pEpEngine/src/pEpEngine.c

// This file is under GNU General Public License 3.0
// see LICENSE.txt

#include "pEp_internal.h"
#include "dynamic_api.h"
#include "cryptotech.h"
#include "transport.h"
#include "blacklist.h"

#include <time.h>
#include <stdlib.h>

static volatile int init_count = -1;

// sql overloaded functions - modified from sqlite3.c
static void _sql_lower(sqlite3_context* ctx, int argc, sqlite3_value** argv) {
    char *z1;
    const char *z2;
    int i, n;
    z2 = (char*)sqlite3_value_text(argv[0]);
    n = sqlite3_value_bytes(argv[0]);
    /* Verify that the call to _bytes() does not invalidate the _text() pointer */
    assert( z2==(char*)sqlite3_value_text(argv[0]) );
    if( z2 ){
        z1 = (char*)sqlite3_malloc(n+1);
        if( z1 ){
            for(i=0; i<n; i++){
                char c = z2[i];
                char c_mod = c | 0x20;
                if (c_mod < 0x61 || c_mod > 0x7a)
                    c_mod = c;
                z1[i] = c_mod;
            }
            z1[n] = '\0';
            sqlite3_result_text(ctx, z1, n, sqlite3_free);
        }
    }
}


// sql manipulation statements
static const char *sql_log = 
    "insert into log (title, entity, description, comment)"
     "values (?1, ?2, ?3, ?4);";

static const char *sql_trustword = 
    "select id, word from wordlist where lang = lower(?1) "
    "and id = ?2 ;";

static const char *sql_get_identity =  
    "select fpr, username, comm_type, lang,"
    "   identity.flags | pgp_keypair.flags,"
    "   is_own"
    "   from identity"
    "   join person on id = identity.user_id"
    "   join pgp_keypair on fpr = identity.main_key_id"
    "   join trust on id = trust.user_id"
    "       and pgp_keypair_fpr = identity.main_key_id"    
    "   where (case when (address = ?1) then (1)"
    "               when (lower(address) = lower(?1)) then (1)"
    "               when (replace(lower(address),'.','') = replace(lower(?1),'.','')) then (1)"
    "               else 0"
    "          end) = 1"
    "   and identity.user_id = ?2;";

static const char *sql_get_identity_without_trust_check =  
    "select identity.main_key_id, username, lang,"
    "   identity.flags, is_own"
    "   from identity"
    "   join person on id = identity.user_id"
    "   where (case when (address = ?1) then (1)"
    "               when (lower(address) = lower(?1)) then (1)"
    "               when (replace(lower(address),'.','') = replace(lower(?1),'.','')) then (1)"
    "               else 0"
    "          end) = 1"
    "   and identity.user_id = ?2;";

static const char *sql_get_identities_by_address =  
    "select user_id, identity.main_key_id, username, lang,"
    "   identity.flags, is_own"
    "   from identity"
    "   join person on id = identity.user_id"
    "   where (case when (address = ?1) then (1)"
    "               when (lower(address) = lower(?1)) then (1)"
    "               when (replace(lower(address),'.','') = replace(lower(?1),'.','')) then (1)"
    "               else 0"
    "          end) = 1;";

static const char *sql_replace_identities_fpr =  
    "update identity"
    "   set main_key_id = ?1 "
    "   where main_key_id = ?2 ;";
    
static const char *sql_remove_fpr_as_default =
    "update person set main_key_id = NULL where main_key_id = ?1 ;"
    "update identity set main_key_id = NULL where main_key_id = ?1 ;";

// Set person, but if already exist, only update.
// if main_key_id already set, don't touch.
static const char *sql_set_person = 
    "insert or replace into person (id, username, lang, main_key_id, device_group)"
    "  values (?1, ?2, ?3,"
    "    (select coalesce((select main_key_id from person "
    "      where id = ?1), upper(replace(?4,' ','')))),"
    "    (select device_group from person where id = ?1)) ;";

static const char *sql_set_device_group = 
    "update person set device_group = ?1 "
    "where id = ?2;";

