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caddy/modules/caddyhttp/reverseproxy/reverseproxy.go
Jens-Uwe Mager 2bb2ecc549
reverseproxy: Change errors writing the response to warning. (#6532)
Most of the errors that can be seen here are write errors due to clients
aborting the request from their side. Often seen ones include:

	* writing: ... write: broken pipe
	* writing: ... connection timed out
	* writing: http2: stream closed
	* writing: timeout...
	* writing: h3 error...

Most of these errors are beyond of the control of caddy on the client side,
probably nothing can be done on the server side. It still warrants
researching when these errors occur very often, so a change in level from
error to warn is better here to not polute the logs with errors in the
normal case.
2024-08-21 11:39:20 -06:00

1445 lines
52 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 (
"bytes"
"context"
"encoding/json"
"errors"
"fmt"
"io"
"net"
"net/http"
"net/http/httptrace"
"net/netip"
"net/textproto"
"net/url"
"strconv"
"strings"
"sync"
"time"
"go.uber.org/zap"
"golang.org/x/net/http/httpguts"
"github.com/caddyserver/caddy/v2"
"github.com/caddyserver/caddy/v2/caddyconfig/caddyfile"
"github.com/caddyserver/caddy/v2/modules/caddyevents"
"github.com/caddyserver/caddy/v2/modules/caddyhttp"
"github.com/caddyserver/caddy/v2/modules/caddyhttp/headers"
"github.com/caddyserver/caddy/v2/modules/caddyhttp/rewrite"
)
func init() {
caddy.RegisterModule(Handler{})
}
// Handler implements a highly configurable and production-ready reverse proxy.
//
// Upon proxying, this module sets the following placeholders (which can be used
// both within and after this handler; for example, in response headers):
//
// Placeholder | Description
// ------------|-------------
// `{http.reverse_proxy.upstream.address}` | The full address to the upstream as given in the config
// `{http.reverse_proxy.upstream.hostport}` | The host:port of the upstream
// `{http.reverse_proxy.upstream.host}` | The host of the upstream
// `{http.reverse_proxy.upstream.port}` | The port of the upstream
// `{http.reverse_proxy.upstream.requests}` | The approximate current number of requests to the upstream
// `{http.reverse_proxy.upstream.max_requests}` | The maximum approximate number of requests allowed to the upstream
// `{http.reverse_proxy.upstream.fails}` | The number of recent failed requests to the upstream
// `{http.reverse_proxy.upstream.latency}` | How long it took the proxy upstream to write the response header.
// `{http.reverse_proxy.upstream.latency_ms}` | Same as 'latency', but in milliseconds.
// `{http.reverse_proxy.upstream.duration}` | Time spent proxying to the upstream, including writing response body to client.
// `{http.reverse_proxy.upstream.duration_ms}` | Same as 'upstream.duration', but in milliseconds.
// `{http.reverse_proxy.duration}` | Total time spent proxying, including selecting an upstream, retries, and writing response.
// `{http.reverse_proxy.duration_ms}` | Same as 'duration', but in milliseconds.
type Handler struct {
// Configures the method of transport for the proxy. A transport
// is what performs the actual "round trip" to the backend.
// The default transport is plaintext HTTP.
TransportRaw json.RawMessage `json:"transport,omitempty" caddy:"namespace=http.reverse_proxy.transport inline_key=protocol"`
// A circuit breaker may be used to relieve pressure on a backend
// that is beginning to exhibit symptoms of stress or latency.
// By default, there is no circuit breaker.
CBRaw json.RawMessage `json:"circuit_breaker,omitempty" caddy:"namespace=http.reverse_proxy.circuit_breakers inline_key=type"`
// Load balancing distributes load/requests between backends.
LoadBalancing *LoadBalancing `json:"load_balancing,omitempty"`
// Health checks update the status of backends, whether they are
// up or down. Down backends will not be proxied to.
HealthChecks *HealthChecks `json:"health_checks,omitempty"`
// Upstreams is the static list of backends to proxy to.
Upstreams UpstreamPool `json:"upstreams,omitempty"`
// A module for retrieving the list of upstreams dynamically. Dynamic
// upstreams are retrieved at every iteration of the proxy loop for
// each request (i.e. before every proxy attempt within every request).
