first cut on XRI resolver

 This commit adds openid service resolver that does discovery using XRI (proxy
 only), Yadis protocol and html-based discovery. It uses expat as xml parsing
 engine, which makes it a bit more strict about html it receives, but I think
 failing to discover links in *severely* broken html is better than
 misdetecting links, hidden in comments or such.

 This is highly experimental code and needs more thoughts and testing.

 Thanks everyone pushing me towards this development. Namely Joseph, John,
 Gen.

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

1 files changed, 294 insertions, 0 deletions

diff --git a/lib/openid_service_resolver.cc b/lib/openid_service_resolver.cc
new file mode 100644
index 0000000..5f82955
--- a/dev/null
+++ b/lib/openid_service_resolver.cc
@@ -0,0 +1,294 @@
+#include <cctype>
+#include <opkele/exception.h>
+#include <opkele/util.h>
+#include <opkele/openid_service_resolver.h>
+#include <opkele/uris.h>
+
+#define LOCATION_HEADER "X-XRDS-Location"
+
+namespace opkele {
+    static const char *whitespace = " \t\r\n";
+
+    openid_service_resolver_t::openid_service_resolver_t(const string& xp)
+        : util::curl_t(easy_init()),
+        util::expat_t(0),
+        xri_proxy(xp.empty()?"http://beta.xri.net/":xp)
+    {
+        CURLcode r;
+        (r=misc_sets())
+        || (r=set_write())
+        || (r==set_header())
+        ;
+        if(r)
+            throw opkele::exception_curl(OPKELE_CP_ "failed to set curly options",r);
+    }
+
+    static bool is_element(const XML_Char *n,const char *en) {
+        if(!strcasecmp(n,en)) return true;
+        int nl = strlen(n), enl = strlen(en);
+        if( (nl>=(enl+1)) && n[nl-enl-1]=='\t'
+                && !strcasecmp(&n[nl-enl],en) )
+            return true;
+        return false;
+    }
+    static inline bool is_qelement(const XML_Char *n,const char *qen) {
+        return !strcasecmp(n,qen);
+    }
+    static inline bool is_element(
+            const openid_service_resolver_t::parser_node_t& n,
+            const char *en) {
+        return is_element(n.element.c_str(),en);
+    }
+    static inline bool is_qelement(
+            const openid_service_resolver_t::parser_node_t& n,
+            const char *qen) {
+        return is_qelement(n.element.c_str(),qen);
+    }
+
+    void openid_service_resolver_t::start_element(const XML_Char *n,const XML_Char **a) {
+        if(state!=state_parse) return;
+        tree.push(n,a);
+        parser_node_t& t = tree.top();
+        if(is_element(n,"html") || is_element(n,"head")
+                || is_qelement(n,NSURI_XRDS "\tXRDS")
+                || is_qelement(n,NSURI_XRD "\tXRD") )
+            t.skip_tags = false;
+        else if(is_qelement(n,NSURI_XRD "\tService")
+                || is_qelement(n,NSURI_XRD "\tType")
+                || is_qelement(n,NSURI_XRD "\tURI")
+                || is_qelement(n,NSURI_OPENID10 "\tDelegate")
+                || is_qelement(n,NSURI_XRD "\tCanonicalID") )
+            t.skip_tags = t.skip_text = false;
+        else if(is_element(n,"body"))
+            state = state_stopping_body;
+    }
+    void openid_service_resolver_t::end_element(const XML_Char *n) {
+        if(state!=state_parse) return;
+        assert(tree.top().element == n);
+        pop_tag();
+    }
+    void openid_service_resolver_t::character_data(const XML_Char *s,int l) {
+        if(state!=state_parse) return;
+        if( !( tree.empty() || tree.top().skip_text ) )
+            tree.top().content.append(s,l);
+    }
+
+    static void copy_trim_whitespace(string& to,const string& from) {
+        string::size_type ns0 = from.find_first_not_of(whitespace);
+        if(ns0==string::npos) {
+            to.clear(); return;
+        }
+        string::size_type ns1 = from.find_last_not_of(whitespace);
+        assert(ns1!=string::npos);
+        to.assign(from,ns0,ns1-ns0+1);
+    }
+
+    void openid_service_resolver_t::pop_tag() {
+        assert(!tree.empty());
+        parser_node_t& t = tree.top();
+        if( is_element(t,"meta")
+                && !strcasecmp(t.attrs["http-equiv"].c_str(),LOCATION_HEADER) ) {
+            xrds_location = t.attrs["content"];
+        }else if( is_element(t,"link") ) {
+            parser_node_t::attrs_t::const_iterator ir = t.attrs.find("rel");
+            if(ir!=t.attrs.end()) {
+                const string& rels = ir->second;
