dict.c

[詳解]

/*++
/* NAME
/*  dict 3
/* SUMMARY
/*  dictionary manager
/* SYNOPSIS
/*  #include <dict.h>
/*
/*  void    dict_register(dict_name, dict_info)
/*  const char *dict_name;
/*  DICT    *dict_info;
/*
/*  DICT    *dict_handle(dict_name)
/*  const char *dict_name;
/*
/*  void    dict_unregister(dict_name)
/*  const char *dict_name;
/*
/*  int dict_update(dict_name, member, value)
/*  const char *dict_name;
/*  const char *member;
/*  const char *value;
/*
/*  const char *dict_lookup(dict_name, member)
/*  const char *dict_name;
/*  const char *member;
/*
/*  int dict_delete(dict_name, member)
/*  const char *dict_name;
/*  const char *member;
/*
/*  int dict_sequence(dict_name, func, member, value)
/*  const char *dict_name;
/*  int func;
/*  const char **member;
/*  const char **value;
/*
/*  const char *dict_eval(dict_name, string, int recursive)
/*  const char *dict_name;
/*  const char *string;
/*  int recursive;
/*
/*  int dict_walk(action, context)
/*  void    (*action)(dict_name, dict_handle, context)
/*  void    *context;
/*
/*  int dict_error(dict_name)
/*  const char *dict_name;
/*
/*  const char *dict_changed_name()
/*
/*  void    DICT_OWNER_AGGREGATE_INIT(aggregate)
/*  DICT_OWNER aggregate;
/*
/*  void    DICT_OWNER_AGGREGATE_UPDATE(aggregate, source)
/*  DICT_OWNER aggregate;
/*  DICT_OWNER source;
/* AUXILIARY FUNCTIONS
/*  int dict_load_file_xt(dict_name, path)
/*  const char *dict_name;
/*  const char *path;
/*
/*  void    dict_load_fp(dict_name, fp)
/*  const char *dict_name;
/*  VSTREAM *fp;
/*
/*  const char *dict_flags_str(dict_flags)
/*  int dict_flags;
/*
/*  int dict_flags_mask(names)
/*  const char *names;
/* DESCRIPTION
/*  This module maintains a collection of name-value dictionaries.
/*  Each dictionary has its own name and has its own methods to read
/*  or update members. Examples of dictionaries that can be accessed
/*  in this manner are the global UNIX-style process environment,
/*  hash tables, NIS maps, DBM files, and so on. Dictionary values
/*  are not limited to strings but can be arbitrary objects as long
/*  as they can be represented by character pointers.
/* FEATURES
/* .fi
/* .ad
/*  Notable features of this module are:
/* .IP "macro expansion (string-valued dictionaries only)"
/*  Macros of the form $\fIname\fR can be expanded to the current
/*  value of \fIname\fR. The forms $(\fIname\fR) and ${\fIname\fR} are
/*  also supported.
/* .IP "unknown names"
/*  An update request for an unknown dictionary name will trigger
/*  the instantiation of an in-memory dictionary with that name.
/*  A lookup request (including delete and sequence) for an
/*  unknown dictionary will result in a "not found" and "no
/*  error" result.
/* .PP
/*  dict_register() adds a new dictionary, including access methods,
/*  to the list of known dictionaries, or increments the reference
/*  count for an existing (name, dictionary) pair.  Otherwise, it is
/*  an error to pass an existing name (this would cause a memory leak).
/*
/*  dict_handle() returns the generic dictionary handle of the
/*  named dictionary, or a null pointer when the named dictionary
/*  is not found.
/*
/*  dict_unregister() decrements the reference count of the named
/*  dictionary. When the reference count reaches zero, dict_unregister()
/*  breaks the (name, dictionary) association and executes the
/*  dictionary's optional \fIremove\fR method.
/*
/*  dict_update() updates the value of the named dictionary member.
/*  The dictionary member and the named dictionary are instantiated
/*  on the fly.  The result value is zero (DICT_STAT_SUCCESS)
/*  when the update was made.
/*
/*  dict_lookup() returns the value of the named member (i.e. without
/*  expanding macros in the member value).  The \fIdict_name\fR argument
/*  specifies the dictionary to search. The result is a null pointer
/*  when no value is found, otherwise the result is owned by the
/*  underlying dictionary method. Make a copy if the result is to be
/*  modified, or if the result is to survive multiple dict_lookup() calls.
/*
/*  dict_delete() removes the named member from the named dictionary.
/*  The result value is zero (DICT_STAT_SUCCESS) when the member
/*  was found.
/*
/*  dict_sequence() steps through the named dictionary and returns
/*  keys and values in some implementation-defined order. The func
/*  argument is DICT_SEQ_FUN_FIRST to set the cursor to the first
/*  entry or DICT_SEQ_FUN_NEXT to select the next entry. The result
/*  is owned by the underlying dictionary method. Make a copy if the
/*  result is to be modified, or if the result is to survive multiple
/*  dict_sequence() calls. The result value is zero (DICT_STAT_SUCCESS)
