ssl_scache_shmcb.c

Apache官方在今天放出产品系列2.2的最新版本2.2.11的源码包 最流行的HTTP服务器软件之一

/*
 * Subcache-level cache operations 
 */

static void shmcb_subcache_expire(server_rec *s, SHMCBHeader *header,
                                  SHMCBSubcache *subcache)
{
    time_t now = time(NULL);
    unsigned int loop = 0;
    unsigned int new_idx_pos = subcache->idx_pos;
    SHMCBIndex *idx = NULL;

    while (loop < subcache->idx_used) {
        idx = SHMCB_INDEX(subcache, new_idx_pos);
        if (idx->expires > now)
            /* it hasn't expired yet, we're done iterating */
            break;
        loop++;
        new_idx_pos = SHMCB_CYCLIC_INCREMENT(new_idx_pos, 1, header->index_num);
    }
    if (!loop)
        /* Nothing to do */
        return;
    ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s,
                 "will be expiring %u sessions", loop);
    if (loop == subcache->idx_used) {
        /* We're expiring everything, piece of cake */
        subcache->idx_used = 0;
        subcache->data_used = 0;
    } else {
        /* There remain other indexes, so we can use idx to adjust 'data' */
        unsigned int diff = SHMCB_CYCLIC_SPACE(subcache->data_pos,
                                               idx->data_pos,
                                               header->subcache_data_size);
        /* Adjust the indexes */
        subcache->idx_used -= loop;
        subcache->idx_pos = new_idx_pos;
        /* Adjust the data area */
        subcache->data_used -= diff;
        subcache->data_pos = idx->data_pos;
    }
    header->stat_expiries += loop;
    ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s,
                 "we now have %u sessions", subcache->idx_used);
}

static BOOL shmcb_subcache_store(server_rec *s, SHMCBHeader *header,
                                 SHMCBSubcache *subcache, 
                                 UCHAR *data, unsigned int data_len,
                                 UCHAR *id, time_t expiry)
{
    unsigned int new_offset, new_idx;
    SHMCBIndex *idx;

    /* Sanity check the input */
    if ((data_len > header->subcache_data_size) || (data_len > SSL_SESSION_MAX_DER)) {
        ap_log_error(APLOG_MARK, APLOG_ERR, 0, s,
                     "inserting session larger (%d) than subcache data area (%d)",
                     data_len, header->subcache_data_size);
        return FALSE;
    }

    /* If there are entries to expire, ditch them first. */
    shmcb_subcache_expire(s, header, subcache);

    /* Loop until there is enough space to insert */
    if (header->subcache_data_size - subcache->data_used < data_len
        || subcache->idx_used == header->index_num) {
        unsigned int loop = 0;

        idx = SHMCB_INDEX(subcache, subcache->idx_pos);
        ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s,
                     "about to force-expire, subcache: idx_used=%d, "
                     "data_used=%d", subcache->idx_used, subcache->data_used);
        do {
            SHMCBIndex *idx2;

            /* Adjust the indexes by one */
            subcache->idx_pos = SHMCB_CYCLIC_INCREMENT(subcache->idx_pos, 1,
                                                       header->index_num);
            subcache->idx_used--;
            if (!subcache->idx_used) {
                /* There's nothing left */
                subcache->data_used = 0;
                break;
            }
            /* Adjust the data */
            idx2 = SHMCB_INDEX(subcache, subcache->idx_pos);
            subcache->data_used -= SHMCB_CYCLIC_SPACE(idx->data_pos, idx2->data_pos,
                                                      header->subcache_data_size);
            subcache->data_pos = idx2->data_pos;
            /* Stats */
            header->stat_scrolled++;
            /* Loop admin */
            idx = idx2;
            loop++;
        } while (header->subcache_data_size - subcache->data_used < data_len);

        ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s,
                     "finished force-expire, subcache: idx_used=%d, "
                     "data_used=%d", subcache->idx_used, subcache->data_used);
    }

    /* HERE WE ASSUME THAT THE NEW SESSION SHOULD GO ON THE END! I'M NOT
     * CHECKING WHETHER IT SHOULD BE GENUINELY "INSERTED" SOMEWHERE.
     *
     * We either fix that, or find out at a "higher" (read "mod_ssl")
     * level whether it is possible to have distinct session caches for
     * any attempted tomfoolery to do with different session timeouts.
     * Knowing in advance that we can have a cache-wide constant timeout
     * would make this stuff *MUCH* more efficient. Mind you, it's very
     * efficient right now because I'm ignoring this problem!!!
     */
    /* Insert the data */
    new_offset = SHMCB_CYCLIC_INCREMENT(subcache->data_pos, subcache->data_used,
                                        header->subcache_data_size);
    shmcb_cyclic_ntoc_memcpy(header->subcache_data_size,
                             SHMCB_DATA(header, subcache), new_offset,
                             data, data_len);
    subcache->data_used += data_len;
    /* Insert the index */
    new_idx = SHMCB_CYCLIC_INCREMENT(subcache->idx_pos, subcache->idx_used,
                                     header->index_num);
    idx = SHMCB_INDEX(subcache, new_idx);
    idx->expires = expiry;
    idx->data_pos = new_offset;
    idx->data_used = data_len;
    idx->s_id2 = id[1];
    idx->removed = 0;
    subcache->idx_used++;
    ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s,
                 "insert happened at idx=%d, data=%d", new_idx, new_offset);
    ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s,
                 "finished insert, subcache: idx_pos/idx_used=%d/%d, "
                 "data_pos/data_used=%d/%d",
                 subcache->idx_pos, subcache->idx_used,
                 subcache->data_pos, subcache->data_used);
    return TRUE;
}

