libvirt/tools/nss/libvirt_nss_leases.c
Michal Privoznik d7dd4e1f89 nss: Don't fail on empty files
Before we rewrote nss plugin so that it doesn't use libvirt's
internal functions it used virLeaseReadCustomLeaseFile() to parse
.status files. After the rewrite it's using read() + yajl_parse()
+ yajl_complete_parse(). There's one catch though,
virLeaseReadCustomLeaseFile() skipped over empty files.

An empty .status file is created when a network is started. This
is because we configure dnsmasq to use our leasehelper. So the
first thing it does it calls it as follows:

  DNSMASQ_INTERFACE=virbr0 /usr/libexec/libvirt_leaseshelper init

which causes the leasehelper to create empty virbr0.status file.
If there is only one libvirt network then that is no problem -
there are no other .status files to parse anyway. But if there
are two or more networks then the first empty .status file causes
whole parsing process and subsequently the whole name lookup
process to fail.

Fixes: v5.7.0-rc1~343

Reported-by: Pavel Hrdina <phrdina@redhat.com>
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
2019-11-28 15:37:41 +01:00

438 lines
11 KiB
C

/*
* libvirt_nss_leases.c: Name Service Switch plugin lease file parser
*
* Copyright (C) 2019 Red Hat, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library. If not, see
* <http://www.gnu.org/licenses/>.
*/
#include <config.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include <stdbool.h>
#include <fcntl.h>
#include <yajl/yajl_gen.h>
#include <yajl/yajl_parse.h>
#include "libvirt_nss_leases.h"
#include "libvirt_nss.h"
enum {
FIND_LEASES_STATE_START,
FIND_LEASES_STATE_LIST,
FIND_LEASES_STATE_ENTRY,
};
typedef struct {
const char *name;
char **macs;
size_t nmacs;
int state;
unsigned long long now;
int af;
bool *found;
leaseAddress **addrs;
size_t *naddrs;
char *key;
struct {
unsigned long long expiry;
char *ipaddr;
char *macaddr;
char *hostname;
} entry;
} findLeasesParser;
static int
appendAddr(const char *name __attribute__((unused)),
leaseAddress **tmpAddress,
size_t *ntmpAddress,
const char *ipAddr,
long long expirytime,
int af)
{
int family;
size_t i;
struct addrinfo hints = {0};
struct addrinfo *res = NULL;
union {
struct sockaddr sa;
struct sockaddr_in sin;
struct sockaddr_in6 sin6;
} sa;
unsigned char addr[16];
int err;
leaseAddress *newAddr;
DEBUG("IP address: %s", ipAddr);
hints.ai_family = AF_UNSPEC;
hints.ai_flags = AI_NUMERICHOST;
if ((err = getaddrinfo(ipAddr, NULL, &hints, &res)) != 0) {
ERROR("Cannot parse socket address '%s': %s",
ipAddr, gai_strerror(err));
return -1;
}
if (!res) {
ERROR("No resolved address for '%s'", ipAddr);
return -1;
}
family = res->ai_family;
memcpy(&sa, res->ai_addr, res->ai_addrlen);
freeaddrinfo(res);
if (family == AF_INET) {
memcpy(addr, &sa.sin.sin_addr, sizeof(sa.sin.sin_addr));
} else if (family == AF_INET6) {
memcpy(addr, &sa.sin6.sin6_addr, sizeof(sa.sin6.sin6_addr));
} else {
DEBUG("Skipping unexpected family %d", family);
return 0;
}
if (af != AF_UNSPEC && af != family) {
DEBUG("Skipping address which family is %d, %d requested", family, af);
