nss.c

/***************************************************************************
 *                                  _   _ ____  _
 *  Project                     ___| | | |  _ \| |
 *                             / __| | | | |_) | |
 *                            | (__| |_| |  _ <| |___
 *                             \___|\___/|_| \_\_____|
 *
 * Copyright (C) 1998 - 2011, Daniel Stenberg, <daniel@haxx.se>, et al.
 *
 * This software is licensed as described in the file COPYING, which
 * you should have received as part of this distribution. The terms
 * are also available at http://curl.haxx.se/docs/copyright.html.
 *
 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
 * copies of the Software, and permit persons to whom the Software is
 * furnished to do so, under the terms of the COPYING file.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 ***************************************************************************/

/*
 * Source file for all NSS-specific code for the TLS/SSL layer. No code
 * but sslgen.c should ever call or use these functions.
 */

#include "setup.h"

#include <string.h>
#include <stdlib.h>
#include <ctype.h>
#ifdef HAVE_SYS_SOCKET_H
#include <sys/socket.h>
#endif

#include "urldata.h"
#include "sendf.h"
#include "formdata.h" /* for the boundary function */
#include "url.h" /* for the ssl config check function */
#include "connect.h"
#include "strequal.h"
#include "select.h"
#include "sslgen.h"

#define _MPRINTF_REPLACE /* use the internal *printf() functions */
#include <curl/mprintf.h>

#ifdef USE_NSS

#include "nssg.h"
#include <nspr.h>
#include <nss.h>
#include <ssl.h>
#include <sslerr.h>
#include <secerr.h>
#include <secmod.h>
#include <sslproto.h>
#include <prtypes.h>
#include <pk11pub.h>
#include <prio.h>
#include <secitem.h>
#include <secport.h>
#include <certdb.h>
#include <base64.h>
#include <cert.h>

#include "curl_memory.h"
#include "rawstr.h"
#include "easyif.h" /* for Curl_convert_from_utf8 prototype */

/* The last #include file should be: */
#include "memdebug.h"

#define SSL_DIR "/etc/pki/nssdb"

/* enough to fit the string "PEM Token #[0|1]" */
#define SLOTSIZE 13

PRFileDesc *PR_ImportTCPSocket(PRInt32 osfd);

PRLock * nss_initlock = NULL;
PRLock * nss_crllock = NULL;

volatile int initialized = 0;

typedef struct {
  const char *name;
  int num;
  PRInt32 version; /* protocol version valid for this cipher */
} cipher_s;

#define PK11_SETATTRS(x,id,v,l) (x)->type = (id);       \
  (x)->pValue=(v); (x)->ulValueLen = (l)

#define CERT_NewTempCertificate __CERT_NewTempCertificate

enum sslversion { SSL2 = 1, SSL3 = 2, TLS = 4 };

