source: libabac/abac_verifier.c @ 669b481

/**
**  abac_verifier.c
**/

// include the GNU extension of asprintf
#define _GNU_SOURCE

#include <stdio.h>
#include <regex.h>
#include <sys/mman.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>


#include <assert.h>
#include <stdio.h>

#include <library.h>

#include "abac_internal.h"
#include "abac_verifier.h"

#include "abac_util.h"
#include "abac_rt.h"

static int debug=0;
 
/* from abac_attribute.c */
extern char *get_cred_encoding(abac_attribute_t *ptr);

extern abac_aspect_t *abac_yy_get_rule_head_aspect();
extern abac_aspect_t *abac_yy_get_rule_tail_aspect();
extern abac_list_t *abac_yy_get_rule_clauses();
extern char* abac_decode_string(char *);
extern void abac_yy_free_rule_clauses();
extern char *generate_pl_type_clause(char *, int);
extern abac_list_t *generate_pl_clauses(abac_aspect_t *, abac_aspect_t *);

extern void abac_print_aspect_string_with_condition(abac_aspect_t *role, FILE*);

struct _abac_id_credential_t {
    char *hashkeyid; 
    abac_id_t *id;
    char *pl_clause;

    UT_hash_handle hh;
};
/* hash table base on sha with a p */
abac_id_credential_t *id_creds = NULL;
/* linked list of all the ids's hashkeyid */
abac_list_t *id_hashkeyid_list = NULL;

/* can store either role or oset */
struct _abac_credential_t {
    char *hashkeyid;
    abac_attribute_t *attr;
    abac_list_t *pl_clauses;

    UT_hash_handle hh;
};
/* hash table base on encoded attr rule */
abac_credential_t *attr_creds = NULL;
/* linked list of all the attr's hashkeyid */
abac_list_t *attr_hashkeyid_list = NULL;

/*****************************************************************************/
void abac_print_cred_info(abac_credential_t *cred, FILE *fp)
{
    if(fp == NULL)
        fp=stdout;

    abac_attribute_t *ptr=cred->attr;
    abac_aspect_t *head=abac_attribute_head(ptr);
    abac_aspect_t *tail=abac_attribute_tail(ptr);

    if(debug) {
        fprintf(fp,"---> printing out credential info cred(%d)..\n", (int) cred);
        if(head) {
            abac_print_aspect_string_with_condition(head,fp);
        }
        if(tail) {
            abac_print_aspect_string_with_condition(tail,fp);
        }

        abac_list_t *clauses=cred->pl_clauses;
        if (clauses != NULL) {
            char *cur=NULL;
            abac_list_foreach(clauses, cur,
                fprintf(fp,"\n  a clause(%d):\n",(int)cur);
                if(cur)
                    fprintf(fp,"strlen(%d)loc(%d)(%s)\n", strlen(cur),(int)cur, cur);
            );
        }
        } else {
            fprintf(fp," ");
            abac_print_aspect_string_with_condition(head,fp);
            fprintf(fp," <- ");
            abac_print_aspect_string_with_condition(tail,fp);
            fprintf(fp,"\n");
   }
}

void abac_print_prin_info(abac_id_credential_t *prin, FILE *fp)
{
    if(fp == NULL)
        return;

    abac_id_t *ptr=abac_id_credential_id(prin);

    if(debug) fprintf(fp,"---> printing out principal info ..\n");
    if(abac_id_has_privkey(ptr))
        fprintf(fp," (%s,%s,y)\n",abac_id_name(ptr),abac_id_idtype_string(ptr));
        else
            fprintf(fp," (%s,%s,n)\n",abac_id_name(ptr),abac_id_idtype_string(ptr));
}

// 
int abac_verify_idtype_type(char *type) {
    int i;

    if (type == NULL)
        return 0;

    for (i = 1; i <= _idtypename_cnt ; i++)
        if(strcmp(type,_idtypename[i])==0)
            return i;
    return 0;
}

char *abac_idtype_string(int i)
{
    if(i > _idtypename_cnt) {
        printf("bad idtypename idx %d\n", i);
        panic("abac_idtype_string: went out of range on idtypename");
    }
    return (char*) _idtypename[i];
}

