caddy/modules/caddyhttp/reverseproxy/caddyfile.go
Francis Lavoie 4a641f6c6f
reverseproxy: Add Caddyfile scheme shorthand for h2c (#3629)
* reverseproxy: Add Caddyfile scheme shorthand for h2c

* reverseproxy: Use parentheses for condition

Co-authored-by: Matt Holt <mholt@users.noreply.github.com>

Co-authored-by: Matt Holt <mholt@users.noreply.github.com>
2020-11-23 12:18:26 -07:00

844 lines
23 KiB
Go

// Copyright 2015 Matthew Holt and The Caddy 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 reverseproxy
import (
"net"
"net/http"
"net/url"
"reflect"
"strconv"
"strings"
"github.com/caddyserver/caddy/v2"
"github.com/caddyserver/caddy/v2/caddyconfig"
"github.com/caddyserver/caddy/v2/caddyconfig/caddyfile"
"github.com/caddyserver/caddy/v2/caddyconfig/httpcaddyfile"
"github.com/caddyserver/caddy/v2/modules/caddyhttp"
"github.com/caddyserver/caddy/v2/modules/caddyhttp/headers"
"github.com/dustin/go-humanize"
)
func init() {
httpcaddyfile.RegisterHandlerDirective("reverse_proxy", parseCaddyfile)
}
func parseCaddyfile(h httpcaddyfile.Helper) (caddyhttp.MiddlewareHandler, error) {
rp := new(Handler)
err := rp.UnmarshalCaddyfile(h.Dispenser)
if err != nil {
return nil, err
}
return rp, nil
}
// UnmarshalCaddyfile sets up the handler from Caddyfile tokens. Syntax:
//
// reverse_proxy [<matcher>] [<upstreams...>] {
// # upstreams
// to <upstreams...>
//
// # load balancing
// lb_policy <name> [<options...>]
// lb_try_duration <duration>
// lb_try_interval <interval>
//
// # active health checking
// health_path <path>
// health_port <port>
// health_interval <interval>
// health_timeout <duration>
// health_status <status>
// health_body <regexp>
//
// # passive health checking
// max_fails <num>
// fail_duration <duration>
// max_conns <num>
// unhealthy_status <status>
// unhealthy_latency <duration>
//
// # streaming
// flush_interval <duration>
// buffer_requests
//
// # header manipulation
// header_up [+|-]<field> [<value|regexp> [<replacement>]]
// header_down [+|-]<field> [<value|regexp> [<replacement>]]
//
// # round trip
// transport <name> {
// ...
// }
// }
//
// Proxy upstream addresses should be network dial addresses such
// as `host:port`, or a URL such as `scheme://host:port`. Scheme
// and port may be inferred from other parts of the address/URL; if
// either are missing, defaults to HTTP.
func (h *Handler) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
// currently, all backends must use the same scheme/protocol (the
// underlying JSON does not yet support per-backend transports)
var commonScheme string
// we'll wait until the very end of parsing before
// validating and encoding the transport
var transport http.RoundTripper
var transportModuleName string
// TODO: the logic in this function is kind of sensitive, we need
// to write tests before making any more changes to it
upstreamDialAddress := func(upstreamAddr string) (string, error) {
var network, scheme, host, port string
if strings.Contains(upstreamAddr, "://") {
// we get a parsing error if a placeholder is specified
// so we return a more user-friendly error message instead
// to explain what to do instead
if strings.Contains(upstreamAddr, "{") {
return "", d.Err("due to parsing difficulties, placeholders are not allowed when an upstream address contains a scheme")
}
toURL, err := url.Parse(upstreamAddr)
if err != nil {
return "", d.Errf("parsing upstream URL: %v", err)
}
// there is currently no way to perform a URL rewrite between choosing
// a backend and proxying to it, so we cannot allow extra components
// in backend URLs
if toURL.Path != "" || toURL.RawQuery != "" || toURL.Fragment != "" {