// Active health checks do not work on dynamic upstreams, and passive
// health checks are only effective on dynamic upstreams if the proxy
// server is busy enough that concurrent requests to the same backends
// are continuous. Instead of health checks for dynamic upstreams, it
// is recommended that the dynamic upstream module only return available
// backends in the first place.
DynamicUpstreamsRaw json.RawMessage `json:"dynamic_upstreams,omitempty" caddy:"namespace=http.reverse_proxy.upstreams inline_key=source"`
// Adjusts how often to flush the response buffer. By default,
// no periodic flushing is done. A negative value disables
// response buffering, and flushes immediately after each
// write to the client. This option is ignored when the upstream's
// response is recognized as a streaming response, or if its
// content length is -1; for such responses, writes are flushed
// to the client immediately.
//
// Normally, a request will be canceled if the client disconnects
// before the response is received from the backend. If explicitly
// set to -1, client disconnection will be ignored and the request
// will be completed to help facilitate low-latency streaming.
FlushInterval caddy.Duration `json:"flush_interval,omitempty"`
// A list of IP ranges (supports CIDR notation) from which
// X-Forwarded-* header values should be trusted. By default,
// no proxies are trusted, so existing values will be ignored
// when setting these headers. If the proxy is trusted, then
// existing values will be used when constructing the final
// header values.
TrustedProxies []string `json:"trusted_proxies,omitempty"`
// Headers manipulates headers between Caddy and the backend.
// By default, all headers are passed-thru without changes,
// with the exceptions of special hop-by-hop headers.
//
// X-Forwarded-For, X-Forwarded-Proto and X-Forwarded-Host
// are also set implicitly.
Headers *headers.Handler `json:"headers,omitempty"`
// If nonzero, the entire request body up to this size will be read
// and buffered in memory before being proxied to the backend. This
// should be avoided if at all possible for performance reasons, but
// could be useful if the backend is intolerant of read latency or
// chunked encodings.
RequestBuffers int64 `json:"request_buffers,omitempty"`
// If nonzero, the entire response body up to this size will be read
// and buffered in memory before being proxied to the client. This
// should be avoided if at all possible for performance reasons, but
// could be useful if the backend has tighter memory constraints.
ResponseBuffers int64 `json:"response_buffers,omitempty"`
// If nonzero, streaming requests such as WebSockets will be
// forcibly closed at the end of the timeout. Default: no timeout.
StreamTimeout caddy.Duration `json:"stream_timeout,omitempty"`
// If nonzero, streaming requests such as WebSockets will not be
// closed when the proxy config is unloaded, and instead the stream
// will remain open until the delay is complete. In other words,
// enabling this prevents streams from closing when Caddy's config
// is reloaded. Enabling this may be a good idea to avoid a thundering
// herd of reconnecting clients which had their connections closed
// by the previous config closing. Default: no delay.
StreamCloseDelay caddy.Duration `json:"stream_close_delay,omitempty"`
// If configured, rewrites the copy of the upstream request.
// Allows changing the request method and URI (path and query).
// Since the rewrite is applied to the copy, it does not persist
// past the reverse proxy handler.
// If the method is changed to `GET` or `HEAD`, the request body
// will not be copied to the backend. This allows a later request
// handler -- either in a `handle_response` route, or after -- to
// read the body.
// By default, no rewrite is performed, and the method and URI
// from the incoming request is used as-is for proxying.
Rewrite *rewrite.Rewrite `json:"rewrite,omitempty"`
// List of handlers and their associated matchers to evaluate
// after successful roundtrips. The first handler that matches
// the response from a backend will be invoked. The response
// body from the backend will not be written to the client;
// it is up to the handler to finish handling the response.
// If passive health checks are enabled, any errors from the
// handler chain will not affect the health status of the
// backend.
//
// Three new placeholders are available in this handler chain:
// - `{http.reverse_proxy.status_code}` The status code from the response
// - `{http.reverse_proxy.status_text}` The status text from the response
// - `{http.reverse_proxy.header.*}` The headers from the response
HandleResponse []caddyhttp.ResponseHandler `json:"handle_response,omitempty"`
// If set, the proxy will write very detailed logs about its
// inner workings. Enable this only when debugging, as it
// will produce a lot of output.
//
// EXPERIMENTAL: This feature is subject to change or removal.
