/usr/share/gocode/src/github.com/google/cups-connector/snmp/snmp.go is in google-cloud-print-connector 0.0~git20151105.24.1902938-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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Copyright 2015 Google Inc. All rights reserved.
Use of this source code is governed by a BSD-style
license that can be found in the LICENSE file or at
https://developers.google.com/open-source/licenses/bsd
*/
package snmp
/*
#cgo CFLAGS: -std=gnu99 -D_GNU_SOURCE
#cgo LDFLAGS: -lnetsnmp
#include <net-snmp/net-snmp-config.h>
#include <net-snmp/net-snmp-includes.h>
#include "snmp.h"
*/
import "C"
import (
"errors"
"reflect"
"sync"
"unsafe"
"github.com/google/cups-connector/lib"
"github.com/google/cups-connector/snmp/oid"
)
type SNMPManager struct {
inUse *lib.Semaphore
community *C.char
maxConnections uint
}
// NewSNMPManager creates a new SNMP manager.
func NewSNMPManager(community string, maxConnections uint) (*SNMPManager, error) {
if community == "" || maxConnections == 0 {
return nil, errors.New(
"SNMP values not set in config file; run connector-util -update-config-file")
}
C.initialize()
s := SNMPManager{
inUse: lib.NewSemaphore(1),
community: C.CString(community),
maxConnections: maxConnections,
}
return &s, nil
}
func (s *SNMPManager) Quit() {
s.inUse.Acquire()
C.free(unsafe.Pointer(s.community))
}
func intArrayToOID(cOID *C.oid, cLength C.size_t) oid.OID {
length := int(cLength)
hdr := reflect.SliceHeader{
Data: uintptr(unsafe.Pointer(cOID)),
Len: length,
Cap: length,
}
o := make([]uint, length)
for i, digit := range *(*[]C.oid)(unsafe.Pointer(&hdr)) {
o[i] = uint(digit)
}
return o
}
func charArrayToSlice(cArr **C.char, cLength C.size_t) []*C.char {
length := int(cLength)
hdr := reflect.SliceHeader{
Data: uintptr(unsafe.Pointer(cArr)),
Len: length,
Cap: length,
}
return *(*[]*C.char)(unsafe.Pointer(&hdr))
}
// getPrinters gets all printer SNMP information for each hostname, concurrently.
func (s *SNMPManager) getPrinters(hostnames []string) (map[string]*oid.VariableSet, error) {
if !s.inUse.TryAcquire() {
return nil, errors.New("Tried to query printers via SNMP twice")
}
defer s.inUse.Release()
wg := sync.WaitGroup{}
wg.Add(len(hostnames))
results := make(map[string]*oid.VariableSet, len(hostnames))
for _, hostname := range hostnames {
results[hostname] = &oid.VariableSet{}
}
semaphore := lib.NewSemaphore(s.maxConnections)
for _, hostname := range hostnames {
go func(hostname string) {
r := results[hostname]
h := C.CString(hostname)
defer C.free(unsafe.Pointer(h))
semaphore.Acquire()
defer semaphore.Release()
response := C.bulkwalk(h, s.community)
for o := response.ov_root; o != nil; o = o.next {
r.AddVariable(intArrayToOID((*o).name, (*o).name_length), C.GoString((*o).value))
defer C.free(unsafe.Pointer((*o).name))
defer C.free(unsafe.Pointer((*o).value))
defer C.free(unsafe.Pointer(o))
}
if response.errors_len > 0 {
for _, err := range charArrayToSlice(response.errors, response.errors_len) {
// Ignore errors. Not all printers support SNMP, so this is best effort.
C.free(unsafe.Pointer(err))
}
C.free(unsafe.Pointer(response.errors))
}
wg.Done()
}(hostname)
}
wg.Wait()
return results, nil
}
// AugmentPrinters queries every printer's SNMP agent, adds anything it
// finds back to the printer object.
func (s *SNMPManager) AugmentPrinters(printers []lib.Printer) error {
hostnames := make([]string, 0, len(printers))
for _, printer := range printers {
if hostname, exists := printer.GetHostname(); exists {
hostnames = append(hostnames, hostname)
}
}
varsByHostname, err := s.getPrinters(hostnames)
if err != nil {
return err
}
for i := range printers {
hostname, ok := printers[i].GetHostname()
if !ok {
continue
}
vars, ok := varsByHostname[hostname]
if !ok {
continue
}
if serialNumber, ok := vars.GetSerialNumber(); ok {
printers[i].Tags["snmp-serial-number"] = serialNumber
}
if covers, coverState, exists := vars.GetCovers(); exists {
printers[i].State.CoverState = coverState
printers[i].Description.Cover = covers
}
if inputTrayUnits, inputTrayState, exists := vars.GetInputTrays(); exists {
printers[i].State.InputTrayState = inputTrayState
printers[i].Description.InputTrayUnit = inputTrayUnits
}
if outputBinUnits, outputBinState, exists := vars.GetOutputBins(); exists {
printers[i].State.OutputBinState = outputBinState
printers[i].Description.OutputBinUnit = outputBinUnits
}
if markers, markerState, vendorState, exists := vars.GetMarkers(); exists {
if len(*markers) > 0 && len(markerState.Item) > 0 {
printers[i].State.MarkerState = markerState
printers[i].Description.Marker = markers
}
if len(vendorState.Item) > 0 {
printers[i].State.VendorState = vendorState
}
}
}
return nil
}
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