return "", d.Err("for now, URLs for proxy upstreams only support scheme, host, and port components")
}
// ensure the port and scheme aren't in conflict
urlPort := toURL.Port()
if toURL.Scheme == "http" && urlPort == "443" {
return "", d.Err("upstream address has conflicting scheme (http://) and port (:443, the HTTPS port)")
}
if toURL.Scheme == "https" && urlPort == "80" {
return "", d.Err("upstream address has conflicting scheme (https://) and port (:80, the HTTP port)")
}
if toURL.Scheme == "h2c" && urlPort == "443" {
return "", d.Err("upstream address has conflicting scheme (h2c://) and port (:443, the HTTPS port)")
}
// if port is missing, attempt to infer from scheme
if toURL.Port() == "" {
var toPort string
switch toURL.Scheme {
case "", "http", "h2c":
toPort = "80"
case "https":
toPort = "443"
}
toURL.Host = net.JoinHostPort(toURL.Hostname(), toPort)
}
scheme, host, port = toURL.Scheme, toURL.Hostname(), toURL.Port()
} else {
// extract network manually, since caddy.ParseNetworkAddress() will always add one
if idx := strings.Index(upstreamAddr, "/"); idx >= 0 {
network = strings.ToLower(strings.TrimSpace(upstreamAddr[:idx]))
upstreamAddr = upstreamAddr[idx+1:]
}
var err error
host, port, err = net.SplitHostPort(upstreamAddr)
if err != nil {
host = upstreamAddr
}
// we can assume a port if only a hostname is specified, but use of a
// placeholder without a port likely means a port will be filled in
if port == "" && !strings.Contains(host, "{") {
port = "80"
}
}
// the underlying JSON does not yet support different
// transports (protocols or schemes) to each backend,
// so we remember the last one we see and compare them
if commonScheme != "" && scheme != commonScheme {
return "", d.Errf("for now, all proxy upstreams must use the same scheme (transport protocol); expecting '%s://' but got '%s://'",
commonScheme, scheme)
}
commonScheme = scheme
// for simplest possible config, we only need to include
// the network portion if the user specified one
if network != "" {
return caddy.JoinNetworkAddress(network, host, port), nil
}
return net.JoinHostPort(host, port), nil
}
// appendUpstream creates an upstream for address and adds
// it to the list. If the address starts with "srv+" it is
// treated as a SRV-based upstream, and any port will be
// dropped.
appendUpstream := func(address string) error {
isSRV := strings.HasPrefix(address, "srv+")
if isSRV {
address = strings.TrimPrefix(address, "srv+")
}
dialAddr, err := upstreamDialAddress(address)
if err != nil {
return err
}
if isSRV {
if host, _, err := net.SplitHostPort(dialAddr); err == nil {
dialAddr = host
}
h.Upstreams = append(h.Upstreams, &Upstream{LookupSRV: dialAddr})
} else {
h.Upstreams = append(h.Upstreams, &Upstream{Dial: dialAddr})
}
return nil
}
for d.Next() {
for _, up := range d.RemainingArgs() {
err := appendUpstream(up)
if err != nil {
return err
}
}
for d.NextBlock(0) {
switch d.Val() {
case "to":
args := d.RemainingArgs()
if len(args) == 0 {
return d.ArgErr()
}
for _, up := range args {
err := appendUpstream(up)
if err != nil {
return err
}
}
case "lb_policy":
if !d.NextArg() {
return d.ArgErr()
}
if h.LoadBalancing != nil && h.LoadBalancing.SelectionPolicyRaw != nil {
return d.Err("load balancing selection policy already specified")
}
name := d.Val()
mod, err := caddy.GetModule("http.reverse_proxy.selection_policies." + name)
if err != nil {
return d.Errf("getting load balancing policy module '%s': %v", mod, err)
}
unm, ok := mod.New().(caddyfile.Unmarshaler)
if !ok {
return d.Errf("load balancing policy module '%s' is not a Caddyfile unmarshaler", mod)
}
err = unm.UnmarshalCaddyfile(d.NewFromNextSegment())
if err != nil {
return err
}
sel, ok := unm.(Selector)
if !ok {
