LibreNMS/Data/Source/SnmpResponse.php
<?php
/**
* SnmpResponse.php
*
* Responsible for parsing net-snmp output into usable PHP data structures.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*
* @link https://www.librenms.org
*
* @copyright 2021 Tony Murray
* @author Tony Murray <murraytony@gmail.com>
*/
namespace LibreNMS\Data\Source;
use Illuminate\Support\Arr;
use Illuminate\Support\Collection;
use Illuminate\Support\Str;
use LibreNMS\Config;
use LibreNMS\Util\Oid;
use Log;
class SnmpResponse
{
protected const KEY_VALUE_DELIMITER = ' = ';
public readonly string $raw;
public readonly int $exitCode;
public readonly string $stderr;
private ?string $errorMessage = null;
private ?array $values = null;
/**
* Create a new response object filling with output from the net-snmp command.
*
* @param string $output
* @param string $errorOutput
* @param int $exitCode
*/
public function __construct(string $output, string $errorOutput = '', int $exitCode = 0)
{
$this->raw = (string) preg_replace('/Wrong Type \(should be .*\): /', '', $output);
$this->stderr = $errorOutput;
$this->exitCode = $exitCode;
}
public function isValid(bool $ignore_partial = false): bool
{
$this->errorMessage = '';
$raw = $ignore_partial ? $this->getRawWithoutBadLines() : $this->raw;
// not checking exitCode because I think it may lead to false negatives
$invalid = preg_match('/(Timeout: No Response from .*|Unknown user name|Authentication failure|Error: OID not increasing: .*)/', $this->stderr, $errors)
|| empty($raw)
|| preg_match('/(No Such Instance|No Such Object|No more variables left).*/', $raw, $errors);
if ($invalid) {
$this->errorMessage = $errors[0] ?? 'Empty Output';
Log::debug(sprintf('SNMP query failed. Exit Code: %s Empty: %s Bad String: %s', $this->exitCode, var_export(empty($raw), true), $errors[0] ?? 'not found'));
return false;
}
return true;
}
/**
* Get the error message if any
*/
public function getErrorMessage(): string
{
if (empty($this->errorMessage)) {
$this->isValid(); // if no error message, double check.
}
return $this->errorMessage;
}
/**
* Gets the first value of this response.
* If an oid or list of oids is given, return the first one found.
* If forceNumeric is set, force the search to use numeric oids even if textual oids are given
*
* @throws \LibreNMS\Exceptions\InvalidOidException
*/
public function value(array|string $oids = [], bool $forceNumeric = false): string
{
$values = $this->values();
if (empty($oids)) {
return Arr::first($values, default: '');
}
$oids = Arr::wrap($oids);
foreach ($oids as $oid) {
if ($forceNumeric) {
// translate all to numeric to make it easier to match
$oid = Oid::toNumeric($oid);
}
if (isset($values[$oid]) && $values[$oid] !== '') {
return $values[$oid];
}
}
// try to match table format
if (str_contains($this->raw, '[')) {
foreach ($oids as $oid) {
$dot_index_oid = preg_replace('/\.([^.]+)/', '[$1]', $oid);
// if new oid is different and exists and is not an empty string
if ($dot_index_oid !== $oid && isset($values[$dot_index_oid]) && $values[$dot_index_oid] !== '') {
return $values[$dot_index_oid];
}
}
}
return '';
}
public function values(): array
{
if (isset($this->values)) {
return $this->values;
}
$this->values = [];
$line = strtok($this->raw, PHP_EOL);
while ($line !== false) {
if (Str::contains($line, ['at this OID', 'this MIB View', 'End of MIB'])) {
// these occur when we seek past the end of data, usually the end of the response, but grab the next line and continue
$line = strtok(PHP_EOL);
continue;
}
$parts = explode(self::KEY_VALUE_DELIMITER, $line, 2);
if (count($parts) == 1) {
array_unshift($parts, '');
}
[$oid, $value] = $parts;
$line = strtok(PHP_EOL); // get the next line and concatenate multi-line values
while ($line !== false && ! Str::contains($line, self::KEY_VALUE_DELIMITER)) {
$value .= PHP_EOL . $line;
$line = strtok(PHP_EOL);
}
// remove extra escapes
if (Config::get('snmp.unescape')) {
$value = stripslashes($value);
}
if (Str::startsWith($value, '"') && Str::endsWith($value, '"')) {
// unformatted string from net-snmp, remove extra escapes
$this->values[$oid] = trim(stripslashes($value), "\" \n\r");
} else {
$this->values[$oid] = trim($value);
}
}
return $this->values;
}
public function valuesByIndex(array &$array = []): array
{
foreach ($this->values() as $oid => $value) {
$parts = $this->getOidParts($oid);
$name = array_shift($parts);
$index = implode('.', $parts);
$array[$index][$name] = $value;
}
return $array;
}
public function table(int $group = 0, array &$array = []): array
{
foreach ($this->values() as $key => $value) {
$parts = $this->getOidParts($key);
// move the oid name to the correct depth
array_splice($parts, $group, 0, array_shift($parts));
// merge the parts into an array, creating keys if they don't exist
$tmp = &$array;
foreach ($parts as $part) {
$key = trim($part, '"');
$tmp = &$tmp[$key];
}
$tmp = $value; // assign the value as the leaf
}
return Arr::wrap($array); // if no parts, wrap the value
}
/**
* Map an snmp table with callback. If invalid data is encountered, an empty collection is returned.
* Variables passed to the callback will be an array of row values followed by each individual index.
*/
public function mapTable(callable $callback): Collection
{
if (! $this->isValid(true)) {
return new Collection;
}
return collect($this->values())
->map(function ($value, $oid) {
$parts = $this->getOidParts($oid);
$key = array_shift($parts);
return [
'_index' => implode('][', $parts),
$key => $value,
];
})
->groupBy('_index')
->map(function ($values, $index) use ($callback) {
$values = array_merge(...$values);
unset($values['_index']);
return call_user_func($callback, $values, ...explode('][', (string) $index));
});
}
/**
* @return int
*/
public function getExitCode(): int
{
return $this->exitCode;
}
/**
* Filter bad lines from the raw output, examples:
* "No Such Instance currently exists at this OID"
* "No more variables left in this MIB View (It is past the end of the MIB tree)"
*/
public function getRawWithoutBadLines(): string
{
return (string) preg_replace([
'/^.*No Such Instance currently exists.*$/m',
'/(\n[^\r\n]+No more variables left[^\r\n]+)+$/',
], '', $this->raw);
}
public function append(SnmpResponse $response): SnmpResponse
{
$newResponse = new static(
$this->raw . $response->raw,
$this->stderr . $response->stderr,
$this->exitCode ?: $response->exitCode,
);
$newResponse->errorMessage = $this->errorMessage ?: $response->errorMessage;
return $newResponse;
}
public function __toString(): string
{
return $this->raw;
}
private function getOidParts(string $key): array
{
// table
if (Str::contains($key, '[')) {
preg_match_all('/([^[\]]+)/', $key, $parts);
return $parts[1]; // get all group 1 matches
}
// regular oid
return explode('.', $key);
}
public function __sleep()
{
return ['raw', 'exitCode', 'stderr'];
}
}