// convert a chunk to a lowercase binary string
// malloc's the string
static char *_chunk_to_string(chunk_t chunk) {
    int i;

    char *ret = abac_xmalloc(chunk.len * 2 + 1);

    for (i = 0; i < chunk.len; ++i)
        sprintf(ret + 2 * i, "%02x", chunk.ptr[i]);

    return ret;
}

// verify that cert was issued by issuer
// cert and issuer can be the same, in which case the self-sig is validated
static int _verify_signature(certificate_t *issuer_cert, certificate_t *cert) {
    if (cert->issued_by(cert, issuer_cert))
        if (cert->get_validity(cert, NULL, NULL, NULL))
            return 1;
    return 0;
}

/**
 * Init the verifier subsystem.
 */
void abac_verifier_init(void) {
    // silence all debugging

    if (!library_init(NULL))
        exit(SS_RC_LIBSTRONGSWAN_INTEGRITY);

    if (!lib->plugins->load(lib->plugins, NULL,
            lib->settings->get_str(lib->settings, "pki.load", PLUGINS)))
        exit(SS_RC_INITIALIZATION_FAILED);

    attr_hashkeyid_list = abac_list_new();
    id_hashkeyid_list = abac_list_new();
}

/**
 * Uninitialize the system, free up any allocated memory.
 */
void abac_verifier_deinit(void) {
    abac_id_credential_t *ptr;
    while ((ptr = id_creds) != NULL) {
        if(debug) printf("abac_verifier_deinit: deleting id (%s)\n",abac_id_name(ptr->id));
        HASH_DEL(id_creds, ptr);

        free(ptr->hashkeyid);
        free(ptr->pl_clause);
        abac_id_free(ptr->id);
        free(ptr);
    }

    abac_credential_t *ptr2;
    while ((ptr2 = attr_creds) != NULL) {
        HASH_DEL(attr_creds, ptr2);
        if(debug) {
           printf("abac_verifier_deinit: deleting attr hashkey(%s)\n",ptr2->hashkeyid); 
        }
        free(ptr2->hashkeyid);
        abac_attribute_free(ptr2->attr);
        char *cur=NULL;
        abac_list_foreach(ptr2->pl_clauses, cur,
              free(cur);
        );
        free(ptr2->pl_clauses);
        free(ptr2);
    }

    if(attr_hashkeyid_list) { 
        char *cur;
        if(attr_hashkeyid_list) {
            abac_list_foreach(attr_hashkeyid_list, cur,
                if(cur) free(cur);
            );
        }
        abac_list_free(attr_hashkeyid_list);
    }
    if(id_hashkeyid_list) { 
        char *cur;
        if(id_hashkeyid_list) {
            abac_list_foreach(id_hashkeyid_list, cur,
                if(cur) free(cur);
            );
        }
        abac_list_free(id_hashkeyid_list);
    }

    library_deinit();
}

abac_id_credential_t *abac_verifier_add_id_credential(abac_id_t *a_id)
{ 
    abac_id_credential_t *id_cred;
    char *cn=abac_id_cn(a_id);
    char *keyid=abac_id_keyid(a_id);

    if(debug) {
         printf("abac_verifier_add_id_credential, cn(%s),keyid(%s)\n",
                cn, keyid);
    }

    // add the abac_id to the map of id credentials
    id_cred = abac_xmalloc(sizeof(abac_id_credential_t));
    id_cred->hashkeyid = abac_xstrdup(keyid);
    id_cred->id=abac_id_dup(a_id);