+                for(string::size_type ns = rels.find_first_not_of(whitespace);
+                        ns!=string::npos;
+                        ns=rels.find_first_not_of(whitespace,ns)) {
+                    string::size_type s = rels.find_first_of(whitespace,ns);
+                    string rel;
+                    if(s==string::npos) {
+                        rel.assign(rels,ns,string::npos);
+                        ns = string::npos;
+                    }else{
+                        rel.assign(rels,ns,s-ns);
+                        ns = s;
+                    }
+                    if(rel=="openid.server")
+                        copy_trim_whitespace(html_SEP.xrd_URI,t.attrs["href"]);
+                    else if(rel=="openid.delegate")
+                        copy_trim_whitespace(html_SEP.openid_Delegate,t.attrs["href"]);
+                }
+            }
+        }else if( is_element(t,"head") )
+            state = state_stopping_head;
+        else if( is_qelement(t,NSURI_XRD "\tXRD")) {
+            if( !(
+                        (
+                         xri_mode
+                         && t.auth_info.canonical_id.empty()
+                        ) ||
+                        t.auth_info.auth_SEP.xrd_Type.empty()
+                 ) )
+                auth_info = t.auth_info;
+        }else if( tree.size()>1 ) {
+            parser_node_t& p = tree.parent();
+            if( is_qelement(p,NSURI_XRD "\tService") ) {
+                if( is_qelement(t,NSURI_XRD "\tType") ) {
+                    if(t.content==STURI_OPENID10) {
+                        string tmp; copy_trim_whitespace(tmp,t.content);
+                        p.auth_info.auth_SEP.xrd_Type.insert(tmp);
+                    }
+                }else if( is_qelement(t,NSURI_XRD "\tURI") )
+                    copy_trim_whitespace(p.auth_info.auth_SEP.xrd_URI,t.content);
+                else if( is_qelement(t,NSURI_OPENID10 "\tDelegate") )
+                    copy_trim_whitespace(p.auth_info.auth_SEP.openid_Delegate,t.content);
+            }else if( is_qelement(p,NSURI_XRD "\tXRD") ) {
+                if(is_qelement(t,NSURI_XRD "\tService") ) {
+                    if( !t.auth_info.auth_SEP.xrd_Type.empty() ) {
+                        parser_node_t::attrs_t::const_iterator ip
+                            = t.attrs.find("priority");
+                        if(ip!=t.attrs.end()) {
+                            const char *nptr = ip->second.c_str();
+                            char *eptr = 0;
+                            t.auth_info.auth_SEP.priority = strtol(nptr,&eptr,10);
+                            if(nptr==eptr)
+                                t.auth_info.auth_SEP.priority = LONG_MAX;
+                        }
+                        if( (t.auth_info.auth_SEP.priority < p.auth_info.auth_SEP.priority)
+                                || p.auth_info.auth_SEP.xrd_Type.empty() )
+                            p.auth_info.auth_SEP = t.auth_info.auth_SEP;
+                    }
+                }else if( is_qelement(t,NSURI_XRD "\tCanonicalID") )
+                    copy_trim_whitespace(p.auth_info.canonical_id,t.content);
+            }
+        }
+        
+        tree.pop();
+    }
+
+    size_t openid_service_resolver_t::write(void *p,size_t s,size_t nm) {
+        if(state != state_parse)
+            return 0;
+        /* TODO: limit total size */
+        size_t bytes = s*nm;
+        parse((const char *)p,bytes,false);
+        return bytes;
+    }
+
+    size_t openid_service_resolver_t::header(void *p,size_t s,size_t nm) {
+        size_t bytes = s*nm;
+        const char *h = (const char *)p;
+        const char *colon = (const char*)memchr(p,':',bytes);
+        const char *space = (const char*)memchr(p,' ',bytes);
+        if(space && ( (!colon) || space<colon ) ) {
+            xrds_location.clear(); http_content_type.clear();
+        }else if(colon) {
+            const char *hv = ++colon;
+            int hnl = colon-h;
+            int rb;
+            for(rb = bytes-hnl-1;
+                    rb>0 && isspace(*hv);
+                    ++hv,--rb );
+            while(rb>0 && isspace(hv[rb-1]))
+                --rb;
+            if(rb) {
+                if( (hnl >= sizeof(LOCATION_HEADER))
+                        && !strncasecmp(h,LOCATION_HEADER ":",
+                            sizeof(LOCATION_HEADER)) ) {
+                    xrds_location.assign(hv,rb);
+                }else if( (hnl >= sizeof("Content-Type"))