#define NUM_OF_CIPHERS sizeof(cipherlist)/sizeof(cipherlist[0])
static const cipher_s cipherlist[] = {
  /* SSL2 cipher suites */
  {"rc4", SSL_EN_RC4_128_WITH_MD5, SSL2},
  {"rc4-md5", SSL_EN_RC4_128_WITH_MD5, SSL2},
  {"rc4export", SSL_EN_RC4_128_EXPORT40_WITH_MD5, SSL2},
  {"rc2", SSL_EN_RC2_128_CBC_WITH_MD5, SSL2},
  {"rc2export", SSL_EN_RC2_128_CBC_EXPORT40_WITH_MD5, SSL2},
  {"des", SSL_EN_DES_64_CBC_WITH_MD5, SSL2},
  {"desede3", SSL_EN_DES_192_EDE3_CBC_WITH_MD5, SSL2},
  /* SSL3/TLS cipher suites */
  {"rsa_rc4_128_md5", SSL_RSA_WITH_RC4_128_MD5, SSL3 | TLS},
  {"rsa_rc4_128_sha", SSL_RSA_WITH_RC4_128_SHA, SSL3 | TLS},
  {"rsa_3des_sha", SSL_RSA_WITH_3DES_EDE_CBC_SHA, SSL3 | TLS},
  {"rsa_des_sha", SSL_RSA_WITH_DES_CBC_SHA, SSL3 | TLS},
  {"rsa_rc4_40_md5", SSL_RSA_EXPORT_WITH_RC4_40_MD5, SSL3 | TLS},
  {"rsa_rc2_40_md5", SSL_RSA_EXPORT_WITH_RC2_CBC_40_MD5, SSL3 | TLS},
  {"rsa_null_md5", SSL_RSA_WITH_NULL_MD5, SSL3 | TLS},
  {"rsa_null_sha", SSL_RSA_WITH_NULL_SHA, SSL3 | TLS},
  {"fips_3des_sha", SSL_RSA_FIPS_WITH_3DES_EDE_CBC_SHA, SSL3 | TLS},
  {"fips_des_sha", SSL_RSA_FIPS_WITH_DES_CBC_SHA, SSL3 | TLS},
  {"fortezza", SSL_FORTEZZA_DMS_WITH_FORTEZZA_CBC_SHA, SSL3 | TLS},
  {"fortezza_rc4_128_sha", SSL_FORTEZZA_DMS_WITH_RC4_128_SHA, SSL3 | TLS},
  {"fortezza_null", SSL_FORTEZZA_DMS_WITH_NULL_SHA, SSL3 | TLS},
  /* TLS 1.0: Exportable 56-bit Cipher Suites. */
  {"rsa_des_56_sha", TLS_RSA_EXPORT1024_WITH_DES_CBC_SHA, SSL3 | TLS},
  {"rsa_rc4_56_sha", TLS_RSA_EXPORT1024_WITH_RC4_56_SHA, SSL3 | TLS},
  /* AES ciphers. */
  {"rsa_aes_128_sha", TLS_RSA_WITH_AES_128_CBC_SHA, SSL3 | TLS},
  {"rsa_aes_256_sha", TLS_RSA_WITH_AES_256_CBC_SHA, SSL3 | TLS},
#ifdef NSS_ENABLE_ECC
  /* ECC ciphers. */
  {"ecdh_ecdsa_null_sha", TLS_ECDH_ECDSA_WITH_NULL_SHA, TLS},
  {"ecdh_ecdsa_rc4_128_sha", TLS_ECDH_ECDSA_WITH_RC4_128_SHA, TLS},
  {"ecdh_ecdsa_3des_sha", TLS_ECDH_ECDSA_WITH_3DES_EDE_CBC_SHA, TLS},
  {"ecdh_ecdsa_aes_128_sha", TLS_ECDH_ECDSA_WITH_AES_128_CBC_SHA, TLS},
  {"ecdh_ecdsa_aes_256_sha", TLS_ECDH_ECDSA_WITH_AES_256_CBC_SHA, TLS},
  {"ecdhe_ecdsa_null_sha", TLS_ECDHE_ECDSA_WITH_NULL_SHA, TLS},
  {"ecdhe_ecdsa_rc4_128_sha", TLS_ECDHE_ECDSA_WITH_RC4_128_SHA, TLS},
  {"ecdhe_ecdsa_3des_sha", TLS_ECDHE_ECDSA_WITH_3DES_EDE_CBC_SHA, TLS},
  {"ecdhe_ecdsa_aes_128_sha", TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA, TLS},
  {"ecdhe_ecdsa_aes_256_sha", TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA, TLS},
  {"ecdh_rsa_null_sha", TLS_ECDH_RSA_WITH_NULL_SHA, TLS},
  {"ecdh_rsa_128_sha", TLS_ECDH_RSA_WITH_RC4_128_SHA, TLS},
  {"ecdh_rsa_3des_sha", TLS_ECDH_RSA_WITH_3DES_EDE_CBC_SHA, TLS},
  {"ecdh_rsa_aes_128_sha", TLS_ECDH_RSA_WITH_AES_128_CBC_SHA, TLS},
  {"ecdh_rsa_aes_256_sha", TLS_ECDH_RSA_WITH_AES_256_CBC_SHA, TLS},
  {"echde_rsa_null", TLS_ECDHE_RSA_WITH_NULL_SHA, TLS},
  {"ecdhe_rsa_rc4_128_sha", TLS_ECDHE_RSA_WITH_RC4_128_SHA, TLS},
  {"ecdhe_rsa_3des_sha", TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA, TLS},
  {"ecdhe_rsa_aes_128_sha", TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA, TLS},
  {"ecdhe_rsa_aes_256_sha", TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA, TLS},
  {"ecdh_anon_null_sha", TLS_ECDH_anon_WITH_NULL_SHA, TLS},
  {"ecdh_anon_rc4_128sha", TLS_ECDH_anon_WITH_RC4_128_SHA, TLS},
  {"ecdh_anon_3des_sha", TLS_ECDH_anon_WITH_3DES_EDE_CBC_SHA, TLS},
  {"ecdh_anon_aes_128_sha", TLS_ECDH_anon_WITH_AES_128_CBC_SHA, TLS},
  {"ecdh_anon_aes_256_sha", TLS_ECDH_anon_WITH_AES_256_CBC_SHA, TLS},
#endif
};

