dict_pgsql.c

[詳解]

/*++
/* NAME
/*  dict_pgsql 3
/* SUMMARY
/*  dictionary manager interface to PostgreSQL databases
/* SYNOPSIS
/*  #include <dict_pgsql.h>
/*
/*  DICT    *dict_pgsql_open(name, open_flags, dict_flags)
/*  const char *name;
/*  int open_flags;
/*  int dict_flags;
/* DESCRIPTION
/*  dict_pgsql_open() creates a dictionary of type 'pgsql'.  This
/*  dictionary is an interface for the postfix key->value mappings
/*  to pgsql.  The result is a pointer to the installed dictionary,
/*  or a null pointer in case of problems.
/*
/*  The pgsql dictionary can manage multiple connections to
/*  different sql servers for the same database.  It assumes that
/*  the underlying data on each server is identical (mirrored) and
/*  maintains one connection at any given time.  If any connection
/*  fails,  any other available ones will be opened and used.
/*  The intent of this feature is to eliminate a single point of
/*  failure for mail systems that would otherwise rely on a single
/*  pgsql server.
/* .PP
/*  Arguments:
/* .IP name
/*  Either the path to the PostgreSQL configuration file (if it
/*  starts with '/' or '.'), or the prefix which will be used to
/*  obtain main.cf configuration parameters for this search.
/*
/*  In the first case, the configuration parameters below are
/*  specified in the file as \fIname\fR=\fIvalue\fR pairs.
/*
/*  In the second case, the configuration parameters are
/*  prefixed with the value of \fIname\fR and an underscore,
/*  and they are specified in main.cf.  For example, if this
/*  value is \fIpgsqlsource\fR, the parameters would look like
/*  \fIpgsqlsource_user\fR, \fIpgsqlsource_table\fR, and so on.
/* .IP other_name
/*  reference for outside use.
/* .IP open_flags
/*  Must be O_RDONLY.
/* .IP dict_flags
/*  See dict_open(3).
/*
/* .PP
/*  Configuration parameters:
/* .IP user
/*  Username for connecting to the database.
/* .IP password
/*  Password for the above.
/* .IP dbname
/*  Name of the database.
/* .IP query
/*  Query template. If not defined a default query template is constructed
/*  from the legacy \fIselect_function\fR or failing that the \fItable\fR,
/*  \fIselect_field\fR, \fIwhere_field\fR, and \fIadditional_conditions\fR
/*  parameters. Before the query is issues, variable substitutions are
/*  performed. See pgsql_table(5).
/* .IP domain
/*  List of domains the queries should be restricted to.  If
/*  specified, only FQDN addresses whose domain parts matching this
/*  list will be queried against the SQL database.  Lookups for
/*  partial addresses are also suppressed.  This can significantly
/*  reduce the query load on the server.
/* .IP result_format
/*  The format used to expand results from queries.  Substitutions
/*  are performed as described in pgsql_table(5). Defaults to returning
/*  the lookup result unchanged.
/* .IP expansion_limit
/*  Limit (if any) on the total number of lookup result values. Lookups which
/*  exceed the limit fail with dict->error=DICT_ERR_RETRY. Note that each
/*  non-empty (and non-NULL) column of a multi-column result row counts as
/*  one result.
/* .IP select_function
/*  When \fIquery\fR is not defined, the function to be used instead of
/*  the default query based on the legacy \fItable\fR, \fIselect_field\fR,
/*  \fIwhere_field\fR, and \fIadditional_conditions\fR parameters.
/* .IP table
/*  When \fIquery\fR and \fIselect_function\fR are not defined, the name of the
/*  FROM table used to construct the default query template, see pgsql_table(5).
/* .IP select_field
/*  When \fIquery\fR and \fIselect_function\fR are not defined, the name of the
/*  SELECT field used to construct the default query template, see pgsql_table(5).
/* .IP where_field
/*  When \fIquery\fR and \fIselect_function\fR are not defined, the name of the
/*  WHERE field used to construct the default query template, see pgsql_table(5).
/* .IP additional_conditions
/*  When \fIquery\fR and \fIselect_function\fR are not defined, the name of the
/*  additional text to add to the WHERE field in the default query template (this
/*  usually begins with "and") see pgsql_table(5).
/* .IP hosts
/*  List of hosts to connect to.
/* .PP
/*  For example, if you want the map to reference databases of
/*  the name "your_db" and execute a query like this: select
/*  forw_addr from aliases where alias like '<some username>'
/*  against any database called "postfix_info" located on hosts
/*  host1.some.domain and host2.some.domain, logging in as user
/*  "postfix" and password "passwd" then the configuration file
/*  should read:
/* .PP
/*  user = postfix
/* .br
/*  password = passwd
/* .br
/*  dbname = postfix_info
/* .br
/*  table = aliases
/* .br
/*  select_field = forw_addr
/* .br
/*  where_field = alias
/* .br
/*  hosts = host1.some.domain host2.some.domain
/* .PP
/* SEE ALSO
/*  dict(3) generic dictionary manager
/* AUTHOR(S)
/*  Aaron Sethman
/*  androsyn@ratbox.org
/*
/*  Based upon dict_mysql.c by
/*
/*  Scott Cotton
/*  IC Group, Inc.
/*  scott@icgroup.com
/*
/*  Joshua Marcus
/*  IC Group, Inc.
/*  josh@icgroup.com
/*--*/

