mirror of
https://github.com/coredns/coredns.git
synced 2025-11-03 18:53:13 -05:00
322 lines
10 KiB
Go
322 lines
10 KiB
Go
package https
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import (
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"bytes"
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"crypto/tls"
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"encoding/pem"
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"io/ioutil"
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"log"
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"os"
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"path/filepath"
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"strconv"
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"strings"
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"github.com/miekg/coredns/core/setup"
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"github.com/miekg/coredns/middleware"
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"github.com/miekg/coredns/server"
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)
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// Setup sets up the TLS configuration and installs certificates that
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// are specified by the user in the config file. All the automatic HTTPS
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// stuff comes later outside of this function.
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func Setup(c *setup.Controller) (middleware.Middleware, error) {
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if c.Port == "80" {
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c.TLS.Enabled = false
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log.Printf("[WARNING] TLS disabled for %s.", c.Address())
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return nil, nil
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}
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c.TLS.Enabled = true
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// TODO(miek): disabled for now
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return nil, nil
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for c.Next() {
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var certificateFile, keyFile, loadDir, maxCerts string
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args := c.RemainingArgs()
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switch len(args) {
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case 1:
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c.TLS.LetsEncryptEmail = args[0]
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// user can force-disable managed TLS this way
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if c.TLS.LetsEncryptEmail == "off" {
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c.TLS.Enabled = false
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return nil, nil
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}
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case 2:
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certificateFile = args[0]
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keyFile = args[1]
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c.TLS.Manual = true
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}
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// Optional block with extra parameters
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var hadBlock bool
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for c.NextBlock() {
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hadBlock = true
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switch c.Val() {
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case "protocols":
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args := c.RemainingArgs()
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if len(args) != 2 {
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return nil, c.ArgErr()
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}
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value, ok := supportedProtocols[strings.ToLower(args[0])]
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if !ok {
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return nil, c.Errf("Wrong protocol name or protocol not supported '%s'", c.Val())
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}
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c.TLS.ProtocolMinVersion = value
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value, ok = supportedProtocols[strings.ToLower(args[1])]
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if !ok {
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return nil, c.Errf("Wrong protocol name or protocol not supported '%s'", c.Val())
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}
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c.TLS.ProtocolMaxVersion = value
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case "ciphers":
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for c.NextArg() {
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value, ok := supportedCiphersMap[strings.ToUpper(c.Val())]
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if !ok {
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return nil, c.Errf("Wrong cipher name or cipher not supported '%s'", c.Val())
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}
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c.TLS.Ciphers = append(c.TLS.Ciphers, value)
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}
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case "clients":
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c.TLS.ClientCerts = c.RemainingArgs()
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if len(c.TLS.ClientCerts) == 0 {
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return nil, c.ArgErr()
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}
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case "load":
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c.Args(&loadDir)
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c.TLS.Manual = true
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case "max_certs":
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c.Args(&maxCerts)
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c.TLS.OnDemand = true
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default:
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return nil, c.Errf("Unknown keyword '%s'", c.Val())
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}
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}
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// tls requires at least one argument if a block is not opened
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if len(args) == 0 && !hadBlock {
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return nil, c.ArgErr()
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}
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// set certificate limit if on-demand TLS is enabled
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if maxCerts != "" {
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maxCertsNum, err := strconv.Atoi(maxCerts)
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if err != nil || maxCertsNum < 1 {
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return nil, c.Err("max_certs must be a positive integer")
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}
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if onDemandMaxIssue == 0 || int32(maxCertsNum) < onDemandMaxIssue { // keep the minimum; TODO: We have to do this because it is global; should be per-server or per-vhost...