/* following ciphers are new in NSS 3.4 and not enabled by default, therefore
   they are enabled explicitly */
static const int enable_ciphers_by_default[] = {
  TLS_DHE_DSS_WITH_AES_128_CBC_SHA,
  TLS_DHE_DSS_WITH_AES_256_CBC_SHA,
  TLS_DHE_RSA_WITH_AES_128_CBC_SHA,
  TLS_DHE_RSA_WITH_AES_256_CBC_SHA,
  TLS_RSA_WITH_AES_128_CBC_SHA,
  TLS_RSA_WITH_AES_256_CBC_SHA,
  SSL_NULL_WITH_NULL_NULL
};

#ifdef HAVE_PK11_CREATEGENERICOBJECT
static const char* pem_library = "libnsspem.so";
#endif
SECMODModule* mod = NULL;

static SECStatus set_ciphers(struct SessionHandle *data, PRFileDesc * model,
                             char *cipher_list)
{
  unsigned int i;
  PRBool cipher_state[NUM_OF_CIPHERS];
  PRBool found;
  char *cipher;
  SECStatus rv;

  /* First disable all ciphers. This uses a different max value in case
   * NSS adds more ciphers later we don't want them available by
   * accident
   */
  for(i=0; i<SSL_NumImplementedCiphers; i++) {
    SSL_CipherPrefSet(model, SSL_ImplementedCiphers[i], SSL_NOT_ALLOWED);
  }

  /* Set every entry in our list to false */
  for(i=0; i<NUM_OF_CIPHERS; i++) {
    cipher_state[i] = PR_FALSE;
  }

  cipher = cipher_list;

  while(cipher_list && (cipher_list[0])) {
    while((*cipher) && (ISSPACE(*cipher)))
      ++cipher;

    if((cipher_list = strchr(cipher, ','))) {
      *cipher_list++ = '\0';
    }

    found = PR_FALSE;

    for(i=0; i<NUM_OF_CIPHERS; i++) {
      if(Curl_raw_equal(cipher, cipherlist[i].name)) {
        cipher_state[i] = PR_TRUE;
        found = PR_TRUE;
        break;
      }
    }

    if(found == PR_FALSE) {
      failf(data, "Unknown cipher in list: %s", cipher);
      return SECFailure;
    }

    if(cipher_list) {
      cipher = cipher_list;
    }
  }

  /* Finally actually enable the selected ciphers */
  for(i=0; i<NUM_OF_CIPHERS; i++) {
    rv = SSL_CipherPrefSet(model, cipherlist[i].num, cipher_state[i]);
    if(rv != SECSuccess) {
      failf(data, "Unknown cipher in cipher list");
      return SECFailure;
    }
  }

  return SECSuccess;
}

/*
 * Get the number of ciphers that are enabled. We use this to determine
 * if we need to call NSS_SetDomesticPolicy() to enable the default ciphers.
 */
static int num_enabled_ciphers(void)
{
  PRInt32 policy = 0;
  int count = 0;
  unsigned int i;

  for(i=0; i<NUM_OF_CIPHERS; i++) {
    SSL_CipherPolicyGet(cipherlist[i].num, &policy);
    if(policy)
      count++;
  }
  return count;
}

/*
 * Determine whether the nickname passed in is a filename that needs to
 * be loaded as a PEM or a regular NSS nickname.
 *
 * returns 1 for a file
 * returns 0 for not a file (NSS nickname)
 */
static int is_file(const char *filename)
{
  struct_stat st;

  if(filename == NULL)
    return 0;

  if(stat(filename, &st) == 0)
    if(S_ISREG(st.st_mode))
      return 1;

  return 0;
}

static char *fmt_nickname(char *str, bool *nickname_alloc)
{
  char *nickname = NULL;
  *nickname_alloc = FALSE;

  if(is_file(str)) {
    char *n = strrchr(str, '/');
    if(n) {
      *nickname_alloc = TRUE;
      n++; /* skip last slash */
      nickname = aprintf("PEM Token #%d:%s", 1, n);
    }
    return nickname;
  }

  return str;
}

static int nss_load_cert(struct ssl_connect_data *ssl,
                         const char *filename, PRBool cacert)
{
#ifdef HAVE_PK11_CREATEGENERICOBJECT
  CK_SLOT_ID slotID;
  PK11SlotInfo * slot = NULL;
  CK_ATTRIBUTE *attrs;
  CK_ATTRIBUTE theTemplate[20];
  CK_BBOOL cktrue = CK_TRUE;
  CK_BBOOL ckfalse = CK_FALSE;
  CK_OBJECT_CLASS objClass = CKO_CERTIFICATE;
  char slotname[SLOTSIZE];
#endif
  CERTCertificate *cert;
  char *nickname = NULL;
  char *n = NULL;

