initial add - go fmt on grpc
Change-Id: Ib0afadd2fe5571d1456a091f94f5644458f7d3f4
diff --git a/vendor/google.golang.org/grpc/resolver/dns/dns_resolver.go b/vendor/google.golang.org/grpc/resolver/dns/dns_resolver.go
new file mode 100644
index 0000000..297492e
--- /dev/null
+++ b/vendor/google.golang.org/grpc/resolver/dns/dns_resolver.go
@@ -0,0 +1,457 @@
+/*
+ *
+ * Copyright 2018 gRPC authors.
+ *
+ * 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.
+ *
+ */
+
+// Package dns implements a dns resolver to be installed as the default resolver
+// in grpc.
+package dns
+
+import (
+ "context"
+ "encoding/json"
+ "errors"
+ "fmt"
+ "net"
+ "os"
+ "strconv"
+ "strings"
+ "sync"
+ "time"
+
+ "google.golang.org/grpc/grpclog"
+ "google.golang.org/grpc/internal/backoff"
+ "google.golang.org/grpc/internal/grpcrand"
+ "google.golang.org/grpc/resolver"
+)
+
+func init() {
+ resolver.Register(NewBuilder())
+}
+
+const (
+ defaultPort = "443"
+ defaultFreq = time.Minute * 30
+ defaultDNSSvrPort = "53"
+ golang = "GO"
+ // txtPrefix is the prefix string to be prepended to the host name for txt record lookup.
+ txtPrefix = "_grpc_config."
+ // In DNS, service config is encoded in a TXT record via the mechanism
+ // described in RFC-1464 using the attribute name grpc_config.
+ txtAttribute = "grpc_config="
+)
+
+var (
+ 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")
+)
+
+var (
+ defaultResolver netResolver = net.DefaultResolver
+ // To prevent excessive re-resolution, we enforce a rate limit on DNS
+ // resolution requests.
+ minDNSResRate = 30 * time.Second
+)
+
+var customAuthorityDialler = func(authority string) func(ctx context.Context, network, address string) (net.Conn, error) {
+ return func(ctx context.Context, network, address string) (net.Conn, error) {
+ var dialer net.Dialer
+ return dialer.DialContext(ctx, network, authority)
+ }
+}
+
+var customAuthorityResolver = func(authority string) (netResolver, error) {
+ host, port, err := parseTarget(authority, defaultDNSSvrPort)
+ if err != nil {
+ return nil, err
+ }
+
+ authorityWithPort := net.JoinHostPort(host, port)
+
+ return &net.Resolver{
+ PreferGo: true,
+ Dial: customAuthorityDialler(authorityWithPort),
+ }, nil
+}
+
+// NewBuilder creates a dnsBuilder which is used to factory DNS resolvers.
+func NewBuilder() resolver.Builder {
+ return &dnsBuilder{minFreq: defaultFreq}
+}
+
+type dnsBuilder struct {
+ // 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.
+func (b *dnsBuilder) Build(target resolver.Target, cc resolver.ClientConn, opts resolver.BuildOption) (resolver.Resolver, error) {
+ host, port, err := parseTarget(target.Endpoint, defaultPort)
+ if err != nil {
+ return nil, err
+ }
+
+ // IP address.
+ if net.ParseIP(host) != nil {
+ host, _ = formatIP(host)
+ addr := []resolver.Address{{Addr: host + ":" + port}}
+ i := &ipResolver{
+ cc: cc,
+ ip: addr,
+ rn: make(chan struct{}, 1),
+ q: make(chan struct{}),
+ }
+ cc.NewAddress(addr)
+ go i.watcher()
+ return i, nil
+ }
+
+ // DNS address (non-IP).
+ ctx, cancel := context.WithCancel(context.Background())
+ d := &dnsResolver{
+ freq: b.minFreq,
+ backoff: backoff.Exponential{MaxDelay: b.minFreq},
+ host: host,
+ port: port,
+ ctx: ctx,
+ cancel: cancel,
+ cc: cc,
+ t: time.NewTimer(0),
+ rn: make(chan struct{}, 1),
+ disableServiceConfig: opts.DisableServiceConfig,
+ }
+
+ if target.Authority == "" {
+ d.resolver = defaultResolver
+ } else {
+ d.resolver, err = customAuthorityResolver(target.Authority)
+ if err != nil {
+ return nil, err
+ }
+ }
+
+ d.wg.Add(1)
+ go d.watcher()
+ return d, nil
+}
+
+// Scheme returns the naming scheme of this resolver builder, which is "dns".