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onDemandMaxIssue = int32(maxCertsNum)
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}
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}
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// don't try to load certificates unless we're supposed to
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if !c.TLS.Enabled || !c.TLS.Manual {
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continue
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}
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// load a single certificate and key, if specified
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if certificateFile != "" && keyFile != "" {
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err := cacheUnmanagedCertificatePEMFile(certificateFile, keyFile)
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if err != nil {
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return nil, c.Errf("Unable to load certificate and key files for %s: %v", c.Host, err)
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}
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log.Printf("[INFO] Successfully loaded TLS assets from %s and %s", certificateFile, keyFile)
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}
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// load a directory of certificates, if specified
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if loadDir != "" {
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err := loadCertsInDir(c, loadDir)
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if err != nil {
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return nil, err
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}
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}
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}
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setDefaultTLSParams(c.Config)
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return nil, nil
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}
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// loadCertsInDir loads all the certificates/keys in dir, as long as
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// the file ends with .pem. This method of loading certificates is
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// modeled after haproxy, which expects the certificate and key to
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// be bundled into the same file:
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// https://cbonte.github.io/haproxy-dconv/configuration-1.5.html#5.1-crt
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//
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// This function may write to the log as it walks the directory tree.
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func loadCertsInDir(c *setup.Controller, dir string) error {
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return filepath.Walk(dir, func(path string, info os.FileInfo, err error) error {
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if err != nil {
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log.Printf("[WARNING] Unable to traverse into %s; skipping", path)
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return nil
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}
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if info.IsDir() {
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return nil
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}
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if strings.HasSuffix(strings.ToLower(info.Name()), ".pem") {
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certBuilder, keyBuilder := new(bytes.Buffer), new(bytes.Buffer)
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var foundKey bool // use only the first key in the file
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bundle, err := ioutil.ReadFile(path)
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if err != nil {
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return err
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}
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for {
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// Decode next block so we can see what type it is
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var derBlock *pem.Block
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derBlock, bundle = pem.Decode(bundle)
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if derBlock == nil {
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break
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}
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if derBlock.Type == "CERTIFICATE" {
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// Re-encode certificate as PEM, appending to certificate chain
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pem.Encode(certBuilder, derBlock)
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} else if derBlock.Type == "EC PARAMETERS" {
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// EC keys generated from openssl can be composed of two blocks:
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// parameters and key (parameter block should come first)
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if !foundKey {
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// Encode parameters
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pem.Encode(keyBuilder, derBlock)
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// Key must immediately follow
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derBlock, bundle = pem.Decode(bundle)
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if derBlock == nil || derBlock.Type != "EC PRIVATE KEY" {
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return c.Errf("%s: expected elliptic private key to immediately follow EC parameters", path)
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}
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pem.Encode(keyBuilder, derBlock)
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foundKey = true
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}
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} else if derBlock.Type == "PRIVATE KEY" || strings.HasSuffix(derBlock.Type, " PRIVATE KEY") {
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// RSA key
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if !foundKey {
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pem.Encode(keyBuilder, derBlock)
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foundKey = true
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}
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} else {
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return c.Errf("%s: unrecognized PEM block type: %s", path, derBlock.Type)
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}
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}
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certPEMBytes, keyPEMBytes := certBuilder.Bytes(), keyBuilder.Bytes()
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if len(certPEMBytes) == 0 {
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return c.Errf("%s: failed to parse PEM data", path)
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}
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if len(keyPEMBytes) == 0 {
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return c.Errf("%s: no private key block found", path)
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}
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err = cacheUnmanagedCertificatePEMBytes(certPEMBytes, keyPEMBytes)
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if err != nil {
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return c.Errf("%s: failed to load cert and key for %s: %v", path, c.Host, err)
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}
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log.Printf("[INFO] Successfully loaded TLS assets from %s", path)
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}
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return nil
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})
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}
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// setDefaultTLSParams sets the default TLS cipher suites, protocol versions,
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// and server preferences of a server.Config if they were not previously set
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// (it does not overwrite; only fills in missing values). It will also set the
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// port to 443 if not already set, TLS is enabled, TLS is manual, and the host
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// does not equal localhost.
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func setDefaultTLSParams(c *server.Config) {
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// If no ciphers provided, use default list
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if len(c.TLS.Ciphers) == 0 {
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c.TLS.Ciphers = defaultCiphers
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}
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// Not a cipher suite, but still important for mitigating protocol downgrade attacks
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// (prepend since having it at end breaks http2 due to non-h2-approved suites before it)
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c.TLS.Ciphers = append([]uint16{tls.TLS_FALLBACK_SCSV}, c.TLS.Ciphers...)