  /* If there is no slash in the filename it is assumed to be a regular
   * NSS nickname.
   */
  if(is_file(filename)) {
    n = strrchr(filename, '/');
    if(n)
      n++;
    if(!mod)
      return 1;
  }
  else {
    /* A nickname from the NSS internal database */
    if(cacert)
      return 0; /* You can't specify an NSS CA nickname this way */
    nickname = strdup(filename);
    if(!nickname)
      return 0;
    goto done;
  }

#ifdef HAVE_PK11_CREATEGENERICOBJECT
  attrs = theTemplate;

  /* All CA and trust objects go into slot 0. Other slots are used
   * for storing certificates. With each new user certificate we increment
   * the slot count. We only support 1 user certificate right now.
   */
  if(cacert)
    slotID = 0;
  else
    slotID = 1;

  snprintf(slotname, SLOTSIZE, "PEM Token #%ld", slotID);

  nickname = aprintf("PEM Token #%ld:%s", slotID, n);
  if(!nickname)
    return 0;

  slot = PK11_FindSlotByName(slotname);

  if(!slot) {
    free(nickname);
    return 0;
  }

  PK11_SETATTRS(attrs, CKA_CLASS, &objClass, sizeof(objClass) );
  attrs++;
  PK11_SETATTRS(attrs, CKA_TOKEN, &cktrue, sizeof(CK_BBOOL) );
  attrs++;
  PK11_SETATTRS(attrs, CKA_LABEL, (unsigned char *)filename,
                strlen(filename)+1);
  attrs++;
  if(cacert) {
    PK11_SETATTRS(attrs, CKA_TRUST, &cktrue, sizeof(CK_BBOOL) );
  }
  else {
    PK11_SETATTRS(attrs, CKA_TRUST, &ckfalse, sizeof(CK_BBOOL) );
  }
  attrs++;

  /* This load the certificate in our PEM module into the appropriate
   * slot.
   */
  ssl->cacert[slotID] = PK11_CreateGenericObject(slot, theTemplate, 4,
                                                 PR_FALSE /* isPerm */);

  PK11_FreeSlot(slot);

  if(ssl->cacert[slotID] == NULL) {
    free(nickname);
    return 0;
  }
#else
  /* We don't have PK11_CreateGenericObject but a file-based cert was passed
   * in. We need to fail.
   */
  return 0;
#endif

  done:
  /* Double-check that the certificate or nickname requested exists in
   * either the token or the NSS certificate database.
   */
  if(!cacert) {
    cert = PK11_FindCertFromNickname((char *)nickname, NULL);

    /* An invalid nickname was passed in */
    if(cert == NULL) {
      free(nickname);
      PR_SetError(SEC_ERROR_UNKNOWN_CERT, 0);
      return 0;
    }

    CERT_DestroyCertificate(cert);
  }

  free(nickname);

  return 1;
}

/* add given CRL to cache if it is not already there */
static SECStatus nss_cache_crl(SECItem *crlDER)
{
  CERTCertDBHandle *db = CERT_GetDefaultCertDB();
  CERTSignedCrl *crl = SEC_FindCrlByDERCert(db, crlDER, 0);
  if(crl) {
    /* CRL already cached */
    SEC_DestroyCrl(crl);
    SECITEM_FreeItem(crlDER, PR_FALSE);
    return SECSuccess;
  }

  /* acquire lock before call of CERT_CacheCRL() */
  PR_Lock(nss_crllock);
  if(SECSuccess != CERT_CacheCRL(db, crlDER)) {
    /* unable to cache CRL */
    PR_Unlock(nss_crllock);
    SECITEM_FreeItem(crlDER, PR_FALSE);
    return SECFailure;
  }

  /* we need to clear session cache, so that the CRL could take effect */
  SSL_ClearSessionCache();
  PR_Unlock(nss_crllock);
  return SECSuccess;
}

static SECStatus nss_load_crl(const char* crlfilename)
{
  PRFileDesc *infile;
  PRFileInfo  info;
  SECItem filedata = { 0, NULL, 0 };
  SECItem crlDER = { 0, NULL, 0 };
  char *body;

  infile = PR_Open(crlfilename, PR_RDONLY, 0);
  if(!infile)
    return SECFailure;

  if(PR_SUCCESS != PR_GetOpenFileInfo(infile, &info))
    goto fail;

  if(!SECITEM_AllocItem(NULL, &filedata, info.size + /* zero ended */ 1))
    goto fail;

  if(info.size != PR_Read(infile, filedata.data, info.size))
    goto fail;