    /* special handling here */
    if(USE("ABAC_CN")) {
        id_cred->pl_clause = generate_pl_type_clause(cn, abac_id_idtype(a_id));
        } else {
           id_cred->pl_clause=generate_pl_type_clause(prologIt(keyid), abac_id_idtype(a_id));
    }
    HASH_ADD_KEYPTR(hh, id_creds, id_cred->hashkeyid, strlen(id_cred->hashkeyid), id_cred);
    if(debug)
        printf("-->adding into id_creds, (%s)..cnt(%d)\n",
                                   id_cred->hashkeyid, HASH_COUNT(id_creds));

    assert(id_hashkeyid_list);
    abac_list_add(id_hashkeyid_list, abac_xstrdup(id_cred->hashkeyid));
    return id_cred;
}

/**
 * Load an ID 
 */
static int _load_id(abac_id_t **a_id,certificate_t *cert, abac_id_credential_t **id_cred_ret) {
    abac_id_credential_t *id_cred = NULL;
    char *keyid = NULL;
    chunk_t id;
    int ret;
    x509_t *x509 = (x509_t *)cert;

    assert(cert != NULL);

    // get the key ID, add p to keyid SHA here */
    id = x509->get_subjectKeyIdentifier(x509);
    keyid = _chunk_to_string(id);

    /* Mike said this is the way it is */
    char *str;
    int rv = asprintf(&str, "%Y", cert->get_issuer(cert));

    /* add p to cn name here */
    char *cn=(char *)abac_xmalloc(strlen(str)+2);
    cn[0]='p';
    int n=sscanf(str,"CN=%s", &(cn[1]));
    if ( n!=1 ) { 
        ret = ABAC_CERT_BAD_CN;
        goto error;
    }

    if(debug) {
        printf ("DEBUG:keyid %s \n", keyid);
        printf( "DEBUG:issuer '%s' \n", str);
        printf ("DEBUG:cn %s \n", cn);
    }
    free(str);

    // if we already have this cert 'error' with success
    HASH_FIND_STR(id_creds, keyid, id_cred);
    if (id_cred != NULL) {
        if(debug) printf("existing cert \n");
        ret = ABAC_CERT_EXISTS;
        goto error;
    }

    // validate sig
    ret = _verify_signature(cert, cert);
    if (!ret) {
        ret = ABAC_CERT_BAD_SIG;
        goto error;
    }

    // success, add a new abac_id
    if(*a_id==NULL) {
        *a_id=abac_id_keyid_new(keyid,cn,cert);
    }

    abac_id_credential_t *n_id_cred=abac_verifier_add_id_credential(*a_id);
    *id_cred_ret=n_id_cred;

    return ABAC_CERT_SUCCESS;

error:
    if (keyid != NULL) free(keyid);
    if (cn != NULL) free(cn);

    return ret;
}

/* collect all the creds stored so far */
abac_stack_t *abac_verifier_dump_creds()
{
    abac_stack_t *cred_list = abac_stack_new();

    int cnt=0;
    if(attr_hashkeyid_list) {
        char *keyid;
        abac_credential_t *cred;
        abac_list_foreach(attr_hashkeyid_list, keyid,
            cred=abac_credential_lookup(keyid);
            abac_stack_push(cred_list, cred);
            cnt++;
        );
    }
    if(debug) printf("abac_verifier_dump_cred: %d\n",cnt);
    return cred_list;
}

/* collect all the id stored so far */
abac_stack_t *abac_verifier_dump_principals()
{
    abac_stack_t *id_list = abac_stack_new();

    int cnt=0;
    if(id_hashkeyid_list) {
        char *keyid;
        abac_id_credential_t *id;
        abac_list_foreach(id_hashkeyid_list, keyid,
            id=abac_id_credential_lookup(keyid);
            abac_stack_push(id_list, id);
            cnt++;
        );
    }
    if(debug) printf("abac_verifier_dump_principals: %d\n",cnt);
    return id_list;
}


static void check_id_cred(abac_id_credential_t *id_cred)
{
    if(id_cred) {
        printf("checking on this id_cred location %d\n", (int)id_cred);
        printf("  --> sha is (%s)\n", abac_id_keyid(id_cred->id));
        printf("  --> cn is (%s)\n", abac_id_cn(id_cred->id));
    }
}

