added support for crappy libpcre c++ bindings

Added optional support for crappy google's c++ bindings. The bindings are
ridiculously googley, so I think, taking into account the amount of pcre
involved, I'll soon drop requirement for any bindings and will use libpcre
directly.

Signed-off-by: Michael Krelin <hacker@klever.net>

3 files changed, 92 insertions, 16 deletions

diff --git a/acinclude.m4 b/acinclude.m4
index 349d3cf..532f978 100644
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -1,213 +1,211 @@
 dnl AC_WITH_PKGCONFIG([ACTION-IF-FOUND[,ACTION-IF-NOT-FOUND]])
 dnl Outputs:
 dnl AC_SUBST: PKGCONFIG_PKGCONFIG PKGCONFIG_DIR
 dnl AM_CONDTIONAL: HAVE_PKGCONFIG
 AC_DEFUN([AC_WITH_PKGCONFIG],[
  PKGCONFIG_PKGCONFIG=""
  PKGCONFIG_DIR=""
  HAVE_PKGCONFIG="no"
  EXPLICIT_PKGCONFIGDIR="no"
  test -z "${WANT_PKGCONFIG}" && WANT_PKGCONFIG=""
  AC_PATH_PROG([PKGCONFIG_PKGCONFIG],[pkg-config],[false])
  if test "${PKGCONFIG_PKGCONFIG}" != "false" ; then
   AC_ARG_WITH([pkgconfigdir],
    AC_HELP_STRING([--with-pkgconfigdir=dir],[Specify pkgconfig directory]),
    [
     if test "${withval}" = "no" ; then
      WANT_PKGCONFIG="no"
     else
      PKGCONFIG_DIR="${withval}"
      EXPLICIT_PKGCONFIGDIR="yes"
     fi
    ],[
     AC_MSG_CHECKING([for pkgconfig directory])
     PKGCONFIG_DIR="`${PKGCONFIG_PKGCONFIG} --debug 2>&1 | grep '^Scanning'| head -n 1 | cut -d\' -f2-|cut -d\' -f1`"
     AC_MSG_RESULT([${PKGCONFIG_DIR}])
    ]
   )
   if test -d "${PKGCONFIG_DIR}" ; then
    HAVE_PKGCONFIG=yes
    AC_SUBST([PKGCONFIG_PKGCONFIG])
    AC_SUBST([PKGCONFIG_DIR])
   else
    AC_MSG_NOTICE([unexistent pkgconfig directory: ${PKGCONFIG_DIR}])
    if test "${EXPLICIT_PKGCONFIGDIR}" = "yes" ; then
     HAVE_PKGCONFIG=yes
     AC_SUBST([PKGCONFIG_PKGCONFIG])
     AC_SUBST([PKGCONFIG_DIR])
    else
     ifelse([$2], , :, [$2])
    fi
   fi
  fi
  AM_CONDITIONAL([HAVE_PKGCONFIG],[test "${HAVE_PKGCONFIG}" = "yes"])
 ])
 
 dnl AC_WITH_DOXYGEN([ACTION-IF-FOUND[,ACTION-IF-NOT-FOUND]])
 dnl Outputs:
 dnl AC_SUBST: DOXYGEN HAVE_DOXYGEN
 dnl AM_CONDTIONAL: HAVE_DOXYGEN
 AC_DEFUN([AC_WITH_DOXYGEN],[
  HAVE_DOXYGEN="no"
  AC_PATH_PROG([DOXYGEN],[doxygen],[false])
  if test "${DOXYGEN}" = "false" ; then
   ifelse([$2], , :, [$2])
  else
   HAVE_DOXYGEN="yes"
   AC_SUBST([DOXYGEN])
   $1
  fi
  AC_SUBST([HAVE_DOXYGEN])
  AM_CONDITIONAL([HAVE_DOXYGEN],[test "${HAVE_DOXYGEN}" = "yes"])
 ])
 
 dnl AC_WITH_DOT([ACTION-IF-FOUND[,ACTION-IF-NOT-FOUND]])
 dnl Outputs:
 dnl AC_SUBST: DOT HAVE_DOT
 dnl AM_CONDITIONAL: HAVE_DOT
 AC_DEFUN([AC_WITH_DOT],[
  HAVE_DOT="no"
  AC_PATH_PROG([DOT],[dot],[false])
  if test "${DOT}" = "false" ; then
   ifelse([$2], , :, [$2])
  else
   HAVE_DOT="yes"
   AC_SUBST([DOT])
   $1
  fi
 AC_SUBST([HAVE_DOT])
  AM_CONDITIONAL([HAVE_DOT],[test "${HAVE_DOT}" = "yes"])
 ])
 
