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// Copyright (c) 2017 Cisco and/or its affiliates.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at:
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// +build !windows,!darwin
// Package vppapiclient is the default VPP adapter being used for the connection with VPP via shared memory.
// It is based on the communication with the vppapiclient VPP library written in C via CGO.
package vppapiclient
/*
#cgo CFLAGS: -DPNG_DEBUG=1
#cgo LDFLAGS: -lvppapiclient
#include <stdlib.h>
#include <stdio.h>
#include <stdint.h>
#include <arpa/inet.h>
#include <vpp-api/client/vppapiclient.h>
extern void go_msg_callback(uint16_t msg_id, uint32_t context, void* data, size_t size);
typedef struct __attribute__((__packed__)) _req_header {
uint16_t msg_id;
uint32_t client_index;
uint32_t context;
} req_header_t;
typedef struct __attribute__((__packed__)) _reply_header {
uint16_t msg_id;
uint32_t context; // currently not all reply messages contain context field
} reply_header_t;
static void
govpp_msg_callback (unsigned char *data, int size)
{
reply_header_t *header = ((reply_header_t *)data);
go_msg_callback(ntohs(header->msg_id), ntohl(header->context), data, size);
}
static int
govpp_send(uint32_t context, void *data, size_t size)
{
req_header_t *header = ((req_header_t *)data);
header->context = htonl(context);
return vac_write(data, size);
}
static int
govpp_connect (char *shm)
{
return vac_connect("govpp", shm, govpp_msg_callback, 32);
}
static int
govvp_disconnect()
{
return vac_disconnect();
}
static uint32_t
govpp_get_msg_index(char *name_and_crc)
{
return vac_get_msg_index(name_and_crc);
}
*/
import "C"
import (
"fmt"
"os"
"path/filepath"
"reflect"
"unsafe"
"git.fd.io/govpp.git/adapter"
"github.com/fsnotify/fsnotify"
)
const (
// watchedFolder is a folder where vpp's shared memory is supposed to be created.
// File system events are monitored in this folder.
watchedFolder = "/dev/shm/"
// watchedFile is a default name of the file in the watchedFolder. Once the file is present,
// the vpp is ready to accept a new connection.
watchedFile = "vpe-api"
)
// vppAPIClientAdapter is the opaque context of the adapter.
type vppAPIClientAdapter struct {
shmPrefix string
callback adapter.MsgCallback
}
var vppClient *vppAPIClientAdapter // global vpp API client adapter context
// NewVppAdapter returns a new vpp API client adapter.
func NewVppAdapter(shmPrefix string) adapter.VppAdapter {
return &vppAPIClientAdapter{
shmPrefix: shmPrefix,
}
}
// Connect connects the process to VPP.
func (a *vppAPIClientAdapter) Connect() error {
vppClient = a
var rc _Ctype_int
if a.shmPrefix == "" {
rc = C.govpp_connect(nil)
} else {
shm := C.CString(a.shmPrefix)
rc = C.govpp_connect(shm)
}
if rc != 0 {
return fmt.Errorf("unable to connect to VPP (error=%d)", rc)
}
return nil
}
// Disconnect disconnects the process from VPP.
func (a *vppAPIClientAdapter) Disconnect() {
C.govvp_disconnect()
}
// GetMsgID returns a runtime message ID for the given message name and CRC.
func (a *vppAPIClientAdapter) GetMsgID(msgName string, msgCrc string) (uint16, error) {
nameAndCrc := C.CString(msgName + "_" + msgCrc)
defer C.free(unsafe.Pointer(nameAndCrc))
msgID := uint16(C.govpp_get_msg_index(nameAndCrc))
if msgID == ^uint16(0) {
// VPP does not know this message
return msgID, fmt.Errorf("unknown message: %v (crc: %v)", msgName, msgCrc)
}
return msgID, nil
}
// SendMsg sends a binary-encoded message to VPP.
func (a *vppAPIClientAdapter) SendMsg(context uint32, data []byte) error {
rc := C.govpp_send(C.uint32_t(context), unsafe.Pointer(&data[0]), C.size_t(len(data)))
if rc != 0 {
return fmt.Errorf("unable to send the message (error=%d)", rc)
}
return nil
}
// SetMsgCallback sets a callback function that will be called by the adapter whenever a message comes from VPP.
func (a *vppAPIClientAdapter) SetMsgCallback(cb adapter.MsgCallback) {
a.callback = cb
}
// WaitReady blocks until shared memory for sending
// binary api calls is present on the file system.
func (a *vppAPIClientAdapter) WaitReady() error {
// Path to the shared memory segment
var path string
if a.shmPrefix == "" {
path = filepath.Join(watchedFolder, watchedFile)
} else {
path = filepath.Join(watchedFolder, a.shmPrefix+"-"+watchedFile)
}
// Watch folder if file does not exist yet
if !fileExists(path) {
watcher, err := fsnotify.NewWatcher()
if err != nil {
return err
}
defer watcher.Close()
if err := watcher.Add(watchedFolder); err != nil {
return err
}
for {
ev := <-watcher.Events
if ev.Name == path && (ev.Op&fsnotify.Create) == fsnotify.Create {
break
}
}
}
return nil
}
func fileExists(name string) bool {
if _, err := os.Stat(name); err != nil {
if os.IsNotExist(err) {
return false
}
}
return true
}
//export go_msg_callback
func go_msg_callback(msgID C.uint16_t, context C.uint32_t, data unsafe.Pointer, size C.size_t) {
// convert unsafe.Pointer to byte slice
slice := &reflect.SliceHeader{Data: uintptr(data), Len: int(size), Cap: int(size)}
byteArr := *(*[]byte)(unsafe.Pointer(slice))
vppClient.callback(uint16(msgID), uint32(context), byteArr)
}
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