// This will cascade to identity and trust
static const char* sql_replace_userid =
    "update person set id = ?1 " 
    "where id = ?2;";

static const char *sql_replace_main_user_fpr =  
    "update person "
    "   set main_key_id = ?1 "
    "   where id = ?2 ;";

static const char *sql_get_main_user_fpr =  
    "select main_key_id from person"
    "   where id = ?1 ;";

static const char *sql_refresh_userid_default_key =
    "update person "
    "   set main_key_id = "
    "       (select identity.main_key_id from identity "
    "           join trust on trust.user_id = identity.user_id "
    "               and trust.pgp_keypair_fpr = identity.main_key_id "
    "           join person on identity.user_id = identity.user_id "
    "       where identity.user_id = ?1 "
    "       order by trust.comm_type desc "
    "       limit 1) "
    "where id = ?1 ; ";

static const char *sql_get_device_group = 
    "select device_group from person "
    "where id = ?1;";

static const char *sql_set_pgp_keypair = 
    "insert or replace into pgp_keypair (fpr) "
    "values (upper(replace(?1,' ',''))) ;";

static const char *sql_set_identity = 
    "insert or replace into identity ("
    " address, main_key_id, "
    " user_id, flags, is_own"
    ") values ("
    " ?1,"
    " upper(replace(?2,' ','')),"
    " ?3,"
    // " (select"
    // "   coalesce("
    // "    (select flags from identity"
    // "     where address = ?1 and"
    // "           user_id = ?3),"
    // "    0)"
    // " ) | (?4 & 255)"
    /* set_identity ignores previous flags, and doesn't filter machine flags */
    " ?4,"
    " ?5"
    ");";
        
static const char *sql_set_identity_flags = 
    "update identity set flags = "
    "    ((?1 & 255) | (select flags from identity"
    "                   where address = ?2 and user_id = ?3)) "
    "where address = ?2 and user_id = ?3 ;";

static const char *sql_unset_identity_flags = 
    "update identity set flags = "
    "    ( ~(?1 & 255) & (select flags from identity"
    "                   where address = ?2 and user_id = ?3)) "
    "where address = ?2 and user_id = ?3 ;";

static const char *sql_set_trust =
    "insert or replace into trust (user_id, pgp_keypair_fpr, comm_type) "
    "values (?1, upper(replace(?2,' ','')), ?3) ;";

static const char *sql_update_trust_for_fpr =
    "update trust "
    "set comm_type = ?1 "
    "where pgp_keypair_fpr = upper(replace(?2,' ','')) ;";

static const char *sql_get_trust = 
    "select comm_type from trust where user_id = ?1 "
    "and pgp_keypair_fpr = upper(replace(?2,' ','')) ;";

static const char *sql_least_trust = 
    "select min(comm_type) from trust where"
    " pgp_keypair_fpr = upper(replace(?1,' ',''))"
    " and comm_type != 0;"; // ignores PEP_ct_unknown
    // returns PEP_ct_unknown only when no known trust is recorded

static const char *sql_mark_as_compromized = 
    "update trust not indexed set comm_type = 15"
    " where pgp_keypair_fpr = upper(replace(?1,' ','')) ;";
    
static const char *sql_crashdump = 
    "select timestamp, title, entity, description, comment"
    " from log order by timestamp desc limit ?1 ;";

static const char *sql_languagelist = 
    "select i18n_language.lang, name, phrase" 
    " from i18n_language join i18n_token using (lang) where i18n_token.id = 1000;" ;

static const char *sql_i18n_token = 
    "select phrase from i18n_token where lang = lower(?1) and id = ?2 ;";

// blacklist
static const char *sql_blacklist_add = 
    "insert or replace into blacklist_keys (fpr) values (upper(replace(?1,' ',''))) ;"
    "delete from identity where main_key_id = upper(replace(?1,' ','')) ;"
    "delete from pgp_keypair where fpr = upper(replace(?1,' ','')) ;";

static const char *sql_blacklist_delete =
    "delete from blacklist_keys where fpr = upper(replace(?1,' ','')) ;";

static const char *sql_blacklist_is_listed = 
    "select count(*) from blacklist_keys where fpr = upper(replace(?1,' ','')) ;";

static const char *sql_blacklist_retrieve = 
    "select * from blacklist_keys ;";
                