 dnl AC_WITH_PCRE([ACTION-IF-FOUND[,ACTION-IF-NOT-FOUND]])
 dnl Outputs:
 dnl AC_SUBST: PCRE_CONFIG PCRE_PREFIX PCRE_EXEC_PREFIX
 dnl           PCRE_VERSION PCRE_CFLAGS PCRE_LIBS
 dnl           PCRE_LIBS_POSIX PCRE_CFLAGS_POSIX
-dnl AM_CONDITIONAL: HAVE_PCRE
 dnl AC_DEFINE: HAVE_PCRE PCRE_VERSION
+dnl env: HAVE_PCRE=yes|no
 AC_DEFUN([AC_WITH_PCRE],[
  HAVE_PCRE="no"
  PCRE_CONFIG=""
  PCRE_PREFIX=""
  PCRE_EXEC_PREFIX=""
  PCRE_VERSION=""
  PCRE_CFLAGS=""
  PCRE_LIBS=""
  PCRE_LOCATIONS="${PATH}:/usr/local/bin:/usr/bin"
  test -z "$WANT_PCRE" && WANT_PCRE=""
  AC_ARG_WITH([pcre],
   AC_HELP_STRING([--with-pcre=location],[Look for pcre in specified locations]),
   [
    if test "${withval}" = "no" ; then
     WANT_PCRE="no"
    else
     if test -x "${withval}" ; then
      PCRE_CONFIG="${withval}"
     elif test -x "${withval}/pcre-config" ; then
      PCRE_CONFIG="${withval}/pcre-config"
     elif test -x "${withval}/bin/pcre-config" ; then
      PCRE_CONFIG="${withval}/bin/pcre-config"
     fi
    fi
   ]
  )
  if test "${WANT_PCRE}" = "no" ; then
   ifelse([$2], , :, [$2])
  else
   if test -z "${PCRE_CONFIG}" ; then
    AC_PATH_PROG(PCRE_CONFIG,[pcre-config],false,[${PCRE_LOCATIONS}])
    if test "${PCRE_CONFIG}" = "false" ; then
     ifelse([$2], , :, [$2])
    else
     HAVE_PCRE="yes"
     PCRE_PREFIX="`${PCRE_CONFIG} --prefix`"
     PCRE_EXEC_PREFIX="`${PCRE_CONFIG} --exec-prefix`"
     PCRE_VERSION="`${PCRE_CONFIG} --version`"
     PCRE_CFLAGS="`${PCRE_CONFIG} --cflags`"
     PCRE_LIBS="`${PCRE_CONFIG} --libs`"
     PCRE_CFLAGS_POSIX="`${PCRE_CONFIG} --cflags-posix`"
     PCRE_LIBS_POSIX="`${PCRE_CONFIG} --libs-posix`"
     AC_SUBST([PCRE_CONFIG])
     AC_SUBST([PCRE_PREFIX])
     AC_SUBST([PCRE_EXEC_PREFIX])
     AC_SUBST([PCRE_VERSION])
     AC_SUBST([PCRE_CFLAGS])
     AC_SUBST([PCRE_LIBS])
     AC_SUBST([PCRE_CFLAGS_POSIX])
     AC_SUBST([PCRE_LIBS_POSIX])
     AC_DEFINE([HAVE_PCRE],,[pcre support])
     AC_DEFINE_UNQUOTED([PCRE_VERSION],["${PCRE_VERSION}"],[pcre version])
     $1
    fi
   fi
  fi
- AM_CONDITIONAL([HAVE_PCRE],[test "${HAVE_PCRE}" = "yes"])
 ])
 