/* System library. */

#include "sys_defs.h"

#ifdef HAS_PGSQL
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <syslog.h>
#include <time.h>

#include <postgres_ext.h>
#include <libpq-fe.h>

/* Utility library. */

#include "dict.h"
#include "msg.h"
#include "mymalloc.h"
#include "argv.h"
#include "vstring.h"
#include "split_at.h"
#include "myrand.h"
#include "events.h"
#include "stringops.h"

/* Global library. */

#include "cfg_parser.h"
#include "db_common.h"

/* Application-specific. */

#include "dict_pgsql.h"

#define STATACTIVE          (1<<0)
#define STATFAIL            (1<<1)
#define STATUNTRIED         (1<<2)

#define TYPEUNIX            (1<<0)
#define TYPEINET            (1<<1)
#define TYPECONNSTRING          (1<<2)

#define RETRY_CONN_MAX          100
#define RETRY_CONN_INTV         60  /* 1 minute */
#define IDLE_CONN_INTV          60  /* 1 minute */

typedef struct {
    PGconn *db;
    char   *hostname;
    char   *name;
    char   *port;
    unsigned type;          /* TYPEUNIX | TYPEINET | TYPECONNSTRING*/
    unsigned stat;          /* STATUNTRIED | STATFAIL | STATCUR */
    time_t  ts;             /* used for attempting reconnection */
} HOST;

typedef struct {
    int     len_hosts;          /* number of hosts */
    HOST  **db_hosts;           /* hosts on which databases reside */
} PLPGSQL;

typedef struct {
    DICT    dict;
    CFG_PARSER *parser;
    char   *query;
    char   *result_format;
    void   *ctx;
    int     expansion_limit;
    char   *username;
    char   *password;
    char   *dbname;
    char   *table;
    ARGV   *hosts;
    PLPGSQL *pldb;
    HOST   *active_host;
} DICT_PGSQL;


/* Just makes things a little easier for me.. */
#define PGSQL_RES PGresult

/* internal function declarations */
static PLPGSQL *plpgsql_init(ARGV *);
static PGSQL_RES *plpgsql_query(DICT_PGSQL *, const char *, VSTRING *, char *,
                        char *, char *);
static void plpgsql_dealloc(PLPGSQL *);
static void plpgsql_close_host(HOST *);
static void plpgsql_down_host(HOST *);
static void plpgsql_connect_single(HOST *, char *, char *, char *);
static const char *dict_pgsql_lookup(DICT *, const char *);
DICT   *dict_pgsql_open(const char *, int, int);
static void dict_pgsql_close(DICT *);
static HOST *host_init(const char *);