/**
 * Load an attribute cert as string.
 * have minimum syntax & validity check
 */
static int _load_attribute_string(char* attr_string) {
    printf("NOT implemented yet!!!");
    return ABAC_CERT_INVALID;
}

int _exist(char *filename)
{
   struct stat stbuf;
   if(stat(filename,&stbuf) == -1)
       return 0;
   return 1;
}

/**
 * Load an ID cert from a file.
 */
int abac_verifier_load_id_file_key_file(char *filename, char *keyfilename, abac_id_credential_t **id_cred_ret) {
    abac_id_t *id=NULL;
    if (lib == NULL)
        errx(1, "looks like you didn't call libabac_init() (lib is NULL)");

    if(debug) printf("loading id file... %s\n", filename);

    // load the cert, with pubic key
    certificate_t *cert = lib->creds->create(
        lib->creds, CRED_CERTIFICATE, CERT_X509,
        BUILD_FROM_FILE, filename,
        BUILD_X509_FLAG, X509_AA, // attribute authority, dumb
        BUILD_END
    );

    if (cert == NULL)
        return ABAC_CERT_INVALID;

    int rc=_load_id(&id,cert,id_cred_ret);
    if(rc==ABAC_CERT_EXISTS) {
        if(debug) printf("abac_verifier_load_id_files: id already exists\n");
        return ABAC_CERT_SUCCESS;
    } 

    /* try to load the private key if it is there */
    if((rc==ABAC_CERT_SUCCESS) && keyfilename!=NULL && _exist(keyfilename)) {
        if(debug) printf("loading... %s\n", keyfilename);
        int keyrc=abac_id_load_privkey_file(id, keyfilename);
        if(debug) {
           if(keyrc == 1) printf("..load_id_file: load(%s) with a private key\n",filename);
               else printf("..load_id_file: load(%s) without a private key\n",filename);
        }
    }
    return rc;
}

/**
 * Load an ID cert from a abac_id_t 
 */
int abac_verifier_load_id_id(abac_id_t *id, abac_id_credential_t **id_cred_ret) {
    certificate_t *cert = abac_id_cert(id);
    return _load_id(&id,cert,id_cred_ret);
}

/**
 * Load an ID cert from a chunk.
 */
int abac_verifier_load_id_pem_chunk(chunk_t chunk, abac_id_credential_t **id_cred_ret) {
    abac_id_t *id=NULL;
    // load the cert
    certificate_t *cert = lib->creds->create(
        lib->creds, CRED_CERTIFICATE, CERT_X509,
        BUILD_BLOB_PEM, chunk,
        BUILD_X509_FLAG, X509_AA, // attribute authority, dumb
        BUILD_END
    );
    if (cert == NULL)
        return ABAC_CERT_INVALID;
    return _load_id(&id, cert,id_cred_ret);
}
/**
 * Load an ID cert from a chunk.
 */
int abac_verifier_load_id_chunk(chunk_t chunk, abac_id_credential_t **id_cred_ret) {
    abac_id_t *id=NULL;
    // load the cert
    certificate_t *cert = lib->creds->create(
        lib->creds, CRED_CERTIFICATE, CERT_X509,
        BUILD_BLOB_ASN1_DER, chunk,
        BUILD_X509_FLAG, X509_AA, // attribute authority, dumb
        BUILD_END
    );
    if (cert == NULL)
        return ABAC_CERT_INVALID;
    return _load_id(&id, cert,id_cred_ret);
}


static int matchex(const char *subject, const char *pattern, int *so, int *eo)
{
int rc; // Returned code
regmatch_t pmatch;

regex_t re; // Compiled regexp pattern

if (regcomp(&re, pattern, 0) != 0) return 0;

rc = regexec(&re, subject, 1 , &pmatch, 0);
regfree(&re); 

if (rc == REG_NOMATCH ) return 0; 