 dnl AC_WITH_PCREPP([ACTION-IF-FOUND[,ACTION-IF-NOT-FOUND]])
 dnl Outputs:
 dnl AC_SUBST: PCREPP_CONFIG PCREPP_PREFIX PCREPP_EXEC_PREFIX
 dnl           PCREPP_VERSION PCREPP_CFLAGS PCREPP_LIBS
-dnl AM_CONDITIONAL: HAVE_PCREPP
 dnl AC_DEFINE: HAVE_PCREPP PCREPP_VERSION
+dnl env: HAVE_PCREPP=yes|no
 AC_DEFUN([AC_WITH_PCREPP],[
  HAVE_PCREPP="no"
  PCREPP_CONFIG=""
  PCREPP_PREFIX=""
  PCREPP_EXEC_PREFIX=""
  PCREPP_VERSION=""
  PCREPP_CFLAGS=""
  PCREPP_LIBS=""
  PCREPP_LOCATIONS="${PATH}:/usr/local/bin:/usr/bin"
  test -z "$WANT_PCREPP" && WANT_PCREPP=""
  AC_ARG_WITH([pcrepp],
   AC_HELP_STRING([--with-pcrepp=location],[Look for pcre++ in specified locations]),
   [
    if test "${withval}" = "no" ; then
     WANT_PCREPP="no"
    else
     if test -x "${withval}" ; then
      PCREPP_CONFIG="${withval}"
     elif test -x "${withval}/pcre++-config" ; then
      PCREPP_CONFIG="${withval}/pcre++-config"
     elif test -x "${withval}/bin/pcre++-config" ; then
      PCREPP_CONFIG="${withval}/bin/pcre++-config"
     fi
    fi
   ]
  )
  if test "${WANT_PCREPP}" = "no" ; then
   ifelse([$2], , :, [$2])
  else
   if test "${HAVE_PCRE}" != "yes" ; then
    ifelse([$2], , :, [$2])
   else
    if test -z "${PCREPP_CONFIG}" ; then
     AC_PATH_PROG([PCREPP_CONFIG],[pcre++-config],false,[${PCREPP_LOCATIONS}])
     if test "${PCREPP_CONFIG}" = "false" ; then
      ifelse([$2], , :, [$2])
     else
      HAVE_PCREPP="yes"
      PCREPP_PREFIX="`${PCREPP_CONFIG} --prefix`"
      PCREPP_EXEC_PREFIX="`${PCREPP_CONFIG} --exec-prefix`"
      PCREPP_VERSION="`${PCREPP_CONFIG} --version`"
      PCREPP_CFLAGS="`${PCREPP_CONFIG} --cflags` ${PCRE_CFLAGS}"
      PCREPP_LIBS="`${PCREPP_CONFIG} --libs` ${PCRE_LIBS}"
      AC_SUBST([PCREPP_CONFIG])
      AC_SUBST([PCREPP_PREFIX])
      AC_SUBST([PCREPP_EXEC_PREFIX])
      AC_SUBST([PCREPP_VERSION])
      AC_SUBST([PCREPP_CFLAGS])
      AC_SUBST([PCREPP_LIBS])
      AC_DEFINE([HAVE_PCREPP],,[pcre++ support])
      AC_DEFINE_UNQUOTED([PCREPP_VERSION],["${PCREPP_VERSION}"],[pcre++ version])
      $1
     fi
    fi
   fi
  fi
- AM_CONDITIONAL([HAVE_PCREPP],[test "${HAVE_PCREPP}" = "yes"])
 ])
 
 m4_include([acinclude.d/libcurl.m4])
diff --git a/configure.ac b/configure.ac
index 2094273..00c6bc4 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1,95 +1,132 @@
 AC_INIT([libopkele], [0.3], [libopkele-bugs@klever.net])
 AC_CONFIG_SRCDIR([include/opkele/opkele-config.h])
 AC_CONFIG_HEADERS([config.h include/opkele/acconfig.h])
 AM_INIT_AUTOMAKE([dist-bzip2])
 
 AC_PROG_INSTALL
 AC_PROG_CXX
 AC_PROG_CC
 AC_PROG_LIBTOOL
 
 AC_HEADER_STDC
 
 AC_PATH_PROG([XSLTPROC],[xsltproc],[true])
 AC_WITH_PKGCONFIG
 
 PKG_CHECK_MODULES([OPENSSL],[openssl],,[
  AC_MSG_ERROR([no openssl library found. get one from http://www.openssl.org/])
 ])
 
 WANT_KONFORKA="yes"
 AC_ARG_ENABLE([konforka],
  AC_HELP_STRING([--disable-konforka],[do not use konforka library (default: use if found)]),
  [
   test "${enableval}" = "no" && WANT_KONFORKA="no"
  ]
 )
 if test "${WANT_KONFORKA}" = "yes" ; then
  PKG_CHECK_MODULES([KONFORKA],[konforka],[
   AC_SUBST([KONFORKA_CFLAGS])
   AC_SUBST([KONFORKA_LIBS])
   AC_DEFINE([HAVE_KONFORKA],,[defined in presence of konforka library])
   AC_DEFINE([OPKELE_HAVE_KONFORKA],,[defined in presence of konforka library])
   AC_SUBST([KONFORKA_KONFORKA],[konforka])
  ],[true])
 fi
 
 WANT_DOXYGEN="yes"
 AC_ARG_ENABLE([doxygen],
  AC_HELP_STRING([--disable-doxygen],[do not generate documentation]),
  [
   test "${enableval}" = "no" && WANT_DOXYGEN="no"
  ]
 )
 if test "${WANT_DOXYGEN}" = "yes" ; then
  AC_WITH_DOXYGEN
  AC_WITH_DOT
 else
  AM_CONDITIONAL([HAVE_DOXYGEN],[false])
  AM_CONDITIONAL([HAVE_DOT],[false])
 fi
 