// Own keys
// We only care if it's 0 or non-zero
static const char *sql_own_key_is_listed = 
    "select count(*) from ("
    "   select pgp_keypair_fpr from trust"
    "      join identity on trust.user_id = identity.user_id"
    "      where pgp_keypair_fpr = upper(replace(?1,' ',''))"
    "           and identity.is_own = 1"
    ");";

static const char *sql_own_identities_retrieve =  
    "select address, fpr, username, identity.user_id, "
    "   lang, identity.flags | pgp_keypair.flags"
    "   from identity"
    "   join person on id = identity.user_id"
    "   join pgp_keypair on fpr = identity.main_key_id"
    "   join trust on id = trust.user_id"
    "       and pgp_keypair_fpr = identity.main_key_id"
    "   where identity.is_own = 1"
    "       and (identity.flags & ?1) = 0;";

static const char *sql_own_keys_retrieve = 
    "select pgp_keypair_fpr from trust"
    "   join identity on trust.user_id = identity.user_id"
    "   where identity.is_own = 1";

static const char* sql_get_user_default_key =
    "select main_key_id from person" 
    "   where id = ?1;";

static const char* sql_get_default_own_userid =
    "select id from person"
    "   join identity on id = identity.user_id"
    "   where identity.is_own = 1";

// Sequence
static const char *sql_sequence_value1 = 
    "insert or replace into sequences (name, value, own) "
    "values (?1, "
    "       (select coalesce((select value + 1 from sequences "
    "           where name = ?1), 1 )), "
    "       (select coalesce((select own or ?2 from sequences "
    "           where name = ?1), ?2))) ; ";

static const char *sql_sequence_value2 = 
    "select value, own from sequences where name = ?1 ;";

static const char *sql_sequence_value3 = 
    "insert or replace into sequences (name, value, own) "
    "values (?1, "
    "        ?2, "
    "       (select coalesce((select own or ?3 from sequences "
    "           where name = ?1), ?3))) ; ";
        
// Revocation tracking
static const char *sql_set_revoked =
    "insert or replace into revoked_keys ("
    "    revoked_fpr, replacement_fpr, revocation_date) "
    "values (upper(replace(?1,' ','')),"
    "        upper(replace(?2,' ','')),"
    "        ?3) ;";
        
static const char *sql_get_revoked = 
    "select revoked_fpr, revocation_date from revoked_keys"
    "    where replacement_fpr = upper(replace(?1,' ','')) ;";

static const char *sql_get_userid_alias_default =
    "select default_id from alternate_user_id "
    "   where alternate_id = ?1 ; ";

static const char *sql_add_userid_alias =
    "insert or replace into alternate_user_id (default_id, alternate_id) "
    "values (?1, ?2) ;";
    
static int user_version(void *_version, int count, char **text, char **name)
{
    assert(_version);
    assert(count == 1);
    assert(text && text[0]);
    if (!(_version && count == 1 && text && text[0]))
        return -1;

    int *version = (int *) _version;
    *version = atoi(text[0]);
    return 0;
}

static int table_contains_column(PEP_SESSION session, const char* table_name,
                                                      const char* col_name) {


    if (!session || !table_name || !col_name)
        return -1;
        
    // Table names can't be SQL parameters, so we do it this way.
    
    // these two must be the same number.
    char sql_buf[500];
    const size_t max_q_len = 500;
    
    size_t t_size, c_size, q_size;
    
    const char* q1 = "SELECT "; // 7
    const char* q2 = " from "; // 6
    const char* q3 = ";";       // 1
    
    q_size = 14;
    t_size = strlen(table_name);
    c_size = strlen(col_name);
    
    size_t query_len = q_size + c_size + t_size + 1;
    
    if (query_len > max_q_len)
        return -1;

    strlcpy(sql_buf, q1, max_q_len);
    strlcat(sql_buf, col_name, max_q_len);
    strlcat(sql_buf, q2, max_q_len);
    strlcat(sql_buf, table_name, max_q_len);
    strlcat(sql_buf, q3, max_q_len);

    sqlite3_stmt *stmt; 

    sqlite3_prepare_v2(session->db, sql_buf, -1, &stmt, NULL);

    int retval = 0;

    int rc = sqlite3_step(stmt);  
    if (rc == SQLITE_DONE || rc == SQLITE_OK || rc == SQLITE_ROW) {
        retval = 1;
    }

    sqlite3_finalize(stmt);      
        
    return retval;
}

DYNAMIC_API PEP_STATUS init(PEP_SESSION *session)
{
    PEP_STATUS status = PEP_STATUS_OK;
    int int_result;
    
    bool in_first = false;
    bool very_first = false;

    assert(sqlite3_threadsafe());
    if (!sqlite3_threadsafe())
        return PEP_INIT_SQLITE3_WITHOUT_MUTEX;

    // a little race condition - but still a race condition
    // mitigated by calling caveat (see documentation)

