dict_cidr.c

[詳解]

/*++
/* NAME
/*  dict_cidr 3
/* SUMMARY
/*  Dictionary interface for CIDR data
/* SYNOPSIS
/*  #include <dict_cidr.h>
/*
/*  DICT    *dict_cidr_open(name, open_flags, dict_flags)
/*  const char *name;
/*  int open_flags;
/*  int dict_flags;
/* DESCRIPTION
/*  dict_cidr_open() opens the named file and stores
/*  the key/value pairs where the key must be either a
/*  "naked" IP address or a netblock in CIDR notation.
/* SEE ALSO
/*  dict(3) generic dictionary manager
/* AUTHOR(S)
/*  Jozsef Kadlecsik
/*  kadlec@blackhole.kfki.hu
/*  KFKI Research Institute for Particle and Nuclear Physics
/*  POB. 49
/*  1525 Budapest, Hungary
/*
/*  Wietse Venema
/*  IBM T.J. Watson Research
/*  P.O. Box 704
/*  Yorktown Heights, NY 10598, USA
/*
/*  Wietse Venema
/*  Google, Inc.
/*  111 8th Avenue
/*  New York, NY 10011, USA
/*--*/

/* System library. */

#include <sys_defs.h>
#include <sys/stat.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <ctype.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

/* Utility library. */

#include <mymalloc.h>
#include <msg.h>
#include <vstream.h>
#include <vstring.h>
#include <stringops.h>
#include <readlline.h>
#include <dict.h>
#include <myaddrinfo.h>
#include <cidr_match.h>
#include <dict_cidr.h>
#include <warn_stat.h>
#include <mvect.h>

/* Application-specific. */

 /*
  * Each rule in a CIDR table is parsed and stored in a linked list.
  */
typedef struct DICT_CIDR_ENTRY {
    CIDR_MATCH cidr_info;       /* must be first */
    char   *value;          /* lookup result */
    int     lineno;
} DICT_CIDR_ENTRY;

typedef struct {
    DICT    dict;           /* generic members */
    DICT_CIDR_ENTRY *head;      /* first entry */
} DICT_CIDR;

/* dict_cidr_lookup - CIDR table lookup */

static const char *dict_cidr_lookup(DICT *dict, const char *key)
{
    DICT_CIDR *dict_cidr = (DICT_CIDR *) dict;
    DICT_CIDR_ENTRY *entry;

    if (msg_verbose)
    msg_info("dict_cidr_lookup: %s: %s", dict->name, key);

    dict->error = 0;

    if ((entry = (DICT_CIDR_ENTRY *)
     cidr_match_execute(&(dict_cidr->head->cidr_info), key)) != 0)
    return (entry->value);
    return (0);
}

/* dict_cidr_close - close the CIDR table */

static void dict_cidr_close(DICT *dict)
{
    DICT_CIDR *dict_cidr = (DICT_CIDR *) dict;
    DICT_CIDR_ENTRY *entry;
    DICT_CIDR_ENTRY *next;

    for (entry = dict_cidr->head; entry; entry = next) {
    next = (DICT_CIDR_ENTRY *) entry->cidr_info.next;
    myfree(entry->value);
    myfree((void *) entry);
    }
    dict_free(dict);
}

/* dict_cidr_parse_rule - parse CIDR table rule into network, mask and value */

static DICT_CIDR_ENTRY *dict_cidr_parse_rule(char *p, int lineno, int nesting,
                                 VSTRING *why)
{
    DICT_CIDR_ENTRY *rule;
    char   *pattern;
    char   *value;
    CIDR_MATCH cidr_info;
    MAI_HOSTADDR_STR hostaddr;
    int     match = 1;

    /*
     * IF must be followed by a pattern.
     */
    if (strncasecmp(p, "IF", 2) == 0 && !ISALNUM(p[2])) {
    p += 2;
    for (;;) {
        if (*p == '!')
        match = !match;
        else if (!ISSPACE(*p))
        break;
        p++;
    }
    if (*p == 0) {
        vstring_sprintf(why, "no address pattern");
        return (0);
    }
    trimblanks(p, 0)[0] = 0;        /* Trim trailing blanks */
    if (cidr_match_parse_if(&cidr_info, p, match, why) != 0)
        return (0);
    value = "";
    }

    /*
     * ENDIF must not be followed by other text.
     */
    else if (strncasecmp(p, "ENDIF", 5) == 0 && !ISALNUM(p[5])) {
    p += 5;
    while (*p && ISSPACE(*p))       /* Skip whitespace */
        p++;
    if (*p != 0) {
        vstring_sprintf(why, "garbage after ENDIF");
        return (0);
    }
    if (nesting == 0) {
        vstring_sprintf(why, "ENDIF without IF");
        return (0);
    }
    cidr_match_endif(&cidr_info);
    value = "";
    }

    /*
     * An address pattern.
     */
    else {

    /*
     * Process negation operators.
     */
    for (;;) {
        if (*p == '!')
        match = !match;
        else if (!ISSPACE(*p))
        break;
        p++;
    }

    /*
     * Split the rule into key and value. We already eliminated leading
     * whitespace, comments, empty lines or lines with whitespace only.
     * This means a null key can't happen but we will handle this anyway.
     */
    pattern = p;
    while (*p && !ISSPACE(*p))      /* Skip over key */
        p++;
    if (*p)                 /* Terminate key */
        *p++ = 0;
    while (*p && ISSPACE(*p))       /* Skip whitespace */
        p++;
    value = p;
    trimblanks(value, 0)[0] = 0;        /* Trim trailing blanks */
    if (*pattern == 0) {
        vstring_sprintf(why, "no address pattern");
        return (0);
    }

