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|
/*++
/* NAME
/* cidr_match 3
/* SUMMARY
/* CIDR-style pattern matching
/* SYNOPSIS
/* #include <cidr_match.h>
/*
/* VSTRING *cidr_match_parse(info, pattern, match, why)
/* CIDR_MATCH *info;
/* char *pattern;
/* VSTRING *why;
/*
/* int cidr_match_execute(info, address)
/* CIDR_MATCH *info;
/* const char *address;
/* AUXILIARY FUNCTIONS
/* VSTRING *cidr_match_parse_if(info, pattern, match, why)
/* CIDR_MATCH *info;
/* char *pattern;
/* VSTRING *why;
/*
/* void cidr_match_endif(info)
/* CIDR_MATCH *info;
/* DESCRIPTION
/* This module parses address or address/length patterns and
/* provides simple address matching. The implementation is
/* such that parsing and execution can be done without dynamic
/* memory allocation. The purpose is to minimize overhead when
/* called by functions that parse and execute on the fly, such
/* as match_hostaddr().
/*
/* cidr_match_parse() parses an address or address/mask
/* expression and stores the result into the info argument.
/* A non-zero (or zero) match argument requests a positive (or
/* negative) match. The symbolic constants CIDR_MATCH_TRUE and
/* CIDR_MATCH_FALSE may help to improve code readability.
/* The result is non-zero in case of problems: either the
/* value of the why argument, or a newly allocated VSTRING
/* (the caller should give the latter to vstring_free()).
/* The pattern argument is destroyed.
/*
/* cidr_match_parse_if() parses the address that follows an IF
/* token, and stores the result into the info argument.
/* The arguments are the same as for cidr_match_parse().
/*
/* cidr_match_endif() handles the occurrence of an ENDIF token,
/* and updates the info argument.
/*
/* cidr_match_execute() matches the specified address against
/* a list of parsed expressions, and returns the matching
/* expression's data structure.
/* SEE ALSO
/* dict_cidr(3) CIDR-style lookup table
/* AUTHOR(S)
/* 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 <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 <msg.h>
#include <vstring.h>
#include <stringops.h>
#include <split_at.h>
#include <myaddrinfo.h>
#include <mask_addr.h>
#include <cidr_match.h>
/* Application-specific. */
/*
* This is how we figure out the address family, address bit count and
* address byte count for a CIDR_MATCH entry.
*/
#ifdef HAS_IPV6
#define CIDR_MATCH_ADDR_FAMILY(a) (strchr((a), ':') ? AF_INET6 : AF_INET)
#define CIDR_MATCH_ADDR_BIT_COUNT(f) \
((f) == AF_INET6 ? MAI_V6ADDR_BITS : \
(f) == AF_INET ? MAI_V4ADDR_BITS : \
(msg_panic("%s: bad address family %d", myname, (f)), 0))
#define CIDR_MATCH_ADDR_BYTE_COUNT(f) \
((f) == AF_INET6 ? MAI_V6ADDR_BYTES : \
(f) == AF_INET ? MAI_V4ADDR_BYTES : \
(msg_panic("%s: bad address family %d", myname, (f)), 0))
#else
#define CIDR_MATCH_ADDR_FAMILY(a) (AF_INET)
#define CIDR_MATCH_ADDR_BIT_COUNT(f) \
((f) == AF_INET ? MAI_V4ADDR_BITS : \
(msg_panic("%s: bad address family %d", myname, (f)), 0))
#define CIDR_MATCH_ADDR_BYTE_COUNT(f) \
((f) == AF_INET ? MAI_V4ADDR_BYTES : \
(msg_panic("%s: bad address family %d", myname, (f)), 0))
#endif
/* cidr_match_entry - match one entry */
static inline int cidr_match_entry(CIDR_MATCH *entry,
unsigned char *addr_bytes)
{
unsigned char *mp;
unsigned char *np;
unsigned char *ap;
/* Unoptimized case: netmask with some or all bits zero. */
if (entry->mask_shift < entry->addr_bit_count) {
for (np = entry->net_bytes, mp = entry->mask_bytes,
ap = addr_bytes; /* void */ ; np++, mp++, ap++) {
if (ap >= addr_bytes + entry->addr_byte_count)
return (entry->match);
if ((*ap & *mp) != *np)
break;
}
}
/* Optimized case: all 1 netmask (i.e. no netmask specified). */
else {
for (np = entry->net_bytes,
ap = addr_bytes; /* void */ ; np++, ap++) {
if (ap >= addr_bytes + entry->addr_byte_count)
return (entry->match);
if (*ap != *np)
break;
}
}
return (!entry->match);
}
/* cidr_match_execute - match address against compiled CIDR pattern list */
CIDR_MATCH *cidr_match_execute(CIDR_MATCH *list, const char *addr)
{
unsigned char addr_bytes[CIDR_MATCH_ABYTES];
unsigned addr_family;
CIDR_MATCH *entry;
addr_family = CIDR_MATCH_ADDR_FAMILY(addr);
if (inet_pton(addr_family, addr, addr_bytes) != 1)
return (0);
for (entry = list; entry; entry = entry->next) {
switch (entry->op) {
case CIDR_MATCH_OP_MATCH:
if (entry->addr_family == addr_family)
if (cidr_match_entry(entry, addr_bytes))
return (entry);
break;
case CIDR_MATCH_OP_IF:
if (entry->addr_family == addr_family)
if (cidr_match_entry(entry, addr_bytes))
continue;
/* An IF without matching ENDIF has no end-of block entry. */
if ((entry = entry->block_end) == 0)
return (0);
/* FALLTHROUGH */
case CIDR_MATCH_OP_ENDIF:
continue;
}
}
return (0);
}
/* cidr_match_parse - parse CIDR pattern */
VSTRING *cidr_match_parse(CIDR_MATCH *ip, char *pattern, int match,
VSTRING *why)
{
const char *myname = "cidr_match_parse";
char *mask_search;
char *mask;
MAI_HOSTADDR_STR hostaddr;
unsigned char *np;
unsigned char *mp;
/*
* Strip [] from [addr/len] or [addr]/len, destroying the pattern. CIDR
* maps don't need [] to eliminate syntax ambiguity, but matchlists need
* it. While stripping [], figure out where we should start looking for
* /mask information.