    // this increment is made atomic IN THE ADAPTERS by
    // guarding the call to init with the appropriate mutex.
    int _count = ++init_count;
    if (_count == 0)
        in_first = true;
    
    // Race condition mitigated by calling caveat starts here :
    // If another call to init() preempts right now, then preemptive call
    // will have in_first false, will not create SQL tables, and following
    // calls relying on those tables will fail.
    //
    // Therefore, as above, adapters MUST guard init() with a mutex.
    // 
    // Therefore, first session
    // is to be created and last session to be deleted alone, and not
    // concurently to other sessions creation or deletion.
    // We expect adapters to enforce this either by implicitely creating a
    // client session, or by using synchronization primitive to protect
    // creation/deletion of first/last session from the app.

    assert(session);
    if (session == NULL)
        return PEP_ILLEGAL_VALUE;

    *session = NULL;

    pEpSession *_session = calloc(1, sizeof(pEpSession));
    assert(_session);
    if (_session == NULL)
        goto enomem;

    _session->version = PEP_ENGINE_VERSION;

#ifdef DEBUG_ERRORSTACK
    _session->errorstack = new_stringlist("init()");
#endif

    assert(LOCAL_DB);
    if (LOCAL_DB == NULL) {
        status = PEP_INIT_CANNOT_OPEN_DB;
        goto pep_error;
    }

    int_result = sqlite3_open_v2(
            LOCAL_DB,
            &_session->db,
            SQLITE_OPEN_READWRITE
                | SQLITE_OPEN_CREATE
                | SQLITE_OPEN_FULLMUTEX
                | SQLITE_OPEN_PRIVATECACHE,
            NULL 
        );

    if (int_result != SQLITE_OK) {
        status = PEP_INIT_CANNOT_OPEN_DB;
        goto pep_error;
    }

    int_result = sqlite3_exec(
            _session->db,
            "PRAGMA locking_mode=NORMAL;\n"
            "PRAGMA journal_mode=WAL;\n",
            NULL,
            NULL,
            NULL
        );


    sqlite3_busy_timeout(_session->db, BUSY_WAIT_TIME);

    assert(SYSTEM_DB);
    if (SYSTEM_DB == NULL) {
        status = PEP_INIT_CANNOT_OPEN_SYSTEM_DB;
        goto pep_error;
    }

    int_result = sqlite3_open_v2(
            SYSTEM_DB, &_session->system_db,
            SQLITE_OPEN_READONLY
                | SQLITE_OPEN_FULLMUTEX
                | SQLITE_OPEN_SHAREDCACHE,
            NULL
        );

    if (int_result != SQLITE_OK) {
        status = PEP_INIT_CANNOT_OPEN_SYSTEM_DB;
        goto pep_error;
    }

    sqlite3_busy_timeout(_session->system_db, 1000);

// increment this when patching DDL
#define _DDL_USER_VERSION "7"