 LIBCURL_CHECK_CONFIG(,,,[
  AC_MSG_ERROR([no required libcurl library. get one from http://curl.haxx.se/])
 ])
-AC_WITH_PCRE([
-  AC_WITH_PCREPP(,[
-   AC_MSG_ERROR([no pcre++ library found. get one at http://www.daemon.de/PCRE])
-  ])
- ],[
-  AC_MSG_ERROR([no pcre library found. get one at http://www.pcre.org/])
+
+want_pcre_impl=""
+AC_ARG_WITH([pcre-bindings],
+ AC_HELP_STRING([--with-pcre-bindings=(pcrepp|none|libpcrecpp)],[Specify which pcre c++ bindings to use. 'pcrepp' stands for quite sensible library, found at http://www.daemon.de/PCRE/, 'libcrecpp' makes use of crappy bindings by google and 'none' disables internal implementation of OP discovery]),
+ [
+  case "$withval" in
+   pcrepp) want_pcre_impl="pcrepp" ;;
+   libpcrecpp) want_pcre_impl="libpcrecpp" ;;
+   none) want_pcre_impl="none";;
+   *) AC_MSG_ERROR([I'm not sure I understand what do you want for a pcre c++ bindings]) ;;
+  esac
  ]
 )
 
+found_pcre_impl=""
+
+if test -z "$want_pcre_impl" -o "$want_pcre_impl" = "pcrepp" ; then
+ AC_WITH_PCRE([
+   AC_WITH_PCREPP([
+    found_pcre_impl=pcrepp
+   ])
+  ],[
+   AC_MSG_ERROR([no pcre library found. get one at http://www.pcre.org/])
+  ]
+ )
+ test "$want_pcre_impl,$found_pcre_impl" = "pcrepp," && AC_MSG_ERROR([no pcre++ library found. get one at http://www.daemon.de/PCRE])
+fi
+
+if test "$found_pcre_impl,$want_pcre_impl" = "," -o "$want_pcre_impl" = "libpcrecpp" ; then
+ test -z "$want_pcre_impl" || AC_MSG_NOTICE([You want to use crappy libpcre c++ bindings])
+ PKG_CHECK_MODULES([LIBPCRECPP],[libpcrecpp],[
+   found_pcre_impl=libpcrecpp
+   CXXFLAGS="$CXXFLAGS $LIBPCRECPP_CFLAGS"
+   LIBS="$LIBS $LIBPCRECPP_LIBS"
+  ],[
+   test -z "$want_pcre_impl" || AC_MSG_ERROR([no libpcre c++ bindings found. why would you want it if you don't have it installed?])
+  ]
+ )
+fi
+test "$want_pcre_impl,$found_pcre_impl" = "," && AC_MSG_ERROR([no pcre c++ bindings found, use --with-pcre-bindings=none to disable code that makes use of it])
+
+case "$found_pcre_impl" in
+ pcrepp) AC_DEFINE([USE_PCREPP],,[defined if pcre++ is to be used]) ;;
+ libpcrecpp) AC_DEFINE([USE_LIBPCRECPP],,[defined if crappy google bindings are to be used]) ;;
+esac
+
 curl_ssl_verify_host="true"
 AC_ARG_ENABLE([ssl-verify-host],
  AC_HELP_STRING([--disable-ssl-verify-host],[disable cURL cert/host relationships verification]),
  [ test "${enableval}" = "no" && curl_ssl_verify_host="false" ]
 )
 ${curl_ssl_verify_host} || AC_DEFINE([DISABLE_CURL_SSL_VERIFYHOST],,[defined if cURL is not to verify cert/host])
 
 curl_ssl_verify_peer="true"
 AC_ARG_ENABLE([ssl-verify-peer],
  AC_HELP_STRING([--disable-ssl-verify-peer],[disable cURL cert validity verification]),
  [ test "${enableval}" = "no" && curl_ssl_verify_peer="false" ]
 )
 ${curl_ssl_verify_peer} || AC_DEFINE([DISABLE_CURL_SSL_VERIFYPEER],,[defined if cURL is not to verify cert validity])
 
 postels_law=true
 AC_ARG_ENABLE([postels-law],
  AC_HELP_STRING([--disable-postels-law],[Be strict, do not adhere to Postel's Law ("be conservative in what you do, be liberal in what you accept from others", RFC 793)]),
  [ test "${enableval}" = "no" && postels_law=false ]
 )
 $postels_law && AC_DEFINE([POSTELS_LAW],,[defined if we want to adhere to Postel's Law])
 
 AC_DEFINE_UNQUOTED([OPKELE_SRC_DIR],["$PWD"],[source directory])
 
