diff options
Diffstat (limited to 'vendor/google.golang.org/grpc/resolver/dns')
| -rw-r--r-- | vendor/google.golang.org/grpc/resolver/dns/dns_resolver.go | 379 | ||||
| -rw-r--r-- | vendor/google.golang.org/grpc/resolver/dns/go17.go | 35 | ||||
| -rw-r--r-- | vendor/google.golang.org/grpc/resolver/dns/go18.go | 29 |
3 files changed, 443 insertions, 0 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 new file mode 100644 index 000000000..c1cabfc99 --- /dev/null +++ b/vendor/google.golang.org/grpc/resolver/dns/dns_resolver.go @@ -0,0 +1,379 @@ +/* + * + * 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" + "math/rand" + "net" + "os" + "strconv" + "strings" + "sync" + "time" + + "golang.org/x/net/context" + "google.golang.org/grpc/grpclog" + "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("missing address") + randomGen = rand.New(rand.NewSource(time.Now().UnixNano())) +) + +// NewBuilder creates a dnsBuilder which is used to factory DNS resolvers. +func NewBuilder() resolver.Builder { + return &dnsBuilder{freq: defaultFreq} +} + +type dnsBuilder struct { + // frequency of polling the DNS server. + freq 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) + 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.freq, + 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 + 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 after an interval defined by d.freq. + 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" +// target: ":" returns host: "localhost", port: "443" +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 { + // 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 { + // 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 randomGen.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 +} diff --git a/vendor/google.golang.org/grpc/resolver/dns/go17.go b/vendor/google.golang.org/grpc/resolver/dns/go17.go new file mode 100644 index 000000000..b466bc8f6 --- /dev/null +++ b/vendor/google.golang.org/grpc/resolver/dns/go17.go @@ -0,0 +1,35 @@ +// +build go1.6, !go1.8 + +/* + * + * 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 + +import ( + "net" + + "golang.org/x/net/context" +) + +var ( + lookupHost = func(ctx context.Context, host string) ([]string, error) { return net.LookupHost(host) } + lookupSRV = func(ctx context.Context, service, proto, name string) (string, []*net.SRV, error) { + return net.LookupSRV(service, proto, name) + } + lookupTXT = func(ctx context.Context, name string) ([]string, error) { return net.LookupTXT(name) } +) diff --git a/vendor/google.golang.org/grpc/resolver/dns/go18.go b/vendor/google.golang.org/grpc/resolver/dns/go18.go new file mode 100644 index 000000000..fa34f14ca --- /dev/null +++ b/vendor/google.golang.org/grpc/resolver/dns/go18.go @@ -0,0 +1,29 @@ +// +build go1.8 + +/* + * + * 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 + +import "net" + +var ( + lookupHost = net.DefaultResolver.LookupHost + lookupSRV = net.DefaultResolver.LookupSRV + lookupTXT = net.DefaultResolver.LookupTXT +) |