VerboseLogs bool `json:"verbose_logs,omitempty"`
Transport http.RoundTripper `json:"-"`
CB CircuitBreaker `json:"-"`
DynamicUpstreams UpstreamSource `json:"-"`
// Holds the parsed CIDR ranges from TrustedProxies
trustedProxies []netip.Prefix
// Holds the named response matchers from the Caddyfile while adapting
responseMatchers map[string]caddyhttp.ResponseMatcher
// Holds the handle_response Caddyfile tokens while adapting
handleResponseSegments []*caddyfile.Dispenser
// Stores upgraded requests (hijacked connections) for proper cleanup
connections map[io.ReadWriteCloser]openConnection
connectionsCloseTimer *time.Timer
connectionsMu *sync.Mutex
ctx caddy.Context
logger *zap.Logger
events *caddyevents.App
}
// CaddyModule returns the Caddy module information.
func (Handler) CaddyModule() caddy.ModuleInfo {
return caddy.ModuleInfo{
ID: "http.handlers.reverse_proxy",
New: func() caddy.Module { return new(Handler) },
}
}
// Provision ensures that h is set up properly before use.
func (h *Handler) Provision(ctx caddy.Context) error {
eventAppIface, err := ctx.App("events")
if err != nil {
return fmt.Errorf("getting events app: %v", err)
}
h.events = eventAppIface.(*caddyevents.App)
h.ctx = ctx
h.logger = ctx.Logger()
h.connections = make(map[io.ReadWriteCloser]openConnection)
h.connectionsMu = new(sync.Mutex)
// warn about unsafe buffering config
if h.RequestBuffers == -1 || h.ResponseBuffers == -1 {
h.logger.Warn("UNLIMITED BUFFERING: buffering is enabled without any cap on buffer size, which can result in OOM crashes")
}
// start by loading modules
if h.TransportRaw != nil {
mod, err := ctx.LoadModule(h, "TransportRaw")
if err != nil {
return fmt.Errorf("loading transport: %v", err)
}
h.Transport = mod.(http.RoundTripper)
}
if h.LoadBalancing != nil && h.LoadBalancing.SelectionPolicyRaw != nil {
mod, err := ctx.LoadModule(h.LoadBalancing, "SelectionPolicyRaw")
if err != nil {
return fmt.Errorf("loading load balancing selection policy: %s", err)
}
h.LoadBalancing.SelectionPolicy = mod.(Selector)
}
if h.CBRaw != nil {
mod, err := ctx.LoadModule(h, "CBRaw")
if err != nil {
return fmt.Errorf("loading circuit breaker: %s", err)
}
h.CB = mod.(CircuitBreaker)
}
if h.DynamicUpstreamsRaw != nil {
mod, err := ctx.LoadModule(h, "DynamicUpstreamsRaw")
if err != nil {
return fmt.Errorf("loading upstream source module: %v", err)
}
h.DynamicUpstreams = mod.(UpstreamSource)
}
// parse trusted proxy CIDRs ahead of time
for _, str := range h.TrustedProxies {
if strings.Contains(str, "/") {
ipNet, err := netip.ParsePrefix(str)
if err != nil {
return fmt.Errorf("parsing CIDR expression: '%s': %v", str, err)
}
h.trustedProxies = append(h.trustedProxies, ipNet)
} else {
ipAddr, err := netip.ParseAddr(str)
if err != nil {
return fmt.Errorf("invalid IP address: '%s': %v", str, err)
}
ipNew := netip.PrefixFrom(ipAddr, ipAddr.BitLen())
h.trustedProxies = append(h.trustedProxies, ipNew)
}
}
// ensure any embedded headers handler module gets provisioned
// (see https://caddy.community/t/set-cookie-manipulation-in-reverse-proxy/7666?u=matt
// for what happens if we forget to provision it)
if h.Headers != nil {
err := h.Headers.Provision(ctx)
if err != nil {
return fmt.Errorf("provisioning embedded headers handler: %v", err)
}
}
if h.Rewrite != nil {
err := h.Rewrite.Provision(ctx)
if err != nil {
return fmt.Errorf("provisioning rewrite: %v", err)
}
}
// set up transport
if h.Transport == nil {
t := &HTTPTransport{}
err := t.Provision(ctx)
if err != nil {
return fmt.Errorf("provisioning default transport: %v", err)
}
h.Transport = t
}
// set up load balancing
if h.LoadBalancing == nil {
h.LoadBalancing = new(LoadBalancing)
}
if h.LoadBalancing.SelectionPolicy == nil {
h.LoadBalancing.SelectionPolicy = RandomSelection{}
}
if h.LoadBalancing.TryDuration > 0 && h.LoadBalancing.TryInterval == 0 {
// a non-zero try_duration with a zero try_interval
// will always spin the CPU for try_duration if the