return d.Errf("module %s is not a Selector", mod)
}
if h.LoadBalancing == nil {
h.LoadBalancing = new(LoadBalancing)
}
h.LoadBalancing.SelectionPolicyRaw = caddyconfig.JSONModuleObject(sel, "policy", name, nil)
case "lb_try_duration":
if !d.NextArg() {
return d.ArgErr()
}
if h.LoadBalancing == nil {
h.LoadBalancing = new(LoadBalancing)
}
dur, err := caddy.ParseDuration(d.Val())
if err != nil {
return d.Errf("bad duration value %s: %v", d.Val(), err)
}
h.LoadBalancing.TryDuration = caddy.Duration(dur)
case "lb_try_interval":
if !d.NextArg() {
return d.ArgErr()
}
if h.LoadBalancing == nil {
h.LoadBalancing = new(LoadBalancing)
}
dur, err := caddy.ParseDuration(d.Val())
if err != nil {
return d.Errf("bad interval value '%s': %v", d.Val(), err)
}
h.LoadBalancing.TryInterval = caddy.Duration(dur)
case "health_path":
if !d.NextArg() {
return d.ArgErr()
}
if h.HealthChecks == nil {
h.HealthChecks = new(HealthChecks)
}
if h.HealthChecks.Active == nil {
h.HealthChecks.Active = new(ActiveHealthChecks)
}
h.HealthChecks.Active.Path = d.Val()
case "health_port":
if !d.NextArg() {
return d.ArgErr()
}
if h.HealthChecks == nil {
h.HealthChecks = new(HealthChecks)
}
if h.HealthChecks.Active == nil {
h.HealthChecks.Active = new(ActiveHealthChecks)
}
portNum, err := strconv.Atoi(d.Val())
if err != nil {
return d.Errf("bad port number '%s': %v", d.Val(), err)
}
h.HealthChecks.Active.Port = portNum
case "health_interval":
if !d.NextArg() {
return d.ArgErr()
}
if h.HealthChecks == nil {
h.HealthChecks = new(HealthChecks)
}
if h.HealthChecks.Active == nil {
h.HealthChecks.Active = new(ActiveHealthChecks)
}
dur, err := caddy.ParseDuration(d.Val())
if err != nil {
return d.Errf("bad interval value %s: %v", d.Val(), err)
}
h.HealthChecks.Active.Interval = caddy.Duration(dur)
case "health_timeout":
if !d.NextArg() {
return d.ArgErr()
}
if h.HealthChecks == nil {
h.HealthChecks = new(HealthChecks)
}
if h.HealthChecks.Active == nil {
h.HealthChecks.Active = new(ActiveHealthChecks)
}
dur, err := caddy.ParseDuration(d.Val())
if err != nil {
return d.Errf("bad timeout value %s: %v", d.Val(), err)
}
h.HealthChecks.Active.Timeout = caddy.Duration(dur)
case "health_status":
if !d.NextArg() {
return d.ArgErr()
}
if h.HealthChecks == nil {
h.HealthChecks = new(HealthChecks)
}
if h.HealthChecks.Active == nil {
h.HealthChecks.Active = new(ActiveHealthChecks)
}
val := d.Val()
if len(val) == 3 && strings.HasSuffix(val, "xx") {
val = val[:1]
}
statusNum, err := strconv.Atoi(val[:1])
if err != nil {
return d.Errf("bad status value '%s': %v", d.Val(), err)
}
h.HealthChecks.Active.ExpectStatus = statusNum
case "health_body":
if !d.NextArg() {
return d.ArgErr()
}
if h.HealthChecks == nil {
h.HealthChecks = new(HealthChecks)
}
if h.HealthChecks.Active == nil {
h.HealthChecks.Active = new(ActiveHealthChecks)
}
h.HealthChecks.Active.ExpectBody = d.Val()
case "max_fails":
if !d.NextArg() {
return d.ArgErr()
}
if h.HealthChecks == nil {
h.HealthChecks = new(HealthChecks)
}
if h.HealthChecks.Passive == nil {
h.HealthChecks.Passive = new(PassiveHealthChecks)
}
maxFails, err := strconv.Atoi(d.Val())
if err != nil {
return d.Errf("invalid maximum fail count '%s': %v", d.Val(), err)
}
h.HealthChecks.Passive.MaxFails = maxFails
case "fail_duration":
if !d.NextArg() {
return d.ArgErr()
}
if h.HealthChecks == nil {
h.HealthChecks = new(HealthChecks)
}
if h.HealthChecks.Passive == nil {
h.HealthChecks.Passive = new(PassiveHealthChecks)
}
dur, err := caddy.ParseDuration(d.Val())
if err != nil {
return d.Errf("bad duration value '%s': %v", d.Val(), err)
}
h.HealthChecks.Passive.FailDuration = caddy.Duration(dur)
case "unhealthy_request_count":
if !d.NextArg() {
return d.ArgErr()
}