*so=pmatch.rm_so;
*eo=pmatch.rm_eo;

return 1;
}



static chunk_t _extract_chunk(char *data, char* startline, char* endline)
{
    int found=0;
    int startos=0;
    int endos=0;
    regex_t re;
    regmatch_t pm;
    int rc;

    int st;
    int et;

    rc=matchex(data, startline, &st, &et);
    if(rc==0) return chunk_empty;
    startos=st;

    rc=matchex(data, endline, &st, &et);
    if(rc==0) return chunk_empty;
    endos=et;
    
    int len=endos - startos; 

    if(debug) printf("making a chunk of size (%d) from %d and %d\n",len, startos,endos);
    char *ptr=strndup(data+startos,len);

    chunk_t ret = { ptr, len };
    return ret;
}

    
int abac_verifier_load_idkey_file(char *filename, abac_id_credential_t **id_cred_ret)
{
    struct stat sb;
    int fd;
    int rc;

    fd = open(filename, O_RDONLY);
    if (fd == -1) { return 1; }
    if(stat(filename, &sb) == -1) {
        close(fd);
        return 1;
    }
    char* data = (char *)mmap(NULL, sb.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
    if(data == MAP_FAILED) {
        close(fd);
        return 1;
    }
    close(fd);

    chunk_t key_pem_chunk=_extract_chunk(data,
               "-----BEGIN RSA PRIVATE KEY-----","-----END RSA PRIVATE KEY-----");
    chunk_t cert_pem_chunk=_extract_chunk(data,
                   "-----BEGIN CERTIFICATE-----","-----END CERTIFICATE-----");

    /* key=0, cert=0 */
    if(key_pem_chunk.len==0 && cert_pem_chunk.len==0) {
        if(debug) printf("abac_verifier_load_idkey_file: no key or id in idkey_file\n");
        goto error;
    }

    /* key=0, cert=1 */
    if(key_pem_chunk.len==0) {
        if(debug) printf("abac_verifier_load_idkey_file: no key in idkey_file\n");
        munmap(data, sb.st_size);
        chunk_free(&key_pem_chunk);
        return abac_verifier_load_id_file_key_file(filename,NULL,id_cred_ret);
    }

    /* key=1, cert=1 */
    if(cert_pem_chunk.len!=0) {
        if(debug) {
            printf("loading cert pem chunk %d\n", cert_pem_chunk.len);
            printf("(%s)\n",cert_pem_chunk.ptr);
        }
        rc=abac_verifier_load_id_pem_chunk(cert_pem_chunk, id_cred_ret);
        if(rc != 0) {
            if(debug) printf("abac_verifier_load_idkey_file: fail to load the id\n");
            goto error;
        }
    /* key=1, cert=0 */
        } else {
            if(debug) printf("abac_verifier_load_idkey_file: there is no id info in there\n");
            goto error;
    }
    
    /* handle the key_pem_chunk */
    if(debug)  {
        printf("loading key pem chunk %d\n", key_pem_chunk.len);
        printf("(%s)\n",key_pem_chunk.ptr);
    }
    abac_id_t *id=abac_id_credential_id(*id_cred_ret);
    rc=abac_id_load_privkey_chunk(id, key_pem_chunk);
    if(rc==0) {
        printf("abac_verifier_load_idkey_file:failed to load priv key!!!\n");
        goto error;
    }

    munmap(data, sb.st_size);
    return 0;

error:
    munmap(data, sb.st_size);
    return 1;
}



void abac_print_clauses(abac_list_t *clauses, FILE *fp)
{
    if (clauses != NULL) {
        char *cur;
        printf("total-- %d clauses\n", abac_list_size(clauses));
        abac_list_foreach(clauses, cur,
            if(cur) {
                if(fp)
                    fprintf (fp,"a clause, %d(%s)\n", (int)cur,cur);
                    else printf ("a clause, %d(%s)\n", (int)cur,cur);
            }
        );
    }
}

abac_id_credential_t *abac_id_credential_dup(abac_id_credential_t *ptr) {
    assert(ptr != NULL);
    abac_id_dup(ptr->id);
    return ptr;
}

