diff options
Diffstat (limited to 'vendor/google.golang.org/grpc/resolver/dns/dns_resolver.go')
| -rw-r--r-- | vendor/google.golang.org/grpc/resolver/dns/dns_resolver.go | 397 |
1 files changed, 0 insertions, 397 deletions
diff --git a/vendor/google.golang.org/grpc/resolver/dns/dns_resolver.go b/vendor/google.golang.org/grpc/resolver/dns/dns_resolver.go deleted file mode 100644 index 084bdbf..0000000 --- a/vendor/google.golang.org/grpc/resolver/dns/dns_resolver.go +++ /dev/null @@ -1,397 +0,0 @@ -/* - * - * Copyright 2017 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 ( - "encoding/json" - "errors" - "fmt" - "net" - "os" - "strconv" - "strings" - "sync" - "time" - - "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" -) - -func init() { - resolver.Register(NewBuilder()) -} - -const ( - defaultPort = "443" - defaultFreq = time.Minute * 30 - golang = "GO" - // 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") -) - -// 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) { - if target.Authority != "" { - return nil, fmt.Errorf("Default DNS resolver does not support custom DNS server") - } - host, port, err := parseTarget(target.Endpoint) - 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, - } - - 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" -} - -// 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 - 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: - } - 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) - } -} - -func (d *dnsResolver) lookupSRV() []resolver.Address { - var newAddrs []resolver.Address - _, srvs, err := 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 := 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 := lookupTXT(d.ctx, 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 := 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, 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 sqarue brackets, brackets -// are strippd when setting the host. -// examples: -// target: "www.google.com" returns host: "www.google.com", port: "443" -// 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" -func parseTarget(target 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 -} |