/* dict_pgsql_quote - escape SQL metacharacters in input string */

static void dict_pgsql_quote(DICT *dict, const char *name, VSTRING *result)
{
    DICT_PGSQL *dict_pgsql = (DICT_PGSQL *) dict;
    HOST   *active_host = dict_pgsql->active_host;
    char   *myname = "dict_pgsql_quote";
    size_t  len = strlen(name);
    size_t  buflen;
    int     err = 1;

    if (active_host == 0)
    msg_panic("%s: bogus dict_pgsql->active_host", myname);

    /*
     * We won't get arithmetic overflows in 2*len + 1, because Postfix input
     * keys have reasonable size limits, better safe than sorry.
     */
    if (len > (SSIZE_T_MAX - VSTRING_LEN(result) - 1) / 2)
    msg_panic("%s: arithmetic overflow in %lu+2*%lu+1",
          myname, (unsigned long) VSTRING_LEN(result),
          (unsigned long) len);
    buflen = 2 * len + 1;

    /*
     * XXX Workaround: stop further processing when PQescapeStringConn()
     * (below) fails. A more proper fix requires invasive changes, not
     * suitable for a stable release.
     */
    if (active_host->stat == STATFAIL)
    return;

    /*
     * Escape the input string, using PQescapeStringConn(), because the older
     * PQescapeString() is not safe anymore, as stated by the documentation.
     * 
     * From current libpq (8.1.4) documentation:
     * 
     * PQescapeStringConn writes an escaped version of the from string to the to
     * buffer, escaping special characters so that they cannot cause any
     * harm, and adding a terminating zero byte.
     * 
     * ...
     * 
     * The parameter from points to the first character of the string that is to
     * be escaped, and the length parameter gives the number of bytes in this
     * string. A terminating zero byte is not required, and should not be
     * counted in length.
     * 
     * ...
     * 
     * (The parameter) to shall point to a buffer that is able to hold at least
     * one more byte than twice the value of length, otherwise the behavior
     * is undefined.
     * 
     * ...
     * 
     * If the error parameter is not NULL, then *error is set to zero on
     * success, nonzero on error ... The output string is still generated on
     * error, but it can be expected that the server will reject it as
     * malformed. On error, a suitable message is stored in the conn object,
     * whether or not error is NULL.
     */
    VSTRING_SPACE(result, buflen);
    PQescapeStringConn(active_host->db, vstring_end(result), name, len, &err);
    if (err == 0) {
    VSTRING_SKIP(result);
    } else {

    /*
     * PQescapeStringConn() failed. According to the docs, we still have
     * a valid, null-terminated output string, but we need not rely on
     * this behavior.
     */
    msg_warn("dict pgsql: (host %s) cannot escape input string: %s",
         active_host->hostname, PQerrorMessage(active_host->db));
    active_host->stat = STATFAIL;
    VSTRING_TERMINATE(result);
    }
}

/* dict_pgsql_lookup - find database entry */

static const char *dict_pgsql_lookup(DICT *dict, const char *name)
{
    const char *myname = "dict_pgsql_lookup";
    PGSQL_RES *query_res;
    DICT_PGSQL *dict_pgsql;
    static VSTRING *query;
    static VSTRING *result;
    int     i;
    int     j;
    int     numrows;
    int     numcols;
    int     expansion;
    const char *r;
    int     domain_rc;

    dict_pgsql = (DICT_PGSQL *) dict;

#define INIT_VSTR(buf, len) do { \
    if (buf == 0) \
        buf = vstring_alloc(len); \
    VSTRING_RESET(buf); \
    VSTRING_TERMINATE(buf); \
    } while (0)

    INIT_VSTR(query, 10);
    INIT_VSTR(result, 10);

    dict->error = 0;