  /* place a trailing zero right after the visible data */
  body = (char*)filedata.data;
  body[--filedata.len] = '\0';

  body = strstr(body, "-----BEGIN");
  if(body) {
    /* assume ASCII */
    char *trailer;
    char *begin = PORT_Strchr(body, '\n');
    if(!begin)
      begin = PORT_Strchr(body, '\r');
    if(!begin)
      goto fail;

    trailer = strstr(++begin, "-----END");
    if(!trailer)
      goto fail;

    /* retrieve DER from ASCII */
    *trailer = '\0';
    if(ATOB_ConvertAsciiToItem(&crlDER, begin))
      goto fail;

    SECITEM_FreeItem(&filedata, PR_FALSE);
  }
  else
    /* assume DER */
    crlDER = filedata;

  PR_Close(infile);
  return nss_cache_crl(&crlDER);

fail:
  PR_Close(infile);
  SECITEM_FreeItem(&filedata, PR_FALSE);
  return SECFailure;
}

static int nss_load_key(struct connectdata *conn, int sockindex,
                        char *key_file)
{
#ifdef HAVE_PK11_CREATEGENERICOBJECT
  PK11SlotInfo * slot = NULL;
  CK_ATTRIBUTE *attrs;
  CK_ATTRIBUTE theTemplate[20];
  CK_BBOOL cktrue = CK_TRUE;
  CK_OBJECT_CLASS objClass = CKO_PRIVATE_KEY;
  CK_SLOT_ID slotID;
  char slotname[SLOTSIZE];
  struct ssl_connect_data *sslconn = &conn->ssl[sockindex];

  attrs = theTemplate;

  /* FIXME: grok the various file types */

  slotID = 1; /* hardcoded for now */

  snprintf(slotname, sizeof(slotname), "PEM Token #%ld", slotID);
  slot = PK11_FindSlotByName(slotname);

  if(!slot)
    return 0;

  PK11_SETATTRS(attrs, CKA_CLASS, &objClass, sizeof(objClass) ); attrs++;
  PK11_SETATTRS(attrs, CKA_TOKEN, &cktrue, sizeof(CK_BBOOL) ); attrs++;
  PK11_SETATTRS(attrs, CKA_LABEL, (unsigned char *)key_file,
                strlen(key_file)+1); attrs++;

  /* When adding an encrypted key the PKCS#11 will be set as removed */
  sslconn->key = PK11_CreateGenericObject(slot, theTemplate, 3,
                                          PR_FALSE /* isPerm */);
  if(sslconn->key == NULL) {
    PR_SetError(SEC_ERROR_BAD_KEY, 0);
    return 0;
  }

  /* This will force the token to be seen as re-inserted */
  SECMOD_WaitForAnyTokenEvent(mod, 0, 0);
  PK11_IsPresent(slot);

  /* parg is initialized in nss_Init_Tokens() */
  if(PK11_Authenticate(slot, PR_TRUE,
                       conn->data->set.str[STRING_KEY_PASSWD]) != SECSuccess) {

    PK11_FreeSlot(slot);
    return 0;
  }
  PK11_FreeSlot(slot);

  return 1;
#else
  /* If we don't have PK11_CreateGenericObject then we can't load a file-based
   * key.
   */
  (void)conn; /* unused */
  (void)key_file; /* unused */
  return 0;
#endif
}

static int display_error(struct connectdata *conn, PRInt32 err,
                         const char *filename)
{
  switch(err) {
  case SEC_ERROR_BAD_PASSWORD:
    failf(conn->data, "Unable to load client key: Incorrect password");
    return 1;
  case SEC_ERROR_UNKNOWN_CERT:
    failf(conn->data, "Unable to load certificate %s", filename);
    return 1;
  default:
    break;
  }
  return 0; /* The caller will print a generic error */
}

static int cert_stuff(struct connectdata *conn,
                      int sockindex, char *cert_file, char *key_file)
{
  struct SessionHandle *data = conn->data;
  int rv = 0;

  if(cert_file) {
    rv = nss_load_cert(&conn->ssl[sockindex], cert_file, PR_FALSE);
    if(!rv) {
      if(!display_error(conn, PR_GetError(), cert_file))
        failf(data, "Unable to load client cert %d.", PR_GetError());
      return 0;
    }
  }
  if(key_file || (is_file(cert_file))) {
    if(key_file)
      rv = nss_load_key(conn, sockindex, key_file);
    else
      /* In case the cert file also has the key */
      rv = nss_load_key(conn, sockindex, cert_file);
    if(!rv) {
      if(!display_error(conn, PR_GetError(), key_file))
        failf(data, "Unable to load client key %d.", PR_GetError());