 AC_CONFIG_FILES([
  Makefile
   libopkele.pc
   Doxyfile
  include/Makefile
  lib/Makefile
  test/Makefile
 ])
 AC_OUTPUT
diff --git a/lib/consumer.cc b/lib/consumer.cc
index 8f66688..299b3bc 100644
--- a/lib/consumer.cc
+++ b/lib/consumer.cc
@@ -1,371 +1,412 @@
 #include <algorithm>
 #include <cassert>
 #include <opkele/util.h>
 #include <opkele/exception.h>
 #include <opkele/data.h>
 #include <opkele/consumer.h>
 #include <openssl/sha.h>
 #include <openssl/hmac.h>
 #include <curl/curl.h>
-#include <pcre++.h>
 
 #include <iostream>
 
 #include "config.h"
 
+#if defined(USE_LIBPCRECPP)
+# include <pcrecpp.h>
+#elif defined(USE_PCREPP)
+# include <pcre++.h>
+#else
+ /* internal implementation won't be built */
+#endif
+
 namespace opkele {
     using namespace std;
 
     class curl_t {
         public:
             CURL *_c;
 
             curl_t() : _c(0) { }
             curl_t(CURL *c) : _c(c) { }
             ~curl_t() throw() { if(_c) curl_easy_cleanup(_c); }
 
             curl_t& operator=(CURL *c) { if(_c) curl_easy_cleanup(_c); _c=c; return *this; }
 
             operator const CURL*(void) const { return _c; }
             operator CURL*(void) { return _c; }
     };
 
     static CURLcode curl_misc_sets(CURL* c) {
         CURLcode r;
         (r=curl_easy_setopt(c,CURLOPT_FOLLOWLOCATION,1))
         || (r=curl_easy_setopt(c,CURLOPT_MAXREDIRS,5))
         || (r=curl_easy_setopt(c,CURLOPT_DNS_CACHE_TIMEOUT,120))
         || (r=curl_easy_setopt(c,CURLOPT_DNS_USE_GLOBAL_CACHE,1))
         || (r=curl_easy_setopt(c,CURLOPT_USERAGENT,PACKAGE_NAME"/"PACKAGE_VERSION))
         || (r=curl_easy_setopt(c,CURLOPT_TIMEOUT,20))
         #ifdefDISABLE_CURL_SSL_VERIFYHOST
         || (r=curl_easy_setopt(c,CURLOPT_SSL_VERIFYHOST,0))
 #endif
         #ifdefDISABLE_CURL_SSL_VERIFYPEER
         || (r=curl_easy_setopt(c,CURLOPT_SSL_VERIFYPEER,0))
 #endif
         ;
         return r;
     }
 
     static size_t _curl_tostring(void *ptr,size_t size,size_t nmemb,void *stream) {
         string *str = (string*)stream;
         size_t bytes = size*nmemb;
         size_t get = min(16384-str->length(),bytes);
         str->append((const char*)ptr,get);
         return get;
     }
 
     assoc_t consumer_t::associate(const string& server) {
         util::dh_t dh = DH_new();
         if(!dh)
             throw exception_openssl(OPKELE_CP_ "failed to DH_new()");
         dh->p = util::dec_to_bignum(data::_default_p);
         dh->g = util::dec_to_bignum(data::_default_g);
         if(!DH_generate_key(dh))
             throw exception_openssl(OPKELE_CP_ "failed to DH_generate_key()");
         string request = 
             "openid.mode=associate"
             "&openid.assoc_type=HMAC-SHA1"
             "&openid.session_type=DH-SHA1"
             "&openid.dh_consumer_public=";
         request += util::url_encode(util::bignum_to_base64(dh->pub_key));
         curl_t curl = curl_easy_init();
         if(!curl)
             throw exception_curl(OPKELE_CP_ "failed to curl_easy_init()");
         string response;
         CURLcode r;
         (r=curl_misc_sets(curl))
         || (r=curl_easy_setopt(curl,CURLOPT_URL,server.c_str()))
         || (r=curl_easy_setopt(curl,CURLOPT_POST,1))
         || (r=curl_easy_setopt(curl,CURLOPT_POSTFIELDS,request.data()))
         || (r=curl_easy_setopt(curl,CURLOPT_POSTFIELDSIZE,request.length()))
         || (r=curl_easy_setopt(curl,CURLOPT_WRITEFUNCTION,_curl_tostring))
         || (r=curl_easy_setopt(curl,CURLOPT_WRITEDATA,&response))
         ;
         if(r)
             throw exception_curl(OPKELE_CP_ "failed to curl_easy_setopt()",r);
         if(r=curl_easy_perform(curl))
             throw exception_curl(OPKELE_CP_ "failed to curl_easy_perform()",r);
         params_t p; p.parse_keyvalues(response);
         if(p.has_param("assoc_type") && p.get_param("assoc_type")!="HMAC-SHA1")
             throw bad_input(OPKELE_CP_ "unsupported assoc_type");
         string st;
         if(p.has_param("session_type")) st = p.get_param("session_type");
         if((!st.empty()) && st!="DH-SHA1")
             throw bad_input(OPKELE_CP_ "unsupported session_type");
         secret_t secret;
         if(st.empty()) {
             secret.from_base64(p.get_param("mac_key"));
         }else{
             util::bignum_t s_pub = util::base64_to_bignum(p.get_param("dh_server_public"));
             vector<unsigned char> ck(DH_size(dh)+1);
             unsigned char *ckptr = &(ck.front())+1;
             int cklen = DH_compute_key(ckptr,s_pub,dh);
             if(cklen<0)
                 throw exception_openssl(OPKELE_CP_ "failed to DH_compute_key()");
             if(cklen && (*ckptr)&0x80) {
                 (*(--ckptr)) = 0; ++cklen;
             }
             unsigned char key_sha1[SHA_DIGEST_LENGTH];
             SHA1(ckptr,cklen,key_sha1);
             secret.enxor_from_base64(key_sha1,p.get_param("enc_mac_key"));
         }
         int expires_in = 0;
         if(p.has_param("expires_in")) {
             expires_in = util::string_to_long(p.get_param("expires_in"));
         }else if(p.has_param("issued") && p.has_param("expiry")) {
             expires_in = util::w3c_to_time(p.get_param("expiry"))-util::w3c_to_time(p.get_param("issued"));
         }else
             throw bad_input(OPKELE_CP_ "no expiration information");
         return store_assoc(server,p.get_param("assoc_handle"),secret,expires_in);
     }
 