    /*
     * Optionally fold the key.
     */
    if (dict->flags & DICT_FLAG_FOLD_FIX) {
    if (dict->fold_buf == 0)
        dict->fold_buf = vstring_alloc(10);
    vstring_strcpy(dict->fold_buf, name);
    name = lowercase(vstring_str(dict->fold_buf));
    }

    /*
     * If there is a domain list for this map, then only search for addresses
     * in domains on the list. This can significantly reduce the load on the
     * server.
     */
    if ((domain_rc = db_common_check_domain(dict_pgsql->ctx, name)) == 0) {
    if (msg_verbose)
        msg_info("%s: Skipping lookup of '%s'", myname, name);
    return (0);
    }
    if (domain_rc < 0)
    DICT_ERR_VAL_RETURN(dict, domain_rc, (char *) 0);

    /*
     * Suppress the actual lookup if the expansion is empty.
     * 
     * This initial expansion is outside the context of any specific host
     * connection, we just want to check the key pre-requisites, so when
     * quoting happens separately for each connection, we don't bother with
     * quoting...
     */
    if (!db_common_expand(dict_pgsql->ctx, dict_pgsql->query,
              name, 0, query, 0))
    return (0);

    /* do the query - set dict->error & cleanup if there's an error */
    if ((query_res = plpgsql_query(dict_pgsql, name, query,
                   dict_pgsql->dbname,
                   dict_pgsql->username,
                   dict_pgsql->password)) == 0) {
    dict->error = DICT_ERR_RETRY;
    return 0;
    }
    numrows = PQntuples(query_res);
    if (msg_verbose)
    msg_info("%s: retrieved %d rows", myname, numrows);
    if (numrows == 0) {
    PQclear(query_res);
    return 0;
    }
    numcols = PQnfields(query_res);

    for (expansion = i = 0; i < numrows && dict->error == 0; i++) {
    for (j = 0; j < numcols; j++) {
        r = PQgetvalue(query_res, i, j);
        if (db_common_expand(dict_pgsql->ctx, dict_pgsql->result_format,
                 r, name, result, 0)
        && dict_pgsql->expansion_limit > 0
        && ++expansion > dict_pgsql->expansion_limit) {
        msg_warn("%s: %s: Expansion limit exceeded for key: '%s'",
             myname, dict_pgsql->parser->name, name);
        dict->error = DICT_ERR_RETRY;
        break;
        }
    }
    }
    PQclear(query_res);
    r = vstring_str(result);
    return ((dict->error == 0 && *r) ? r : 0);
}

/* dict_pgsql_check_stat - check the status of a host */

static int dict_pgsql_check_stat(HOST *host, unsigned stat, unsigned type,
                         time_t t)
{
    if ((host->stat & stat) && (!type || host->type & type)) {
    /* try not to hammer the dead hosts too often */
    if (host->stat == STATFAIL && host->ts > 0 && host->ts >= t)
        return 0;
    return 1;
    }
    return 0;
}

/* dict_pgsql_find_host - find a host with the given status */

static HOST *dict_pgsql_find_host(PLPGSQL *PLDB, unsigned stat, unsigned type)
{
    time_t  t;
    int     count = 0;
    int     idx;
    int     i;

    t = time((time_t *) 0);
    for (i = 0; i < PLDB->len_hosts; i++) {
    if (dict_pgsql_check_stat(PLDB->db_hosts[i], stat, type, t))
        count++;
    }

    if (count) {
    idx = (count > 1) ?
        1 + count * (double) myrand() / (1.0 + RAND_MAX) : 1;

    for (i = 0; i < PLDB->len_hosts; i++) {
        if (dict_pgsql_check_stat(PLDB->db_hosts[i], stat, type, t) &&
        --idx == 0)
        return PLDB->db_hosts[i];
    }
    }
    return 0;
}