static SSL_SESSION *shmcb_subcache_retrieve(server_rec *s, SHMCBHeader *header,
                                            SHMCBSubcache *subcache, UCHAR *id,
                                            unsigned int idlen)
{
    unsigned int pos;
    unsigned int loop = 0;

    /* If there are entries to expire, ditch them first. */
    shmcb_subcache_expire(s, header, subcache);
    pos = subcache->idx_pos;

    while (loop < subcache->idx_used) {
        SHMCBIndex *idx = SHMCB_INDEX(subcache, pos);

        /* Only consider 'idx' if;
         * (a) the s_id2 byte matches
         * (b) the "removed" flag isn't set.
         */
        if ((idx->s_id2 == id[1]) && !idx->removed) {
            SSL_SESSION *pSession;
            unsigned char *s_id;
            unsigned int s_idlen;
            unsigned char tempasn[SSL_SESSION_MAX_DER];
            MODSSL_D2I_SSL_SESSION_CONST unsigned char *ptr = tempasn;

            ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s,
                         "possible match at idx=%d, data=%d", pos, idx->data_pos);
            /* Copy the data */
            shmcb_cyclic_cton_memcpy(header->subcache_data_size,
                                     tempasn, SHMCB_DATA(header, subcache),
                                     idx->data_pos, idx->data_used);
            /* Decode the session */
            pSession = d2i_SSL_SESSION(NULL, &ptr, idx->data_used);
            if (!pSession) {
                ap_log_error(APLOG_MARK, APLOG_ERR, 0, s,
                             "shmcb_subcache_retrieve internal error");
                return NULL;
            }
            s_id = SSL_SESSION_get_session_id(pSession);
            s_idlen = SSL_SESSION_get_session_id_length(pSession);
            if (s_idlen == idlen && memcmp(s_id, id, idlen) == 0) {
                /* Found the matching session */
                ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s,
                             "shmcb_subcache_retrieve returning matching session");
                return pSession;
            }
            SSL_SESSION_free(pSession);
        }
        /* Increment */
        loop++;
        pos = SHMCB_CYCLIC_INCREMENT(pos, 1, header->index_num);
    }

    ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s,
                 "shmcb_subcache_retrieve found no match");
    return NULL;
}

static BOOL shmcb_subcache_remove(server_rec *s, SHMCBHeader *header,
                                  SHMCBSubcache *subcache,
                                  UCHAR *id, unsigned int idlen)
{
    unsigned int pos;
    unsigned int loop = 0;
    BOOL to_return = FALSE;

    /* Unlike the others, we don't do an expire-run first. This is to keep
     * consistent statistics where a "remove" operation may actually be the
     * higher layer spotting an expiry issue prior to us. Our caller is
     * handling stats, so a failure return would be inconsistent if the
     * intended session was in fact removed by an expiry run. */

    pos = subcache->idx_pos;
    while (!to_return && (loop < subcache->idx_used)) {
        SHMCBIndex *idx = SHMCB_INDEX(subcache, pos);
        /* Only consider 'idx' if the s_id2 byte matches and it's not already
         * removed - easiest way to avoid costly ASN decodings. */
        if ((idx->s_id2 == id[1]) && !idx->removed) {
            SSL_SESSION *pSession;
            unsigned char *s_id;
            unsigned int s_idlen;
            unsigned char tempasn[SSL_SESSION_MAX_DER];
            MODSSL_D2I_SSL_SESSION_CONST unsigned char *ptr = tempasn;

            ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s,
                         "possible match at idx=%d, data=%d", pos, idx->data_pos);
            /* Copy the data */
            shmcb_cyclic_cton_memcpy(header->subcache_data_size,
                                     tempasn, SHMCB_DATA(header, subcache),
                                     idx->data_pos, idx->data_used);
            /* Decode the session */
            pSession = d2i_SSL_SESSION(NULL, &ptr, idx->data_used);
            if (!pSession) {
                ap_log_error(APLOG_MARK, APLOG_ERR, 0, s,
                             "shmcb_subcache_remove internal error");
                return FALSE;
            }
            s_id = SSL_SESSION_get_session_id(pSession);
            s_idlen = SSL_SESSION_get_session_id_length(pSession);
            if (s_idlen == idlen && memcmp(s_id, id, idlen) == 0) {
                /* Found the matching session, remove it quietly. */
                idx->removed = 1;
                to_return = TRUE;
                ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s,
                             "shmcb_subcache_remove removing matching session");
            }
            SSL_SESSION_free(pSession);
        }
        /* Increment */
        loop++;
        pos = SHMCB_CYCLIC_INCREMENT(pos, 1, header->index_num);
    }

    return to_return;
}