/*  when a member was found.
/*
/*  dict_eval() expands macro references in the specified string.
/*  The result is owned by the dictionary manager. Make a copy if the
/*  result is to survive multiple dict_eval() calls. When the
/*  \fIrecursive\fR argument is non-zero, macro references in macro
/*  lookup results are expanded recursively.
/*
/*  dict_walk() iterates over all registered dictionaries in some
/*  arbitrary order, and invokes the specified action routine with
/*  as arguments:
/* .IP "const char *dict_name"
/*  Dictionary name.
/* .IP "DICT *dict_handle"
/*  Generic dictionary handle.
/* .IP "char *context"
/*  Application context from the caller.
/* .PP
/*  dict_changed_name() returns non-zero when any dictionary needs to
/*  be re-opened because it has changed or because it was unlinked.
/*  A non-zero result is the name of a changed dictionary.
/*
/*  dict_load_file_xt() reads name-value entries from the named file.
/*  Lines that begin with whitespace are concatenated to the preceding
/*  line (the newline is deleted).
/*  Each entry is stored in the dictionary named by \fIdict_name\fR.
/*  The result is zero if the file could not be opened.
/*
/*  dict_load_fp() reads name-value entries from an open stream.
/*  It has the same semantics as the dict_load_file_xt() function.
/*
/*  dict_flags_str() returns a printable representation of the
/*  specified dictionary flags. The result is overwritten upon
/*  each call.
/*
/*  dict_flags_mask() returns the bitmask for the specified
/*  comma/space-separated dictionary flag names.
/* TRUST AND PROVENANCE
/* .ad
/* .fi
/*  Each dictionary has an owner attribute that contains (status,
/*  uid) information about the owner of a dictionary.  The
/*  status is one of the following:
/* .IP DICT_OWNER_TRUSTED
/*  The dictionary is owned by a trusted user. The uid is zero,
/*  and specifies a UNIX user ID.
/* .IP DICT_OWNER_UNTRUSTED
/*  The dictionary is owned by an untrusted user.  The uid is
/*  non-zero, and specifies a UNIX user ID.
/* .IP DICT_OWNER_UNKNOWN
/*  The dictionary is owned by an unspecified user.  For example,
/*  the origin is unauthenticated, or different parts of a
/*  dictionary aggregate (see below) are owned by different
/*  untrusted users.  The uid is non-zero and does not specify
/*  a UNIX user ID.
/* .PP
/*  Note that dictionary ownership does not necessarily imply
/*  ownership of lookup results. For example, a PCRE table may
/*  be owned by the trusted root user, but the result of $number
/*  expansion can contain data from an arbitrary remote SMTP
/*  client.  See dict_open(3) for how to disallow $number
/*  expansions with security-sensitive operations.
/*
/*  Two macros are available to help determine the provenance
/*  and trustworthiness of a dictionary aggregate. The macros
/*  are unsafe because they may evaluate arguments more than
/*  once.
/*
/*  DICT_OWNER_AGGREGATE_INIT() initialize aggregate owner
/*  attributes to the highest trust level.
/*
/*  DICT_OWNER_AGGREGATE_UPDATE() updates the aggregate owner
/*  attributes with the attributes of the specified source, and
/*  reduces the aggregate trust level as appropriate.
/* SEE ALSO
/*  htable(3)
/* BUGS
/* DIAGNOSTICS
/*  Fatal errors: out of memory, malformed macro name.
/*
/*  The lookup routine returns non-null when the request is
/*  satisfied. The update, delete and sequence routines return
/*  zero (DICT_STAT_SUCCESS) when the request is satisfied.
/*  The dict_error() function returns non-zero only when the
/*  last operation was not satisfied due to a dictionary access
/*  error. The result can have the following values:
/* .IP DICT_ERR_NONE(zero)
/*  There was no dictionary access error. For example, the
/*  request was satisfied, the requested information did not
/*  exist in the dictionary, or the information already existed
/*  when it should not exist (collision).
/* .IP DICT_ERR_RETRY(<0)
/*  The dictionary was temporarily unavailable. This can happen
/*  with network-based services.
/* .IP DICT_ERR_CONFIG(<0)
/*  The dictionary was unavailable due to a configuration error.
/* .PP
/*  Generally, a program is expected to test the function result
/*  value for "success" first. If the operation was not successful,
/*  a program is expected to test for a non-zero dict->error
/*  status to distinguish between a data notfound/collision
/*  condition or a dictionary access error.
/* LICENSE
/* .ad
/* .fi
/*  The Secure Mailer license must be distributed with this software.
/* AUTHOR(S)
/*  Wietse Venema
/*  IBM T.J. Watson Research
/*  P.O. Box 704
/*  Yorktown Heights, NY 10598, USA
/*--*/