    if (in_first) {

        int_result = sqlite3_exec(
            _session->db,
                "create table if not exists version_info (\n"
                "   id integer primary key,\n"
                "   timestamp integer default (datetime('now')),\n"
                "   version text,\n"
                "   comment text\n"
                ");\n",
                NULL,
                NULL,
                NULL
        );
        int_result = sqlite3_exec(
            _session->db,
                "PRAGMA application_id = 0x23423423;\n"
                "create table if not exists log (\n"
                "   timestamp integer default (datetime('now')),\n"
                "   title text not null,\n"
                "   description text,\n"
                "   entity text not null,\n"
                "   comment text\n"
                ");\n"
                "create index if not exists log_timestamp on log (\n"
                "   timestamp\n"
                ");\n"
                "create table if not exists pgp_keypair (\n"
                "   fpr text primary key,\n"
                "   created integer,\n"
                "   expires integer,\n"
                "   comment text,\n"
                "   flags integer default 0\n"
                ");\n"
                "create index if not exists pgp_keypair_expires on pgp_keypair (\n"
                "   expires\n"
                ");\n"
                "create table if not exists person (\n"
                "   id text primary key,\n"
                "   username text not null,\n"
                "   main_key_id text\n"
                "       references pgp_keypair (fpr)\n"
                "       on delete set null,\n"
                "   lang text,\n"
                "   comment text,\n"
                "   device_group text\n"
                ");\n"
                "create table if not exists identity (\n"
                "   address text,\n"
                "   user_id text\n"
                "       references person (id)\n"
                "       on delete cascade on update cascade,\n"
                "   main_key_id text\n"
                "       references pgp_keypair (fpr)\n"
                "       on delete set null,\n"
                "   comment text,\n"
                "   flags integer default 0,\n"
                "   is_own integer default 0,\n"
                "   primary key (address, user_id)\n"
                ");\n"
                "create table if not exists trust (\n"
                "   user_id text not null\n"
                "       references person (id)\n"
                "       on delete cascade on update cascade,\n"
                "   pgp_keypair_fpr text not null\n"
                "       references pgp_keypair (fpr)\n"
                "       on delete cascade,\n"
                "   comm_type integer not null,\n"
                "   comment text,\n"
                "   primary key (user_id, pgp_keypair_fpr)\n"
                ");\n"
                // blacklist
                "create table if not exists blacklist_keys (\n"
                "   fpr text primary key\n"
                ");\n"
                // sequences
                "create table if not exists sequences(\n"
                "   name text primary key,\n"
                "   value integer default 0,\n"
                "   own integer default 0\n"
                ");\n"
                "create table if not exists revoked_keys (\n"
                "   revoked_fpr text primary key,\n"
                "   replacement_fpr text not null\n"
                "       references pgp_keypair (fpr)\n"
                "       on delete cascade,\n"
                "   revocation_date integer\n"
                ");\n"
                // user id aliases
                "create table if not exists alternate_user_id (\n"
                "    default_id text references person (id)\n"
                "       on delete cascade on update cascade,\n"
                "    alternate_id text primary key\n"
                ");\n"
                // mistrusted keys
                "create table if not exists mistrusted_keys (\n"
                "    fpr text primary key\n"
                ");\n"
                ,
            NULL,
            NULL,
            NULL
        );
        assert(int_result == SQLITE_OK);

        int version;
        int_result = sqlite3_exec(
            _session->db,
            "pragma user_version;",
            user_version,
            &version,
            NULL
        );

        assert(int_result == SQLITE_OK);
        
        void (*xFunc_lower)(sqlite3_context*,int,sqlite3_value**) = &_sql_lower;
        
        int_result = sqlite3_create_function_v2(
            _session->db,
            "lower",
            1,
            SQLITE_UTF8 | SQLITE_DETERMINISTIC,
            NULL,
            xFunc_lower,
            NULL,
            NULL,
            NULL);
        assert(int_result == SQLITE_OK);
        
        // Sometimes the user_version wasn't set correctly. Check to see if this
        // is really necessary...
        if (version == 1) {
            bool version_changed = true;
            
            if (table_contains_column(_session, "identity", "is_own") > 0) {
                version = 6;
            }
            else if (table_contains_column(_session, "sequences", "own") > 0) {
                version = 3;
            }
            else if (table_contains_column(_session, "pgp_keypair", "flags") > 0) {
                version = 2;
            }
            else {
                version_changed = false;
            }
            
            if (version_changed) {
                // set it in the DB, finally. Yeesh.
                char verbuf[21]; // enough digits for a max-sized 64 bit int, cmon. 
                sprintf(verbuf,"%d",version);
                
                size_t query_size = strlen(verbuf) + 25;
                char* query = calloc(query_size, 1);
                
                strlcpy(query, "pragma user_version = ", query_size);
                strlcat(query, verbuf, query_size);
                strlcat(query, ";", query_size);
                
                int_result = sqlite3_exec(
                    _session->db,
                    query,
                    user_version,
                    &version,
                    NULL
                );
                free(query);
            }
        }


        if(version != 0) { 
            // Version has been already set

            // Early mistake : version 0 shouldn't have existed.
            // Numbering should have started at 1 to detect newly created DB.
            // Version 0 DBs are not anymore compatible.

            // // Was version 0 compat code.
            // if (version < 1) {
            //     int_result = sqlite3_exec(
            //         _session->db,
            //         "alter table identity\n"
            //         "   add column flags integer default 0;\n",
            //         NULL,
            //         NULL,
            //         NULL
            //     );
            //     assert(int_result == SQLITE_OK);
            // }
            
            if (version < 2) {
                int_result = sqlite3_exec(
                    _session->db,
                    "alter table pgp_keypair\n"
                    "   add column flags integer default 0;\n"
                    "alter table person\n"
                    "   add column device_group text;\n",
                    NULL,
                    NULL,
                    NULL
                );
                assert(int_result == SQLITE_OK);
            }

