wget/src/gen_sslfunc.c

/* SSL support.
   Copyright (C) 2000 Free Software Foundation, Inc.
   Contributed by Christian Fraenkel.

This file is part of GNU Wget.

GNU Wget is free software; you can redistribute it and/or modify
it under the terms of 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.

GNU Wget is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with Wget; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */

#include <config.h>

#ifdef HAVE_SSL

#include <assert.h>
#include <errno.h>
#ifdef HAVE_UNISTD_H
# include <unistd.h>
#endif
#ifdef HAVE_STRING_H
# include <string.h>
#else
# include <strings.h>
#endif

#include <openssl/bio.h>
#include <openssl/crypto.h>
#include <openssl/x509.h>
#include <openssl/ssl.h>
#include <openssl/err.h>
#include <openssl/pem.h>
#include <openssl/rand.h>

#include "wget.h"
#include "utils.h"
#include "connect.h"
#include "url.h"

#ifndef errno
extern int errno;
#endif

void
ssl_init_prng (void)
{
  /* It is likely that older versions of OpenSSL will fail on
     non-Linux machines because this code is unable to seed the PRNG
     on older versions of the library.  */

#if SSLEAY_VERSION_NUMBER >= 0x00905100
  char rand_file[256];
  int maxrand = 500;

  /* First, seed from a file specified by the user.  This will be
     $RANDFILE, if set, or ~/.rnd.  */
  RAND_file_name (rand_file, sizeof (rand_file));
  if (rand_file)
    /* Seed at most 16k (value borrowed from curl) from random file. */
    RAND_load_file (rand_file, 16384);

  if (RAND_status ())
    return;

  /* Get random data from EGD if opt.sslegdsock was set.  */
  if (opt.sslegdsock && *opt.sslegdsock)
    RAND_egd (opt.sslegdsock);

  if (RAND_status ())
    return;

#ifdef WINDOWS
  /* Under Windows, we can try to seed the PRNG using screen content.
     This may or may not work, depending on whether we'll calling Wget
     interactively.  */

  RAND_screen ();
  if (RAND_status ())
    return;
#endif

  /* Still not enough randomness, presumably because neither random
     file nor EGD have been available.  Use the stupidest possible
     method -- seed OpenSSL's PRNG with the system's PRNG.  This is
     insecure in the cryptographic sense, but people who care about
     security will use /dev/random or their own source of randomness
     anyway.  */

  while (RAND_status () == 0 && maxrand-- > 0)
    {
      unsigned char rnd = random_number (256);
      RAND_seed (&rnd, sizeof (rnd));
    }

  if (RAND_status () == 0)
    {
      logprintf (LOG_NOTQUIET,
		 _("Could not seed OpenSSL PRNG; disabling SSL.\n"));
      scheme_disable (SCHEME_HTTPS);
    }
#endif /* SSLEAY_VERSION_NUMBER >= 0x00905100 */
}

int
verify_callback (int ok, X509_STORE_CTX *ctx)
{
  char *s, buf[256];
  s = X509_NAME_oneline (X509_get_subject_name (ctx->current_cert), buf, 256);
  if (ok == 0) {
    switch (ctx->error) {
    case X509_V_ERR_CERT_NOT_YET_VALID:
    case X509_V_ERR_CERT_HAS_EXPIRED:
      /* This mean the CERT is not valid !!! */
      ok = 0;
      break;
    case X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT:
      /* Unsure if we should handle that this way */
      ok = 1;
      break;
    }
  }
  return ok;
}

/* pass all ssl errors to DEBUGP
   returns the number of printed errors */
int
ssl_printerrors (void) 
{
  int ocerr = 0;
  unsigned long curerr = 0;
  char errbuff[1024];
  memset(errbuff, 0, sizeof(errbuff));
  while ( 0 != (curerr = ERR_get_error ()))
    {
      DEBUGP (("OpenSSL: %s\n", ERR_error_string (curerr, errbuff)));
      ++ocerr;
    }
  return ocerr;
}

/* Creates a SSL Context and sets some defaults for it */
uerr_t
init_ssl (SSL_CTX **ctx)
{
  SSL_METHOD *meth = NULL;
  int verify;
  int can_validate;
  SSL_library_init ();
  SSL_load_error_strings ();
  SSLeay_add_all_algorithms ();
  SSLeay_add_ssl_algorithms ();
  switch (opt.sslprotocol)
    {
      default:
	meth = SSLv23_client_method ();
	break;
      case 1 :
	meth = SSLv2_client_method ();
	break;
      case 2 :
	meth = SSLv3_client_method ();
	break;
      case 3 :
	meth = TLSv1_client_method ();
	break;
    }
  if (meth == NULL)
    {
      ssl_printerrors ();
      return SSLERRCTXCREATE;
    }

