written.
	// WARNING WARNING WARNING, are there any situations in which a 0 or -1 return
	// from SSL_write means we should immediately retry? The socket-machine loop
	// will probably wait for a time-out cycle (perhaps a second) before re-trying.
	// THIS WOULD CAUSE A PERCEPTIBLE DELAY!

	/* We internally queue any outbound plaintext that can't be dispatched
	 * because we're in the middle of a handshake or something.
	 * When we get called, try to send any queued data first, and then
	 * send the caller's data (or queue it). We may get called with no outbound
	 * data, which means we try to send the outbound queue and that's all.
	 *
	 * Return >0 if we wrote any data, 0 if we didn't, and <0 for a fatal error.
	 * Note that if we return 0, the connection is still considered live
	 * and we are signalling that we have accepted the outbound data (if any).
	 */

	OutboundQ.Push (buf, bufsize);

	if (!SSL_is_init_finished (pSSL))
		return 0;

	bool fatal = false;
	bool did_work = false;
	int pending =  BIO_pending(pbioWrite);

	while (OutboundQ.HasPages() && pending < SSLBOX_WRITE_BUFFER_SIZE) {
		const char *page;
		int length;
		OutboundQ.Front (&page, &length);
		assert (page && (length > 0));
		int n = SSL_write (pSSL, page, length);
		pending =  BIO_pending(pbioWrite);

		if (n > 0) {
			did_work = true;
			OutboundQ.PopFront();
		}
		else {
			int er = SSL_get_error (pSSL, n);
			if ((er != SSL_ERROR_WANT_READ) && (er != SSL_ERROR_WANT_WRITE))
				fatal = true;
			break;
		}
	}


	if (did_work)
		return 1;
	else if (fatal)
		return -1;
	else
		return 0;
}

/**********************
SslBox_t::GetPeerCert
**********************/

X509 *SslBox_t::GetPeerCert()
{
	X509 *cert = NULL;

	if (pSSL)
		cert = SSL_get_peer_certificate(pSSL);

	return cert;
}


/******************
ssl_verify_wrapper
*******************/

extern "C" int ssl_verify_wrapper(int preverify_ok, X509_STORE_CTX *ctx)
{
	unsigned long binding;
	X509 *cert;
	SSL *ssl;
	BUF_MEM *buf;
	BIO *out;
	int result;

	cert = X509_STORE_CTX_get_current_cert(ctx);
	ssl = (SSL*) X509_STORE_CTX_get_ex_data(ctx, SSL_get_ex_data_X509_STORE_CTX_idx());
	binding = (unsigned long) SSL_get_ex_data(ssl, 0);

	out = BIO_new(BIO_s_mem());
	PEM_write_bio_X509(out, cert);
	BIO_write(out, "\0", 1);
	BIO_get_mem_ptr(out, &buf);

	ConnectionDescriptor *cd = dynamic_cast <ConnectionDescriptor*> (Bindable_t::GetObject(binding));
	result = (cd->VerifySslPeer(buf->data) == true ? 1 : 0);
	BIO_free(out);

	return result;
}

#endif // WITH_SSL