      return 0;
    }
  }
  return 1;
}

static char * nss_get_password(PK11SlotInfo * slot, PRBool retry, void *arg)
{
  (void)slot; /* unused */
  if(retry || NULL == arg)
    return NULL;
  else
    return (char *)PORT_Strdup((char *)arg);
}

static SECStatus BadCertHandler(void *arg, PRFileDesc *sock)
{
  SECStatus success = SECSuccess;
  struct connectdata *conn = (struct connectdata *)arg;
  PRErrorCode err = PR_GetError();
  CERTCertificate *cert = NULL;
  char *subject, *subject_cn, *issuer;

  if(conn->data->set.ssl.certverifyresult!=0)
    return success;

  conn->data->set.ssl.certverifyresult=err;
  cert = SSL_PeerCertificate(sock);
  subject = CERT_NameToAscii(&cert->subject);
  subject_cn = CERT_GetCommonName(&cert->subject);
  issuer = CERT_NameToAscii(&cert->issuer);
  CERT_DestroyCertificate(cert);

  switch(err) {
  case SEC_ERROR_CA_CERT_INVALID:
    infof(conn->data, "Issuer certificate is invalid: '%s'\n", issuer);
    if(conn->data->set.ssl.verifypeer)
      success = SECFailure;
    break;
  case SEC_ERROR_UNTRUSTED_ISSUER:
    if(conn->data->set.ssl.verifypeer)
      success = SECFailure;
    infof(conn->data, "Certificate is signed by an untrusted issuer: '%s'\n",
          issuer);
    break;
  case SSL_ERROR_BAD_CERT_DOMAIN:
    if(conn->data->set.ssl.verifyhost) {
      failf(conn->data, "SSL: certificate subject name '%s' does not match "
            "target host name '%s'", subject_cn, conn->host.dispname);
      success = SECFailure;
    } else {
      infof(conn->data, "warning: SSL: certificate subject name '%s' does not "
            "match target host name '%s'\n", subject_cn, conn->host.dispname);
    }
    break;
  case SEC_ERROR_EXPIRED_CERTIFICATE:
    if(conn->data->set.ssl.verifypeer)
      success = SECFailure;
    infof(conn->data, "Remote Certificate has expired.\n");
    break;
  case SEC_ERROR_UNKNOWN_ISSUER:
    if(conn->data->set.ssl.verifypeer)
      success = SECFailure;
    infof(conn->data, "Peer's certificate issuer is not recognized: '%s'\n",
          issuer);
    break;
  default:
    if(conn->data->set.ssl.verifypeer)
      success = SECFailure;
    infof(conn->data, "Bad certificate received. Subject = '%s', "
          "Issuer = '%s'\n", subject, issuer);
    break;
  }
  if(success == SECSuccess)
    infof(conn->data, "SSL certificate verify ok.\n");
  PR_Free(subject);
  PR_Free(subject_cn);
  PR_Free(issuer);

  return success;
}

/**
 * Inform the application that the handshake is complete.
 */
static SECStatus HandshakeCallback(PRFileDesc *sock, void *arg)
{
  (void)sock;
  (void)arg;
  return SECSuccess;
}

static void display_cert_info(struct SessionHandle *data,
                              CERTCertificate *cert)
{
  char *subject, *issuer, *common_name;
  PRExplodedTime printableTime;
  char timeString[256];
  PRTime notBefore, notAfter;

  subject = CERT_NameToAscii(&cert->subject);
  issuer = CERT_NameToAscii(&cert->issuer);
  common_name = CERT_GetCommonName(&cert->subject);
  infof(data, "\tsubject: %s\n", subject);

  CERT_GetCertTimes(cert, &notBefore, &notAfter);
  PR_ExplodeTime(notBefore, PR_GMTParameters, &printableTime);
  PR_FormatTime(timeString, 256, "%b %d %H:%M:%S %Y GMT", &printableTime);
  infof(data, "\tstart date: %s\n", timeString);
  PR_ExplodeTime(notAfter, PR_GMTParameters, &printableTime);
  PR_FormatTime(timeString, 256, "%b %d %H:%M:%S %Y GMT", &printableTime);
  infof(data, "\texpire date: %s\n", timeString);
  infof(data, "\tcommon name: %s\n", common_name);
  infof(data, "\tissuer: %s\n", issuer);

