/*
 * This file implements the CLIENT Session ID cache.
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "cert.h"
#include "pk11pub.h"
#include "secitem.h"
#include "ssl.h"
#include "nss.h"

#include "sslimpl.h"
#include "sslproto.h"
#include "nssilock.h"
#if defined(XP_UNIX) || defined(XP_WIN) || defined(_WINDOWS) || defined(XP_BEOS)
#include <time.h>
#endif

PRUint32 ssl_sid_timeout = 100;
PRUint32 ssl3_sid_timeout = 86400L; /* 24 hours */

static sslSessionID *cache = NULL;
static PZLock *cacheLock = NULL;

/* sids can be in one of 4 states:
 *
 * never_cached,        created, but not yet put into cache.
 * in_client_cache,     in the client cache's linked list.
 * in_server_cache,     entry came from the server's cache file.
 * invalid_cache        has been removed from the cache.
 */

#define LOCK_CACHE lock_cache()
#define UNLOCK_CACHE PZ_Unlock(cacheLock)

static SECStatus
ssl_InitClientSessionCacheLock(void)
{
    cacheLock = PZ_NewLock(nssILockCache);
    return cacheLock ? SECSuccess : SECFailure;
}

static SECStatus
ssl_FreeClientSessionCacheLock(void)
{
    if (cacheLock) {
        PZ_DestroyLock(cacheLock);
        cacheLock = NULL;
        return SECSuccess;
    }
    PORT_SetError(SEC_ERROR_NOT_INITIALIZED);
    return SECFailure;
}

static PRBool LocksInitializedEarly = PR_FALSE;

static SECStatus
FreeSessionCacheLocks()
{
    SECStatus rv1, rv2;
    rv1 = ssl_FreeSymWrapKeysLock();
    rv2 = ssl_FreeClientSessionCacheLock();
    if ((SECSuccess == rv1) && (SECSuccess == rv2)) {
        return SECSuccess;
    }
    return SECFailure;
}

static SECStatus
InitSessionCacheLocks(void)
{
    SECStatus rv1, rv2;
    PRErrorCode rc;
    rv1 = ssl_InitSymWrapKeysLock();
    rv2 = ssl_InitClientSessionCacheLock();
    if ((SECSuccess == rv1) && (SECSuccess == rv2)) {
        return SECSuccess;
    }
    rc = PORT_GetError();
    FreeSessionCacheLocks();
    PORT_SetError(rc);
    return SECFailure;
}

/* free the session cache locks if they were initialized early */
SECStatus
ssl_FreeSessionCacheLocks()
{
    PORT_Assert(PR_TRUE == LocksInitializedEarly);
    if (!LocksInitializedEarly) {
        PORT_SetError(SEC_ERROR_NOT_INITIALIZED);
        return SECFailure;
    }
    FreeSessionCacheLocks();
    LocksInitializedEarly = PR_FALSE;
    return SECSuccess;
}

static PRCallOnceType lockOnce;

/* free the session cache locks if they were initialized lazily */
static SECStatus
ssl_ShutdownLocks(void *appData, void *nssData)
{
    PORT_Assert(PR_FALSE == LocksInitializedEarly);
    if (LocksInitializedEarly) {
        PORT_SetError(SEC_ERROR_LIBRARY_FAILURE);
        return SECFailure;
    }
    FreeSessionCacheLocks();
    memset(&lockOnce, 0, sizeof(lockOnce));
    return SECSuccess;
}

static PRStatus
initSessionCacheLocksLazily(void)
{
    SECStatus rv = InitSessionCacheLocks();
    if (SECSuccess != rv) {
        return PR_FAILURE;
    }
    rv = NSS_RegisterShutdown(ssl_ShutdownLocks, NULL);
    PORT_Assert(SECSuccess == rv);
    if (SECSuccess != rv) {
        return PR_FAILURE;
    }
    return PR_SUCCESS;
}

/* lazyInit means that the call is not happening during a 1-time
 * initialization function, but rather during dynamic, lazy initialization
 */
SECStatus
ssl_InitSessionCacheLocks(PRBool lazyInit)
{
    if (LocksInitializedEarly) {
        return SECSuccess;
    }

    if (lazyInit) {
        return (PR_SUCCESS ==
                PR_CallOnce(&lockOnce, initSessionCacheLocksLazily))
                   ? SECSuccess
                   : SECFailure;
    }

    if (SECSuccess == InitSessionCacheLocks()) {
        LocksInitializedEarly = PR_TRUE;
        return SECSuccess;
    }

    return SECFailure;
}

static void
lock_cache(void)
{
    ssl_InitSessionCacheLocks(PR_TRUE);
    PZ_Lock(cacheLock);
}