+func (b *dnsBuilder) Scheme() string {
+ return "dns"
+}
+
+type netResolver interface {
+ LookupHost(ctx context.Context, host string) (addrs []string, err error)
+ LookupSRV(ctx context.Context, service, proto, name string) (cname string, addrs []*net.SRV, err error)
+ LookupTXT(ctx context.Context, name string) (txts []string, err error)
+}
+
+// ipResolver watches for the name resolution update for an IP address.
+type ipResolver struct {
+ cc resolver.ClientConn
+ ip []resolver.Address
+ // rn channel is used by ResolveNow() to force an immediate resolution of the target.
+ rn chan struct{}
+ q chan struct{}
+}
+
+// ResolveNow resend the address it stores, no resolution is needed.
+func (i *ipResolver) ResolveNow(opt resolver.ResolveNowOption) {
+ select {
+ case i.rn <- struct{}{}:
+ default:
+ }
+}
+
+// Close closes the ipResolver.
+func (i *ipResolver) Close() {
+ close(i.q)
+}
+
+func (i *ipResolver) watcher() {
+ for {
+ select {
+ case <-i.rn:
+ i.cc.NewAddress(i.ip)
+ case <-i.q:
+ return
+ }
+ }
+}
+
+// dnsResolver watches for the name resolution update for a non-IP target.
+type dnsResolver struct {
+ freq time.Duration
+ backoff backoff.Exponential
+ retryCount int
+ host string
+ port string
+ resolver netResolver
+ 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
+ // wg is used to enforce Close() to return after the watcher() goroutine has finished.
+ // Otherwise, data race will be possible. [Race Example] in dns_resolver_test we
+ // replace the real lookup functions with mocked ones to facilitate testing.
+ // If Close() doesn't wait for watcher() goroutine finishes, race detector sometimes
+ // will warns lookup (READ the lookup function pointers) inside watcher() goroutine
+ // has data race with replaceNetFunc (WRITE the lookup function pointers).
+ wg sync.WaitGroup
+ disableServiceConfig bool
+}
+
+// ResolveNow invoke an immediate resolution of the target that this dnsResolver watches.
+func (d *dnsResolver) ResolveNow(opt resolver.ResolveNowOption) {
+ select {
+ case d.rn <- struct{}{}:
+ default:
+ }
+}
+
+// Close closes the dnsResolver.
+func (d *dnsResolver) Close() {
+ d.cancel()
+ d.wg.Wait()
+ d.t.Stop()
+}
+
+func (d *dnsResolver) watcher() {
+ defer d.wg.Done()
+ for {
+ select {
+ case <-d.ctx.Done():
+ return
+ case <-d.t.C:
+ case <-d.rn:
+ if !d.t.Stop() {
+ // Before resetting a timer, it should be stopped to prevent racing with
+ // reads on it's channel.
+ <-d.t.C
+ }
+ }
+
+ result, sc := d.lookup()
+ // 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)
+
+ // Sleep to prevent excessive re-resolutions. Incoming resolution requests
+ // will be queued in d.rn.
+ t := time.NewTimer(minDNSResRate)
+ select {
+ case <-t.C:
+ case <-d.ctx.Done():
+ t.Stop()
+ return
+ }
+ }
+}
+
+func (d *dnsResolver) lookupSRV() []resolver.Address {
+ var newAddrs []resolver.Address
+ _, srvs, err := d.resolver.LookupSRV(d.ctx, "grpclb", "tcp", d.host)
+ if err != nil {
+ grpclog.Infof("grpc: failed dns SRV record lookup due to %v.\n", err)
+ return nil
+ }
+ for _, s := range srvs {
+ lbAddrs, err := d.resolver.LookupHost(d.ctx, s.Target)
+ if err != nil {
+ grpclog.Infof("grpc: failed load balancer address dns lookup due to %v.\n", err)
+ continue
+ }
+ for _, a := range lbAddrs {
+ a, ok := formatIP(a)
+ if !ok {
+ grpclog.Errorf("grpc: failed IP parsing due to %v.\n", err)
+ continue
+ }
+ addr := a + ":" + strconv.Itoa(int(s.Port))
+ newAddrs = append(newAddrs, resolver.Address{Addr: addr, Type: resolver.GRPCLB, ServerName: s.Target})
+ }
+ }
+ return newAddrs
+}
+
+func (d *dnsResolver) lookupTXT() string {
+ ss, err := d.resolver.LookupTXT(d.ctx, txtPrefix+d.host)
+ if err != nil {
+ grpclog.Infof("grpc: failed dns TXT record lookup due to %v.\n", err)
+ return ""
+ }
+ var res string
+ for _, s := range ss {
+ res += s
+ }
+
+ // TXT record must have "grpc_config=" attribute in order to be used as service config.
