libpurple/certificate.c

/**
 * @file certificate.c Public-Key Certificate API
 * @ingroup core
 */

/*
 *
 * purple
 *
 * Purple is the legal property of its developers, whose names are too numerous
 * to list here.  Please refer to the COPYRIGHT file distributed with this
 * source distribution.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02111-1301  USA
 */

#include <glib.h>

#include "internal.h"
#include "certificate.h"
#include "dbus-maybe.h"
#include "debug.h"
#include "request.h"
#include "signals.h"
#include "util.h"

/** List holding pointers to all registered certificate schemes */
static GList *cert_schemes = NULL;
/** List of registered Verifiers */
static GList *cert_verifiers = NULL;
/** List of registered Pools */
static GList *cert_pools = NULL;

void
purple_certificate_verify (PurpleCertificateVerifier *verifier,
			   const gchar *subject_name, GList *cert_chain,
			   PurpleCertificateVerifiedCallback cb,
			   gpointer cb_data)
{
	PurpleCertificateVerificationRequest *vrq;
	PurpleCertificateScheme *scheme;
	
	g_return_if_fail(subject_name != NULL);
	/* If you don't have a cert to check, why are you requesting that it
	   be verified? */
	g_return_if_fail(cert_chain != NULL);
	g_return_if_fail(cb != NULL);

	/* Look up the CertificateScheme */
	scheme = purple_certificate_find_scheme(verifier->scheme_name);
	g_return_if_fail(scheme);

	/* Check that at least the first cert in the chain matches the
	   Verifier scheme */
	g_return_if_fail(scheme ==
			 ((PurpleCertificate *) (cert_chain->data))->scheme);

	/* Construct and fill in the request fields */
	vrq = g_new0(PurpleCertificateVerificationRequest, 1);
	vrq->verifier = verifier;
	vrq->scheme = scheme;
	vrq->subject_name = g_strdup(subject_name);
	vrq->cert_chain = purple_certificate_copy_list(cert_chain);
	vrq->cb = cb;
	vrq->cb_data = cb_data;

	/* Initiate verification */
	(verifier->start_verification)(vrq);
}

void
purple_certificate_verify_complete(PurpleCertificateVerificationRequest *vrq,
				   PurpleCertificateVerificationStatus st)
{
	PurpleCertificateVerifier *vr;

	g_return_if_fail(vrq);

	if (st == PURPLE_CERTIFICATE_VALID) {
		purple_debug_info("certificate",
				  "Successfully verified certificate for %s\n",
				  vrq->subject_name);
	} else {
		purple_debug_info("certificate",
				  "Failed to verify certificate for %s\n",
				  vrq->subject_name);
	}
		
		
	/* Pass the results on to the request's callback */
	(vrq->cb)(st, vrq->cb_data);

	/* And now to eliminate the request */
	/* Fetch the Verifier responsible... */
	vr = vrq->verifier;
	/* ...and order it to KILL */
	(vr->destroy_request)(vrq);

	/* Now the internals have been cleaned up, so clean up the libpurple-
	   created elements */
	g_free(vrq->subject_name);
	purple_certificate_destroy_list(vrq->cert_chain);

	/*  A structure born
	 *          to much ado
	 *                   and with so much within.
	 * It reaches now
	 *             its quiet end. */
	g_free(vrq);
}


PurpleCertificate *
purple_certificate_copy(PurpleCertificate *crt)
{
	g_return_val_if_fail(crt, NULL);
	g_return_val_if_fail(crt->scheme, NULL);
	g_return_val_if_fail(crt->scheme->copy_certificate, NULL);

	return (crt->scheme->copy_certificate)(crt);
}

GList *
purple_certificate_copy_list(GList *crt_list)
{
	GList *new, *l;

	/* First, make a shallow copy of the list */
	new = g_list_copy(crt_list);

	/* Now go through and actually duplicate each certificate */
	for (l = new; l; l = l->next) {
		l->data = purple_certificate_copy(l->data);
	}

	return new;
}

void
purple_certificate_destroy (PurpleCertificate *crt)
{
	PurpleCertificateScheme *scheme;
	
	if (NULL == crt) return;

	scheme = crt->scheme;

	(scheme->destroy_certificate)(crt);
}

void
purple_certificate_destroy_list (GList * crt_list)
{
	PurpleCertificate *crt;
	GList *l;

	for (l=crt_list; l; l = l->next) {
		crt = (PurpleCertificate *) l->data;
		purple_certificate_destroy(crt);
	}

	g_list_free(crt_list);
}

gboolean
purple_certificate_signed_by(PurpleCertificate *crt, PurpleCertificate *issuer)
{
	PurpleCertificateScheme *scheme;

	g_return_val_if_fail(crt, FALSE);
	g_return_val_if_fail(issuer, FALSE);

	scheme = crt->scheme;
	g_return_val_if_fail(scheme, FALSE);
	/* We can't compare two certs of unrelated schemes, obviously */
	g_return_val_if_fail(issuer->scheme == scheme, FALSE);

	return (scheme->signed_by)(crt, issuer);
}

gboolean
purple_certificate_check_signature_chain(GList *chain)
{
	GList *cur;
	PurpleCertificate *crt, *issuer;
	gchar *uid;

	g_return_val_if_fail(chain, FALSE);

	uid = purple_certificate_get_unique_id((PurpleCertificate *) chain->data);
	purple_debug_info("certificate",
			  "Checking signature chain for uid=%s\n",
			  uid);
	g_free(uid);
	
	/* If this is a single-certificate chain, say that it is valid */
	if (chain->next == NULL) {
		purple_debug_info("certificate",
				  "...Singleton. We'll say it's valid.\n");
		return TRUE;
	}

	/* Load crt with the first certificate */
	crt = (PurpleCertificate *)(chain->data);
	/* And start with the second certificate in the chain */
	for ( cur = chain->next; cur; cur = cur->next ) {
		
		issuer = (PurpleCertificate *)(cur->data);
		
		/* Check the signature for this link */
		if (! purple_certificate_signed_by(crt, issuer) ) {
			uid = purple_certificate_get_unique_id(issuer);
			purple_debug_info("certificate",
					  "...Bad or missing signature by %s\nChain is INVALID\n",
					  uid);
			g_free(uid);
		
			return FALSE;
		}

		uid = purple_certificate_get_unique_id(issuer);
		purple_debug_info("certificate",
				  "...Good signature by %s\n",
				  uid);
		g_free(uid);
		
		/* The issuer is now the next crt whose signature is to be
		   checked */
		crt = issuer;
	}

	/* If control reaches this point, the chain is valid */
	purple_debug_info("certificate", "Chain is VALID\n");
	return TRUE;
}