// upstream is local or low-latency; avoid that by
// defaulting to a sane wait period between attempts
h.LoadBalancing.TryInterval = caddy.Duration(250 * time.Millisecond)
}
lbMatcherSets, err := ctx.LoadModule(h.LoadBalancing, "RetryMatchRaw")
if err != nil {
return err
}
err = h.LoadBalancing.RetryMatch.FromInterface(lbMatcherSets)
if err != nil {
return err
}
// set up upstreams
for _, u := range h.Upstreams {
h.provisionUpstream(u)
}
if h.HealthChecks != nil {
// set defaults on passive health checks, if necessary
if h.HealthChecks.Passive != nil {
h.HealthChecks.Passive.logger = h.logger.Named("health_checker.passive")
if h.HealthChecks.Passive.MaxFails == 0 {
h.HealthChecks.Passive.MaxFails = 1
}
}
// if active health checks are enabled, configure them and start a worker
if h.HealthChecks.Active != nil {
err := h.HealthChecks.Active.Provision(ctx, h)
if err != nil {
return err
}
if h.HealthChecks.Active.IsEnabled() {
go h.activeHealthChecker()
}
}
}
// set up any response routes
for i, rh := range h.HandleResponse {
err := rh.Provision(ctx)
if err != nil {
return fmt.Errorf("provisioning response handler %d: %v", i, err)
}
}
upstreamHealthyUpdater := newMetricsUpstreamsHealthyUpdater(h)
upstreamHealthyUpdater.Init()
return nil
}
// Cleanup cleans up the resources made by h.
func (h *Handler) Cleanup() error {
err := h.cleanupConnections()
// remove hosts from our config from the pool
for _, upstream := range h.Upstreams {
_, _ = hosts.Delete(upstream.String())
}
return err
}
func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request, next caddyhttp.Handler) error {
repl := r.Context().Value(caddy.ReplacerCtxKey).(*caddy.Replacer)
// prepare the request for proxying; this is needed only once
clonedReq, err := h.prepareRequest(r, repl)
if err != nil {
return caddyhttp.Error(http.StatusInternalServerError,
fmt.Errorf("preparing request for upstream round-trip: %v", err))
}
// we will need the original headers and Host value if
// header operations are configured; this is so that each
// retry can apply the modifications, because placeholders
// may be used which depend on the selected upstream for
// their values
reqHost := clonedReq.Host
reqHeader := clonedReq.Header
start := time.Now()
defer func() {
// total proxying duration, including time spent on LB and retries
repl.Set("http.reverse_proxy.duration", time.Since(start))
repl.Set("http.reverse_proxy.duration_ms", time.Since(start).Seconds()*1e3) // multiply seconds to preserve decimal (see #4666)
}()
// in the proxy loop, each iteration is an attempt to proxy the request,
// and because we may retry some number of times, carry over the error
// from previous tries because of the nuances of load balancing & retries
var proxyErr error
var retries int
for {
// if the request body was buffered (and only the entire body, hence no body
// set to read from after the buffer), make reading from the body idempotent
// and reusable, so if a backend partially or fully reads the body but then
// produces an error, the request can be repeated to the next backend with
// the full body (retries should only happen for idempotent requests) (see #6259)
if reqBodyBuf, ok := r.Body.(bodyReadCloser); ok && reqBodyBuf.body == nil {
r.Body = io.NopCloser(bytes.NewReader(reqBodyBuf.buf.Bytes()))
}
var done bool
done, proxyErr = h.proxyLoopIteration(clonedReq, r, w, proxyErr, start, retries, repl, reqHeader, reqHost, next)
if done {
break
}
if h.VerboseLogs {
var lbWait time.Duration
if h.LoadBalancing != nil {
lbWait = time.Duration(h.LoadBalancing.TryInterval)
}
h.logger.Debug("retrying", zap.Error(proxyErr), zap.Duration("after", lbWait))
}
retries++
}
if proxyErr != nil {
return statusError(proxyErr)
}
return nil
}
// proxyLoopIteration implements an iteration of the proxy loop. Despite the enormous amount of local state
// that has to be passed in, we brought this into its own method so that we could run defer more easily.