     string consumer_t::checkid_immediate(const string& identity,const string& return_to,const string& trust_root,extension_t *ext) {
         return checkid_(mode_checkid_immediate,identity,return_to,trust_root,ext);
     }
     string consumer_t::checkid_setup(const string& identity,const string& return_to,const string& trust_root,extension_t *ext) {
         return checkid_(mode_checkid_setup,identity,return_to,trust_root,ext);
     }
     string consumer_t::checkid_(mode_t mode,const string& identity,const string& return_to,const string& trust_root,extension_t *ext) {
         params_t p;
         if(mode==mode_checkid_immediate)
             p["mode"]="checkid_immediate";
         else if(mode==mode_checkid_setup)
             p["mode"]="checkid_setup";
         else
             throw bad_input(OPKELE_CP_ "unknown checkid_* mode");
         string iurl = canonicalize(identity);
         string server, delegate;
         retrieve_links(iurl,server,delegate);
         p["identity"] = delegate.empty()?iurl:delegate;
         if(!trust_root.empty())
             p["trust_root"] = trust_root;
         p["return_to"] = return_to;
         try {
             string ah = find_assoc(server)->handle();
             p["assoc_handle"] = ah;
         }catch(failed_lookup& fl) {
             string ah = associate(server)->handle();
             p["assoc_handle"] = ah;
         }
         if(ext) ext->checkid_hook(p,identity);
         return p.append_query(server);
     }
 
     void consumer_t::id_res(const params_t& pin,const string& identity,extension_t *ext) {
         if(pin.has_param("openid.user_setup_url"))
             throw id_res_setup(OPKELE_CP_ "assertion failed, setup url provided",pin.get_param("openid.user_setup_url"));
         string server,delegate;
         retrieve_links(identity.empty()?pin.get_param("openid.identity"):canonicalize(identity),server,delegate);
         params_t ps;
         try {
             assoc_t assoc = retrieve_assoc(server,pin.get_param("openid.assoc_handle"));
             if(assoc->is_expired()) /* TODO: or should I throw some other exception to force programmer fix his implementation? */
                 throw failed_lookup(OPKELE_CP_ "retrieve_assoc() has returned expired handle");
             const string& sigenc = pin.get_param("openid.sig");
             vector<unsigned char> sig;
             util::decode_base64(sigenc,sig);
             const string& slist = pin.get_param("openid.signed");
             string kv;
             string::size_type p = 0;
             while(true) {
                 string::size_type co = slist.find(',',p);
                 string f = (co==string::npos)?slist.substr(p):slist.substr(p,co-p);
                 kv += f;
                 kv += ':';
                 f.insert(0,"openid.");
                 kv += pin.get_param(f);
                 kv += '\n';
                 if(ext) ps[f.substr(sizeof("openid.")-1)] = pin.get_param(f);
                 if(co==string::npos)
                     break;
                 p = co+1;
             }
             secret_t secret = assoc->secret();
             unsigned int md_len = 0;
             unsigned char *md = HMAC(
                     EVP_sha1(),
                     &(secret.front()),secret.size(),
                     (const unsigned char *)kv.data(),kv.length(),
                     0,&md_len);
             if(sig.size()!=md_len || memcmp(&(sig.front()),md,md_len))
                 throw id_res_mismatch(OPKELE_CP_ "signature mismatch");
         }catch(failed_lookup& e) { /* XXX: more specific? */
             const string& slist = pin.get_param("openid.signed");
             string::size_type pp = 0;
             params_t p;
             while(true) {
                 string::size_type co = slist.find(',',pp);
                 string f = "openid.";
                 f += (co==string::npos)?slist.substr(pp):slist.substr(pp,co-pp);
                 p[f] = pin.get_param(f);
                 if(co==string::npos)
                     break;
                 pp = co+1;
             }
             p["openid.assoc_handle"] = pin.get_param("openid.assoc_handle");
             p["openid.sig"] = pin.get_param("openid.sig");
             p["openid.signed"] = pin.get_param("openid.signed");
             try {
                 string ih = pin.get_param("openid.invalidate_handle");
                 p["openid.invalidate_handle"] = ih;
             }catch(failed_lookup& fl) { }
             try {
                 check_authentication(server,p);
             }catch(failed_check_authentication& fca) {
                 throw id_res_failed(OPKELE_CP_ "failed to check_authentication()");
             }
         }
         if(ext) ext->id_res_hook(pin,ps,identity);
     }
 
