mirror of https://github.com/status-im/consul.git
Support DNS recursion and TCP queries
This commit is contained in:
parent
b9e0eef1ff
commit
29fe144b5b
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@ -52,6 +52,7 @@ func (c *Command) readConfig() *Config {
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"address to bind RPC listener to")
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"address to bind RPC listener to")
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cmdFlags.StringVar(&cmdConfig.DataDir, "data", "", "path to the data directory")
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cmdFlags.StringVar(&cmdConfig.DataDir, "data", "", "path to the data directory")
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cmdFlags.StringVar(&cmdConfig.Datacenter, "dc", "", "node datacenter")
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cmdFlags.StringVar(&cmdConfig.Datacenter, "dc", "", "node datacenter")
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cmdFlags.StringVar(&cmdConfig.DNSRecursor, "recursor", "", "address of dns recursor")
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cmdFlags.BoolVar(&cmdConfig.Server, "server", false, "run agent as server")
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cmdFlags.BoolVar(&cmdConfig.Server, "server", false, "run agent as server")
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cmdFlags.BoolVar(&cmdConfig.Bootstrap, "bootstrap", false, "enable server bootstrap mode")
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cmdFlags.BoolVar(&cmdConfig.Bootstrap, "bootstrap", false, "enable server bootstrap mode")
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if err := cmdFlags.Parse(c.args); err != nil {
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if err := cmdFlags.Parse(c.args); err != nil {
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@ -148,7 +149,8 @@ func (c *Command) setupAgent(config *Config, logOutput io.Writer, logWriter *log
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}
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}
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if config.DNSAddr != "" {
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if config.DNSAddr != "" {
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server, err := NewDNSServer(agent, logOutput, config.Domain, config.DNSAddr)
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server, err := NewDNSServer(agent, logOutput, config.Domain,
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config.DNSAddr, config.DNSRecursor)
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if err != nil {
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if err != nil {
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agent.Shutdown()
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agent.Shutdown()
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c.Ui.Error(fmt.Sprintf("Error starting dns server: %s", err))
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c.Ui.Error(fmt.Sprintf("Error starting dns server: %s", err))
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@ -30,6 +30,10 @@ type Config struct {
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// DNSAddr is the address of the DNS server for the agent
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// DNSAddr is the address of the DNS server for the agent
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DNSAddr string
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DNSAddr string
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// DNSRecursor can be set to allow the DNS server to recursively
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// resolve non-consul domains
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DNSRecursor string
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// Domain is the DNS domain for the records. Defaults to "consul."
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// Domain is the DNS domain for the records. Defaults to "consul."
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Domain string
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Domain string
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@ -154,6 +158,9 @@ func MergeConfig(a, b *Config) *Config {
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if b.DNSAddr != "" {
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if b.DNSAddr != "" {
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result.DNSAddr = b.DNSAddr
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result.DNSAddr = b.DNSAddr
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}
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}
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if b.DNSRecursor != "" {
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result.DNSRecursor = b.DNSRecursor
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}
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if b.Domain != "" {
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if b.Domain != "" {
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result.Domain = b.Domain
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result.Domain = b.Domain
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}
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}
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@ -22,32 +22,41 @@ type DNSServer struct {
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agent *Agent
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agent *Agent
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dnsHandler *dns.ServeMux
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dnsHandler *dns.ServeMux
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dnsServer *dns.Server
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dnsServer *dns.Server
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dnsServerTCP *dns.Server
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domain string
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domain string
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recursor string
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logger *log.Logger
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logger *log.Logger
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}
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}
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// NewDNSServer starts a new DNS server to provide an agent interface
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// NewDNSServer starts a new DNS server to provide an agent interface
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func NewDNSServer(agent *Agent, logOutput io.Writer, domain, bind string) (*DNSServer, error) {
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func NewDNSServer(agent *Agent, logOutput io.Writer, domain, bind, recursor string) (*DNSServer, error) {
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// Make sure domain is FQDN
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// Make sure domain is FQDN
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domain = dns.Fqdn(domain)
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domain = dns.Fqdn(domain)
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// Construct the DNS components
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// Construct the DNS components
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mux := dns.NewServeMux()
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mux := dns.NewServeMux()
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// Setup the server
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// Setup the servers
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server := &dns.Server{
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server := &dns.Server{
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Addr: bind,