/* dict_pgsql_get_active - get an active connection */

static HOST *dict_pgsql_get_active(PLPGSQL *PLDB, char *dbname,
                           char *username, char *password)
{
    const char *myname = "dict_pgsql_get_active";
    HOST   *host;
    int     count = RETRY_CONN_MAX;

    /* try the active connections first; prefer the ones to UNIX sockets */
    if ((host = dict_pgsql_find_host(PLDB, STATACTIVE, TYPEUNIX)) != NULL ||
    (host = dict_pgsql_find_host(PLDB, STATACTIVE, TYPEINET)) != NULL ||
    (host = dict_pgsql_find_host(PLDB, STATACTIVE, TYPECONNSTRING)) != NULL) {
    if (msg_verbose)
        msg_info("%s: found active connection to host %s", myname,
             host->hostname);
    return host;
    }

    /*
     * Try the remaining hosts. "count" is a safety net, in case the loop
     * takes more than RETRY_CONN_INTV and the dead hosts are no longer
     * skipped.
     */
    while (--count > 0 &&
       ((host = dict_pgsql_find_host(PLDB, STATUNTRIED | STATFAIL,
                     TYPEUNIX)) != NULL ||
        (host = dict_pgsql_find_host(PLDB, STATUNTRIED | STATFAIL,
                     TYPEINET)) != NULL ||
        (host = dict_pgsql_find_host(PLDB, STATUNTRIED | STATFAIL,
                     TYPECONNSTRING)) != NULL)) {
    if (msg_verbose)
        msg_info("%s: attempting to connect to host %s", myname,
             host->hostname);
    plpgsql_connect_single(host, dbname, username, password);
    if (host->stat == STATACTIVE)
        return host;
    }

    /* bad news... */
    return 0;
}

/* dict_pgsql_event - callback: close idle connections */

static void dict_pgsql_event(int unused_event, void *context)
{
    HOST   *host = (HOST *) context;

    if (host->db)
    plpgsql_close_host(host);
}

/*
 * plpgsql_query - process a PostgreSQL query.  Return PGSQL_RES* on success.
 *          On failure, log failure and try other db instances.
 *          on failure of all db instances, return 0;
 *          close unnecessary active connections
 */

static PGSQL_RES *plpgsql_query(DICT_PGSQL *dict_pgsql,
                        const char *name,
                        VSTRING *query,
                        char *dbname,
                        char *username,
                        char *password)
{
    PLPGSQL *PLDB = dict_pgsql->pldb;
    HOST   *host;
    PGSQL_RES *res = 0;
    ExecStatusType status;

    while ((host = dict_pgsql_get_active(PLDB, dbname, username, password)) != NULL) {

    /*
     * The active host is used to escape strings in the context of the
     * active connection's character encoding.
     */
    dict_pgsql->active_host = host;
    VSTRING_RESET(query);
    VSTRING_TERMINATE(query);
    db_common_expand(dict_pgsql->ctx, dict_pgsql->query,
             name, 0, query, dict_pgsql_quote);
    dict_pgsql->active_host = 0;

    /* Check for potential dict_pgsql_quote() failure. */
    if (host->stat == STATFAIL) {
        plpgsql_down_host(host);
        continue;
    }

    /*
     * Submit a command to the server. Be paranoid when processing the
     * result set: try to enumerate every successful case, and reject
     * everything else.
     * 
     * From PostgreSQL 8.1.4 docs: (PQexec) returns a PGresult pointer or
     * possibly a null pointer. A non-null pointer will generally be
     * returned except in out-of-memory conditions or serious errors such
     * as inability to send the command to the server.
     */
    if ((res = PQexec(host->db, vstring_str(query))) != 0) {

