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grpc-echo.go
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/
grpc-echo.go
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package services
import (
"bytes"
"context"
"crypto/tls"
"encoding/json"
"fmt"
"log"
"net"
"time"
// "os"
"strconv"
"strings"
pb "github.com/datawire/kat-backend/echo"
grpc "google.golang.org/grpc"
codes "google.golang.org/grpc/codes"
metadata "google.golang.org/grpc/metadata"
status "google.golang.org/grpc/status"
)
// GRPC server object (all fields are required).
type GRPC struct {
Port int16
Backend string
SecurePort int16
SecureBackend string
Cert string
Key string
}
// DefaultOpts sets gRPC service options.
func DefaultOpts() []grpc.ServerOption {
return []grpc.ServerOption{
grpc.MaxRecvMsgSize(1024 * 1024 * 5),
grpc.MaxSendMsgSize(1024 * 1024 * 5),
}
}
// Start initializes the gRPC server.
func (g *GRPC) Start() <-chan bool {
log.Printf("GRPC: %s listening on %d/%d", g.Backend, g.Port, g.SecurePort)
exited := make(chan bool)
proto := "tcp"
go func() {
port := fmt.Sprintf(":%d", g.Port)
ln, err := net.Listen(proto, port)
if err != nil {
log.Fatal()
}
s := grpc.NewServer(DefaultOpts()...)
pb.RegisterEchoServiceServer(s, g)
s.Serve(ln)
defer ln.Close()
close(exited)
}()
go func() {
cer, err := tls.LoadX509KeyPair(g.Cert, g.Key)
if err != nil {
log.Fatal(err)
return
}
config := &tls.Config{Certificates: []tls.Certificate{cer}}
port := fmt.Sprintf(":%d", g.SecurePort)
ln, err := tls.Listen(proto, port, config)
if err != nil {
log.Fatal(err)
return
}
s := grpc.NewServer(DefaultOpts()...)
pb.RegisterEchoServiceServer(s, g)
s.Serve(ln)
defer ln.Close()
close(exited)
}()
log.Print("starting gRPC echo service")
return exited
}
// Echo returns the an object with the HTTP context of the request.
func (g *GRPC) Echo(ctx context.Context, r *pb.EchoRequest) (*pb.EchoResponse, error) {
md, ok := metadata.FromIncomingContext(ctx)
if !ok {
return nil, status.Error(codes.Code(13), "request has not valid context metadata")
}
buf := bytes.Buffer{}
buf.WriteString("metadata received: \n")
for k, v := range md {
buf.WriteString(fmt.Sprintf("%v : %s\n", k, strings.Join(v, ",")))
}
log.Println(buf.String())
request := &pb.Request{
Headers: make(map[string]string),
}
response := &pb.Response{
Headers: make(map[string]string),
}
// Sets request headers.
for k, v := range md {
request.Headers[k] = strings.Join(v, ",")
response.Headers[k] = strings.Join(v, ",")
}
// Set default backend and assume we're the clear side of the world.
backend := g.Backend
// Checks scheme and set TLS info.
if len(md["x-forwarded-proto"]) > 0 && md["x-forwarded-proto"][0] == "https" {
// We're the secure side of the world, I guess.
backend = g.SecureBackend
request.Tls = &pb.TLS{
Enabled: true,
}
}
// Check header and delay response.
if h, ok := md["Requested-Backend-Delay"]; ok {
if v, err := strconv.Atoi(h[0]); err == nil {
log.Printf("Delaying response by %v ms", v)
time.Sleep(time.Duration(v) * time.Millisecond)
}
}
// Set response date header.
response.Headers["date"] = time.Now().Format(time.RFC1123)
// Sets client requested metadata.
if len(md["requested-headers"]) > 0 {
for _, v := range md["requested-headers"] {
if len(md[v]) > 0 {
s := strings.Join(md[v], ",")
response.Headers[v] = s
p := metadata.Pairs(v, s)
grpc.SendHeader(ctx, p)
}
}
}
// Sets grpc response.
echoRES := &pb.EchoResponse{
Backend: backend,
Request: request,
Response: response,
}
// Set a log message.
if data, err := json.MarshalIndent(echoRES, "", " "); err == nil {
log.Printf("setting response: %s\n", string(data))
}
// Checks if requested-status is a valid and not OK gRPC status.
if len(md["requested-status"]) > 0 {
val, err := strconv.Atoi(md["requested-status"][0])
if err == nil {
if val < 18 || val > 0 {
// Return response and the not OK status.
return echoRES, status.Error(codes.Code(val), "requested-error")
}
}
}
// Returns response and the OK status.
return echoRES, nil
}