     void consumer_t::check_authentication(const string& server,const params_t& p) {
         string request = "openid.mode=check_authentication";
         for(params_t::const_iterator i=p.begin();i!=p.end();++i) {
             if(i->first!="openid.mode") {
                 request += '&';
                 request += i->first;
                 request += '=';
                 request += util::url_encode(i->second);
             }
         }
         curl_t curl = curl_easy_init();
         if(!curl)
             throw exception_curl(OPKELE_CP_ "failed to curl_easy_init()");
         string response;
         CURLcode r;
         (r=curl_misc_sets(curl))
         || (r=curl_easy_setopt(curl,CURLOPT_URL,server.c_str()))
         || (r=curl_easy_setopt(curl,CURLOPT_POST,1))
         || (r=curl_easy_setopt(curl,CURLOPT_POSTFIELDS,request.data()))
         || (r=curl_easy_setopt(curl,CURLOPT_POSTFIELDSIZE,request.length()))
         || (r=curl_easy_setopt(curl,CURLOPT_WRITEFUNCTION,_curl_tostring))
         || (r=curl_easy_setopt(curl,CURLOPT_WRITEDATA,&response))
         ;
         if(r)
             throw exception_curl(OPKELE_CP_ "failed to curl_easy_setopt()",r);
         if(r=curl_easy_perform(curl))
             throw exception_curl(OPKELE_CP_ "failed to curl_easy_perform()",r);
         params_t pp; pp.parse_keyvalues(response);
         if(pp.has_param("invalidate_handle"))
             invalidate_assoc(server,pp.get_param("invalidate_handle"));
         if(pp.has_param("is_valid")) {
             if(pp.get_param("is_valid")=="true")
                 return;
         }else if(pp.has_param("lifetime")) {
             if(util::string_to_long(pp.get_param("lifetime")))
                 return;
         }
         throw failed_check_authentication(OPKELE_CP_ "failed to verify response");
     }
 