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Addr: bind,
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Net: "udp",
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Net: "udp",
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Handler: mux,
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Handler: mux,
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UDPSize: 65535,
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UDPSize: 65535,
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}
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}
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serverTCP := &dns.Server{
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Addr: bind,
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Net: "tcp",
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Handler: mux,
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}
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// Create the server
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// Create the server
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srv := &DNSServer{
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srv := &DNSServer{
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agent: agent,
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agent: agent,
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dnsHandler: mux,
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dnsHandler: mux,
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dnsServer: server,
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dnsServer: server,
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dnsServerTCP: serverTCP,
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domain: domain,
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domain: domain,
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recursor: recursor,
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logger: log.New(logOutput, "", log.LstdFlags),
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logger: log.New(logOutput, "", log.LstdFlags),
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}
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}
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@ -56,15 +65,25 @@ func NewDNSServer(agent *Agent, logOutput io.Writer, domain, bind string) (*DNSS
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if domain != consulDomain {
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if domain != consulDomain {
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mux.HandleFunc(consulDomain, srv.handleTest)
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mux.HandleFunc(consulDomain, srv.handleTest)
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}
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}
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if recursor != "" {
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mux.HandleFunc(".", srv.handleRecurse)
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}
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// Async start the DNS Server, handle a potential error
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// Async start the DNS Servers, handle a potential error
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errCh := make(chan error, 1)
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errCh := make(chan error, 1)
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go func() {
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go func() {
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err := server.ListenAndServe()
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err := server.ListenAndServe()
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srv.logger.Printf("[ERR] dns: error starting server: %v", err)
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srv.logger.Printf("[ERR] dns: error starting udp server: %v", err)
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errCh <- err
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errCh <- err
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}()
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}()
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errChTCP := make(chan error, 1)
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go func() {
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err := serverTCP.ListenAndServe()
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srv.logger.Printf("[ERR] dns: error starting tcp server: %v", err)
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errChTCP <- err
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}()
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// Check the server is running, do a test lookup
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// Check the server is running, do a test lookup
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checkCh := make(chan error, 1)
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checkCh := make(chan error, 1)
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go func() {
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go func() {
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@ -93,6 +112,8 @@ func NewDNSServer(agent *Agent, logOutput io.Writer, domain, bind string) (*DNSS
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select {
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select {
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case e := <-errCh:
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case e := <-errCh:
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return srv, e
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return srv, e
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case e := <-errChTCP:
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return srv, e
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case e := <-checkCh:
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case e := <-checkCh:
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return srv, e
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return srv, e
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case <-time.After(time.Second):
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case <-time.After(time.Second):
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@ -119,10 +140,14 @@ func (d *DNSServer) handleQuery(resp dns.ResponseWriter, req *dns.Msg) {
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m.SetReply(req)
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m.SetReply(req)
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m.Authoritative = true
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m.Authoritative = true
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d.addSOA(d.domain, m)
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d.addSOA(d.domain, m)
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defer resp.WriteMsg(m)
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// Dispatch the correct handler
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// Dispatch the correct handler
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d.dispatch(req, m)
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d.dispatch(req, m)
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// Write out the complete response
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if err := resp.WriteMsg(m); err != nil {
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d.logger.Printf("[WARN] dns: failed to respond: %v", err)
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}
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}
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}
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// handleTest is used to handle DNS queries in the ".consul." domain