/* BEWARE: This function gets called for both client and server SIDs !!
 * If the unreferenced sid is not in the cache, Free sid and its contents.
 */
static void
ssl_DestroySID(sslSessionID *sid)
{
    SSL_TRC(8, ("SSL: destroy sid: sid=0x%x cached=%d", sid, sid->cached));
    PORT_Assert(sid->references == 0);
    PORT_Assert(sid->cached != in_client_cache);

    if (sid->version < SSL_LIBRARY_VERSION_3_0) {
        SECITEM_ZfreeItem(&sid->u.ssl2.masterKey, PR_FALSE);
        SECITEM_ZfreeItem(&sid->u.ssl2.cipherArg, PR_FALSE);
    } else {
        if (sid->u.ssl3.locked.sessionTicket.ticket.data) {
            SECITEM_FreeItem(&sid->u.ssl3.locked.sessionTicket.ticket,
                             PR_FALSE);
        }
        if (sid->u.ssl3.srvName.data) {
            SECITEM_FreeItem(&sid->u.ssl3.srvName, PR_FALSE);
        }
        if (sid->u.ssl3.signedCertTimestamps.data) {
            SECITEM_FreeItem(&sid->u.ssl3.signedCertTimestamps, PR_FALSE);
        }

        if (sid->u.ssl3.lock) {
            PR_DestroyRWLock(sid->u.ssl3.lock);
        }
    }

    if (sid->peerID != NULL)
        PORT_Free((void *)sid->peerID); /* CONST */

    if (sid->urlSvrName != NULL)
        PORT_Free((void *)sid->urlSvrName); /* CONST */

    if (sid->peerCert) {
        CERT_DestroyCertificate(sid->peerCert);
    }
    if (sid->peerCertStatus.items) {
        SECITEM_FreeArray(&sid->peerCertStatus, PR_FALSE);
    }

    if (sid->localCert) {
        CERT_DestroyCertificate(sid->localCert);
    }

    PORT_ZFree(sid, sizeof(sslSessionID));
}

/* BEWARE: This function gets called for both client and server SIDs !!
 * Decrement reference count, and
 *    free sid if ref count is zero, and sid is not in the cache.
 * Does NOT remove from the cache first.
 * If the sid is still in the cache, it is left there until next time
 * the cache list is traversed.
 */
static void
ssl_FreeLockedSID(sslSessionID *sid)
{
    PORT_Assert(sid->references >= 1);
    if (--sid->references == 0) {
        ssl_DestroySID(sid);
    }
}

/* BEWARE: This function gets called for both client and server SIDs !!
 * Decrement reference count, and
 *    free sid if ref count is zero, and sid is not in the cache.
 * Does NOT remove from the cache first.
 * These locks are necessary because the sid _might_ be in the cache list.
 */
void
ssl_FreeSID(sslSessionID *sid)
{
    LOCK_CACHE;
    ssl_FreeLockedSID(sid);
    UNLOCK_CACHE;
}

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

/*
**  Lookup sid entry in cache by Address, port, and peerID string.
**  If found, Increment reference count, and return pointer to caller.
**  If it has timed out or ref count is zero, remove from list and free it.
*/

sslSessionID *
ssl_LookupSID(const PRIPv6Addr *addr, PRUint16 port, const char *peerID,
              const char *urlSvrName)
{
    sslSessionID **sidp;
    sslSessionID *sid;
    PRUint32 now;

    if (!urlSvrName)
        return NULL;
    now = ssl_Time();
    LOCK_CACHE;
    sidp = &cache;
    while ((sid = *sidp) != 0) {
        PORT_Assert(sid->cached == in_client_cache);
        PORT_Assert(sid->references >= 1);

        SSL_TRC(8, ("SSL: Lookup1: sid=0x%x", sid));

        if (sid->expirationTime < now) {
            /*
            ** This session-id timed out.
            ** Don't even care who it belongs to, blow it out of our cache.
            */
            SSL_TRC(7, ("SSL: lookup1, throwing sid out, age=%d refs=%d",
                        now - sid->creationTime, sid->references));