        /*
         * XXX Because non-null result pointer does not imply success, we
         * need to check the command's result status.
         * 
         * Section 28.3.1: A result of status PGRES_NONFATAL_ERROR will
         * never be returned directly by PQexec or other query execution
         * functions; results of this kind are instead passed to the
         * notice processor.
         * 
         * PGRES_EMPTY_QUERY is being sent by the server when the query
         * string is empty. The sanity-checking done by the Postfix
         * infrastructure makes this case impossible, so we need not
         * handle this situation explicitly.
         */
        switch ((status = PQresultStatus(res))) {
        case PGRES_TUPLES_OK:
        case PGRES_COMMAND_OK:
        /* Success. */
        if (msg_verbose)
            msg_info("dict_pgsql: successful query from host %s",
                 host->hostname);
        event_request_timer(dict_pgsql_event, (void *) host,
                    IDLE_CONN_INTV);
        return (res);
        case PGRES_FATAL_ERROR:
        msg_warn("pgsql query failed: fatal error from host %s: %s",
             host->hostname, PQresultErrorMessage(res));
        break;
        case PGRES_BAD_RESPONSE:
        msg_warn("pgsql query failed: protocol error, host %s",
             host->hostname);
        break;
        default:
        msg_warn("pgsql query failed: unknown code 0x%lx from host %s",
             (unsigned long) status, host->hostname);
        break;
        }
    } else {

        /*
         * This driver treats null pointers like fatal, non-null result
         * pointer errors, as suggested by the PostgreSQL 8.1.4
         * documentation.
         */
        msg_warn("pgsql query failed: fatal error from host %s: %s",
             host->hostname, PQerrorMessage(host->db));
    }

    /*
     * XXX An error occurred. Clean up memory and skip this connection.
     */
    if (res != 0)
        PQclear(res);
    plpgsql_down_host(host);
    }

    return (0);
}

/*
 * plpgsql_connect_single -
 * used to reconnect to a single database when one is down or none is
 * connected yet. Log all errors and set the stat field of host accordingly
 */
static void plpgsql_connect_single(HOST *host, char *dbname, char *username, char *password)
{
    if (host->type == TYPECONNSTRING) {
    host->db = PQconnectdb(host->name);
    } else {
    host->db = PQsetdbLogin(host->name, host->port, NULL, NULL,
                dbname, username, password);
    }
    if (host->db == NULL || PQstatus(host->db) != CONNECTION_OK) {
    msg_warn("connect to pgsql server %s: %s",
         host->hostname, PQerrorMessage(host->db));
    plpgsql_down_host(host);
    return;
    }
    if (msg_verbose)
    msg_info("dict_pgsql: successful connection to host %s",
         host->hostname);

    /*
     * XXX Postfix does not send multi-byte characters. The following piece
     * of code is an explicit statement of this fact, and the database server
     * should not accept multi-byte information after this point.
     */
    if (PQsetClientEncoding(host->db, "LATIN1") != 0) {
    msg_warn("dict_pgsql: cannot set the encoding to LATIN1, skipping %s",
         host->hostname);
    plpgsql_down_host(host);
    return;
    }
    /* Success. */
    host->stat = STATACTIVE;
}

/* plpgsql_close_host - close an established PostgreSQL connection */

static void plpgsql_close_host(HOST *host)
{
    if (host->db)
    PQfinish(host->db);
    host->db = 0;
    host->stat = STATUNTRIED;
}

/*
 * plpgsql_down_host - close a failed connection AND set a "stay away from
 * this host" timer.
 */
static void plpgsql_down_host(HOST *host)
{
    if (host->db)
    PQfinish(host->db);
    host->db = 0;
    host->ts = time((time_t *) 0) + RETRY_CONN_INTV;
    host->stat = STATFAIL;
    event_cancel_timer(dict_pgsql_event, (void *) host);
}

/* pgsql_parse_config - parse pgsql configuration file */

static void pgsql_parse_config(DICT_PGSQL *dict_pgsql, const char *pgsqlcf)
{
    const char *myname = "pgsql_parse_config";
    CFG_PARSER *p = dict_pgsql->parser;
    char   *hosts;
    VSTRING *query;
    char   *select_function;

    dict_pgsql->username = cfg_get_str(p, "user", "", 0, 0);
    dict_pgsql->password = cfg_get_str(p, "password", "", 0, 0);
    dict_pgsql->dbname = cfg_get_str(p, "dbname", "", 1, 0);
    dict_pgsql->result_format = cfg_get_str(p, "result_format", "%s", 1, 0);