  PR_Free(subject);
  PR_Free(issuer);
  PR_Free(common_name);
}

static void display_conn_info(struct connectdata *conn, PRFileDesc *sock)
{
  SSLChannelInfo channel;
  SSLCipherSuiteInfo suite;
  CERTCertificate *cert;

  if(SSL_GetChannelInfo(sock, &channel, sizeof channel) ==
     SECSuccess && channel.length == sizeof channel &&
     channel.cipherSuite) {
    if(SSL_GetCipherSuiteInfo(channel.cipherSuite,
                              &suite, sizeof suite) == SECSuccess) {
      infof(conn->data, "SSL connection using %s\n", suite.cipherSuiteName);
    }
  }

  infof(conn->data, "Server certificate:\n");

  cert = SSL_PeerCertificate(sock);
  display_cert_info(conn->data, cert);
  CERT_DestroyCertificate(cert);

  return;
}

/**
 *
 * Check that the Peer certificate's issuer certificate matches the one found
 * by issuer_nickname.  This is not exactly the way OpenSSL and GNU TLS do the
 * issuer check, so we provide comments that mimic the OpenSSL
 * X509_check_issued function (in x509v3/v3_purp.c)
 */
static SECStatus check_issuer_cert(PRFileDesc *sock,
                                   char *issuer_nickname)
{
  CERTCertificate *cert,*cert_issuer,*issuer;
  SECStatus res=SECSuccess;
  void *proto_win = NULL;

  /*
    PRArenaPool   *tmpArena = NULL;
    CERTAuthKeyID *authorityKeyID = NULL;
    SECITEM       *caname = NULL;
  */

  cert = SSL_PeerCertificate(sock);
  cert_issuer = CERT_FindCertIssuer(cert,PR_Now(),certUsageObjectSigner);

  proto_win = SSL_RevealPinArg(sock);
  issuer = NULL;
  issuer = PK11_FindCertFromNickname(issuer_nickname, proto_win);

  if ((!cert_issuer) || (!issuer))
    res = SECFailure;
  else if (SECITEM_CompareItem(&cert_issuer->derCert,
                               &issuer->derCert)!=SECEqual)
    res = SECFailure;

  CERT_DestroyCertificate(cert);
  CERT_DestroyCertificate(issuer);
  CERT_DestroyCertificate(cert_issuer);
  return res;
}

/**
 *
 * Callback to pick the SSL client certificate.
 */
static SECStatus SelectClientCert(void *arg, PRFileDesc *sock,
                                  struct CERTDistNamesStr *caNames,
                                  struct CERTCertificateStr **pRetCert,
                                  struct SECKEYPrivateKeyStr **pRetKey)
{
  static const char pem_nickname[] = "PEM Token #1";
  const char *pem_slotname = pem_nickname;

  struct ssl_connect_data *connssl = (struct ssl_connect_data *)arg;
  struct SessionHandle *data = connssl->data;
  const char *nickname = connssl->client_nickname;

  if (mod && nickname &&
      0 == strncmp(nickname, pem_nickname, /* length of "PEM Token" */ 9)) {

    /* use the cert/key provided by PEM reader */
    PK11SlotInfo *slot;
    void *proto_win = SSL_RevealPinArg(sock);
    *pRetKey = NULL;

    *pRetCert = PK11_FindCertFromNickname(nickname, proto_win);
    if (NULL == *pRetCert) {
      failf(data, "NSS: client certificate not found: %s", nickname);
      return SECFailure;
    }

    slot = PK11_FindSlotByName(pem_slotname);
    if (NULL == slot) {
      failf(data, "NSS: PK11 slot not found: %s", pem_slotname);
      return SECFailure;
    }

    *pRetKey = PK11_FindPrivateKeyFromCert(slot, *pRetCert, NULL);
    PK11_FreeSlot(slot);
    if (NULL == *pRetKey) {
      failf(data, "NSS: private key not found for certificate: %s", nickname);
      return SECFailure;
    }

    infof(data, "NSS: client certificate: %s\n", nickname);
    display_cert_info(data, *pRetCert);
    return SECSuccess;
  }

  /* use the default NSS hook */
  if (SECSuccess != NSS_GetClientAuthData((void *)nickname, sock, caNames,
                                          pRetCert, pRetKey)
      || NULL == *pRetCert) {

    if (NULL == nickname)
      failf(data, "NSS: client certificate not found (nickname not "
            "specified)");
    else
      failf(data, "NSS: client certificate not found: %s", nickname);

    return SECFailure;
  }

  /* get certificate nickname if any */
  nickname = (*pRetCert)->nickname;
  if (NULL == nickname)
    nickname = "[unknown]";

  if (NULL == *pRetKey) {
    failf(data, "NSS: private key not found for certificate: %s", nickname);
    return SECFailure;
  }

  infof(data, "NSS: using client certificate: %s\n", nickname);
  display_cert_info(data, *pRetCert);
  return SECSuccess;
}