            *sidp = sid->next;                                      /* delink it from the list. */
            sid->cached = invalid_cache;                            /* mark not on list. */
            ssl_FreeLockedSID(sid);                                 /* drop ref count, free. */
        } else if (!memcmp(&sid->addr, addr, sizeof(PRIPv6Addr)) && /* server IP addr matches */
                   (sid->port == port) &&                           /* server port matches */
                   /* proxy (peerID) matches */
                   (((peerID == NULL) && (sid->peerID == NULL)) ||
                    ((peerID != NULL) && (sid->peerID != NULL) &&
                     PORT_Strcmp(sid->peerID, peerID) == 0)) &&
                   /* is cacheable */
                   (sid->version < SSL_LIBRARY_VERSION_3_0 ||
                    sid->u.ssl3.keys.resumable) &&
                   /* server hostname matches. */
                   (sid->urlSvrName != NULL) &&
                   (0 == PORT_Strcmp(urlSvrName, sid->urlSvrName))) {
            /* Hit */
            sid->lastAccessTime = now;
            sid->references++;
            break;
        } else {
            sidp = &sid->next;
        }
    }
    UNLOCK_CACHE;
    return sid;
}

/*
** Add an sid to the cache or return a previously cached entry to the cache.
** Although this is static, it is called via ss->sec.cache().
*/
static void
CacheSID(sslSessionID *sid)
{
    PRUint32 expirationPeriod;

    PORT_Assert(sid->cached == never_cached);

    SSL_TRC(8, ("SSL: Cache: sid=0x%x cached=%d addr=0x%08x%08x%08x%08x port=0x%04x "
                "time=%x cached=%d",
                sid, sid->cached, sid->addr.pr_s6_addr32[0],
                sid->addr.pr_s6_addr32[1], sid->addr.pr_s6_addr32[2],
                sid->addr.pr_s6_addr32[3], sid->port, sid->creationTime,
                sid->cached));

    if (!sid->urlSvrName) {
        /* don't cache this SID because it can never be matched */
        return;
    }

    /* XXX should be different trace for version 2 vs. version 3 */
    if (sid->version < SSL_LIBRARY_VERSION_3_0) {
        expirationPeriod = ssl_sid_timeout;
        PRINT_BUF(8, (0, "sessionID:",
                      sid->u.ssl2.sessionID, sizeof(sid->u.ssl2.sessionID)));
        PRINT_BUF(8, (0, "masterKey:",
                      sid->u.ssl2.masterKey.data, sid->u.ssl2.masterKey.len));
        PRINT_BUF(8, (0, "cipherArg:",
                      sid->u.ssl2.cipherArg.data, sid->u.ssl2.cipherArg.len));
    } else {
        if (sid->u.ssl3.sessionIDLength == 0 &&
            sid->u.ssl3.locked.sessionTicket.ticket.data == NULL)
            return;

        /* Client generates the SessionID if this was a stateless resume. */
        if (sid->u.ssl3.sessionIDLength == 0) {
            SECStatus rv;
            rv = PK11_GenerateRandom(sid->u.ssl3.sessionID,
                                     SSL3_SESSIONID_BYTES);
            if (rv != SECSuccess)
                return;
            sid->u.ssl3.sessionIDLength = SSL3_SESSIONID_BYTES;
        }
        expirationPeriod = ssl3_sid_timeout;
        PRINT_BUF(8, (0, "sessionID:",
                      sid->u.ssl3.sessionID, sid->u.ssl3.sessionIDLength));

        sid->u.ssl3.lock = PR_NewRWLock(PR_RWLOCK_RANK_NONE, NULL);
        if (!sid->u.ssl3.lock) {
            return;
        }
    }
    PORT_Assert(sid->creationTime != 0 && sid->expirationTime != 0);
    if (!sid->creationTime)
        sid->lastAccessTime = sid->creationTime = ssl_Time();
    if (!sid->expirationTime)
        sid->expirationTime = sid->creationTime + expirationPeriod;

    /*
     * Put sid into the cache.  Bump reference count to indicate that
     * cache is holding a reference. Uncache will reduce the cache
     * reference.
     */
    LOCK_CACHE;
    sid->references++;
    sid->cached = in_client_cache;
    sid->next = cache;
    cache = sid;
    UNLOCK_CACHE;
}