if h.HealthChecks == nil {
h.HealthChecks = new(HealthChecks)
}
if h.HealthChecks.Passive == nil {
h.HealthChecks.Passive = new(PassiveHealthChecks)
}
maxConns, err := strconv.Atoi(d.Val())
if err != nil {
return d.Errf("invalid maximum connection count '%s': %v", d.Val(), err)
}
h.HealthChecks.Passive.UnhealthyRequestCount = maxConns
case "unhealthy_status":
args := d.RemainingArgs()
if len(args) == 0 {
return d.ArgErr()
}
if h.HealthChecks == nil {
h.HealthChecks = new(HealthChecks)
}
if h.HealthChecks.Passive == nil {
h.HealthChecks.Passive = new(PassiveHealthChecks)
}
for _, arg := range args {
if len(arg) == 3 && strings.HasSuffix(arg, "xx") {
arg = arg[:1]
}
statusNum, err := strconv.Atoi(arg[:1])
if err != nil {
return d.Errf("bad status value '%s': %v", d.Val(), err)
}
h.HealthChecks.Passive.UnhealthyStatus = append(h.HealthChecks.Passive.UnhealthyStatus, statusNum)
}
case "unhealthy_latency":
if !d.NextArg() {
return d.ArgErr()
}
if h.HealthChecks == nil {
h.HealthChecks = new(HealthChecks)
}
if h.HealthChecks.Passive == nil {
h.HealthChecks.Passive = new(PassiveHealthChecks)
}
dur, err := caddy.ParseDuration(d.Val())
if err != nil {
return d.Errf("bad duration value '%s': %v", d.Val(), err)
}
h.HealthChecks.Passive.UnhealthyLatency = caddy.Duration(dur)
case "flush_interval":
if !d.NextArg() {
return d.ArgErr()
}
if fi, err := strconv.Atoi(d.Val()); err == nil {
h.FlushInterval = caddy.Duration(fi)
} else {
dur, err := caddy.ParseDuration(d.Val())
if err != nil {
return d.Errf("bad duration value '%s': %v", d.Val(), err)
}
h.FlushInterval = caddy.Duration(dur)
}
case "buffer_requests":
if d.NextArg() {
return d.ArgErr()
}
h.BufferRequests = true
case "header_up":
var err error
if h.Headers == nil {
h.Headers = new(headers.Handler)
}
if h.Headers.Request == nil {
h.Headers.Request = new(headers.HeaderOps)
}
args := d.RemainingArgs()
switch len(args) {
case 1:
err = headers.CaddyfileHeaderOp(h.Headers.Request, args[0], "", "")
case 2:
err = headers.CaddyfileHeaderOp(h.Headers.Request, args[0], args[1], "")
case 3:
err = headers.CaddyfileHeaderOp(h.Headers.Request, args[0], args[1], args[2])
default:
return d.ArgErr()
}
if err != nil {
return d.Err(err.Error())
}
case "header_down":
var err error
if h.Headers == nil {
h.Headers = new(headers.Handler)
}
if h.Headers.Response == nil {
h.Headers.Response = &headers.RespHeaderOps{
HeaderOps: new(headers.HeaderOps),
}
}
args := d.RemainingArgs()
switch len(args) {
case 1:
err = headers.CaddyfileHeaderOp(h.Headers.Response.HeaderOps, args[0], "", "")
case 2:
err = headers.CaddyfileHeaderOp(h.Headers.Response.HeaderOps, args[0], args[1], "")
case 3:
err = headers.CaddyfileHeaderOp(h.Headers.Response.HeaderOps, args[0], args[1], args[2])
default:
return d.ArgErr()
}
if err != nil {
return d.Err(err.Error())
}
case "transport":
if !d.NextArg() {
return d.ArgErr()
}
if h.TransportRaw != nil {
return d.Err("transport already specified")
}
transportModuleName = d.Val()
mod, err := caddy.GetModule("http.reverse_proxy.transport." + transportModuleName)
if err != nil {
return d.Errf("getting transport module '%s': %v", mod, err)
}
unm, ok := mod.New().(caddyfile.Unmarshaler)
if !ok {
return d.Errf("transport module '%s' is not a Caddyfile unmarshaler", mod)
}
err = unm.UnmarshalCaddyfile(d.NewFromNextSegment())
if err != nil {
return err
}
rt, ok := unm.(http.RoundTripper)
if !ok {
return d.Errf("module %s is not a RoundTripper", mod)
}
transport = rt
default:
return d.Errf("unrecognized subdirective %s", d.Val())
}
}
}
// if the scheme inferred from the backends' addresses is
// HTTPS, we will need a non-nil transport to enable TLS,
// or if H2C, to set the transport versions.