PurpleCertificate *
purple_certificate_import(PurpleCertificateScheme *scheme, const gchar *filename)
{
	g_return_val_if_fail(scheme, NULL);
	g_return_val_if_fail(scheme->import_certificate, NULL);
	g_return_val_if_fail(filename, NULL);

	return (scheme->import_certificate)(filename);
}

gboolean
purple_certificate_export(const gchar *filename, PurpleCertificate *crt)
{
	PurpleCertificateScheme *scheme;

	g_return_val_if_fail(filename, FALSE);
	g_return_val_if_fail(crt, FALSE);
	g_return_val_if_fail(crt->scheme, FALSE);

	scheme = crt->scheme;
	g_return_val_if_fail(scheme->export_certificate, FALSE);

	return (scheme->export_certificate)(filename, crt);
}

GByteArray *
purple_certificate_get_fingerprint_sha1(PurpleCertificate *crt)
{
	PurpleCertificateScheme *scheme;
	GByteArray *fpr;

	g_return_val_if_fail(crt, NULL);
	g_return_val_if_fail(crt->scheme, NULL);

	scheme = crt->scheme;
	
	g_return_val_if_fail(scheme->get_fingerprint_sha1, NULL);

	fpr = (scheme->get_fingerprint_sha1)(crt);

	return fpr;
}

gchar *
purple_certificate_get_unique_id(PurpleCertificate *crt)
{
	g_return_val_if_fail(crt, NULL);
	g_return_val_if_fail(crt->scheme, NULL);
	g_return_val_if_fail(crt->scheme->get_unique_id, NULL);

	return (crt->scheme->get_unique_id)(crt);
}

gchar *
purple_certificate_get_issuer_unique_id(PurpleCertificate *crt)
{
	g_return_val_if_fail(crt, NULL);
	g_return_val_if_fail(crt->scheme, NULL);
	g_return_val_if_fail(crt->scheme->get_issuer_unique_id, NULL);

	return (crt->scheme->get_issuer_unique_id)(crt);
}

gchar *
purple_certificate_get_subject_name(PurpleCertificate *crt)
{
	PurpleCertificateScheme *scheme;
	gchar *subject_name;

	g_return_val_if_fail(crt, NULL);
	g_return_val_if_fail(crt->scheme, NULL);

	scheme = crt->scheme;

	g_return_val_if_fail(scheme->get_subject_name, NULL);

	subject_name = (scheme->get_subject_name)(crt);

	return subject_name;
}

gboolean
purple_certificate_check_subject_name(PurpleCertificate *crt, const gchar *name)
{
	PurpleCertificateScheme *scheme;

	g_return_val_if_fail(crt, FALSE);
	g_return_val_if_fail(crt->scheme, FALSE);
	g_return_val_if_fail(name, FALSE);

	scheme = crt->scheme;

	/* TODO: Instead of failing, maybe use get_subject_name and strcmp? */
	g_return_val_if_fail(scheme->check_subject_name, FALSE);

	return (scheme->check_subject_name)(crt, name);
}

gboolean
purple_certificate_get_times(PurpleCertificate *crt, time_t *activation, time_t *expiration)
{
	PurpleCertificateScheme *scheme;

	g_return_val_if_fail(crt, FALSE);

	scheme = crt->scheme;
	
	g_return_val_if_fail(scheme, FALSE);

	/* If both provided references are NULL, what are you doing calling
	   this? */
	g_return_val_if_fail( (activation != NULL) || (expiration != NULL), FALSE);

	/* Throw the request on down to the certscheme */
	return (scheme->get_times)(crt, activation, expiration);
}


gchar *
purple_certificate_pool_mkpath(PurpleCertificatePool *pool, const gchar *id)
{
	gchar *path;
	gchar *esc_scheme_name, *esc_name, *esc_id;
	
	g_return_val_if_fail(pool, NULL);
	g_return_val_if_fail(pool->scheme_name, NULL);
	g_return_val_if_fail(pool->name, NULL);

	/* Escape all the elements for filesystem-friendliness */
	esc_scheme_name = pool ? g_strdup(purple_escape_filename(pool->scheme_name)) : NULL;
	esc_name = pool ? g_strdup(purple_escape_filename(pool->name)) : NULL;
	esc_id = id ? g_strdup(purple_escape_filename(id)) : NULL;
	
	path = g_build_filename(purple_user_dir(),
				"certificates", /* TODO: constantize this? */
				esc_scheme_name,
				esc_name,
				esc_id,
				NULL);

	g_free(esc_scheme_name);
	g_free(esc_name);
	g_free(esc_id);
	return path;
}

gboolean
purple_certificate_pool_usable(PurpleCertificatePool *pool)
{
	g_return_val_if_fail(pool, FALSE);
	g_return_val_if_fail(pool->scheme_name, FALSE);

	/* Check that the pool's scheme is loaded */
	if (purple_certificate_find_scheme(pool->scheme_name) == NULL) {
		return FALSE;
	}
	
	return TRUE;
}

PurpleCertificateScheme *
purple_certificate_pool_get_scheme(PurpleCertificatePool *pool)
{
	g_return_val_if_fail(pool, NULL);
	g_return_val_if_fail(pool->scheme_name, NULL);

	return purple_certificate_find_scheme(pool->scheme_name);
}

gboolean
purple_certificate_pool_contains(PurpleCertificatePool *pool, const gchar *id)
{
	g_return_val_if_fail(pool, FALSE);
	g_return_val_if_fail(id, FALSE);
	g_return_val_if_fail(pool->cert_in_pool, FALSE);

	return (pool->cert_in_pool)(id);
}

PurpleCertificate *
purple_certificate_pool_retrieve(PurpleCertificatePool *pool, const gchar *id)
{
	g_return_val_if_fail(pool, NULL);
	g_return_val_if_fail(id, NULL);
	g_return_val_if_fail(pool->get_cert, NULL);

	return (pool->get_cert)(id);
}

gboolean
purple_certificate_pool_store(PurpleCertificatePool *pool, const gchar *id, PurpleCertificate *crt)
{
	gboolean ret = FALSE;
	
	g_return_val_if_fail(pool, FALSE);
	g_return_val_if_fail(id, FALSE);
	g_return_val_if_fail(pool->put_cert, FALSE);

	/* Whether crt->scheme matches find_scheme(pool->scheme_name) is not
	   relevant... I think... */
	g_return_val_if_fail(
		g_ascii_strcasecmp(pool->scheme_name, crt->scheme->name) == 0,
		FALSE);

	ret = (pool->put_cert)(id, crt);

	/* Signal that the certificate was stored if success*/
	if (ret) {
		purple_signal_emit(pool, "certificate-stored",
				   pool, id);
	}

	return ret;
}	

gboolean
purple_certificate_pool_delete(PurpleCertificatePool *pool, const gchar *id)
{
	gboolean ret = FALSE;
	
	g_return_val_if_fail(pool, FALSE);
	g_return_val_if_fail(id, FALSE);
	g_return_val_if_fail(pool->delete_cert, FALSE);

	ret = (pool->delete_cert)(id);

	/* Signal that the certificate was deleted if success */
	if (ret) {
		purple_signal_emit(pool, "certificate-deleted",
				   pool, id);
	}

	return ret;
}

GList *
purple_certificate_pool_get_idlist(PurpleCertificatePool *pool)
{
	g_return_val_if_fail(pool, NULL);
	g_return_val_if_fail(pool->get_idlist, NULL);

	return (pool->get_idlist)();
}

void
purple_certificate_pool_destroy_idlist(GList *idlist)
{
	GList *l;
	
	/* Iterate through and free them strings */
	for ( l = idlist; l; l = l->next ) {
		g_free(l->data);
	}

	g_list_free(idlist);
}


/****************************************************************************/
/* Builtin Verifiers, Pools, etc.                                           */
/****************************************************************************/

static void
x509_singleuse_verify_cb (PurpleCertificateVerificationRequest *vrq, gint id)
{
	g_return_if_fail(vrq);

	purple_debug_info("certificate/x509_singleuse",
			  "VRQ on cert from %s gave %d\n",
			  vrq->subject_name, id);