/*
 * If sid "zap" is in the cache,
 *    removes sid from cache, and decrements reference count.
 * Caller must hold cache lock.
 */
static void
UncacheSID(sslSessionID *zap)
{
    sslSessionID **sidp = &cache;
    sslSessionID *sid;

    if (zap->cached != in_client_cache) {
        return;
    }

    SSL_TRC(8, ("SSL: Uncache: zap=0x%x cached=%d addr=0x%08x%08x%08x%08x port=0x%04x "
                "time=%x cipher=%d",
                zap, zap->cached, zap->addr.pr_s6_addr32[0],
                zap->addr.pr_s6_addr32[1], zap->addr.pr_s6_addr32[2],
                zap->addr.pr_s6_addr32[3], zap->port, zap->creationTime,
                zap->u.ssl2.cipherType));
    if (zap->version < SSL_LIBRARY_VERSION_3_0) {
        PRINT_BUF(8, (0, "sessionID:",
                      zap->u.ssl2.sessionID, sizeof(zap->u.ssl2.sessionID)));
        PRINT_BUF(8, (0, "masterKey:",
                      zap->u.ssl2.masterKey.data, zap->u.ssl2.masterKey.len));
        PRINT_BUF(8, (0, "cipherArg:",
                      zap->u.ssl2.cipherArg.data, zap->u.ssl2.cipherArg.len));
    }

    /* See if it's in the cache, if so nuke it */
    while ((sid = *sidp) != 0) {
        if (sid == zap) {
            /*
            ** Bingo. Reduce reference count by one so that when
            ** everyone is done with the sid we can free it up.
            */
            *sidp = zap->next;
            zap->cached = invalid_cache;
            ssl_FreeLockedSID(zap);
            return;
        }
        sidp = &sid->next;
    }
}

/* If sid "zap" is in the cache,
 *    removes sid from cache, and decrements reference count.
 * Although this function is static, it is called externally via
 *    ss->sec.uncache().
 */
static void
LockAndUncacheSID(sslSessionID *zap)
{
    LOCK_CACHE;
    UncacheSID(zap);
    UNLOCK_CACHE;
}

/* choose client or server cache functions for this sslsocket. */
void
ssl_ChooseSessionIDProcs(sslSecurityInfo *sec)
{
    if (sec->isServer) {
        sec->cache = ssl_sid_cache;
        sec->uncache = ssl_sid_uncache;
    } else {
        sec->cache = CacheSID;
        sec->uncache = LockAndUncacheSID;
    }
}

/* wipe out the entire client session cache. */
void
SSL_ClearSessionCache(void)
{
    LOCK_CACHE;
    while (cache != NULL)
        UncacheSID(cache);
    UNLOCK_CACHE;
}

/* returns an unsigned int containing the number of seconds in PR_Now() */
PRUint32
ssl_Time(void)
{
    PRUint32 myTime;
#if defined(XP_UNIX) || defined(XP_WIN) || defined(_WINDOWS) || defined(XP_BEOS)
    myTime = time(NULL); /* accurate until the year 2038. */
#else
    /* portable, but possibly slower */
    PRTime now;
    PRInt64 ll;

    now = PR_Now();
    LL_I2L(ll, 1000000L);
    LL_DIV(now, now, ll);
    LL_L2UI(myTime, now);
#endif
    return myTime;
}

void
ssl3_SetSIDSessionTicket(sslSessionID *sid,
                         /*in/out*/ NewSessionTicket *newSessionTicket)
{
    PORT_Assert(sid);
    PORT_Assert(newSessionTicket);
    PORT_Assert(newSessionTicket->ticket.data);
    PORT_Assert(newSessionTicket->ticket.len != 0);

    /* if sid->u.ssl3.lock, we are updating an existing entry that is already
     * cached or was once cached, so we need to acquire and release the write
     * lock. Otherwise, this is a new session that isn't shared with anything
     * yet, so no locking is needed.
     */
    if (sid->u.ssl3.lock) {
        PR_RWLock_Wlock(sid->u.ssl3.lock);
        if (sid->u.ssl3.locked.sessionTicket.ticket.data) {
            SECITEM_FreeItem(&sid->u.ssl3.locked.sessionTicket.ticket,
                             PR_FALSE);
        }
    }

    PORT_Assert(!sid->u.ssl3.locked.sessionTicket.ticket.data);

    /* Do a shallow copy, moving the ticket data. */
    sid->u.ssl3.locked.sessionTicket = *newSessionTicket;
    newSessionTicket->ticket.data = NULL;
    newSessionTicket->ticket.len = 0;

    if (sid->u.ssl3.lock) {
        PR_RWLock_Unlock(sid->u.ssl3.lock);
    }
}