if (commonScheme == "https" || commonScheme == "h2c") && transport == nil {
transport = new(HTTPTransport)
transportModuleName = "http"
}
// verify transport configuration, and finally encode it
if transport != nil {
if te, ok := transport.(TLSTransport); ok {
if commonScheme == "https" && !te.TLSEnabled() {
err := te.EnableTLS(new(TLSConfig))
if err != nil {
return err
}
}
if commonScheme == "http" && te.TLSEnabled() {
return d.Errf("upstream address scheme is HTTP but transport is configured for HTTP+TLS (HTTPS)")
}
if te, ok := transport.(*HTTPTransport); ok && commonScheme == "h2c" {
te.Versions = []string{"h2c", "2"}
}
} else if commonScheme == "https" {
return d.Errf("upstreams are configured for HTTPS but transport module does not support TLS: %T", transport)
}
// no need to encode empty default transport
if !reflect.DeepEqual(transport, new(HTTPTransport)) {
h.TransportRaw = caddyconfig.JSONModuleObject(transport, "protocol", transportModuleName, nil)
}
}
return nil
}
// UnmarshalCaddyfile deserializes Caddyfile tokens into h.
//
// transport http {
// read_buffer <size>
// write_buffer <size>
// max_response_header <size>
// dial_timeout <duration>
// dial_fallback_delay <duration>
// response_header_timeout <duration>
// expect_continue_timeout <duration>
// tls
// tls_client_auth <automate_name> | <cert_file> <key_file>
// tls_insecure_skip_verify
// tls_timeout <duration>
// tls_trusted_ca_certs <cert_files...>
// tls_server_name <sni>
// keepalive [off|<duration>]
// keepalive_idle_conns <max_count>
// versions <versions...>
// compression off
// max_conns_per_host <count>
// max_idle_conns_per_host <count>
// }
//
func (h *HTTPTransport) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
for d.Next() {
for d.NextBlock(0) {
switch d.Val() {
case "read_buffer":
if !d.NextArg() {
return d.ArgErr()
}
size, err := humanize.ParseBytes(d.Val())
if err != nil {
return d.Errf("invalid read buffer size '%s': %v", d.Val(), err)
}
h.ReadBufferSize = int(size)
case "write_buffer":
if !d.NextArg() {
return d.ArgErr()
}
size, err := humanize.ParseBytes(d.Val())
if err != nil {
return d.Errf("invalid write buffer size '%s': %v", d.Val(), err)
}
h.WriteBufferSize = int(size)
case "max_response_header":
if !d.NextArg() {
return d.ArgErr()
}
size, err := humanize.ParseBytes(d.Val())
if err != nil {
return d.Errf("invalid max response header size '%s': %v", d.Val(), err)
}
h.MaxResponseHeaderSize = int64(size)
case "dial_timeout":
if !d.NextArg() {
return d.ArgErr()
}
dur, err := caddy.ParseDuration(d.Val())
if err != nil {
return d.Errf("bad timeout value '%s': %v", d.Val(), err)
}
h.DialTimeout = caddy.Duration(dur)
case "dial_fallback_delay":
if !d.NextArg() {
return d.ArgErr()
}
dur, err := caddy.ParseDuration(d.Val())
if err != nil {
return d.Errf("bad fallback delay value '%s': %v", d.Val(), err)
}
h.FallbackDelay = caddy.Duration(dur)
case "response_header_timeout":