	/* Signal what happened back to the caller */
	if (1 == id) {		
		/* Accepted! */
		purple_certificate_verify_complete(vrq,
						   PURPLE_CERTIFICATE_VALID);
	} else {
		/* Not accepted */
		purple_certificate_verify_complete(vrq,
						   PURPLE_CERTIFICATE_INVALID);

	}
}

static void
x509_singleuse_start_verify (PurpleCertificateVerificationRequest *vrq)
{
	gchar *sha_asc;
	GByteArray *sha_bin;
	gchar *cn;
	const gchar *cn_match;
	gchar *primary, *secondary;
	PurpleCertificate *crt = (PurpleCertificate *) vrq->cert_chain->data;

	/* Pull out the SHA1 checksum */
	sha_bin = purple_certificate_get_fingerprint_sha1(crt);
	/* Now decode it for display */
	sha_asc = purple_base16_encode_chunked(sha_bin->data,
					       sha_bin->len);

	/* Get the cert Common Name */
	cn = purple_certificate_get_subject_name(crt);

	/* Determine whether the name matches */
	if (purple_certificate_check_subject_name(crt, vrq->subject_name)) {
		cn_match = "";
	} else {
		cn_match = _("(DOES NOT MATCH)");
	}
	
	/* Make messages */
	primary = g_strdup_printf(_("%s has presented the following certificate for just-this-once use:"), vrq->subject_name);
	secondary = g_strdup_printf(_("Common name: %s %s\nFingerprint (SHA1): %s"), cn, cn_match, sha_asc);
	
	/* Make a semi-pretty display */
	purple_request_accept_cancel(
		vrq->cb_data, /* TODO: Find what the handle ought to be */
		_("Single-use Certificate Verification"),
		primary,
		secondary,
		0,            /* Accept by default */
		NULL,         /* No account */
		NULL,         /* No other user */
		NULL,         /* No associated conversation */
		vrq,
		x509_singleuse_verify_cb,
		x509_singleuse_verify_cb );
	
	/* Cleanup */
	g_free(primary);
	g_free(secondary);
	g_free(sha_asc);
	g_byte_array_free(sha_bin, TRUE);
}

static void
x509_singleuse_destroy_request (PurpleCertificateVerificationRequest *vrq)
{
	/* I don't do anything! */
}

PurpleCertificateVerifier x509_singleuse = {
	"x509",                         /* Scheme name */
	"singleuse",                    /* Verifier name */
	x509_singleuse_start_verify,    /* start_verification function */
	x509_singleuse_destroy_request, /* Request cleanup operation */

	NULL,
	NULL,
	NULL,
	NULL
};


/***** X.509 Certificate Authority pool, keyed by Distinguished Name *****/
/* This is implemented in what may be the most inefficient and bugprone way
   possible; however, future optimizations should not be difficult. */

static PurpleCertificatePool x509_ca;

/** Holds a key-value pair for quickish certificate lookup */
typedef struct {
	gchar *dn;
	PurpleCertificate *crt;
} x509_ca_element;

static void
x509_ca_element_free(x509_ca_element *el)
{
	if (NULL == el) return;

	g_free(el->dn);
	purple_certificate_destroy(el->crt);
	g_free(el);
}

/** System directory to probe for CA certificates */
/* This is set in the lazy_init function */
static GList *x509_ca_paths = NULL;

/** A list of loaded CAs, populated from the above path whenever the lazy_init
    happens. Contains pointers to x509_ca_elements */
static GList *x509_ca_certs = NULL;

/** Used for lazy initialization purposes. */
static gboolean x509_ca_initialized = FALSE;

/** Adds a certificate to the in-memory cache, doing nothing else */
static gboolean
x509_ca_quiet_put_cert(PurpleCertificate *crt)
{
	x509_ca_element *el;

	/* lazy_init calls this function, so calling lazy_init here is a
	   Bad Thing */
	
	g_return_val_if_fail(crt, FALSE);
	g_return_val_if_fail(crt->scheme, FALSE);
	/* Make sure that this is some kind of X.509 certificate */
	/* TODO: Perhaps just check crt->scheme->name instead? */
	g_return_val_if_fail(crt->scheme == purple_certificate_find_scheme(x509_ca.scheme_name), FALSE);
	
	el = g_new0(x509_ca_element, 1);
	el->dn = purple_certificate_get_unique_id(crt);
	el->crt = purple_certificate_copy(crt);
	x509_ca_certs = g_list_prepend(x509_ca_certs, el);

	return TRUE;
}

/* Since the libpurple CertificatePools get registered before plugins are
   loaded, an X.509 Scheme is generally not available when x509_ca_init is
   called, but x509_ca requires X.509 operations in order to properly load.

   To solve this, I present the lazy_init function. It attempts to finish
   initialization of the Pool, but it usually fails when it is called from
   x509_ca_init. However, this is OK; initialization is then simply deferred
   until someone tries to use functions from the pool. */
static gboolean
x509_ca_lazy_init(void)
{
	PurpleCertificateScheme *x509;
	GDir *certdir;
	const gchar *entry;
	GPatternSpec *pempat;
	GList *iter = NULL;
	
	if (x509_ca_initialized) return TRUE;

	/* Check that X.509 is registered */
	x509 = purple_certificate_find_scheme(x509_ca.scheme_name);
	if ( !x509 ) {
		purple_debug_info("certificate/x509/ca",
				  "Lazy init failed because an X.509 Scheme "
				  "is not yet registered. Maybe it will be "
				  "better later.\n");
		return FALSE;
	}

	/* Use a glob to only read .pem files */
	pempat = g_pattern_spec_new("*.pem");

	/* Populate the certificates pool from the search path(s) */
	for (iter = x509_ca_paths; iter; iter = iter->next) {
		certdir = g_dir_open(iter->data, 0, NULL);
		if (!certdir) {
			purple_debug_error("certificate/x509/ca", "Couldn't open location '%s'\n", (const char *)iter->data);
			continue;
		}

		while ( (entry = g_dir_read_name(certdir)) ) {
			gchar *fullpath;
			PurpleCertificate *crt;

			if ( !g_pattern_match_string(pempat, entry) ) {
				continue;
			}

			fullpath = g_build_filename(iter->data, entry, NULL);

			/* TODO: Respond to a failure in the following? */
			crt = purple_certificate_import(x509, fullpath);

			if (x509_ca_quiet_put_cert(crt)) {
				purple_debug_info("certificate/x509/ca",
						  "Loaded %s\n",
						  fullpath);
			} else {
				purple_debug_error("certificate/x509/ca",
						  "Failed to load %s\n",
						  fullpath);
			}

			purple_certificate_destroy(crt);
			g_free(fullpath);
		}
		g_dir_close(certdir);
	}

	g_pattern_spec_free(pempat);

	purple_debug_info("certificate/x509/ca",
			  "Lazy init completed.\n");
	x509_ca_initialized = TRUE;
	return TRUE;
}

static gboolean
x509_ca_init(void)
{
	/* Attempt to point at the appropriate system path */
	if (NULL == x509_ca_paths) {
#ifdef _WIN32
		x509_ca_paths = g_list_append(NULL, g_build_filename(DATADIR,
						   "ca-certs", NULL));
#else
		x509_ca_paths = g_list_append(NULL, g_build_filename(DATADIR,
						   "purple", "ca-certs", NULL));
#endif
	}