abac_id_t *abac_id_credential_id(abac_id_credential_t *ptr)
{
    assert(ptr);
    return ptr->id;
}


abac_id_credential_t *abac_id_credential_lookup(char *pname)
{
    abac_id_credential_t *id_cred=NULL;
    HASH_FIND_STR(id_creds, pname, id_cred);
    if(id_cred != NULL)
        return abac_id_credential_dup(id_cred);
    else return NULL;
}

void abac_id_credential_free(abac_id_credential_t *ptr)
{
    if (ptr == NULL)
        return;

    if(debug)
        printf("abac_id_credential_free:freeing (%s)\n", abac_id_name(ptr->id));

    // this is very hacky...
    int last=abac_id_lastone(ptr->id);
    if(!last) {
        if(debug) printf("abac_id_credential_free:not last one\n");
        abac_id_free(ptr->id);
        } else {
            if(debug) printf("abac_id_credential_free: deleting id (%s)\n",abac_id_name(ptr->id));
            free(ptr->hashkeyid);
            if(ptr->pl_clause)
                free(ptr->pl_clause);
            abac_id_free(ptr->id);
            HASH_DEL(id_creds, ptr);
            free(ptr);
    }
}

/****************************************************************************/

static int _verify_valid_credential_string(certificate_t *cert,
abac_credential_t **cred_ret, char *encoded_attr_string)
{
    abac_aspect_t *head_aspect = NULL;
    abac_aspect_t *tail_aspect = NULL;
    abac_list_t *clauses=NULL;
    abac_id_credential_t *id_cred;
    abac_id_t *issuer_id;
    int ret, i;

    // get the attr
    head_aspect = abac_yy_get_rule_head_aspect();
    tail_aspect = abac_yy_get_rule_tail_aspect();
    clauses = abac_yy_get_rule_clauses();

    // get the issuer based on keyid
    char *principalname = abac_aspect_principal_principalname(head_aspect);
    if(debug) printf("LOOKING for %s\n", principalname);

    HASH_FIND_STR(id_creds, principalname, id_cred);
    if(id_cred == NULL) {
        ret = ABAC_CERT_MISSING_ISSUER;
        if(debug)
             printf("can not find %s in id_creds\n", principalname);
        goto error;
    }
    issuer_id=id_cred->id;
    if (issuer_id == NULL) {
        ret = ABAC_CERT_MISSING_ISSUER;
        if(debug)
             printf("can not find %s in id_creds\n", principalname);
        goto error;
    }


    // make sure the issuer's signed it
    ret = _verify_signature(abac_id_cert(issuer_id), cert);
    if (!ret) {
        abac_yy_set_error_code(ABAC_RT_CERT_BAD_SIG);
        ret=ABAC_CERT_BAD_SIG;
        goto error;
    }

    // at this point we know we have a good attribute cert baked it in
    abac_attribute_t *attr=abac_attribute_new(issuer_id, cert, cert->get_ref(cert));
    abac_attribute_set_head(attr, head_aspect);
    abac_attribute_add_tail(attr, tail_aspect);

    abac_credential_t *cred = abac_xmalloc(sizeof(abac_credential_t));
    cred->hashkeyid=abac_xstrdup(encoded_attr_string);
    cred->attr=attr;
    cred->pl_clauses = clauses;
    *cred_ret = cred;

    // success, add the key to the map of certificates
    HASH_ADD_KEYPTR(hh, attr_creds, cred->hashkeyid, strlen(cred->hashkeyid), cred);

    assert(attr_hashkeyid_list);
    abac_list_add(attr_hashkeyid_list, abac_xstrdup(cred->hashkeyid));
    return ABAC_CERT_SUCCESS;

error:
    if (head_aspect) abac_aspect_free(head_aspect);
    if (tail_aspect) abac_aspect_free(tail_aspect);
    abac_yy_free_rule_clauses();

    return ret;
}

/**
 * Load an attribute cert.
 * Returns true only if the certificate is valid and is issued by the proper
 * authority.
 * attribute string is parsed via yyparse call
 */
static int _load_attribute_cert(certificate_t *cert, abac_credential_t **cred_ret) {
    ietf_attributes_t *attr_cert = NULL;
    abac_id_credential_t *issuer;
    int ret, i;