/* System libraries. */

#include "sys_defs.h"
#include <sys/stat.h>
#include <fcntl.h>
#include <ctype.h>
#include <string.h>
#include <time.h>

/* Utility library. */

#include "msg.h"
#include "htable.h"
#include "mymalloc.h"
#include "vstream.h"
#include "vstring.h"
#include "readlline.h"
#include "mac_expand.h"
#include "stringops.h"
#include "iostuff.h"
#include "name_mask.h"
#include "dict.h"
#include "dict_ht.h"
#include "warn_stat.h"
#include "line_number.h"

static HTABLE *dict_table;

 /*
  * Each (name, dictionary) instance has a reference count. The count is part
  * of the name, not the dictionary. The same dictionary may be registered
  * under multiple names. The structure below keeps track of instances and
  * reference counts.
  */
typedef struct {
    DICT   *dict;
    int     refcount;
} DICT_NODE;

#define dict_node(dict) \
    (dict_table ? (DICT_NODE *) htable_find(dict_table, dict) : 0)

/* Find a dictionary handle by name for lookup purposes. */

#define DICT_FIND_FOR_LOOKUP(dict, dict_name) do { \
    DICT_NODE *node; \
    if ((node = dict_node(dict_name)) != 0) \
    dict = node->dict; \
    else \
    dict = 0; \
} while (0)

/* Find a dictionary handle by name for update purposes. */

#define DICT_FIND_FOR_UPDATE(dict, dict_name) do { \
    DICT_NODE *node; \
    if ((node = dict_node(dict_name)) == 0) { \
    dict = dict_ht_open(dict_name, O_CREAT | O_RDWR, 0); \
    dict_register(dict_name, dict); \
    } else \
    dict = node->dict; \
} while (0)

#define STR(x)  vstring_str(x)

/* dict_register - make association with dictionary */

void    dict_register(const char *dict_name, DICT *dict_info)
{
    const char *myname = "dict_register";
    DICT_NODE *node;

    if (dict_table == 0)
    dict_table = htable_create(0);
    if ((node = dict_node(dict_name)) == 0) {
    node = (DICT_NODE *) mymalloc(sizeof(*node));
    node->dict = dict_info;
    node->refcount = 0;
    htable_enter(dict_table, dict_name, (void *) node);
    } else if (dict_info != node->dict)
    msg_fatal("%s: dictionary name exists: %s", myname, dict_name);
    node->refcount++;
    if (msg_verbose > 1)
    msg_info("%s: %s %d", myname, dict_name, node->refcount);
}

