From 347c11ec42264c579eb3f19494e4f75ab8bb8f0d Mon Sep 17 00:00:00 2001
From: Niall Sheridan <nsheridan@gmail.com>
Date: Thu, 9 Aug 2018 23:29:20 +0100
Subject: Remove gRPC

This hasn't been enabled in a while due to gRPC limitations
---
 .../grpc/resolver/dns/dns_resolver.go              | 52 ++++++++++++++--------
 1 file changed, 34 insertions(+), 18 deletions(-)

(limited to 'vendor/google.golang.org/grpc/resolver/dns/dns_resolver.go')

diff --git a/vendor/google.golang.org/grpc/resolver/dns/dns_resolver.go b/vendor/google.golang.org/grpc/resolver/dns/dns_resolver.go
index 048fde6..084bdbf 100644
--- a/vendor/google.golang.org/grpc/resolver/dns/dns_resolver.go
+++ b/vendor/google.golang.org/grpc/resolver/dns/dns_resolver.go
@@ -33,6 +33,7 @@ import (
 
 	"golang.org/x/net/context"
 	"google.golang.org/grpc/grpclog"
+	"google.golang.org/grpc/internal/backoff"
 	"google.golang.org/grpc/internal/grpcrand"
 	"google.golang.org/grpc/resolver"
 )
@@ -51,17 +52,23 @@ const (
 )
 
 var (
-	errMissingAddr = errors.New("missing address")
+	errMissingAddr = errors.New("dns resolver: missing address")
+
+	// Addresses ending with a colon that is supposed to be the separator
+	// between host and port is not allowed.  E.g. "::" is a valid address as
+	// it is an IPv6 address (host only) and "[::]:" is invalid as it ends with
+	// a colon as the host and port separator
+	errEndsWithColon = errors.New("dns resolver: missing port after port-separator colon")
 )
 
 // NewBuilder creates a dnsBuilder which is used to factory DNS resolvers.
 func NewBuilder() resolver.Builder {
-	return &dnsBuilder{freq: defaultFreq}
+	return &dnsBuilder{minFreq: defaultFreq}
 }
 
 type dnsBuilder struct {
-	// frequency of polling the DNS server.
-	freq time.Duration
+	// minimum frequency of polling the DNS server.
+	minFreq time.Duration
 }
 
 // Build creates and starts a DNS resolver that watches the name resolution of the target.
@@ -92,7 +99,8 @@ func (b *dnsBuilder) Build(target resolver.Target, cc resolver.ClientConn, opts
 	// DNS address (non-IP).
 	ctx, cancel := context.WithCancel(context.Background())
 	d := &dnsResolver{
-		freq:                 b.freq,
+		freq:                 b.minFreq,
+		backoff:              backoff.Exponential{MaxDelay: b.minFreq},
 		host:                 host,
 		port:                 port,
 		ctx:                  ctx,
@@ -148,12 +156,14 @@ func (i *ipResolver) watcher() {
 
 // dnsResolver watches for the name resolution update for a non-IP target.
 type dnsResolver struct {
-	freq   time.Duration
-	host   string
-	port   string
-	ctx    context.Context
-	cancel context.CancelFunc
-	cc     resolver.ClientConn
+	freq       time.Duration
+	backoff    backoff.Exponential
+	retryCount int
+	host       string
+	port       string
+	ctx        context.Context
+	cancel     context.CancelFunc
+	cc         resolver.ClientConn
 	// rn channel is used by ResolveNow() to force an immediate resolution of the target.
 	rn chan struct{}
 	t  *time.Timer
@@ -192,8 +202,15 @@ func (d *dnsResolver) watcher() {
 		case <-d.rn:
 		}
 		result, sc := d.lookup()
-		// Next lookup should happen after an interval defined by d.freq.
-		d.t.Reset(d.freq)
+		// Next lookup should happen within an interval defined by d.freq. It may be
+		// more often due to exponential retry on empty address list.
+		if len(result) == 0 {
+			d.retryCount++
+			d.t.Reset(d.backoff.Backoff(d.retryCount))
+		} else {
+			d.retryCount = 0
+			d.t.Reset(d.freq)
+		}
 		d.cc.NewServiceConfig(sc)
 		d.cc.NewAddress(result)
 	}
@@ -297,7 +314,6 @@ func formatIP(addr string) (addrIP string, ok bool) {
 // target: "ipv4-host:80" returns host: "ipv4-host", port: "80"
 // target: "[ipv6-host]" returns host: "ipv6-host", port: "443"
 // target: ":80" returns host: "localhost", port: "80"
-// target: ":" returns host: "localhost", port: "443"
 func parseTarget(target string) (host, port string, err error) {
 	if target == "" {
 		return "", "", errMissingAddr
@@ -307,15 +323,15 @@ func parseTarget(target string) (host, port string, err error) {
 		return target, defaultPort, nil
 	}
 	if host, port, err = net.SplitHostPort(target); err == nil {
+		if port == "" {
+			// If the port field is empty (target ends with colon), e.g. "[::1]:", this is an error.
+			return "", "", errEndsWithColon
+		}
 		// target has port, i.e ipv4-host:port, [ipv6-host]:port, host-name:port
 		if host == "" {
 			// Keep consistent with net.Dial(): If the host is empty, as in ":80", the local system is assumed.
 			host = "localhost"
 		}
-		if port == "" {
-			// If the port field is empty(target ends with colon), e.g. "[::1]:", defaultPort is used.
-			port = defaultPort
-		}
 		return host, port, nil
 	}
 	if host, port, err = net.SplitHostPort(target + ":" + defaultPort); err == nil {
-- 
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