	/* Attempt to initialize now, but if it doesn't work, that's OK;
	   it will get done later */
	if ( ! x509_ca_lazy_init()) {
		purple_debug_info("certificate/x509/ca",
				  "Init failed, probably because a "
				  "dependency is not yet registered. "
				  "It has been deferred to later.\n");
	}

	return TRUE;
}

static void
x509_ca_uninit(void)
{
	GList *l;

	for (l = x509_ca_certs; l; l = l->next) {
		x509_ca_element *el = l->data;
		x509_ca_element_free(el);
	}
	g_list_free(x509_ca_certs);
	x509_ca_certs = NULL;
	x509_ca_initialized = FALSE;
	g_list_foreach(x509_ca_paths, (GFunc)g_free, NULL);
	g_list_free(x509_ca_paths);
	x509_ca_paths = NULL;
}

/** Look up a ca_element by dn */
static x509_ca_element *
x509_ca_locate_cert(GList *lst, const gchar *dn)
{
	GList *cur;

	for (cur = lst; cur; cur = cur->next) {
		x509_ca_element *el = cur->data;
		/* TODO: Unsafe? */
		if ( !strcmp(dn, el->dn) ) {
			return el;
		}
	}
	return NULL;
}

static gboolean
x509_ca_cert_in_pool(const gchar *id)
{
	g_return_val_if_fail(x509_ca_lazy_init(), FALSE);
	g_return_val_if_fail(id, FALSE);

	if (x509_ca_locate_cert(x509_ca_certs, id) != NULL) {
		return TRUE;
	} else {
		return FALSE;
	}

	return FALSE;
}

static PurpleCertificate *
x509_ca_get_cert(const gchar *id)
{
	PurpleCertificate *crt = NULL;
	x509_ca_element *el;

	g_return_val_if_fail(x509_ca_lazy_init(), NULL);
	g_return_val_if_fail(id, NULL);

	/* Search the memory-cached pool */
	el = x509_ca_locate_cert(x509_ca_certs, id);

	if (el != NULL) {
		/* Make a copy of the memcached one for the function caller
		   to play with */
		crt = purple_certificate_copy(el->crt);
	} else {
		crt = NULL;
	}
	
	return crt;
}

static gboolean
x509_ca_put_cert(const gchar *id, PurpleCertificate *crt)
{
	gboolean ret = FALSE;
	
	g_return_val_if_fail(x509_ca_lazy_init(), FALSE);

	/* TODO: This is a quick way of doing this. At some point the change
	   ought to be flushed to disk somehow. */
	ret = x509_ca_quiet_put_cert(crt);

	return ret;
}

static gboolean
x509_ca_delete_cert(const gchar *id)
{
	x509_ca_element *el;
	
	g_return_val_if_fail(x509_ca_lazy_init(), FALSE);
	g_return_val_if_fail(id, FALSE);

	/* Is the id even in the pool? */
	el = x509_ca_locate_cert(x509_ca_certs, id);
	if ( el == NULL ) {
		purple_debug_warning("certificate/x509/ca",
				     "Id %s wasn't in the pool\n",
				     id);
		return FALSE;
	}

	/* Unlink it from the memory cache and destroy it */
	x509_ca_certs = g_list_remove(x509_ca_certs, el);
	x509_ca_element_free(el);
	
	return TRUE;
}

static GList *
x509_ca_get_idlist(void)
{
	GList *l, *idlist;
	
	g_return_val_if_fail(x509_ca_lazy_init(), NULL);

	idlist = NULL;
	for (l = x509_ca_certs; l; l = l->next) {
		x509_ca_element *el = l->data;
		idlist = g_list_prepend(idlist, g_strdup(el->dn));
	}
	
	return idlist;
}


static PurpleCertificatePool x509_ca = {
	"x509",                       /* Scheme name */
	"ca",                         /* Pool name */
	N_("Certificate Authorities"),/* User-friendly name */
	NULL,                         /* Internal data */
	x509_ca_init,                 /* init */
	x509_ca_uninit,               /* uninit */
	x509_ca_cert_in_pool,         /* Certificate exists? */
	x509_ca_get_cert,             /* Cert retriever */
	x509_ca_put_cert,             /* Cert writer */
	x509_ca_delete_cert,          /* Cert remover */
	x509_ca_get_idlist,           /* idlist retriever */

	NULL,
	NULL,
	NULL,
	NULL

};


/***** Cache of certificates given by TLS/SSL peers *****/
static PurpleCertificatePool x509_tls_peers;

static gboolean
x509_tls_peers_init(void)
{
	gchar *poolpath;
	int ret;
	
	/* Set up key cache here if it isn't already done */
	poolpath = purple_certificate_pool_mkpath(&x509_tls_peers, NULL);
	ret = purple_build_dir(poolpath, 0700); /* Make it this user only */

	g_free(poolpath);

	g_return_val_if_fail(ret == 0, FALSE);
	return TRUE;
}

static gboolean
x509_tls_peers_cert_in_pool(const gchar *id)
{
	gchar *keypath;
	gboolean ret = FALSE;
	
	g_return_val_if_fail(id, FALSE);

	keypath = purple_certificate_pool_mkpath(&x509_tls_peers, id);

	ret = g_file_test(keypath, G_FILE_TEST_IS_REGULAR);
	
	g_free(keypath);
	return ret;
}

static PurpleCertificate *
x509_tls_peers_get_cert(const gchar *id)
{
	PurpleCertificateScheme *x509;
	PurpleCertificate *crt;
	gchar *keypath;
	
	g_return_val_if_fail(id, NULL);

	/* Is it in the pool? */
	if ( !x509_tls_peers_cert_in_pool(id) ) {
		return NULL;
	}
	
	/* Look up the X.509 scheme */
	x509 = purple_certificate_find_scheme("x509");
	g_return_val_if_fail(x509, NULL);

	/* Okay, now find and load that key */
	keypath = purple_certificate_pool_mkpath(&x509_tls_peers, id);
	crt = purple_certificate_import(x509, keypath);

	g_free(keypath);

	return crt;
}

static gboolean
x509_tls_peers_put_cert(const gchar *id, PurpleCertificate *crt)
{
	gboolean ret = FALSE;
	gchar *keypath;

	g_return_val_if_fail(crt, FALSE);
	g_return_val_if_fail(crt->scheme, FALSE);
	/* Make sure that this is some kind of X.509 certificate */
	/* TODO: Perhaps just check crt->scheme->name instead? */
	g_return_val_if_fail(crt->scheme == purple_certificate_find_scheme(x509_tls_peers.scheme_name), FALSE);

	/* Work out the filename and export */
	keypath = purple_certificate_pool_mkpath(&x509_tls_peers, id);
	ret = purple_certificate_export(keypath, crt);
	
	g_free(keypath);
	return ret;
}

static gboolean
x509_tls_peers_delete_cert(const gchar *id)
{
	gboolean ret = FALSE;
	gchar *keypath;

	g_return_val_if_fail(id, FALSE);