    // get the attr
    ac_t *ac = (ac_t *)cert;
    attr_cert = ac->get_groups(ac);
    if (attr_cert == NULL) {
        ret = ABAC_CERT_INVALID;
        goto error;
    }

    char *encoded_attr_string=attr_cert->get_string(attr_cert);
    char *attr_string = abac_decode_string(encoded_attr_string);
    if(debug)
         printf("string to be yyparse..(%d)(%s)\n",strlen(attr_string),attr_string);

    if (attr_string == NULL) {
        ret = ABAC_CERT_INVALID;
        goto error;
    }

    /* call into yacc parser */
    abac_reset_yyfptr(attr_string);
    abac_yy_init();
    int rc=yyparse();
    if (rc) {
        ret = ABAC_CERT_INVALID;
        goto error;
    }

    ret=_verify_valid_credential_string(cert,cred_ret,encoded_attr_string);

    if(ret != ABAC_CERT_SUCCESS) {
        panic("_load_attribute_cert: fail to process (%s)",encoded_attr_string);
    }

    // free up some crap
    attr_cert->destroy(attr_cert);

    return ret;

error:
    if (cert) cert->destroy(cert);
    if (attr_cert) attr_cert->destroy(attr_cert);
    return ret;
}

/**
 * Load an attribute cert from a abac_attribute_t.
 * attr should be all checked out before arriving here
 */
int abac_verifier_load_attribute_cert_attribute(abac_attribute_t *ptr, abac_credential_t **cred_ret) {
    // get the attr
    abac_aspect_t *head=abac_attribute_head(ptr);
    abac_aspect_t *tail=abac_attribute_tail(ptr);

    // preprocess for constraint part
    preprocess_pl_head(head);
    preprocess_pl_tail(tail);

/* XXX collect up type clauses, constraint clauses and
   generate rule clauses */
    abac_list_t *clauses=generate_pl_clauses(head,tail);
    char *encoded_attr_string=get_cred_encoding(ptr);

    abac_credential_t *cred = abac_xmalloc(sizeof(abac_credential_t));
    cred->hashkeyid=abac_xstrdup(encoded_attr_string);
    cred->attr=abac_attribute_dup(ptr);
    cred->pl_clauses = clauses;
    *cred_ret = cred;

    // success, add the key to the map of certificates
    HASH_ADD_KEYPTR(hh, attr_creds, cred->hashkeyid, strlen(cred->hashkeyid), cred);

    assert(attr_hashkeyid_list);
    abac_list_add(attr_hashkeyid_list, abac_xstrdup(cred->hashkeyid));
    return ABAC_CERT_SUCCESS;
}

/**
 * Load an attribute cert from a file.
 */
int abac_verifier_load_attribute_cert_file(char *filename, abac_credential_t **cred) {
    // load the cert
    if(debug) printf("..loading attr file %s\n", filename);
    certificate_t *cert = lib->creds->create(
        lib->creds, CRED_CERTIFICATE, CERT_X509_AC,
        BUILD_FROM_FILE, filename,
        BUILD_END
    );
    if (cert == NULL)
        return ABAC_CERT_INVALID;
    return _load_attribute_cert(cert, cred);
}

/**
 * Load an attribute cert from a chunk.
 */
int abac_verifier_load_attribute_cert_chunk(chunk_t chunk, abac_credential_t **cred) {
    // load the cert
    certificate_t *cert = lib->creds->create(
        lib->creds, CRED_CERTIFICATE, CERT_X509_AC,
        BUILD_BLOB_ASN1_DER, chunk,
        BUILD_END
    );
    if (cert == NULL)
        return ABAC_CERT_INVALID;
    return _load_attribute_cert(cert, cred);
}