+                        && !strncasecmp(h,"Content-Type:",
+                            sizeof("Content-Type")) ) {
+                    const char *sc = (const char*)memchr(
+                            hv,';',rb);
+                    http_content_type.assign(
+                            hv,sc?(sc-hv):rb );
+                }
+            }
+        }
+        return curl_t::header(p,s,nm);
+    }
+
+    void openid_service_resolver_t::discover_service(const string& url,bool xri) {
+        CURLcode r = easy_setopt(CURLOPT_URL,url.c_str());
+        if(r)
+            throw opkele::exception_curl(OPKELE_CP_ "failed to set curly urlie",r);
+
+        (*(expat_t*)this) = parser_create_ns();
+        set_user_data(); set_element_handler();
+        set_character_data_handler();
+        tree.clear();
+        state = state_parse;
+
+        r = easy_perform();
+        if(r && r!=CURLE_WRITE_ERROR)
+            throw exception_curl(OPKELE_CP_ "failed to perform curly request",r);
+
+        parse(0,0,true);
+        while(!tree.empty()) pop_tag();
+    }
+
+    const openid_auth_info_t& openid_service_resolver_t::resolve(const string& id) {
+        auth_info = openid_auth_info_t();
+        html_SEP = openid_auth_SEP_t();
+
+        string::size_type fns = id.find_first_not_of(whitespace);
+        if(fns==string::npos)
+            throw opkele::bad_input(OPKELE_CP_ "whitespace-only identity");
+        string::size_type lns = id.find_last_not_of(whitespace);
+        assert(lns!=string::npos);
+        if(!strncasecmp(
+                    id.c_str()+fns,"xri://",
+                    sizeof("xri://")-1))
+            fns+=sizeof("xri://")-1;
+        string nid(id,fns,lns-fns+1);
+        if(nid.empty())
+            throw opkele::bad_input(OPKELE_CP_ "nothing significant in identity");
+        if(strchr("=@+$!(",*nid.c_str())) {
+            discover_service(
+                    xri_proxy + util::url_encode(nid) +
+                    "?_xrd_t=" STURI_OPENID10 "&_xrd_r=application/xrd+xml;sep=true",
+                    true );
+            if(auth_info.canonical_id.empty()
+                    || auth_info.auth_SEP.xrd_Type.empty() )
+                throw opkele::failed_lookup(OPKELE_CP_ "no OpenID service for XRI found");
+            return auth_info;
+        }else{
+            const char *np = nid.c_str();
+            if( (strncasecmp(np,"http",4) || strncmp(
+                            tolower(*(np+4))=='s'? np+5 : np+4, "://", 3))
+#ifndef NDEBUG
+                    && strncasecmp(np,"file:///",sizeof("file:///")-1)
+        #endif  /* XXX: or how do I let tests work? */
+                    )
+                nid.insert(0,"http://");
+            string::size_type fp = nid.find('#');
+            if(fp!=string::npos) {
+                string::size_type qp = nid.find('?');
+                if(qp==string::npos || qp<fp) {
+                    nid.erase(fp);
+                }else if(qp>fp)
+                    nid.erase(fp,qp-fp);
+            }
+            discover_service(nid);
+            const char *eu = 0;
+            CURLcode r = easy_getinfo(CURLINFO_EFFECTIVE_URL,&eu);
+            if(r)
+                throw exception_curl(OPKELE_CP_ "failed to get CURLINFO_EFFECTIVE_URL",r);
+            string canonicalized_id = util::rfc_3986_normalize_uri(eu);
+            if(xrds_location.empty()) {
+                if(auth_info.auth_SEP.xrd_Type.empty()) {
+                    if(html_SEP.xrd_URI.empty())
+                        throw opkele::failed_lookup(OPKELE_CP_ "no OpenID service discovered");
+                    auth_info.auth_SEP = html_SEP;
+                    auth_info.auth_SEP.xrd_Type.clear(); auth_info.auth_SEP.xrd_Type.insert( STURI_OPENID10 );
+                    auth_info.canonical_id = canonicalized_id;
+                }else{
+                    if(auth_info.canonical_id.empty())
+                        auth_info.canonical_id = canonicalized_id;
+                }
+                return auth_info;
+            }else{
+                discover_service(xrds_location);
+                if(auth_info.auth_SEP.xrd_Type.empty())
+                    throw opkele::failed_lookup(OPKELE_CP_ "no OpenID service found in Yadis document");
+                if(auth_info.canonical_id.empty())
+                    auth_info.canonical_id = canonicalized_id;
+                return auth_info;
+            }
+        }
+    }
+
+}