/* This function is supposed to decide, which error codes should be used
 * to conclude server is TLS intolerant.
 *
 * taken from xulrunner - nsNSSIOLayer.cpp
 */
static PRBool
isTLSIntoleranceError(PRInt32 err)
{
  switch (err) {
  case SSL_ERROR_BAD_MAC_ALERT:
  case SSL_ERROR_BAD_MAC_READ:
  case SSL_ERROR_HANDSHAKE_FAILURE_ALERT:
  case SSL_ERROR_HANDSHAKE_UNEXPECTED_ALERT:
  case SSL_ERROR_CLIENT_KEY_EXCHANGE_FAILURE:
  case SSL_ERROR_ILLEGAL_PARAMETER_ALERT:
  case SSL_ERROR_NO_CYPHER_OVERLAP:
  case SSL_ERROR_BAD_SERVER:
  case SSL_ERROR_BAD_BLOCK_PADDING:
  case SSL_ERROR_UNSUPPORTED_VERSION:
  case SSL_ERROR_PROTOCOL_VERSION_ALERT:
  case SSL_ERROR_RX_MALFORMED_FINISHED:
  case SSL_ERROR_BAD_HANDSHAKE_HASH_VALUE:
  case SSL_ERROR_DECODE_ERROR_ALERT:
  case SSL_ERROR_RX_UNKNOWN_ALERT:
    return PR_TRUE;
  default:
    return PR_FALSE;
  }
}

static CURLcode init_nss(struct SessionHandle *data)
{
  char *cert_dir;
  struct_stat st;
  if(initialized)
    return CURLE_OK;

  /* First we check if $SSL_DIR points to a valid dir */
  cert_dir = getenv("SSL_DIR");
  if(cert_dir) {
    if((stat(cert_dir, &st) != 0) ||
        (!S_ISDIR(st.st_mode))) {
      cert_dir = NULL;
    }
  }

  /* Now we check if the default location is a valid dir */
  if(!cert_dir) {
    if((stat(SSL_DIR, &st) == 0) &&
        (S_ISDIR(st.st_mode))) {
      cert_dir = (char *)SSL_DIR;
    }
  }

  if(!NSS_IsInitialized()) {
    SECStatus rv;
    initialized = 1;
    infof(data, "Initializing NSS with certpath: %s\n",
          cert_dir ? cert_dir : "none");
    if(!cert_dir) {
      rv = NSS_NoDB_Init(NULL);
    }
    else {
      char *certpath =
        PR_smprintf("%s%s", NSS_VersionCheck("3.12.0") ? "sql:" : "", cert_dir);
      rv = NSS_Initialize(certpath, "", "", "", NSS_INIT_READONLY);
      PR_smprintf_free(certpath);
    }
    if(rv != SECSuccess) {
      infof(data, "Unable to initialize NSS database\n");
      initialized = 0;
      return CURLE_SSL_CACERT_BADFILE;
    }
  }

  if(num_enabled_ciphers() == 0)
    NSS_SetDomesticPolicy();

  return CURLE_OK;
}

/**
 * Global SSL init
 *
 * @retval 0 error initializing SSL
 * @retval 1 SSL initialized successfully
 */
int Curl_nss_init(void)
{
  /* curl_global_init() is not thread-safe so this test is ok */
  if (nss_initlock == NULL) {
    PR_Init(PR_USER_THREAD, PR_PRIORITY_NORMAL, 256);
    nss_initlock = PR_NewLock();
    nss_crllock = PR_NewLock();
  }

  /* We will actually initialize NSS later */

  return 1;
}

CURLcode Curl_nss_force_init(struct SessionHandle *data)
{
  CURLcode rv;
  if(!nss_initlock) {
    failf(data, "unable to initialize NSS, curl_global_init() should have been "
                "called with CURL_GLOBAL_SSL or CURL_GLOBAL_ALL");
    return CURLE_OUT_OF_MEMORY;
  }

  PR_Lock(nss_initlock);
  rv = init_nss(data);
  PR_Unlock(nss_initlock);
  return rv;
}

/* Global cleanup */
void Curl_nss_cleanup(void)
{
  /* This function isn't required to be threadsafe and this is only done
   * as a safety feature.
   */
  PR_Lock(nss_initlock);
  if (initialized) {
    /* Free references to client certificates held in the SSL session cache.
     * Omitting this hampers destruction of the security module owning
     * the certificates. */
    SSL_ClearSessionCache();

    if(mod && SECSuccess == SECMOD_UnloadUserModule(mod)) {
      SECMOD_DestroyModule(mod);
      mod = NULL;
    }
    NSS_Shutdown();
  }
  PR_Unlock(nss_initlock);