	/* Is the id even in the pool? */
	if (!x509_tls_peers_cert_in_pool(id)) {
		purple_debug_warning("certificate/tls_peers",
				     "Id %s wasn't in the pool\n",
				     id);
		return FALSE;
	}

	/* OK, so work out the keypath and delete the thing */
	keypath = purple_certificate_pool_mkpath(&x509_tls_peers, id);	
	if ( unlink(keypath) != 0 ) {
		purple_debug_error("certificate/tls_peers",
				   "Unlink of %s failed!\n",
				   keypath);
		ret = FALSE;
	} else {
		ret = TRUE;
	}

	g_free(keypath);
	return ret;
}

static GList *
x509_tls_peers_get_idlist(void)
{
	GList *idlist = NULL;
	GDir *dir;
	const gchar *entry;
	gchar *poolpath;

	/* Get a handle on the pool directory */
	poolpath = purple_certificate_pool_mkpath(&x509_tls_peers, NULL);
	dir = g_dir_open(poolpath,
			 0,     /* No flags */
			 NULL); /* Not interested in what the error is */
	g_free(poolpath);

	g_return_val_if_fail(dir, NULL);

	/* Traverse the directory listing and create an idlist */
	while ( (entry = g_dir_read_name(dir)) != NULL ) {
		/* Unescape the filename */
		const char *unescaped = purple_unescape_filename(entry);
		
		/* Copy the entry name into our list (GLib owns the original
		   string) */
		idlist = g_list_prepend(idlist, g_strdup(unescaped));
	}

	/* Release the directory */
	g_dir_close(dir);
	
	return idlist;
}

static PurpleCertificatePool x509_tls_peers = {
	"x509",                       /* Scheme name */
	"tls_peers",                  /* Pool name */
	N_("SSL Peers Cache"),        /* User-friendly name */
	NULL,                         /* Internal data */
	x509_tls_peers_init,          /* init */
	NULL,                         /* uninit not required */
	x509_tls_peers_cert_in_pool,  /* Certificate exists? */
	x509_tls_peers_get_cert,      /* Cert retriever */
	x509_tls_peers_put_cert,      /* Cert writer */
	x509_tls_peers_delete_cert,   /* Cert remover */
	x509_tls_peers_get_idlist,    /* idlist retriever */

	NULL,
	NULL,
	NULL,
	NULL
};


/***** A Verifier that uses the tls_peers cache and the CA pool to validate certificates *****/
static PurpleCertificateVerifier x509_tls_cached;


/* The following is several hacks piled together and needs to be fixed.
 * It exists because show_cert (see its comments) needs the original reason
 * given to user_auth in order to rebuild the dialog.
 */
/* TODO: This will cause a ua_ctx to become memleaked if the request(s) get
   closed by handle or otherwise abnormally. */
typedef struct {
	PurpleCertificateVerificationRequest *vrq;
	gchar *reason;
} x509_tls_cached_ua_ctx;

static x509_tls_cached_ua_ctx *
x509_tls_cached_ua_ctx_new(PurpleCertificateVerificationRequest *vrq,
			   const gchar *reason)
{
	x509_tls_cached_ua_ctx *c;

	c = g_new0(x509_tls_cached_ua_ctx, 1);
	c->vrq = vrq;
	c->reason = g_strdup(reason);

	return c;
}


static void
x509_tls_cached_ua_ctx_free(x509_tls_cached_ua_ctx *c)
{
	g_return_if_fail(c);
	g_free(c->reason);
	g_free(c);
}

static void
x509_tls_cached_user_auth(PurpleCertificateVerificationRequest *vrq,
			  const gchar *reason);

static void
x509_tls_cached_show_cert(x509_tls_cached_ua_ctx *c, gint id)
{
	PurpleCertificate *disp_crt = c->vrq->cert_chain->data;

	/* Since clicking a button closes the request, show it again */
	x509_tls_cached_user_auth(c->vrq, c->reason);

	/* Show the certificate AFTER re-opening the dialog so that this
	   appears above the other */
	purple_certificate_display_x509(disp_crt);

	x509_tls_cached_ua_ctx_free(c);
}

static void
x509_tls_cached_user_auth_cb (x509_tls_cached_ua_ctx *c, gint id)
{
	PurpleCertificateVerificationRequest *vrq;
	PurpleCertificatePool *tls_peers;

	g_return_if_fail(c);
	g_return_if_fail(c->vrq);
	
	vrq = c->vrq;

	x509_tls_cached_ua_ctx_free(c);

	tls_peers = purple_certificate_find_pool("x509","tls_peers");

	if (2 == id) {
		gchar *cache_id = vrq->subject_name;
		purple_debug_info("certificate/x509/tls_cached",
				  "User ACCEPTED cert\nCaching first in chain for future use as %s...\n",
				  cache_id);
		
		purple_certificate_pool_store(tls_peers, cache_id,
					      vrq->cert_chain->data);

		purple_certificate_verify_complete(vrq,
						   PURPLE_CERTIFICATE_VALID);
	} else {
		purple_debug_info("certificate/x509/tls_cached",
				  "User REJECTED cert\n");
		purple_certificate_verify_complete(vrq,
						   PURPLE_CERTIFICATE_INVALID);
	}
}

static void
x509_tls_cached_user_auth_accept_cb(x509_tls_cached_ua_ctx *c, gint ignore)
{
	x509_tls_cached_user_auth_cb(c, 2);
}

static void
x509_tls_cached_user_auth_reject_cb(x509_tls_cached_ua_ctx *c, gint ignore)
{
	x509_tls_cached_user_auth_cb(c, 1);
}

/** Validates a certificate by asking the user
 * @param reason    String to explain why the user needs to accept/refuse the
 *                  certificate.
 * @todo Needs a handle argument
 */
static void
x509_tls_cached_user_auth(PurpleCertificateVerificationRequest *vrq,
			  const gchar *reason)
{
	gchar *primary;

	/* Make messages */
	primary = g_strdup_printf(_("Accept certificate for %s?"),
				  vrq->subject_name);
		
	/* Make a semi-pretty display */
	purple_request_action(
		vrq->cb_data, /* TODO: Find what the handle ought to be */
		_("SSL Certificate Verification"),
		primary,
		reason,
		0,            /* Accept by default */
		NULL,         /* No account */
		NULL,         /* No other user */
		NULL,         /* No associated conversation */
		x509_tls_cached_ua_ctx_new(vrq, reason),
		3,            /* Number of actions */
		_("Accept"), x509_tls_cached_user_auth_accept_cb,
		_("Reject"),  x509_tls_cached_user_auth_reject_cb,
		_("_View Certificate..."), x509_tls_cached_show_cert);
	
	/* Cleanup */
	g_free(primary);
}

static void
x509_tls_cached_peer_cert_changed(PurpleCertificateVerificationRequest *vrq)
{
	/* TODO: Prompt the user, etc. */

	purple_debug_info("certificate/x509/tls_cached",
			  "Certificate for %s does not match cached. "
			  "Auto-rejecting!\n",
			  vrq->subject_name);
	
	purple_certificate_verify_complete(vrq, PURPLE_CERTIFICATE_INVALID);
	return;
}

static void
x509_tls_cached_unknown_peer(PurpleCertificateVerificationRequest *vrq);

static void
x509_tls_cached_cert_in_cache(PurpleCertificateVerificationRequest *vrq)
{
	/* TODO: Looking this up by name over and over is expensive.
	   Fix, please! */
	PurpleCertificatePool *tls_peers =
		purple_certificate_find_pool(x509_tls_cached.scheme_name,
					     "tls_peers");