return 0;
}
for (i = 0; i < *ntmpAddress; i++) {
if (family == AF_INET) {
if ((*tmpAddress)[i].af == AF_INET &&
memcmp((*tmpAddress)[i].addr,
&sa.sin.sin_addr,
sizeof(sa.sin.sin_addr)) == 0) {
DEBUG("IP address already in the list");
return 0;
}
} else {
if ((*tmpAddress)[i].af == AF_INET6 &&
memcmp((*tmpAddress)[i].addr,
&sa.sin6.sin6_addr,
sizeof(sa.sin6.sin6_addr)) == 0) {
DEBUG("IP address already in the list");
return 0;
}
}
}
newAddr = realloc(*tmpAddress, sizeof(*newAddr) * (*ntmpAddress + 1));
if (!newAddr) {
ERROR("Out of memory");
return -1;
}
*tmpAddress = newAddr;
(*tmpAddress)[*ntmpAddress].expirytime = expirytime;
(*tmpAddress)[*ntmpAddress].af = family;
if (family == AF_INET)
memcpy((*tmpAddress)[*ntmpAddress].addr,
&sa.sin.sin_addr,
sizeof(sa.sin.sin_addr));
else
memcpy((*tmpAddress)[*ntmpAddress].addr,
&sa.sin6.sin6_addr,
sizeof(sa.sin6.sin6_addr));
(*ntmpAddress)++;
return 0;
}
static int
findLeasesParserInteger(void *ctx,
long long val)
{
findLeasesParser *parser = ctx;
DEBUG("Parse int state=%d '%lld' (map key '%s')",
parser->state, val, NULLSTR(parser->key));
if (!parser->key)
return 0;
if (parser->state == FIND_LEASES_STATE_ENTRY) {
if (strcmp(parser->key, "expiry-time"))
return 0;
parser->entry.expiry = val;
} else {
return 0;
}
return 1;
}
static int
findLeasesParserString(void *ctx,
const unsigned char *stringVal,
size_t stringLen)
{
findLeasesParser *parser = ctx;
DEBUG("Parse string state=%d '%.*s' (map key '%s')",
parser->state, (int)stringLen, (const char *)stringVal,
NULLSTR(parser->key));
if (!parser->key)
return 0;
if (parser->state == FIND_LEASES_STATE_ENTRY) {
if (!strcmp(parser->key, "ip-address")) {
if (!(parser->entry.ipaddr = strndup((char *)stringVal, stringLen)))
return 0;
} else if (!strcmp(parser->key, "mac-address")) {
if (!(parser->entry.macaddr = strndup((char *)stringVal, stringLen)))
return 0;
} else if (!strcmp(parser->key, "hostname")) {
if (!(parser->entry.hostname = strndup((char *)stringVal, stringLen)))
return 0;
} else {
return 1;
}
} else {
return 0;
}
return 1;
}
static int
findLeasesParserMapKey(void *ctx,
const unsigned char *stringVal,
size_t stringLen)
{
findLeasesParser *parser = ctx;
DEBUG("Parse map key state=%d '%.*s'",
parser->state, (int)stringLen, (const char *)stringVal);
free(parser->key);
if (!(parser->key = strndup((char *)stringVal, stringLen)))
return 0;
return 1;
}
static int
findLeasesParserStartMap(void *ctx)
{
findLeasesParser *parser = ctx;
DEBUG("Parse start map state=%d", parser->state);
if (parser->state != FIND_LEASES_STATE_LIST)
return 0;
free(parser->key);
parser->key = NULL;
parser->state = FIND_LEASES_STATE_ENTRY;
return 1;
}
static int
findLeasesParserEndMap(void *ctx)
{
findLeasesParser *parser = ctx;
size_t i;
bool found = false;
DEBUG("Parse end map state=%d", parser->state);
if (parser->entry.macaddr == NULL)
return 0;
if (parser->state != FIND_LEASES_STATE_ENTRY)
return 0;
if (parser->nmacs) {
DEBUG("Check %zu macs", parser->nmacs);
for (i = 0; i < parser->nmacs && !found; i++) {
DEBUG("Check mac '%s' vs '%s'", parser->macs[i], NULLSTR(parser->entry.macaddr));