+ if !strings.HasPrefix(res, txtAttribute) {
+ grpclog.Warningf("grpc: TXT record %v missing %v attribute", res, txtAttribute)
+ return ""
+ }
+ return strings.TrimPrefix(res, txtAttribute)
+}
+
+func (d *dnsResolver) lookupHost() []resolver.Address {
+ var newAddrs []resolver.Address
+ addrs, err := d.resolver.LookupHost(d.ctx, d.host)
+ if err != nil {
+ grpclog.Warningf("grpc: failed dns A record lookup due to %v.\n", err)
+ return nil
+ }
+ for _, a := range addrs {
+ a, ok := formatIP(a)
+ if !ok {
+ grpclog.Errorf("grpc: failed IP parsing due to %v.\n", err)
+ continue
+ }
+ addr := a + ":" + d.port
+ newAddrs = append(newAddrs, resolver.Address{Addr: addr})
+ }
+ return newAddrs
+}
+
+func (d *dnsResolver) lookup() ([]resolver.Address, string) {
+ newAddrs := d.lookupSRV()
+ // Support fallback to non-balancer address.
+ newAddrs = append(newAddrs, d.lookupHost()...)
+ if d.disableServiceConfig {
+ return newAddrs, ""
+ }
+ sc := d.lookupTXT()
+ return newAddrs, canaryingSC(sc)
+}
+
+// formatIP returns ok = false if addr is not a valid textual representation of an IP address.
+// If addr is an IPv4 address, return the addr and ok = true.
+// If addr is an IPv6 address, return the addr enclosed in square brackets and ok = true.
+func formatIP(addr string) (addrIP string, ok bool) {
+ ip := net.ParseIP(addr)
+ if ip == nil {
+ return "", false
+ }
+ if ip.To4() != nil {
+ return addr, true
+ }
+ return "[" + addr + "]", true
+}
+
+// parseTarget takes the user input target string and default port, returns formatted host and port info.
+// If target doesn't specify a port, set the port to be the defaultPort.
+// If target is in IPv6 format and host-name is enclosed in square brackets, brackets
+// are stripped when setting the host.
+// examples:
+// target: "www.google.com" defaultPort: "443" returns host: "www.google.com", port: "443"
+// target: "ipv4-host:80" defaultPort: "443" returns host: "ipv4-host", port: "80"
+// target: "[ipv6-host]" defaultPort: "443" returns host: "ipv6-host", port: "443"
+// target: ":80" defaultPort: "443" returns host: "localhost", port: "80"
+func parseTarget(target, defaultPort string) (host, port string, err error) {
+ if target == "" {
+ return "", "", errMissingAddr
+ }
+ if ip := net.ParseIP(target); ip != nil {
+ // target is an IPv4 or IPv6(without brackets) address
+ 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"
+ }
+ return host, port, nil
+ }
+ if host, port, err = net.SplitHostPort(target + ":" + defaultPort); err == nil {
+ // target doesn't have port
+ return host, port, nil
+ }
+ return "", "", fmt.Errorf("invalid target address %v, error info: %v", target, err)
+}
+
+type rawChoice struct {
+ ClientLanguage *[]string `json:"clientLanguage,omitempty"`
+ Percentage *int `json:"percentage,omitempty"`
+ ClientHostName *[]string `json:"clientHostName,omitempty"`
+ ServiceConfig *json.RawMessage `json:"serviceConfig,omitempty"`
+}
+
+func containsString(a *[]string, b string) bool {
+ if a == nil {
+ return true
+ }
+ for _, c := range *a {
+ if c == b {
+ return true
+ }
+ }
+ return false
+}
+
+func chosenByPercentage(a *int) bool {
+ if a == nil {
+ return true
+ }
+ return grpcrand.Intn(100)+1 <= *a
+}
+
+func canaryingSC(js string) string {
+ if js == "" {
+ return ""
+ }
+ var rcs []rawChoice
+ err := json.Unmarshal([]byte(js), &rcs)
+ if err != nil {
+ grpclog.Warningf("grpc: failed to parse service config json string due to %v.\n", err)
+ return ""
+ }
+ cliHostname, err := os.Hostname()
+ if err != nil {
+ grpclog.Warningf("grpc: failed to get client hostname due to %v.\n", err)
+ return ""
+ }
+ var sc string
+ for _, c := range rcs {
+ if !containsString(c.ClientLanguage, golang) ||
+ !chosenByPercentage(c.Percentage) ||
+ !containsString(c.ClientHostName, cliHostname) ||
+ c.ServiceConfig == nil {
+ continue
+ }
+ sc = string(*c.ServiceConfig)
+ break
+ }
+ return sc
+}