if !d.NextArg() {
return d.ArgErr()
}
dur, err := caddy.ParseDuration(d.Val())
if err != nil {
return d.Errf("bad timeout value '%s': %v", d.Val(), err)
}
h.ResponseHeaderTimeout = caddy.Duration(dur)
case "expect_continue_timeout":
if !d.NextArg() {
return d.ArgErr()
}
dur, err := caddy.ParseDuration(d.Val())
if err != nil {
return d.Errf("bad timeout value '%s': %v", d.Val(), err)
}
h.ExpectContinueTimeout = caddy.Duration(dur)
case "tls_client_auth":
if h.TLS == nil {
h.TLS = new(TLSConfig)
}
args := d.RemainingArgs()
switch len(args) {
case 1:
h.TLS.ClientCertificateAutomate = args[0]
case 2:
h.TLS.ClientCertificateFile = args[0]
h.TLS.ClientCertificateKeyFile = args[1]
default:
return d.ArgErr()
}
case "tls":
if h.TLS == nil {
h.TLS = new(TLSConfig)
}
case "tls_insecure_skip_verify":
if d.NextArg() {
return d.ArgErr()
}
if h.TLS == nil {
h.TLS = new(TLSConfig)
}
h.TLS.InsecureSkipVerify = true
case "tls_timeout":
if !d.NextArg() {
return d.ArgErr()
}
dur, err := caddy.ParseDuration(d.Val())
if err != nil {
return d.Errf("bad timeout value '%s': %v", d.Val(), err)
}
if h.TLS == nil {
h.TLS = new(TLSConfig)
}
h.TLS.HandshakeTimeout = caddy.Duration(dur)
case "tls_trusted_ca_certs":
args := d.RemainingArgs()
if len(args) == 0 {
return d.ArgErr()
}
if h.TLS == nil {
h.TLS = new(TLSConfig)
}
h.TLS.RootCAPEMFiles = args
case "tls_server_name":
if !d.NextArg() {
return d.ArgErr()
}
if h.TLS == nil {
h.TLS = new(TLSConfig)
}
h.TLS.ServerName = d.Val()
case "keepalive":
if !d.NextArg() {
return d.ArgErr()
}
if h.KeepAlive == nil {
h.KeepAlive = new(KeepAlive)
}
if d.Val() == "off" {
var disable bool
h.KeepAlive.Enabled = &disable
break
}
dur, err := caddy.ParseDuration(d.Val())
if err != nil {
return d.Errf("bad duration value '%s': %v", d.Val(), err)
}
h.KeepAlive.IdleConnTimeout = caddy.Duration(dur)
case "keepalive_idle_conns":
if !d.NextArg() {
return d.ArgErr()
}
num, err := strconv.Atoi(d.Val())
if err != nil {
return d.Errf("bad integer value '%s': %v", d.Val(), err)
}
if h.KeepAlive == nil {
h.KeepAlive = new(KeepAlive)
}
h.KeepAlive.MaxIdleConns = num
h.KeepAlive.MaxIdleConnsPerHost = num
case "versions":
h.Versions = d.RemainingArgs()
if len(h.Versions) == 0 {
return d.ArgErr()
}
case "compression":
if d.NextArg() {
if d.Val() == "off" {
var disable bool
h.Compression = &disable
}
}
case "max_conns_per_host":
if !d.NextArg() {
return d.ArgErr()
}
num, err := strconv.Atoi(d.Val())
if err != nil {
return d.Errf("bad integer value '%s': %v", d.Val(), err)
}
h.MaxConnsPerHost = num
case "max_idle_conns_per_host":
if !d.NextArg() {
return d.ArgErr()
}
num, err := strconv.Atoi(d.Val())
if err != nil {
return d.Errf("bad integer value '%s': %v", d.Val(), err)
}
h.MaxIdleConnsPerHost = num
default:
return d.Errf("unrecognized subdirective %s", d.Val())
}
}
}
return nil
}
// Interface guards
var (
_ caddyfile.Unmarshaler = (*Handler)(nil)
_ caddyfile.Unmarshaler = (*HTTPTransport)(nil)
)