     void consumer_t::retrieve_links(const string& url,string& server,string& delegate) {
+#if defined(USE_LIBPCRECPP) || defined(USE_PCREPP)
         server.erase();
         delegate.erase();
         curl_t curl = curl_easy_init();
         if(!curl)
             throw exception_curl(OPKELE_CP_ "failed to curl_easy_init()");
         string html;
         CURLcode r;
         (r=curl_misc_sets(curl))
         || (r=curl_easy_setopt(curl,CURLOPT_URL,url.c_str()))
         || (r=curl_easy_setopt(curl,CURLOPT_WRITEFUNCTION,_curl_tostring))
         || (r=curl_easy_setopt(curl,CURLOPT_WRITEDATA,&html))
         ;
         if(r)
             throw exception_curl(OPKELE_CP_ "failed to curl_easy_setopt()",r);
         r = curl_easy_perform(curl);
         if(r && r!=CURLE_WRITE_ERROR)
             throw exception_curl(OPKELE_CP_ "failed to curl_easy_perform()",r);
-        pcrepp::Pcre bre("<body\\b",PCRE_CASELESS);
         // strip out everything past body
+        static const char *re_hdre = "<head[^>]*>",
+                     *re_lre = "<link\\b([^>]+)>",
+                     *re_rre = "\\brel=['\"]([^'\"]+)['\"]",
+                     *re_hre = "\\bhref=['\"]([^'\"]+)['\"]";
+#if defined(USE_LIBPCRECPP)
+        static pcrecpp::RE_Options ro(PCRE_CASELESS|PCRE_DOTALL);
+        static pcrecpp::RE
+            bre("<body\\b.*",ro), hdre(re_hdre,ro),
+            lre(re_lre,ro), rre(re_rre), hre(re_hre,ro);
+        bre.Replace("",&html);
+        pcrecpp::StringPiece hpiece(html);
+        if(!hdre.FindAndConsume(&hpiece))
+            throw bad_input(OPKELE_CP_ "failed to find head");
+        string attrs;
+        while(lre.FindAndConsume(&hpiece,&attrs)) {
+            pcrecpp::StringPiece rel, href;
+            if(!(rre.PartialMatch(attrs,&rel) && hre.PartialMatch(attrs,&href)))
+                continue;
+            if(rel=="openid.server") {
+                href.CopyToString(&server);
+                if(!delegate.empty())
+                    break;
+            }else if(rel=="openid.delegate") {
+                href.CopyToString(&delegate);
+                if(!server.empty())
+                    break;
+            }
+        }
+#elif defined(USE_PCREPP)
+        pcrepp::Pcre bre("<body\\b",PCRE_CASELESS);
         if(bre.search(html))
             html.erase(bre.get_match_start());
-        pcrepp::Pcre hdre("<head[^>]*>",PCRE_CASELESS);
+        pcrepp::Pcre hdre(re_hdre,PCRE_CASELESS);
         if(!hdre.search(html))
             throw bad_input(OPKELE_CP_ "failed to find head");
         html.erase(0,hdre.get_match_end()+1);
-        pcrepp::Pcre lre("<link\\b([^>]+)>",PCRE_CASELESS),
-            rre("\\brel=['\"]([^'\"]+)['\"]",PCRE_CASELESS),
-            hre("\\bhref=['\"]([^'\"]+)['\"]",PCRE_CASELESS);
+        pcrepp::Pcre lre(re_lre,PCRE_CASELESS), rre(re_rre,PCRE_CASELESS), hre(re_hre,PCRE_CASELESS);
         while(lre.search(html)) {
             string attrs = lre[0];
             html.erase(0,lre.get_match_end()+1);
             if(!(rre.search(attrs)&&hre.search(attrs)))
                 continue;
             if(rre[0]=="openid.server") {
                 server = hre[0];
                 if(!delegate.empty())
                     break;
             }else if(rre[0]=="openid.delegate") {
                 delegate = hre[0];
                 if(!server.empty())
                     break;
             }
         }
+#else
+        #error "I must have gone crazy"
+#endif
         if(server.empty())
             throw failed_assertion(OPKELE_CP_ "The location has no openid.server declaration");
+#else /* none of the RE bindings enabled */
+        throw not_implemented(OPKELE_CP_ "No internal implementation of retrieve_links were provided at compile-time");
+#endif
     }
 
     assoc_t consumer_t::find_assoc(const string& server) {
         throw failed_lookup(OPKELE_CP_ "no find_assoc() provided");
     }
 
     string consumer_t::normalize(const string& url) {
         string rv = url;
         // strip leading and trailing spaces
         string::size_type i = rv.find_first_not_of(" \t\r\n");
         if(i==string::npos)
             throw bad_input(OPKELE_CP_ "empty URL");
         if(i)
             rv.erase(0,i);
         i = rv.find_last_not_of(" \t\r\n");
         assert(i!=string::npos);
         if(i<(rv.length()-1))
             rv.erase(i+1);
         // add missing http://
         i = rv.find("://");
         if(i==string::npos) { // primitive. but do we need more?
             rv.insert(0,"http://");
             i = sizeof("http://")-1;
         }else{
             i += sizeof("://")-1;
         }
         string::size_type qm = rv.find('?',i);
         string::size_type sl = rv.find('/',i);
         if(qm!=string::npos) {
             if(sl==string::npos || sl>qm)
                 rv.insert(qm,1,'/');
         }else{
             if(sl==string::npos)
                 rv += '/';
         }
         return rv;
     }
 
     string consumer_t::canonicalize(const string& url) {
         string rv = normalize(url);
         curl_t curl = curl_easy_init();
         if(!curl)
             throw exception_curl(OPKELE_CP_ "failed to curl_easy_init()");
         string html;
         CURLcode r;
         (r=curl_misc_sets(curl))
         || (r=curl_easy_setopt(curl,CURLOPT_URL,rv.c_str()))
         || (r=curl_easy_setopt(curl,CURLOPT_NOBODY,1))
         ;
         if(r)
             throw exception_curl(OPKELE_CP_ "failed to curl_easy_setopt()",r);
         r = curl_easy_perform(curl);
         if(r)
             throw exception_curl(OPKELE_CP_ "failed to curl_easy_perform()",r);
         const char *eu = 0;
         r = curl_easy_getinfo(curl,CURLINFO_EFFECTIVE_URL,&eu);
         if(r)
             throw exception_curl(OPKELE_CP_ "failed to curl_easy_getinfo(..CURLINFO_EFFECTIVE_URL..)",r);
         rv = eu;
         return normalize(rv);
     }
 
 }