	/* The peer's certificate should be the first in the list */
	PurpleCertificate *peer_crt =
		(PurpleCertificate *) vrq->cert_chain->data;
	
	PurpleCertificate *cached_crt;
	GByteArray *peer_fpr, *cached_fpr;

	/* Load up the cached certificate */
	cached_crt = purple_certificate_pool_retrieve(
		tls_peers, vrq->subject_name);
	if ( !cached_crt ) {
		purple_debug_error("certificate/x509/tls_cached",
				   "Lookup failed on cached certificate!\n"
				   "It was here just a second ago. Forwarding "
				   "to cert_changed.\n");
		/* vrq now becomes the problem of cert_changed */
		x509_tls_cached_peer_cert_changed(vrq);
	}

	/* Now get SHA1 sums for both and compare them */
	/* TODO: This is not an elegant way to compare certs */
	peer_fpr = purple_certificate_get_fingerprint_sha1(peer_crt);
	cached_fpr = purple_certificate_get_fingerprint_sha1(cached_crt);
	if (!memcmp(peer_fpr->data, cached_fpr->data, peer_fpr->len)) {
		purple_debug_info("certificate/x509/tls_cached",
				  "Peer cert matched cached\n");
		/* vrq is now finished */
		purple_certificate_verify_complete(vrq,
						   PURPLE_CERTIFICATE_VALID);
	} else {
		purple_debug_info("certificate/x509/tls_cached",
				  "Peer cert did NOT match cached\n");
		/* vrq now becomes the problem of the user */
		x509_tls_cached_unknown_peer(vrq);
	}
	
	purple_certificate_destroy(cached_crt);
	g_byte_array_free(peer_fpr, TRUE);
	g_byte_array_free(cached_fpr, TRUE);
}

/* For when we've never communicated with this party before */
/* TODO: Need ways to specify possibly multiple problems with a cert, or at
   least  reprioritize them. For example, maybe the signature ought to be
   checked BEFORE the hostname checking?
   Stu thinks we should check the signature before the name, so we do now.
   The above TODO still stands. */
static void
x509_tls_cached_unknown_peer(PurpleCertificateVerificationRequest *vrq)
{
	PurpleCertificatePool *ca, *tls_peers;
	PurpleCertificate *end_crt, *ca_crt, *peer_crt;
	GList *chain = vrq->cert_chain;
	GList *last;
	gchar *ca_id;

	peer_crt = (PurpleCertificate *) chain->data;

	/* TODO: Figure out a way to check for a bad signature, as opposed to
	   "not self-signed" */
	if ( purple_certificate_signed_by(peer_crt, peer_crt) ) {
		gchar *msg;
		
		purple_debug_info("certificate/x509/tls_cached",
				  "Certificate for %s is self-signed.\n",
				  vrq->subject_name);

		/* Prompt the user to authenticate the certificate */
		/* vrq will be completed by user_auth */
		msg = g_strdup_printf(_("The certificate presented by \"%s\" "
					"is self-signed. It cannot be "
					"automatically checked."),
				      vrq->subject_name);
				      
		x509_tls_cached_user_auth(vrq,msg);

		g_free(msg);
		return;
	} /* if (self signed) */
	
	/* Next, check that the certificate chain is valid */
	if ( ! purple_certificate_check_signature_chain(chain) ) {
		/* TODO: Tell the user where the chain broke? */
		/* TODO: This error will hopelessly confuse any
		   non-elite user. */
		gchar *secondary;

		secondary = g_strdup_printf(_("The certificate chain presented"
					      " for %s is not valid."),
					    vrq->subject_name);

		/* TODO: Make this error either block the ensuing SSL
		   connection error until the user dismisses this one, or
		   stifle it. */
		purple_notify_error(NULL, /* TODO: Probably wrong. */
				    _("SSL Certificate Error"),
				    _("Invalid certificate chain"),
				    secondary );
		g_free(secondary);

		/* Okay, we're done here */
		purple_certificate_verify_complete(vrq,
						   PURPLE_CERTIFICATE_INVALID);
		return;
	} /* if (signature chain not good) */

	/* Next, attempt to verify the last certificate against a CA */
	ca = purple_certificate_find_pool(x509_tls_cached.scheme_name, "ca");

	/* If, for whatever reason, there is no Certificate Authority pool
	   loaded, we will simply present it to the user for checking. */
	if ( !ca ) {
		purple_debug_error("certificate/x509/tls_cached",
				   "No X.509 Certificate Authority pool "
				   "could be found!\n");

		/* vrq will be completed by user_auth */
		x509_tls_cached_user_auth(vrq,_("You have no database of root "
						"certificates, so this "
						"certificate cannot be "
						"validated."));
		return;
	}

	last = g_list_last(chain);
	end_crt = (PurpleCertificate *) last->data;

	/* Attempt to look up the last certificate's issuer */
	ca_id = purple_certificate_get_issuer_unique_id(end_crt);
	purple_debug_info("certificate/x509/tls_cached",
			  "Checking for a CA with DN=%s\n",
			  ca_id);
	ca_crt = purple_certificate_pool_retrieve(ca, ca_id);
	if ( NULL == ca_crt ) {
		purple_debug_info("certificate/x509/tls_cached",
				  "Certificate Authority with DN='%s' not "
				  "found. I'll prompt the user, I guess.\n",
				  ca_id);
		g_free(ca_id);
		/* vrq will be completed by user_auth */
		x509_tls_cached_user_auth(vrq,_("The root certificate this "
						"one claims to be issued by "
						"is unknown to Pidgin."));
		return;
	}

	g_free(ca_id);
	
	/* Check the signature */
	if ( !purple_certificate_signed_by(end_crt, ca_crt) ) {
		/* TODO: If signed_by ever returns a reason, maybe mention
		   that, too. */
		/* TODO: Also mention the CA involved. While I could do this
		   now, a full DN is a little much with which to assault the
		   user's poor, leaky eyes. */
		/* TODO: This error message makes my eyes cross, and I wrote it */
		gchar * secondary =
			g_strdup_printf(_("The certificate chain presented by "
					  "%s does not have a valid digital "
					  "signature from the Certificate "
					  "Authority from which it claims to "
					  "have a signature."),
					vrq->subject_name);
		
		purple_notify_error(NULL, /* TODO: Probably wrong */
				    _("SSL Certificate Error"),
				    _("Invalid certificate authority"
				      " signature"),
				    secondary);
		g_free(secondary);

		/* Signal "bad cert" */
		purple_certificate_verify_complete(vrq,
						   PURPLE_CERTIFICATE_INVALID);
		return;
	} /* if (CA signature not good) */

	/* Last, check that the hostname matches */
	if ( ! purple_certificate_check_subject_name(peer_crt,
						     vrq->subject_name) ) {
		gchar *sn = purple_certificate_get_subject_name(peer_crt);
		gchar *msg;
		
		purple_debug_info("certificate/x509/tls_cached",
				  "Name mismatch: Certificate given for %s "
				  "has a name of %s\n",
				  vrq->subject_name, sn);