/**
 * Return the encoding of the attribute cert.
 */
abac_chunk_t abac_credential_attribute_cert(abac_credential_t *cred) {
    abac_attribute_t *ptr=cred->attr;
    certificate_t *cert=abac_attribute_cert(ptr);
    chunk_t encoding = cert->get_encoding(cert);
    abac_chunk_t ret = { encoding.ptr, encoding.len };
    return ret;
}

/**
 * Return the encoding of the issuer cert.
 */
abac_chunk_t abac_credential_issuer_cert(abac_credential_t *cred) {
    certificate_t *issuer_cert=abac_attribute_issuer_cert(cred->attr);
    assert(issuer_cert);
    chunk_t encoding = issuer_cert->get_encoding(issuer_cert);
    abac_chunk_t ret = { encoding.ptr, encoding.len };
    return ret;
}

/**
 * Return the clause of the cert
 */
abac_list_t *abac_credential_clauses(abac_credential_t *cred) {
    return cred->pl_clauses;
}

abac_attribute_t *abac_credential_attribute(abac_credential_t *cred) {
    assert(cred);
    return cred->attr;
}

/**
 * Increase the ref count of a credential.
 */
abac_credential_t *abac_credential_dup(abac_credential_t *cred) {
    assert(cred != NULL);

    abac_attribute_dup(cred->attr);
    return cred;
}

/**
 *  lookup for a credential.
 */
abac_credential_t *abac_credential_lookup(char* cred_string)
{
    if(debug)
        printf("abac_credential_lookup: looking for (%s)\n", cred_string);
    abac_credential_t *attr_cred;
    HASH_FIND_STR(attr_creds, cred_string, attr_cred);
    if (attr_cred == NULL) {
        if(debug) printf("DEBUG:NOT FOUND..\n");
        return NULL;
    }
    abac_credential_t *rt=abac_credential_dup(attr_cred);
    if(debug) printf("DEBUG:FOUND.. (%d) returning, (%d)\n", (int)attr_cred, (int) rt);
    return rt;
}

/**
 * Decrease the reference count of a credential, freeing it when it reaches 0.
 */
void abac_credential_free(abac_credential_t *cred)
{
    if(debug)
        printf("abac_credential_free:freeing cred(%d)clause(%d)\n", (int)cred, (int)cred->pl_clauses);

    if (cred == NULL)
        return;

    // this is very hacky...
    int last=abac_attribute_lastone(cred->attr);
    if(!last) {
        abac_attribute_free(cred->attr);
        } else {
            free(cred->hashkeyid);
            char *cur=NULL;
            abac_list_foreach(cred->pl_clauses, cur,
                free(cur);
            );
            abac_attribute_free(cred->attr);
            HASH_DEL(attr_creds, cred);
            free(cred);
    }
}

char *abac_id_clause(abac_id_credential_t *id_cred)
{
    if(id_cred)
        return id_cred->pl_clause;
    return NULL;
}

/* retrieve the cn that is associated with this sha_string */
char *abac_cn_with_sha(char *sha_string)
{
    // get the issuer based on keyid
    abac_id_credential_t *id_cred;
    HASH_FIND_STR(id_creds, sha_string, id_cred);
    if (id_cred == NULL) {
        return NULL;
    }
    if(debug)
        check_id_cred(id_cred);
    return abac_id_cn(id_cred->id);
}

char *abac_idtype_with_sha(char* sha_string)
{ 
    // get the issuer based on keyid
    abac_id_credential_t *id_cred;
    HASH_FIND_STR(id_creds, sha_string, id_cred);
    if (id_cred == NULL) {
        return NULL;
    }
    int idtype=abac_id_idtype(id_cred->id);
    
    return abac_idtype_string(idtype);
}

abac_aspect_t *abac_credential_head(abac_credential_t *cred) {
    return abac_attribute_head(cred->attr); 
}

abac_aspect_t *abac_credential_tail(abac_credential_t *cred) {
    return abac_attribute_tail(cred->attr); 
}