/* dict_handle - locate generic dictionary handle */

DICT   *dict_handle(const char *dict_name)
{
    DICT_NODE *node;

    return ((node = dict_node(dict_name)) != 0 ? node->dict : 0);
}

/* dict_node_free - dict_unregister() callback */

static void dict_node_free(void *ptr)
{
    DICT_NODE *node = (DICT_NODE *) ptr;
    DICT   *dict = node->dict;

    if (dict->close)
    dict->close(dict);
    myfree((void *) node);
}

/* dict_unregister - break association with named dictionary */

void    dict_unregister(const char *dict_name)
{
    const char *myname = "dict_unregister";
    DICT_NODE *node;

    if ((node = dict_node(dict_name)) == 0)
    msg_panic("non-existing dictionary: %s", dict_name);
    if (msg_verbose > 1)
    msg_info("%s: %s %d", myname, dict_name, node->refcount);
    if (--(node->refcount) == 0)
    htable_delete(dict_table, dict_name, dict_node_free);
}

/* dict_update - replace or add dictionary entry */

int     dict_update(const char *dict_name, const char *member, const char *value)
{
    const char *myname = "dict_update";
    DICT   *dict;

    DICT_FIND_FOR_UPDATE(dict, dict_name);
    if (msg_verbose > 1)
    msg_info("%s: %s = %s", myname, member, value);
    return (dict->update(dict, member, value));
}

/* dict_lookup - look up dictionary entry */

const char *dict_lookup(const char *dict_name, const char *member)
{
    const char *myname = "dict_lookup";
    DICT   *dict;
    const char *ret;

    DICT_FIND_FOR_LOOKUP(dict, dict_name);
    if (dict != 0) {
    ret = dict->lookup(dict, member);
    if (msg_verbose > 1)
        msg_info("%s: %s = %s", myname, member, ret ? ret :
             dict->error ? "(error)" : "(notfound)");
    return (ret);
    } else {
    if (msg_verbose > 1)
        msg_info("%s: %s = %s", myname, member, "(notfound)");
    return (0);
    }
}

/* dict_delete - delete dictionary entry */

int     dict_delete(const char *dict_name, const char *member)
{
    const char *myname = "dict_delete";
    DICT   *dict;

    DICT_FIND_FOR_LOOKUP(dict, dict_name);
    if (msg_verbose > 1)
    msg_info("%s: delete %s", myname, member);
    return (dict ? dict->delete(dict, member) : DICT_STAT_FAIL);
}

/* dict_sequence - traverse dictionary */

int     dict_sequence(const char *dict_name, const int func,
                      const char **member, const char **value)
{
    const char *myname = "dict_sequence";
    DICT   *dict;

    DICT_FIND_FOR_LOOKUP(dict, dict_name);
    if (msg_verbose > 1)
    msg_info("%s: sequence func %d", myname, func);
    return (dict ? dict->sequence(dict, func, member, value) : DICT_STAT_FAIL);
}

/* dict_error - return last error */

int     dict_error(const char *dict_name)
{
    DICT   *dict;

    DICT_FIND_FOR_LOOKUP(dict, dict_name);
    return (dict ? dict->error : DICT_ERR_NONE);
}

/* dict_load_file_xt - read entries from text file */

int     dict_load_file_xt(const char *dict_name, const char *path)
{
    VSTREAM *fp;
    struct stat st;
    time_t  before;
    time_t  after;