    /*
     * XXX: The default should be non-zero for safety, but that is not
     * backwards compatible.
     */
    dict_pgsql->expansion_limit = cfg_get_int(dict_pgsql->parser,
                          "expansion_limit", 0, 0, 0);

    if ((dict_pgsql->query = cfg_get_str(p, "query", 0, 0, 0)) == 0) {

    /*
     * No query specified -- fallback to building it from components (
     * old style "select %s from %s where %s" )
     */
    query = vstring_alloc(64);
    select_function = cfg_get_str(p, "select_function", 0, 0, 0);
    if (select_function != 0) {
        vstring_sprintf(query, "SELECT %s('%%s')", select_function);
        myfree(select_function);
    } else
        db_common_sql_build_query(query, p);
    dict_pgsql->query = vstring_export(query);
    }

    /*
     * Must parse all templates before we can use db_common_expand()
     */
    dict_pgsql->ctx = 0;
    (void) db_common_parse(&dict_pgsql->dict, &dict_pgsql->ctx,
               dict_pgsql->query, 1);
    (void) db_common_parse(0, &dict_pgsql->ctx, dict_pgsql->result_format, 0);
    db_common_parse_domain(p, dict_pgsql->ctx);

    /*
     * Maps that use substring keys should only be used with the full input
     * key.
     */
    if (db_common_dict_partial(dict_pgsql->ctx))
    dict_pgsql->dict.flags |= DICT_FLAG_PATTERN;
    else
    dict_pgsql->dict.flags |= DICT_FLAG_FIXED;
    if (dict_pgsql->dict.flags & DICT_FLAG_FOLD_FIX)
    dict_pgsql->dict.fold_buf = vstring_alloc(10);

    hosts = cfg_get_str(p, "hosts", "", 0, 0);

    dict_pgsql->hosts = argv_split(hosts, CHARS_COMMA_SP);
    if (dict_pgsql->hosts->argc == 0) {
    argv_add(dict_pgsql->hosts, "localhost", ARGV_END);
    argv_terminate(dict_pgsql->hosts);
    if (msg_verbose)
        msg_info("%s: %s: no hostnames specified, defaulting to '%s'",
             myname, pgsqlcf, dict_pgsql->hosts->argv[0]);
    }
    myfree(hosts);
}

/* dict_pgsql_open - open PGSQL data base */

DICT   *dict_pgsql_open(const char *name, int open_flags, int dict_flags)
{
    DICT_PGSQL *dict_pgsql;
    CFG_PARSER *parser;

    /*
     * Sanity check.
     */
    if (open_flags != O_RDONLY)
    return (dict_surrogate(DICT_TYPE_PGSQL, name, open_flags, dict_flags,
                   "%s:%s map requires O_RDONLY access mode",
                   DICT_TYPE_PGSQL, name));

    /*
     * Open the configuration file.
     */
    if ((parser = cfg_parser_alloc(name)) == 0)
    return (dict_surrogate(DICT_TYPE_PGSQL, name, open_flags, dict_flags,
                   "open %s: %m", name));

    dict_pgsql = (DICT_PGSQL *) dict_alloc(DICT_TYPE_PGSQL, name,
                       sizeof(DICT_PGSQL));
    dict_pgsql->dict.lookup = dict_pgsql_lookup;
    dict_pgsql->dict.close = dict_pgsql_close;
    dict_pgsql->dict.flags = dict_flags;
    dict_pgsql->parser = parser;
    pgsql_parse_config(dict_pgsql, name);
    dict_pgsql->active_host = 0;
    dict_pgsql->pldb = plpgsql_init(dict_pgsql->hosts);
    if (dict_pgsql->pldb == NULL)
    msg_fatal("couldn't initialize pldb!\n");
    dict_pgsql->dict.owner = cfg_get_owner(dict_pgsql->parser);
    return (DICT_DEBUG (&dict_pgsql->dict));
}