		/* Prompt the user to authenticate the certificate */
		/* TODO: Provide the user with more guidance about why he is
		   being prompted */
		/* vrq will be completed by user_auth */
		msg = g_strdup_printf(_("The certificate presented by \"%s\" "
					"claims to be from \"%s\" instead.  "
					"This could mean that you are not "
					"connecting to the service you "
					"believe you are."),
				      vrq->subject_name, sn);
				      
		x509_tls_cached_user_auth(vrq,msg);

		g_free(sn);
		g_free(msg);
		return;
	} /* if (name mismatch) */

	/* If we reach this point, the certificate is good. */
	/* Look up the local cache and store it there for future use */
	tls_peers = purple_certificate_find_pool(x509_tls_cached.scheme_name,
						 "tls_peers");

	if (tls_peers) {
		if (!purple_certificate_pool_store(tls_peers,vrq->subject_name,
						   peer_crt) ) {
			purple_debug_error("certificate/x509/tls_cached",
					   "FAILED to cache peer certificate\n");
		}
	} else {
		purple_debug_error("certificate/x509/tls_cached",
				   "Unable to locate tls_peers certificate "
				   "cache.\n");
	}
	
	/* Whew! Done! */
	purple_certificate_verify_complete(vrq, PURPLE_CERTIFICATE_VALID);
}

static void
x509_tls_cached_start_verify(PurpleCertificateVerificationRequest *vrq)
{
	const gchar *tls_peers_name = "tls_peers"; /* Name of local cache */
	PurpleCertificatePool *tls_peers;

	g_return_if_fail(vrq);

	purple_debug_info("certificate/x509/tls_cached",
			  "Starting verify for %s\n",
			  vrq->subject_name);
	
	tls_peers = purple_certificate_find_pool(x509_tls_cached.scheme_name,tls_peers_name);

	if (!tls_peers) {
		purple_debug_error("certificate/x509/tls_cached",
				   "Couldn't find local peers cache %s\nPrompting the user\n",
				   tls_peers_name);


		/* vrq now becomes the problem of unknown_peer */
		x509_tls_cached_unknown_peer(vrq);
		return;
	}
	
	/* Check if the peer has a certificate cached already */
	purple_debug_info("certificate/x509/tls_cached",
			  "Checking for cached cert...\n");
	if (purple_certificate_pool_contains(tls_peers, vrq->subject_name)) {
		purple_debug_info("certificate/x509/tls_cached",
				  "...Found cached cert\n");
		/* vrq is now the responsibility of cert_in_cache */
		x509_tls_cached_cert_in_cache(vrq);
	} else {
		purple_debug_info("certificate/x509/tls_cached",
				  "...Not in cache\n");
		/* vrq now becomes the problem of unknown_peer */
		x509_tls_cached_unknown_peer(vrq);
	}
}

static void
x509_tls_cached_destroy_request(PurpleCertificateVerificationRequest *vrq)
{
	g_return_if_fail(vrq);
}

static PurpleCertificateVerifier x509_tls_cached = {
	"x509",                         /* Scheme name */
	"tls_cached",                   /* Verifier name */
	x509_tls_cached_start_verify,   /* Verification begin */
	x509_tls_cached_destroy_request,/* Request cleanup */

	NULL,
	NULL,
	NULL,
	NULL

};

/****************************************************************************/
/* Subsystem                                                                */
/****************************************************************************/
void
purple_certificate_init(void)
{
	/* Register builtins */
	purple_certificate_register_verifier(&x509_singleuse);
	purple_certificate_register_pool(&x509_ca);
	purple_certificate_register_pool(&x509_tls_peers);
	purple_certificate_register_verifier(&x509_tls_cached);
}

void
purple_certificate_uninit(void)
{
	GList *full_list, *l;

	/* Unregister all Schemes */
	full_list = g_list_copy(cert_schemes); /* Make a working copy */
	for (l = full_list; l; l = l->next) {
		purple_certificate_unregister_scheme(
			(PurpleCertificateScheme *) l->data );
	}
	g_list_free(full_list);

	/* Unregister all Verifiers */
	full_list = g_list_copy(cert_verifiers); /* Make a working copy */
	for (l = full_list; l; l = l->next) {
		purple_certificate_unregister_verifier(
			(PurpleCertificateVerifier *) l->data );
	}
	g_list_free(full_list);

	/* Unregister all Pools */
	full_list = g_list_copy(cert_pools); /* Make a working copy */
	for (l = full_list; l; l = l->next) {
		purple_certificate_unregister_pool(
			(PurpleCertificatePool *) l->data );
	}
	g_list_free(full_list);
}

gpointer
purple_certificate_get_handle(void)
{
	static gint handle;
	return &handle;
}

PurpleCertificateScheme *
purple_certificate_find_scheme(const gchar *name)
{
	PurpleCertificateScheme *scheme = NULL;
	GList *l;

	g_return_val_if_fail(name, NULL);

	/* Traverse the list of registered schemes and locate the
	   one whose name matches */
	for(l = cert_schemes; l; l = l->next) {
		scheme = (PurpleCertificateScheme *)(l->data);

		/* Name matches? that's our man */
		if(!g_ascii_strcasecmp(scheme->name, name))
			return scheme;
	}

	purple_debug_warning("certificate",
			     "CertificateScheme %s requested but not found.\n",
			     name);

	/* TODO: Signalling and such? */
	
	return NULL;
}

GList *
purple_certificate_get_schemes(void)
{
	return cert_schemes;
}

gboolean
purple_certificate_register_scheme(PurpleCertificateScheme *scheme)
{
	g_return_val_if_fail(scheme != NULL, FALSE);

	/* Make sure no scheme is registered with the same name */
	if (purple_certificate_find_scheme(scheme->name) != NULL) {
		return FALSE;
	}

	/* Okay, we're golden. Register it. */
	cert_schemes = g_list_prepend(cert_schemes, scheme);

	/* TODO: Signalling and such? */

	purple_debug_info("certificate",
			  "CertificateScheme %s registered\n",
			  scheme->name);
	
	return TRUE;
}

gboolean
purple_certificate_unregister_scheme(PurpleCertificateScheme *scheme)
{
	if (NULL == scheme) {
		purple_debug_warning("certificate",
				     "Attempting to unregister NULL scheme\n");
		return FALSE;
	}

	/* TODO: signalling? */

	/* TODO: unregister all CertificateVerifiers for this scheme?*/
	/* TODO: unregister all CertificatePools for this scheme? */
	/* Neither of the above should be necessary, though */
	cert_schemes = g_list_remove(cert_schemes, scheme);

	purple_debug_info("certificate",
			  "CertificateScheme %s unregistered\n",
			  scheme->name);


	return TRUE;
}

PurpleCertificateVerifier *
purple_certificate_find_verifier(const gchar *scheme_name, const gchar *ver_name)
{
	PurpleCertificateVerifier *vr = NULL;
	GList *l;

	g_return_val_if_fail(scheme_name, NULL);
	g_return_val_if_fail(ver_name, NULL);

	/* Traverse the list of registered verifiers and locate the
	   one whose name matches */
	for(l = cert_verifiers; l; l = l->next) {
		vr = (PurpleCertificateVerifier *)(l->data);