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// handleTest is used to handle DNS queries in the ".consul." domain
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@ -147,7 +172,9 @@ func (d *DNSServer) handleTest(resp dns.ResponseWriter, req *dns.Msg) {
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txt := &dns.TXT{header, []string{"ok"}}
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txt := &dns.TXT{header, []string{"ok"}}
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m.Answer = append(m.Answer, txt)
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m.Answer = append(m.Answer, txt)
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d.addSOA(consulDomain, m)
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d.addSOA(consulDomain, m)
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resp.WriteMsg(m)
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if err := resp.WriteMsg(m); err != nil {
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d.logger.Printf("[WARN] dns: failed to respond: %v", err)
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}
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}
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}
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// addSOA is used to add an SOA record to a message for the given domain
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// addSOA is used to add an SOA record to a message for the given domain
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@ -353,3 +380,40 @@ func (d *DNSServer) serviceSRVRecords(dc string, nodes structs.ServiceNodes, req
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resp.Extra = append(resp.Extra, aRec)
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resp.Extra = append(resp.Extra, aRec)
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}
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}
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}
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}
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// handleRecurse is used to handle recursive DNS queries
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func (d *DNSServer) handleRecurse(resp dns.ResponseWriter, req *dns.Msg) {
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q := req.Question[0]
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network := "udp"
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defer func(s time.Time) {
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d.logger.Printf("[DEBUG] dns: request for %v (%s) (%v)", q, network, time.Now().Sub(s))
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}(time.Now())
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// Switch to TCP if the client is
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if _, ok := resp.RemoteAddr().(*net.TCPAddr); ok {
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network = "tcp"
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}
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// Recursively resolve
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c := &dns.Client{Net: network}
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r, rtt, err := c.Exchange(req, d.recursor)
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// On failure, return a SERVFAIL message
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if err != nil {
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d.logger.Printf("[ERR] dns: recurse failed: %v", err)
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m := &dns.Msg{}
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m.SetReply(req)
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m.SetRcode(req, dns.RcodeServerFailure)
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resp.WriteMsg(m)
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return
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}
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d.logger.Printf("[DEBUG] dns: recurse RTT for %v (%v)", q, rtt)
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// Seems to be a bug that forcing compression fixes...
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r.Compress = true
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// Forward the response
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if err := resp.WriteMsg(r); err != nil {
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d.logger.Printf("[WARN] dns: failed to respond: %v", err)
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}
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}
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@ -11,7 +11,8 @@ import (
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func makeDNSServer(t *testing.T) (string, *DNSServer) {
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func makeDNSServer(t *testing.T) (string, *DNSServer) {
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conf := nextConfig()
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conf := nextConfig()
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dir, agent := makeAgent(t, conf)
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dir, agent := makeAgent(t, conf)
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server, err := NewDNSServer(agent, agent.logOutput, conf.Domain, conf.DNSAddr)
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server, err := NewDNSServer(agent, agent.logOutput, conf.Domain,
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conf.DNSAddr, "8.8.8.8:53")
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if err != nil {
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if err != nil {
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t.Fatalf("err: %v", err)
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t.Fatalf("err: %v", err)
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}
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}
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@ -173,3 +174,26 @@ func TestDNS_ServiceLookup(t *testing.T) {
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t.Fatalf("Bad: %#v", in.Extra[0])
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t.Fatalf("Bad: %#v", in.Extra[0])
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}
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}
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}
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}
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func TestDNS_Recurse(t *testing.T) {
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dir, srv := makeDNSServer(t)
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defer os.RemoveAll(dir)
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defer srv.agent.Shutdown()
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m := new(dns.Msg)
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m.SetQuestion("apple.com.", dns.TypeANY)
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c := new(dns.Client)
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c.Net = "tcp"
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in, _, err := c.Exchange(m, srv.agent.config.DNSAddr)
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if err != nil {
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t.Fatalf("err: %v", err)
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}
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if len(in.Answer) == 0 {
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t.Fatalf("Bad: %#v", in)
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}
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if in.Rcode != dns.RcodeSuccess {
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t.Fatalf("Bad: %#v", in)
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}
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}
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