*/
if (*pattern == '[') {
pattern++;
if ((mask_search = split_at(pattern, ']')) == 0) {
vstring_sprintf(why ? why : (why = vstring_alloc(20)),
"missing ']' character after \"[%s\"", pattern);
return (why);
} else if (*mask_search != '/') {
if (*mask_search != 0) {
vstring_sprintf(why ? why : (why = vstring_alloc(20)),
"garbage after \"[%s]\"", pattern);
return (why);
}
mask_search = pattern;
}
} else
mask_search = pattern;
/*
* Parse the pattern into network and mask, destroying the pattern.
*/
if ((mask = split_at(mask_search, '/')) != 0) {
const char *parse_error;
ip->addr_family = CIDR_MATCH_ADDR_FAMILY(pattern);
ip->addr_bit_count = CIDR_MATCH_ADDR_BIT_COUNT(ip->addr_family);
ip->addr_byte_count = CIDR_MATCH_ADDR_BYTE_COUNT(ip->addr_family);
if (!alldig(mask)) {
parse_error = "bad mask value";
} else if ((ip->mask_shift = atoi(mask)) > ip->addr_bit_count) {
parse_error = "bad mask length";
} else if (inet_pton(ip->addr_family, pattern, ip->net_bytes) != 1) {
parse_error = "bad network value";
} else {
parse_error = 0;
}
if (parse_error != 0) {
vstring_sprintf(why ? why : (why = vstring_alloc(20)),
"%s in \"%s/%s\"", parse_error, pattern, mask);
return (why);
}
if (ip->mask_shift > 0) {
/* Allow for bytes > 8. */
memset(ip->mask_bytes, ~0U, ip->addr_byte_count);
mask_addr(ip->mask_bytes, ip->addr_byte_count, ip->mask_shift);
} else
memset(ip->mask_bytes, 0, ip->addr_byte_count);
/*
* Sanity check: all host address bits must be zero.
*/
for (np = ip->net_bytes, mp = ip->mask_bytes;
np < ip->net_bytes + ip->addr_byte_count; np++, mp++) {
if (*np & ~(*mp)) {
mask_addr(ip->net_bytes, ip->addr_byte_count, ip->mask_shift);
if (inet_ntop(ip->addr_family, ip->net_bytes, hostaddr.buf,
sizeof(hostaddr.buf)) == 0)
msg_fatal("inet_ntop: %m");
vstring_sprintf(why ? why : (why = vstring_alloc(20)),
"non-null host address bits in \"%s/%s\", "
"perhaps you should use \"%s/%d\" instead",
pattern, mask, hostaddr.buf, ip->mask_shift);
return (why);
}
}
}
/*
* No /mask specified. Treat a bare network address as /allbits.
*/
else {
ip->addr_family = CIDR_MATCH_ADDR_FAMILY(pattern);
ip->addr_bit_count = CIDR_MATCH_ADDR_BIT_COUNT(ip->addr_family);
ip->addr_byte_count = CIDR_MATCH_ADDR_BYTE_COUNT(ip->addr_family);
if (inet_pton(ip->addr_family, pattern, ip->net_bytes) != 1) {
vstring_sprintf(why ? why : (why = vstring_alloc(20)),
"bad address pattern: \"%s\"", pattern);
return (why);
}
ip->mask_shift = ip->addr_bit_count;
/* Allow for bytes > 8. */
memset(ip->mask_bytes, ~0U, ip->addr_byte_count);
}
/*
* Wrap up the result.
*/
ip->op = CIDR_MATCH_OP_MATCH;
ip->match = match;
ip->next = 0;
ip->block_end = 0;
return (0);
}
/* cidr_match_parse_if - parse CIDR pattern after IF */
VSTRING *cidr_match_parse_if(CIDR_MATCH *ip, char *pattern, int match,
VSTRING *why)
{
VSTRING *ret;
if ((ret = cidr_match_parse(ip, pattern, match, why)) == 0)
ip->op = CIDR_MATCH_OP_IF;
return (ret);
}
/* cidr_match_endif - handle ENDIF pattern */
void cidr_match_endif(CIDR_MATCH *ip)
{
memset(ip, 0, sizeof(*ip));
ip->op = CIDR_MATCH_OP_ENDIF;
ip->next = 0; /* maybe not all bits 0 */
ip->block_end = 0;
}
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