/*
* Copyright (c) 2002 - 2003
* NetGroup, Politecnico di Torino (Italy)
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the Politecnico di Torino nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/

#include <config.h>

#ifdef HAVE_OPENSSL
#include <stdlib.h>

#include "sslutils.h"
#include "portability.h"


static const char *ssl_keyfile = "";   //!< file containing the private key in PEM format
static const char *ssl_certfile = "";  //!< file containing the server's certificate in PEM format
static const char *ssl_rootfile = "";  //!< file containing the list of CAs trusted by the client
// TODO: a way to set ssl_rootfile from the command line, or an envvar?

// TODO: lock?
static SSL_CTX *ctx;

void ssl_set_certfile(const char *certfile)
{
       ssl_certfile = certfile;
}

void ssl_set_keyfile(const char *keyfile)
{
       ssl_keyfile = keyfile;
}

int ssl_init_once(int is_server, int enable_compression, char *errbuf, size_t errbuflen)
{
       static int inited = 0;
       if (inited) return 0;

       SSL_library_init();
       SSL_load_error_strings();
       OpenSSL_add_ssl_algorithms();
       if (enable_compression)
               SSL_COMP_get_compression_methods();

       SSL_METHOD const *meth =
           is_server ? SSLv23_server_method() : SSLv23_client_method();
       ctx = SSL_CTX_new(meth);
       if (! ctx)
       {
               snprintf(errbuf, errbuflen, "Cannot get a new SSL context: %s", ERR_error_string(ERR_get_error(), NULL));
               goto die;
       }

       SSL_CTX_set_mode(ctx, SSL_MODE_AUTO_RETRY);

       if (is_server)
       {
               char const *certfile = ssl_certfile[0] ? ssl_certfile : "cert.pem";
               if (1 != SSL_CTX_use_certificate_file(ctx, certfile, SSL_FILETYPE_PEM))
               {
                       snprintf(errbuf, errbuflen, "Cannot read certificate file %s: %s", certfile, ERR_error_string(ERR_get_error(), NULL));
                       goto die;
               }

               char const *keyfile = ssl_keyfile[0] ? ssl_keyfile : "key.pem";
               if (1 != SSL_CTX_use_PrivateKey_file(ctx, keyfile, SSL_FILETYPE_PEM))
               {
                       snprintf(errbuf, errbuflen, "Cannot read private key file %s: %s", keyfile, ERR_error_string(ERR_get_error(), NULL));
                       goto die;
               }
       }
       else
       {
               if (ssl_rootfile[0])
               {
                       if (! SSL_CTX_load_verify_locations(ctx, ssl_rootfile, 0))
                       {
                               snprintf(errbuf, errbuflen, "Cannot read CA list from %s", ssl_rootfile);
                               goto die;
                       }
               }
               else
               {
                       SSL_CTX_set_verify(ctx, SSL_VERIFY_NONE, NULL);
               }
       }

#if 0
       if (! RAND_load_file(RANDOM, 1024*1024))
       {
               snprintf(errbuf, errbuflen, "Cannot init random");
               goto die;
       }

       if (is_server)
       {
               SSL_CTX_set_session_id_context(ctx, (void *)&s_server_session_id_context, sizeof(s_server_session_id_context));
       }
#endif

       inited = 1;
       return 0;

die:
       return -1;
}

SSL *ssl_promotion(int is_server, PCAP_SOCKET s, char *errbuf, size_t errbuflen)
{
       if (ssl_init_once(is_server, 1, errbuf, errbuflen) < 0) {
               return NULL;
       }

       SSL *ssl = SSL_new(ctx); // TODO: also a DTLS context
       SSL_set_fd(ssl, (int)s);

       if (is_server) {
               if (SSL_accept(ssl) <= 0) {
                       snprintf(errbuf, errbuflen, "SSL_accept(): %s",
                                       ERR_error_string(ERR_get_error(), NULL));
                       return NULL;
               }
       } else {
               if (SSL_connect(ssl) <= 0) {
                       snprintf(errbuf, errbuflen, "SSL_connect(): %s",
                                       ERR_error_string(ERR_get_error(), NULL));
                       return NULL;
               }
       }

       return ssl;
}

// Finish using an SSL handle; shut down the connection and free the
// handle.
void ssl_finish(SSL *ssl)
{
       //
       // We won't be using this again, so we can just send the
       // shutdown alert and free up the handle, and have our
       // caller close the socket.
       //
       // XXX - presumably, if the connection is shut down on
       // our side, either our peer won't have a problem sending
       // their shutdown alert or will not treat such a problem
       // as an error.  If this causes errors to be reported,
       // fix that as appropriate.
       //
       SSL_shutdown(ssl);
       SSL_free(ssl);
}

// Same return value as sock_send:
// 0 on OK, -1 on error but closed connection (-2).
int ssl_send(SSL *ssl, char const *buffer, int size, char *errbuf, size_t errbuflen)
{
       int status = SSL_write(ssl, buffer, size);
       if (status > 0)
       {
               // "SSL_write() will only return with success, when the complete contents (...) has been written."
               return 0;
       }
       else
       {
               int ssl_err = SSL_get_error(ssl, status); // TODO: does it pop the error?
               if (ssl_err == SSL_ERROR_ZERO_RETURN)
               {
                       return -2;
               }
               else if (ssl_err == SSL_ERROR_SYSCALL)
               {
#ifndef _WIN32
                       if (errno == ECONNRESET || errno == EPIPE) return -2;
#endif
               }
               snprintf(errbuf, errbuflen, "SSL_write(): %s",
                   ERR_error_string(ERR_get_error(), NULL));
               return -1;
       }
}

// Returns the number of bytes read, or -1 on syserror, or -2 on SSL error.
int ssl_recv(SSL *ssl, char *buffer, int size, char *errbuf, size_t errbuflen)
{
       int status = SSL_read(ssl, buffer, size);
       if (status <= 0)
       {
               int ssl_err = SSL_get_error(ssl, status);
               if (ssl_err == SSL_ERROR_ZERO_RETURN)
               {
                       return 0;
               }
               else if (ssl_err == SSL_ERROR_SYSCALL)
               {
                       return -1;
               }
               else
               {
                       // Should not happen
                       snprintf(errbuf, errbuflen, "SSL_read(): %s",
                           ERR_error_string(ERR_get_error(), NULL));
                       return -2;
               }
       }
       else
       {
               return status;
       }
}

#endif // HAVE_OPENSSL

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