/* plpgsql_init - initialize a PGSQL database */

static PLPGSQL *plpgsql_init(ARGV *hosts)
{
    PLPGSQL *PLDB;
    int     i;

    PLDB = (PLPGSQL *) mymalloc(sizeof(PLPGSQL));
    PLDB->len_hosts = hosts->argc;
    PLDB->db_hosts = (HOST **) mymalloc(sizeof(HOST *) * hosts->argc);
    for (i = 0; i < hosts->argc; i++)
    PLDB->db_hosts[i] = host_init(hosts->argv[i]);

    return PLDB;
}


/* host_init - initialize HOST structure */

static HOST *host_init(const char *hostname)
{
    const char *myname = "pgsql host_init";
    HOST   *host = (HOST *) mymalloc(sizeof(HOST));
    const char *d = hostname;

    host->db = 0;
    host->hostname = mystrdup(hostname);
    host->stat = STATUNTRIED;
    host->ts = 0;

    /*
     * Modern syntax: "postgresql://connection-info".
     */
    if (strncmp(d, "postgresql:", 11) == 0) {
    host->type = TYPECONNSTRING;
    host->name = mystrdup(d);
    host->port = 0;
    }

    /*
     * Historical syntax: "unix:/pathname" and "inet:host:port". Strip the
     * "unix:" and "inet:" prefixes. Look at the first character, which is
     * how PgSQL historically distinguishes between UNIX and INET.
     */
    else {
    if (strncmp(d, "unix:", 5) == 0 || strncmp(d, "inet:", 5) == 0)
        d += 5;
    host->name = mystrdup(d);
    if (host->name[0] && host->name[0] != '/') {
        host->type = TYPEINET;
        host->port = split_at_right(host->name, ':');
    } else {
        host->type = TYPEUNIX;
        host->port = 0;
    }
    }
    if (msg_verbose > 1)
    msg_info("%s: host=%s, port=%s, type=%s", myname, host->name,
         host->port ? host->port : "",
         host->type == TYPEUNIX ? "unix" :
         host->type == TYPEINET ? "inet" :
         "uri");
    return host;
}

/* dict_pgsql_close - close PGSQL data base */

static void dict_pgsql_close(DICT *dict)
{
    DICT_PGSQL *dict_pgsql = (DICT_PGSQL *) dict;

    plpgsql_dealloc(dict_pgsql->pldb);
    cfg_parser_free(dict_pgsql->parser);
    myfree(dict_pgsql->username);
    myfree(dict_pgsql->password);
    myfree(dict_pgsql->dbname);
    myfree(dict_pgsql->query);
    myfree(dict_pgsql->result_format);
    if (dict_pgsql->hosts)
    argv_free(dict_pgsql->hosts);
    if (dict_pgsql->ctx)
    db_common_free_ctx(dict_pgsql->ctx);
    if (dict->fold_buf)
    vstring_free(dict->fold_buf);
    dict_free(dict);
}

/* plpgsql_dealloc - free memory associated with PLPGSQL close databases */

static void plpgsql_dealloc(PLPGSQL *PLDB)
{
    int     i;

    for (i = 0; i < PLDB->len_hosts; i++) {
    event_cancel_timer(dict_pgsql_event, (void *) (PLDB->db_hosts[i]));
    if (PLDB->db_hosts[i]->db)
        PQfinish(PLDB->db_hosts[i]->db);
    myfree(PLDB->db_hosts[i]->hostname);
    myfree(PLDB->db_hosts[i]->name);
    myfree((void *) PLDB->db_hosts[i]);
    }
    myfree((void *) PLDB->db_hosts);
    myfree((void *) (PLDB));
}

#endif