    /*
     * Read the file again if it is hot. This may result in reading a partial
     * parameter name when a file changes in the middle of a read.
     */
    for (before = time((time_t *) 0); /* see below */ ; before = after) {
    if ((fp = vstream_fopen(path, O_RDONLY, 0)) == 0)
        return (0);
    dict_load_fp(dict_name, fp);
    if (fstat(vstream_fileno(fp), &st) < 0)
        msg_fatal("fstat %s: %m", path);
    if (vstream_ferror(fp) || vstream_fclose(fp))
        msg_fatal("read %s: %m", path);
    after = time((time_t *) 0);
    if (st.st_mtime < before - 1 || st.st_mtime > after)
        break;
    if (msg_verbose > 1)
        msg_info("pausing to let %s cool down", path);
    doze(300000);
    }
    return (1);
}

/* dict_load_fp - read entries from open stream */

void    dict_load_fp(const char *dict_name, VSTREAM *fp)
{
    const char *myname = "dict_load_fp";
    VSTRING *buf;
    char   *member;
    char   *val;
    const char *old;
    int     last_line;
    int     lineno;
    const char *err;
    struct stat st;
    DICT   *dict;

    /*
     * Instantiate the dictionary even if the file is empty.
     */
    DICT_FIND_FOR_UPDATE(dict, dict_name);
    buf = vstring_alloc(100);
    last_line = 0;

    if (fstat(vstream_fileno(fp), &st) < 0)
    msg_fatal("fstat %s: %m", VSTREAM_PATH(fp));
    while (readllines(buf, fp, &last_line, &lineno)) {
    if ((err = split_nameval(STR(buf), &member, &val)) != 0)
        msg_fatal("%s, line %d: %s: \"%s\"",
              VSTREAM_PATH(fp),
              lineno,
              err, STR(buf));
    if (msg_verbose > 1)
        msg_info("%s: %s = %s", myname, member, val);
    if ((old = dict->lookup(dict, member)) != 0
        && strcmp(old, val) != 0)
        msg_warn("%s, line %d: overriding earlier entry: %s=%s",
             VSTREAM_PATH(fp), lineno, member, old);
    if (dict->update(dict, member, val) != 0)
        msg_fatal("%s, line %d: unable to update %s:%s",
              VSTREAM_PATH(fp), lineno, dict->type, dict->name);
    }
    vstring_free(buf);
    dict->owner.uid = st.st_uid;
    dict->owner.status = (st.st_uid != 0);
}

/* dict_eval_lookup - macro parser call-back routine */

static const char *dict_eval_lookup(const char *key, int unused_type,
                            void *context)
{
    char   *dict_name = (char *) context;
    const char *pp = 0;
    DICT   *dict;

    /*
     * XXX how would one recover?
     */
    DICT_FIND_FOR_LOOKUP(dict, dict_name);
    if (dict != 0
    && (pp = dict->lookup(dict, key)) == 0 && dict->error != 0)
    msg_fatal("dictionary %s: lookup %s: operation failed", dict_name, key);
    return (pp);
}

/* dict_eval - expand embedded dictionary references */

const char *dict_eval(const char *dict_name, const char *value, int recursive)
{
    const char *myname = "dict_eval";
    static VSTRING *buf;
    int     status;

    /*
     * Initialize.
     */
    if (buf == 0)
    buf = vstring_alloc(10);

    /*
     * Expand macros, possibly recursively.
     */
#define DONT_FILTER (char *) 0

    status = mac_expand(buf, value,
            recursive ? MAC_EXP_FLAG_RECURSE : MAC_EXP_FLAG_NONE,
            DONT_FILTER, dict_eval_lookup, (void *) dict_name);
    if (status & MAC_PARSE_ERROR)
    msg_fatal("dictionary %s: macro processing error", dict_name);
    if (msg_verbose > 1) {
    if (strcmp(value, STR(buf)) != 0)
        msg_info("%s: expand %s -> %s", myname, value, STR(buf));
    else
        msg_info("%s: const  %s", myname, value);
    }
    return (STR(buf));
}

/* dict_walk - iterate over all dictionaries in arbitrary order */

void    dict_walk(DICT_WALK_ACTION action, void *ptr)
{
    HTABLE_INFO **ht_info_list;
    HTABLE_INFO **ht;
    HTABLE_INFO *h;

    ht_info_list = htable_list(dict_table);
    for (ht = ht_info_list; (h = *ht) != 0; ht++)
    action(h->key, (DICT *) h->value, ptr);
    myfree((void *) ht_info_list);
}