if (parser->entry.macaddr && !strcmp(parser->macs[i], parser->entry.macaddr))
found = true;
}
} else {
DEBUG("Check name '%s' vs '%s'", parser->name, NULLSTR(parser->entry.hostname));
if (parser->entry.hostname && !strcmp(parser->name, parser->entry.hostname))
found = true;
}
DEBUG("Found %d", found);
if (parser->entry.expiry < parser->now) {
DEBUG("Entry expired at %llu vs now %llu",
parser->entry.expiry, parser->now);
found = false;
}
if (!parser->entry.ipaddr)
found = false;
if (found) {
*parser->found = true;
if (appendAddr(parser->name,
parser->addrs, parser->naddrs,
parser->entry.ipaddr,
parser->entry.expiry,
parser->af) < 0)
return 0;
}
free(parser->entry.macaddr);
free(parser->entry.ipaddr);
free(parser->entry.hostname);
parser->entry.macaddr = NULL;
parser->entry.ipaddr = NULL;
parser->entry.hostname = NULL;
parser->state = FIND_LEASES_STATE_LIST;
return 1;
}
static int
findLeasesParserStartArray(void *ctx)
{
findLeasesParser *parser = ctx;
DEBUG("Parse start array state=%d", parser->state);
if (parser->state == FIND_LEASES_STATE_START) {
parser->state = FIND_LEASES_STATE_LIST;
} else {
return 0;
}
return 1;
}
static int
findLeasesParserEndArray(void *ctx)
{
findLeasesParser *parser = ctx;
DEBUG("Parse end array state=%d", parser->state);
if (parser->state == FIND_LEASES_STATE_LIST)
parser->state = FIND_LEASES_STATE_START;
else
return 0;
return 1;
}
int
findLeases(const char *file,
const char *name,
char **macs,
size_t nmacs,
int af,
time_t now,
leaseAddress **addrs,
size_t *naddrs,
bool *found)
{
int fd = -1;
int ret = -1;
const yajl_callbacks parserCallbacks = {
NULL, /* null */
NULL, /* bool */
findLeasesParserInteger,
NULL, /* double */
NULL, /* number */
findLeasesParserString,
findLeasesParserStartMap,
findLeasesParserMapKey,
findLeasesParserEndMap,
findLeasesParserStartArray,
findLeasesParserEndArray,
};
findLeasesParser parserState = {
.name = name,
.macs = macs,
.nmacs = nmacs,
.af = af,
.now = now,
.found = found,
.addrs = addrs,
.naddrs = naddrs,
};
yajl_handle parser = NULL;
char line[1024];
ssize_t nreadTotal = 0;
int rv;
if ((fd = open(file, O_RDONLY)) < 0) {
ERROR("Cannot open %s", file);
goto cleanup;
}
parser = yajl_alloc(&parserCallbacks, NULL, &parserState);
if (!parser) {
ERROR("Unable to create JSON parser");
goto cleanup;
}
while (1) {
rv = read(fd, line, sizeof(line));
if (rv < 0)
goto cleanup;
if (rv == 0)
break;
nreadTotal += rv;
if (yajl_parse(parser, (const unsigned char *)line, rv) !=
yajl_status_ok) {
unsigned char *err = yajl_get_error(parser, 1,
(const unsigned char*)line, rv);
ERROR("Parse failed %s", (const char *) err);
yajl_free_error(parser, err);
goto cleanup;
}
}
if (nreadTotal > 0 &&
yajl_complete_parse(parser) != yajl_status_ok) {
ERROR("Parse failed %s",
yajl_get_error(parser, 1, NULL, 0));
goto cleanup;
}
ret = 0;
cleanup:
if (ret != 0) {
free(*addrs);
*addrs = NULL;
*naddrs = 0;
}
yajl_free(parser);
free(parserState.entry.ipaddr);
free(parserState.entry.macaddr);
free(parserState.entry.hostname);
free(parserState.key);
if (fd != -1)
close(fd);
return ret;
}