            if (version < 3) {
                int_result = sqlite3_exec(
                    _session->db,
                    "alter table sequences\n"
                    "   add column own integer default 0;\n",
                    NULL,
                    NULL,
                    NULL
                );
                assert(int_result == SQLITE_OK);
            }

            if (version < 5) {
                int_result = sqlite3_exec(
                    _session->db,
                    "delete from pgp_keypair where fpr = '';",
                    NULL,
                    NULL,
                    NULL
                );
                assert(int_result == SQLITE_OK);
                int_result = sqlite3_exec(
                    _session->db,
                    "delete from trust where pgp_keypair_fpr = '';",
                    NULL,
                    NULL,
                    NULL
                );
                assert(int_result == SQLITE_OK);
            }
            
            if (version < 6) {
                int_result = sqlite3_exec(
                    _session->db,
                    "alter table identity\n"
                    "   add column is_own integer default 0;\n",
                    NULL,
                    NULL,
                    NULL
                );
                assert(int_result == SQLITE_OK);                
                int_result = sqlite3_exec(
                    _session->db,
                    "update identity\n"
                    "   set is_own = 1\n"
                    "   where (user_id = '" PEP_OWN_USERID "');\n",
                    NULL,
                    NULL,
                    NULL
                );
                assert(int_result == SQLITE_OK);    

                // Turns out that just adding "on update cascade" in
                // sqlite is a PITA. We need to be able to cascade
                // person->id replacements (for temp ids like "TOFU_")
                // so here we go...
                int_result = sqlite3_exec(
                    _session->db,
                    "PRAGMA foreign_keys=off;\n"
                    "BEGIN TRANSACTION;\n"
                    "ALTER TABLE identity RENAME TO _identity_old;\n"
                    "create table identity (\n"
                    "   address text,\n"
                    "   user_id text\n"
                    "       references person (id)\n"
                    "       on delete cascade on update cascade,\n"
                    "   main_key_id text\n"
                    "       references pgp_keypair (fpr)\n"
                    "       on delete set null,\n"
                    "   comment text,\n"
                    "   flags integer default 0,\n"
                    "   is_own integer default 0,\n"
                    "   primary key (address, user_id)\n"
                    ");\n"
                    "INSERT INTO identity SELECT * FROM _identity_old;\n"
                    "DROP TABLE _identity_old;\n"
                    "ALTER TABLE trust RENAME TO _trust_old;\n"
                    "create table trust (\n"
                    "   user_id text not null\n"
                    "       references person (id)\n"
                    "       on delete cascade on update cascade,\n"
                    "   pgp_keypair_fpr text not null\n"
                    "       references pgp_keypair (fpr)\n"
                    "       on delete cascade,\n"
                    "   comm_type integer not null,\n"
                    "   comment text,\n"
                    "   primary key (user_id, pgp_keypair_fpr)\n"
                    ");\n"
                    "INSERT INTO trust SELECT * FROM _trust_old;\n"
                    "DROP TABLE _trust_old;\n"
                    "COMMIT;\n"
                    "\n"
                    "PRAGMA foreign_keys=on;\n"
                    "create table if not exists alternate_user_id (\n"
                    "    default_id text references person (id)\n"
                    "       on delete cascade on update cascade,\n"
                    "    alternate_id text primary key\n"
                    ");\n"
                    ,
                    NULL,
                    NULL,
                    NULL
                );
                assert(int_result == SQLITE_OK);    
            }
        }
        if (version < 7) {
            int_result = sqlite3_exec(
                _session->db,
                "create table if not exists mistrusted_keys (\n"
                "    fpr text primary key\n"
                ");\n"            
                NULL,
                NULL,
                NULL
            );
        }
        else { 
            // Version from DB was 0, it means this is initial setup.
            // DB has just been created, and all tables are empty.
            very_first = true;
        }

        if (version < atoi(_DDL_USER_VERSION)) {
            int_result = sqlite3_exec(
                _session->db,
                "pragma user_version = "_DDL_USER_VERSION";\n"
                "insert or replace into version_info (id, version)"
                    "values (1, '" PEP_ENGINE_VERSION "');",
                NULL,
                NULL,
                NULL
            );
            assert(int_result == SQLITE_OK);
        }
        
        // We need to init a few globals for message id that we'd rather not
        // calculate more than once.
        _init_globals();
    }

    int_result = sqlite3_prepare_v2(_session->db, sql_log,
            (int)strlen(sql_log), &_session->log, NULL);