/* dict_changed_name - see if any dictionary has changed */

const char *dict_changed_name(void)
{
    const char *myname = "dict_changed_name";
    struct stat st;
    HTABLE_INFO **ht_info_list;
    HTABLE_INFO **ht;
    HTABLE_INFO *h;
    const char *status;
    DICT   *dict;

    ht_info_list = htable_list(dict_table);
    for (status = 0, ht = ht_info_list; status == 0 && (h = *ht) != 0; ht++) {
    dict = ((DICT_NODE *) h->value)->dict;
    if (dict->stat_fd < 0)          /* not file-based */
        continue;
    if (dict->mtime == 0)           /* not bloody likely */
        msg_warn("%s: table %s: null time stamp", myname, h->key);
    if (fstat(dict->stat_fd, &st) < 0)
        msg_fatal("%s: fstat: %m", myname);
    if (((dict->flags & DICT_FLAG_MULTI_WRITER) == 0
         && st.st_mtime != dict->mtime)
        || st.st_nlink == 0)
        status = h->key;
    }
    myfree((void *) ht_info_list);
    return (status);
}

/* dict_changed - backwards compatibility */

int     dict_changed(void)
{
    return (dict_changed_name() != 0);
}

 /*
  * Mapping between flag names and flag values.
  */
static const NAME_MASK dict_mask[] = {
    "warn_dup", DICT_FLAG_DUP_WARN, /* if file, warn about dups */
    "ignore_dup", DICT_FLAG_DUP_IGNORE, /* if file, ignore dups */
    "try0null", DICT_FLAG_TRY0NULL, /* do not append 0 to key/value */
    "try1null", DICT_FLAG_TRY1NULL, /* append 0 to key/value */
    "fixed", DICT_FLAG_FIXED,       /* fixed key map */
    "pattern", DICT_FLAG_PATTERN,   /* keys are patterns */
    "lock", DICT_FLAG_LOCK,     /* lock before access */
    "replace", DICT_FLAG_DUP_REPLACE,   /* if file, replace dups */
    "sync_update", DICT_FLAG_SYNC_UPDATE,   /* if file, sync updates */
    "debug", DICT_FLAG_DEBUG,       /* log access */
    "no_regsub", DICT_FLAG_NO_REGSUB,   /* disallow regexp substitution */
    "no_proxy", DICT_FLAG_NO_PROXY, /* disallow proxy mapping */
    "no_unauth", DICT_FLAG_NO_UNAUTH,   /* disallow unauthenticated data */
    "fold_fix", DICT_FLAG_FOLD_FIX, /* case-fold with fixed-case key map */
    "fold_mul", DICT_FLAG_FOLD_MUL, /* case-fold with multi-case key map */
    "open_lock", DICT_FLAG_OPEN_LOCK,   /* permanent lock upon open */
    "bulk_update", DICT_FLAG_BULK_UPDATE,   /* bulk update if supported */
    "multi_writer", DICT_FLAG_MULTI_WRITER, /* multi-writer safe */
    "utf8_request", DICT_FLAG_UTF8_REQUEST, /* request UTF-8 activation */
    "utf8_active", DICT_FLAG_UTF8_ACTIVE,   /* UTF-8 is activated */
    0,
};

/* dict_flags_str - convert bitmask to symbolic flag names */

const char *dict_flags_str(int dict_flags)
{
    static VSTRING *buf = 0;

    if (buf == 0)
    buf = vstring_alloc(1);

    return (str_name_mask_opt(buf, "dictionary flags", dict_mask, dict_flags,
                  NAME_MASK_NUMBER | NAME_MASK_PIPE));
}

/* dict_flags_mask - convert symbolic flag names to bitmask */

int     dict_flags_mask(const char *names)
{
    return (name_mask("dictionary flags", dict_mask, names));
}