		/* Scheme and name match? */
		if(!g_ascii_strcasecmp(vr->scheme_name, scheme_name) &&
		   !g_ascii_strcasecmp(vr->name, ver_name))
			return vr;
	}

	purple_debug_warning("certificate",
			     "CertificateVerifier %s, %s requested but not found.\n",
			     scheme_name, ver_name);

	/* TODO: Signalling and such? */
	
	return NULL;
}


GList *
purple_certificate_get_verifiers(void)
{
	return cert_verifiers;
}

gboolean
purple_certificate_register_verifier(PurpleCertificateVerifier *vr)
{
	g_return_val_if_fail(vr != NULL, FALSE);

	/* Make sure no verifier is registered with the same scheme/name */
	if (purple_certificate_find_verifier(vr->scheme_name, vr->name) != NULL) {
		return FALSE;
	}

	/* Okay, we're golden. Register it. */
	cert_verifiers = g_list_prepend(cert_verifiers, vr);

	/* TODO: Signalling and such? */

	purple_debug_info("certificate",
			  "CertificateVerifier %s registered\n",
			  vr->name);
	return TRUE;
}

gboolean
purple_certificate_unregister_verifier(PurpleCertificateVerifier *vr)
{
	if (NULL == vr) {
		purple_debug_warning("certificate",
				     "Attempting to unregister NULL verifier\n");
		return FALSE;
	}

	/* TODO: signalling? */

	cert_verifiers = g_list_remove(cert_verifiers, vr);


	purple_debug_info("certificate",
			  "CertificateVerifier %s unregistered\n",
			  vr->name);

	return TRUE;
}

PurpleCertificatePool *
purple_certificate_find_pool(const gchar *scheme_name, const gchar *pool_name)
{
	PurpleCertificatePool *pool = NULL;
	GList *l;

	g_return_val_if_fail(scheme_name, NULL);
	g_return_val_if_fail(pool_name, NULL);

	/* Traverse the list of registered pools and locate the
	   one whose name matches */
	for(l = cert_pools; l; l = l->next) {
		pool = (PurpleCertificatePool *)(l->data);

		/* Scheme and name match? */
		if(!g_ascii_strcasecmp(pool->scheme_name, scheme_name) &&
		   !g_ascii_strcasecmp(pool->name, pool_name))
			return pool;
	}

	purple_debug_warning("certificate",
			     "CertificatePool %s, %s requested but not found.\n",
			     scheme_name, pool_name);

	/* TODO: Signalling and such? */
	
	return NULL;

}

GList *
purple_certificate_get_pools(void)
{
	return cert_pools;
}

gboolean
purple_certificate_register_pool(PurpleCertificatePool *pool)
{
	g_return_val_if_fail(pool, FALSE);
	g_return_val_if_fail(pool->scheme_name, FALSE);
	g_return_val_if_fail(pool->name, FALSE);
	g_return_val_if_fail(pool->fullname, FALSE);

	/* Make sure no pools are registered under this name */
	if (purple_certificate_find_pool(pool->scheme_name, pool->name)) {
		return FALSE;
	}

	/* Initialize the pool if needed */
	if (pool->init) {
		gboolean success;

		success = pool->init();
		if (!success)
			return FALSE;
	}

	/* Register the Pool */
	cert_pools = g_list_prepend(cert_pools, pool);

	/* TODO: Emit a signal that the pool got registered */

	PURPLE_DBUS_REGISTER_POINTER(pool, PurpleCertificatePool);
	purple_signal_register(pool, /* Signals emitted from pool */
			       "certificate-stored",
			       purple_marshal_VOID__POINTER_POINTER,
			       NULL, /* No callback return value */
			       2,    /* Two non-data arguments */
			       purple_value_new(PURPLE_TYPE_SUBTYPE,
						PURPLE_SUBTYPE_CERTIFICATEPOOL),
			       purple_value_new(PURPLE_TYPE_STRING));

	purple_signal_register(pool, /* Signals emitted from pool */
			       "certificate-deleted",
			       purple_marshal_VOID__POINTER_POINTER,
			       NULL, /* No callback return value */
			       2,    /* Two non-data arguments */
			       purple_value_new(PURPLE_TYPE_SUBTYPE,
						PURPLE_SUBTYPE_CERTIFICATEPOOL),
			       purple_value_new(PURPLE_TYPE_STRING));

	purple_debug_info("certificate",
		  "CertificatePool %s registered\n",
		  pool->name);

	return TRUE;
}

gboolean
purple_certificate_unregister_pool(PurpleCertificatePool *pool)
{
	if (NULL == pool) {
		purple_debug_warning("certificate",
				     "Attempting to unregister NULL pool\n");
		return FALSE;
	}

	/* Check that the pool is registered */
	if (!g_list_find(cert_pools, pool)) {
		purple_debug_warning("certificate",
				     "Pool to unregister isn't registered!\n");

		return FALSE;
	}

	/* Uninit the pool if needed */
	PURPLE_DBUS_UNREGISTER_POINTER(pool);
	if (pool->uninit) {
		pool->uninit();
	}

	cert_pools = g_list_remove(cert_pools, pool);
	
	/* TODO: Signalling? */
	purple_signal_unregister(pool, "certificate-stored");
	purple_signal_unregister(pool, "certificate-deleted");
		
	purple_debug_info("certificate",
			  "CertificatePool %s unregistered\n",
			  pool->name);
	return TRUE;
}

/****************************************************************************/
/* Scheme-specific functions                                                */
/****************************************************************************/

void
purple_certificate_display_x509(PurpleCertificate *crt)
{
	gchar *sha_asc;
	GByteArray *sha_bin;
	gchar *cn;
	time_t activation, expiration;
	gchar *activ_str, *expir_str;
	gchar *secondary;

	/* Pull out the SHA1 checksum */
	sha_bin = purple_certificate_get_fingerprint_sha1(crt);
	/* Now decode it for display */
	sha_asc = purple_base16_encode_chunked(sha_bin->data,
					       sha_bin->len);

	/* Get the cert Common Name */
	/* TODO: Will break on CA certs */
	cn = purple_certificate_get_subject_name(crt);

	/* Get the certificate times */
	/* TODO: Check the times against localtime */
	/* TODO: errorcheck? */
	if (!purple_certificate_get_times(crt, &activation, &expiration)) {
		purple_debug_error("certificate",
				   "Failed to get certificate times!\n");
		activation = expiration = 0;
	}
	activ_str = g_strdup(ctime(&activation));
	expir_str = g_strdup(ctime(&expiration));

	/* Make messages */
	secondary = g_strdup_printf(_("Common name: %s\n\n"
				      "Fingerprint (SHA1): %s\n\n"
				      "Activation date: %s\n"
				      "Expiration date: %s\n"),
				    cn, sha_asc, activ_str, expir_str);

	/* Make a semi-pretty display */
	purple_notify_info(
		NULL,         /* TODO: Find what the handle ought to be */
		_("Certificate Information"),
		"",
		secondary);

	/* Cleanup */
	g_free(cn);
	g_free(secondary);
	g_free(sha_asc);
	g_free(activ_str);
	g_free(expir_str);
	g_byte_array_free(sha_bin, TRUE);
}

void purple_certificate_add_ca_search_path(const char *path)
{
	if (g_list_find_custom(x509_ca_paths, path, (GCompareFunc)strcmp))
		return;
	x509_ca_paths = g_list_append(x509_ca_paths, g_strdup(path));
}