    /*
     * Parse the pattern, destroying it in the process.
     */
    if (cidr_match_parse(&cidr_info, pattern, match, why) != 0)
        return (0);

    if (*value == 0) {
        vstring_sprintf(why, "no lookup result");
        return (0);
    }
    }

    /*
     * Bundle up the result.
     */
    rule = (DICT_CIDR_ENTRY *) mymalloc(sizeof(DICT_CIDR_ENTRY));
    rule->cidr_info = cidr_info;
    rule->value = mystrdup(value);
    rule->lineno = lineno;

    if (msg_verbose) {
    if (inet_ntop(cidr_info.addr_family, cidr_info.net_bytes,
              hostaddr.buf, sizeof(hostaddr.buf)) == 0)
        msg_fatal("inet_ntop: %m");
    msg_info("dict_cidr_open: add %s/%d %s",
         hostaddr.buf, cidr_info.mask_shift, rule->value);
    }
    return (rule);
}

/* dict_cidr_open - parse CIDR table */

DICT   *dict_cidr_open(const char *mapname, int open_flags, int dict_flags)
{
    const char myname[] = "dict_cidr_open";
    DICT_CIDR *dict_cidr;
    VSTREAM *map_fp = 0;
    struct stat st;
    VSTRING *line_buffer = 0;
    VSTRING *why = 0;
    DICT_CIDR_ENTRY *rule;
    DICT_CIDR_ENTRY *last_rule = 0;
    int     last_line = 0;
    int     lineno;
    int     nesting = 0;
    DICT_CIDR_ENTRY **rule_stack = 0;
    MVECT   mvect;

    /*
     * Let the optimizer worry about eliminating redundant code.
     */
#define DICT_CIDR_OPEN_RETURN(d) do { \
    DICT *__d = (d); \
    if (map_fp != 0 && vstream_fclose(map_fp)) \
        msg_fatal("cidr map %s: read error: %m", mapname); \
    if (line_buffer != 0) \
        vstring_free(line_buffer); \
    if (why != 0) \
        vstring_free(why); \
    return (__d); \
    } while (0)

    /*
     * Sanity checks.
     */
    if (open_flags != O_RDONLY)
    DICT_CIDR_OPEN_RETURN(dict_surrogate(DICT_TYPE_CIDR, mapname,
                         open_flags, dict_flags,
                  "%s:%s map requires O_RDONLY access mode",
                         DICT_TYPE_CIDR, mapname));

    /*
     * Open the configuration file.
     */
    if ((map_fp = vstream_fopen(mapname, O_RDONLY, 0)) == 0)
    DICT_CIDR_OPEN_RETURN(dict_surrogate(DICT_TYPE_CIDR, mapname,
                         open_flags, dict_flags,
                         "open %s: %m", mapname));
    if (fstat(vstream_fileno(map_fp), &st) < 0)
    msg_fatal("fstat %s: %m", mapname);

    line_buffer = vstring_alloc(100);
    why = vstring_alloc(100);

    /*
     * XXX Eliminate unnecessary queries by setting a flag that says "this
     * map matches network addresses only".
     */
    dict_cidr = (DICT_CIDR *) dict_alloc(DICT_TYPE_CIDR, mapname,
                     sizeof(*dict_cidr));
    dict_cidr->dict.lookup = dict_cidr_lookup;
    dict_cidr->dict.close = dict_cidr_close;
    dict_cidr->dict.flags = dict_flags | DICT_FLAG_PATTERN;
    dict_cidr->head = 0;

    dict_cidr->dict.owner.uid = st.st_uid;
    dict_cidr->dict.owner.status = (st.st_uid != 0);

    while (readllines(line_buffer, map_fp, &last_line, &lineno)) {
    rule = dict_cidr_parse_rule(vstring_str(line_buffer), lineno,
                    nesting, why);
    if (rule == 0) {
        msg_warn("cidr map %s, line %d: %s: skipping this rule",
             mapname, lineno, vstring_str(why));
        continue;
    }
    if (rule->cidr_info.op == CIDR_MATCH_OP_IF) {
        if (rule_stack == 0)
        rule_stack = (DICT_CIDR_ENTRY **) mvect_alloc(&mvect,
                       sizeof(*rule_stack), nesting + 1,
                        (MVECT_FN) 0, (MVECT_FN) 0);
        else
        rule_stack =
            (DICT_CIDR_ENTRY **) mvect_realloc(&mvect, nesting + 1);
        rule_stack[nesting] = rule;
        nesting++;
    } else if (rule->cidr_info.op == CIDR_MATCH_OP_ENDIF) {
        DICT_CIDR_ENTRY *if_rule;

        if (nesting-- <= 0)
        /* Already handled in dict_cidr_parse_rule(). */
        msg_panic("%s: ENDIF without IF", myname);
        if_rule = rule_stack[nesting];
        if (if_rule->cidr_info.op != CIDR_MATCH_OP_IF)
        msg_panic("%s: unexpected rule stack element type %d",
              myname, if_rule->cidr_info.op);
        if_rule->cidr_info.block_end = &(rule->cidr_info);
    }
    if (last_rule == 0)
        dict_cidr->head = rule;
    else
        last_rule->cidr_info.next = &(rule->cidr_info);
    last_rule = rule;
    }

    while (nesting-- > 0)
    msg_warn("cidr map %s, line %d: IF has no matching ENDIF",
         mapname, rule_stack[nesting]->lineno);

    if (rule_stack)
    (void) mvect_free(&mvect);

    DICT_CIDR_OPEN_RETURN(DICT_DEBUG (&dict_cidr->dict));
}