  *ctx = SSL_CTX_new (meth);
  if (meth == NULL)
    {
      ssl_printerrors ();
      return SSLERRCTXCREATE;
    }
  /* Can we validate the server Cert ? */
  if (opt.sslcadir != NULL || opt.sslcafile != NULL)
    {
      SSL_CTX_load_verify_locations (*ctx, opt.sslcafile, opt.sslcadir);
      can_validate = 1;
    }
  else
    {
      can_validate = 0;
    }

  if (!opt.sslcheckcert)
    {
      /* check cert but ignore error, do not break handshake on error */
      verify = SSL_VERIFY_NONE;
    }
  else
    {
      if (!can_validate)
	{
	  logprintf (LOG_NOTQUIET, "Warrining validation of Server Cert not possible!\n");
	  verify = SSL_VERIFY_NONE;
	}
     else
	{
	  /* break handshake if server cert is not valid but allow NO-Cert mode */
	  verify = SSL_VERIFY_PEER;
	}
    }

  SSL_CTX_set_verify (*ctx, verify, verify_callback);

  if (opt.sslcertfile != NULL || opt.sslcertkey != NULL)
    {
      int ssl_cert_type;
      if (!opt.sslcerttype)
	ssl_cert_type = SSL_FILETYPE_PEM;
      else
	ssl_cert_type = SSL_FILETYPE_ASN1;

      if (opt.sslcertkey == NULL) 
	opt.sslcertkey = opt.sslcertfile;
      if (opt.sslcertfile == NULL)
	opt.sslcertfile = opt.sslcertkey; 

      if (SSL_CTX_use_certificate_file (*ctx, opt.sslcertfile, ssl_cert_type) <= 0)
	{
	  ssl_printerrors ();
  	  return SSLERRCERTFILE;
	}
      if (SSL_CTX_use_PrivateKey_file  (*ctx, opt.sslcertkey , ssl_cert_type) <= 0)
	{
	  ssl_printerrors ();
	  return SSLERRCERTKEY;
	}
    }

  return 0; /* Succeded */
}

void
shutdown_ssl (SSL* con)
{
  if (con == NULL)
    return;
  if (0==SSL_shutdown (con))
    SSL_shutdown (con);
  SSL_free (con);
}

/* Sets up a SSL structure and performs the handshake on fd 
   Returns 0 if everything went right
   Returns 1 if something went wrong ----- TODO: More exit codes
*/
int
connect_ssl (SSL **con, SSL_CTX *ctx, int fd) 
{
  if (NULL == (*con = SSL_new (ctx)))
    {
      ssl_printerrors ();
      return 1;
    }
  if (!SSL_set_fd (*con, fd))
    {
      ssl_printerrors ();
      return 1;
    }
  SSL_set_connect_state (*con);
  switch (SSL_connect (*con))
    {
      case 1 : 
	return (*con)->state != SSL_ST_OK;
      default:
        ssl_printerrors ();
	shutdown_ssl (*con);
	*con = NULL;
	return 1;
      case 0 :
        ssl_printerrors ();
	SSL_free (*con);
       	*con = NULL;
 	return 1;
    }
  return 0;
}

void
free_ssl_ctx (SSL_CTX * ctx)
{
  SSL_CTX_free (ctx);
}

/* SSL version of iread.  Only exchanged read for SSL_read Read at
   most LEN bytes from FD, storing them to BUF. */

int
ssl_iread (SSL *con, char *buf, int len)
{
  int res, fd;
  BIO_get_fd (con->rbio, &fd);
#ifdef HAVE_SELECT
  if (opt.timeout && !SSL_pending (con))
    if (select_fd (fd, opt.timeout, 0) <= 0)
      return -1;
#endif
  do
    res = SSL_read (con, buf, len);
  while (res == -1 && errno == EINTR);

  return res;
}

/* SSL version of iwrite.  Only exchanged write for SSL_write Write
   LEN bytes from BUF to FD.  */

int
ssl_iwrite (SSL *con, char *buf, int len)
{
  int res = 0, fd;
  BIO_get_fd (con->rbio, &fd);
  /* `write' may write less than LEN bytes, thus the outward loop
     keeps trying it until all was written, or an error occurred.  The
     inner loop is reserved for the usual EINTR f*kage, and the
     innermost loop deals with the same during select().  */
  while (len > 0)
    {
#ifdef HAVE_SELECT
      if (opt.timeout)
	if (select_fd (fd, opt.timeout, 1) <= 0)
	  return -1;
#endif
      do
	res = SSL_write (con, buf, len);
      while (res == -1 && errno == EINTR);
      if (res <= 0)
	break;
      buf += res;
      len -= res;
    }
  return res;
}
#endif /* HAVE_SSL */