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// Set default protocol min and max versions - must balance compatibility and security
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if c.TLS.ProtocolMinVersion == 0 {
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c.TLS.ProtocolMinVersion = tls.VersionTLS10
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}
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if c.TLS.ProtocolMaxVersion == 0 {
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c.TLS.ProtocolMaxVersion = tls.VersionTLS12
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}
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// Prefer server cipher suites
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c.TLS.PreferServerCipherSuites = true
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// Default TLS port is 443; only use if port is not manually specified,
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// TLS is enabled, and the host is not localhost
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if c.Port == "" && c.TLS.Enabled && (!c.TLS.Manual || c.TLS.OnDemand) && c.Host != "localhost" {
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c.Port = "443"
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}
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}
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// Map of supported protocols.
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// SSLv3 will be not supported in future release.
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// HTTP/2 only supports TLS 1.2 and higher.
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var supportedProtocols = map[string]uint16{
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"ssl3.0": tls.VersionSSL30,
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"tls1.0": tls.VersionTLS10,
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"tls1.1": tls.VersionTLS11,
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"tls1.2": tls.VersionTLS12,
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}
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// Map of supported ciphers, used only for parsing config.
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//
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// Note that, at time of writing, HTTP/2 blacklists 276 cipher suites,
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// including all but two of the suites below (the two GCM suites).
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// See https://http2.github.io/http2-spec/#BadCipherSuites
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//
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// TLS_FALLBACK_SCSV is not in this list because we manually ensure
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// it is always added (even though it is not technically a cipher suite).
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//
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// This map, like any map, is NOT ORDERED. Do not range over this map.
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var supportedCiphersMap = map[string]uint16{
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"ECDHE-RSA-AES256-GCM-SHA384": tls.TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,
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"ECDHE-ECDSA-AES256-GCM-SHA384": tls.TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,
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"ECDHE-RSA-AES128-GCM-SHA256": tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
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"ECDHE-ECDSA-AES128-GCM-SHA256": tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
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"ECDHE-RSA-AES128-CBC-SHA": tls.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA,
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"ECDHE-RSA-AES256-CBC-SHA": tls.TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA,
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"ECDHE-ECDSA-AES256-CBC-SHA": tls.TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA,
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"ECDHE-ECDSA-AES128-CBC-SHA": tls.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA,
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"RSA-AES128-CBC-SHA": tls.TLS_RSA_WITH_AES_128_CBC_SHA,
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"RSA-AES256-CBC-SHA": tls.TLS_RSA_WITH_AES_256_CBC_SHA,
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"ECDHE-RSA-3DES-EDE-CBC-SHA": tls.TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA,
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"RSA-3DES-EDE-CBC-SHA": tls.TLS_RSA_WITH_3DES_EDE_CBC_SHA,
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}
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// List of supported cipher suites in descending order of preference.
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// Ordering is very important! Getting the wrong order will break
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// mainstream clients, especially with HTTP/2.
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//
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// Note that TLS_FALLBACK_SCSV is not in this list since it is always
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// added manually.
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var supportedCiphers = []uint16{
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tls.TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,
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tls.TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,
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tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
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tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
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tls.TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA,
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tls.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA,
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tls.TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA,
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tls.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA,
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tls.TLS_RSA_WITH_AES_256_CBC_SHA,
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tls.TLS_RSA_WITH_AES_128_CBC_SHA,
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tls.TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA,
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tls.TLS_RSA_WITH_3DES_EDE_CBC_SHA,
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}
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// List of all the ciphers we want to use by default
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var defaultCiphers = []uint16{
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tls.TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,
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tls.TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,
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tls.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
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tls.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
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tls.TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA,
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tls.TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA,
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tls.TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA,
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tls.TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA,
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tls.TLS_RSA_WITH_AES_256_CBC_SHA,
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tls.TLS_RSA_WITH_AES_128_CBC_SHA,
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}
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