// It returns true when the loop is done and should break; false otherwise. The error value returned should
// be assigned to the proxyErr value for the next iteration of the loop (or the error handled after break).
func (h *Handler) proxyLoopIteration(r *http.Request, origReq *http.Request, w http.ResponseWriter, proxyErr error, start time.Time, retries int,
repl *caddy.Replacer, reqHeader http.Header, reqHost string, next caddyhttp.Handler,
) (bool, error) {
// get the updated list of upstreams
upstreams := h.Upstreams
if h.DynamicUpstreams != nil {
dUpstreams, err := h.DynamicUpstreams.GetUpstreams(r)
if err != nil {
h.logger.Error("failed getting dynamic upstreams; falling back to static upstreams", zap.Error(err))
} else {
upstreams = dUpstreams
for _, dUp := range dUpstreams {
h.provisionUpstream(dUp)
}
h.logger.Debug("provisioned dynamic upstreams", zap.Int("count", len(dUpstreams)))
defer func() {
// these upstreams are dynamic, so they are only used for this iteration
// of the proxy loop; be sure to let them go away when we're done with them
for _, upstream := range dUpstreams {
_, _ = hosts.Delete(upstream.String())
}
}()
}
}
// choose an available upstream
upstream := h.LoadBalancing.SelectionPolicy.Select(upstreams, r, w)
if upstream == nil {
if proxyErr == nil {
proxyErr = caddyhttp.Error(http.StatusServiceUnavailable, errNoUpstream)
}
if !h.LoadBalancing.tryAgain(h.ctx, start, retries, proxyErr, r) {
return true, proxyErr
}
return false, proxyErr
}
// the dial address may vary per-request if placeholders are
// used, so perform those replacements here; the resulting
// DialInfo struct should have valid network address syntax
dialInfo, err := upstream.fillDialInfo(r)
if err != nil {
return true, fmt.Errorf("making dial info: %v", err)
}
h.logger.Debug("selected upstream",
zap.String("dial", dialInfo.Address),
zap.Int("total_upstreams", len(upstreams)))
// attach to the request information about how to dial the upstream;
// this is necessary because the information cannot be sufficiently
// or satisfactorily represented in a URL
caddyhttp.SetVar(r.Context(), dialInfoVarKey, dialInfo)
// set placeholders with information about this upstream
repl.Set("http.reverse_proxy.upstream.address", dialInfo.String())
repl.Set("http.reverse_proxy.upstream.hostport", dialInfo.Address)
repl.Set("http.reverse_proxy.upstream.host", dialInfo.Host)
repl.Set("http.reverse_proxy.upstream.port", dialInfo.Port)
repl.Set("http.reverse_proxy.upstream.requests", upstream.Host.NumRequests())
repl.Set("http.reverse_proxy.upstream.max_requests", upstream.MaxRequests)
repl.Set("http.reverse_proxy.upstream.fails", upstream.Host.Fails())
// mutate request headers according to this upstream;
// because we're in a retry loop, we have to copy
// headers (and the r.Host value) from the original
// so that each retry is identical to the first
if h.Headers != nil && h.Headers.Request != nil {
r.Header = make(http.Header)
copyHeader(r.Header, reqHeader)
r.Host = reqHost
h.Headers.Request.ApplyToRequest(r)
}
// proxy the request to that upstream
proxyErr = h.reverseProxy(w, r, origReq, repl, dialInfo, next)
if proxyErr == nil || errors.Is(proxyErr, context.Canceled) {
// context.Canceled happens when the downstream client
// cancels the request, which is not our failure
return true, nil
}
// if the roundtrip was successful, don't retry the request or
// ding the health status of the upstream (an error can still
// occur after the roundtrip if, for example, a response handler
// after the roundtrip returns an error)
if succ, ok := proxyErr.(roundtripSucceeded); ok {
return true, succ.error
}
// remember this failure (if enabled)
h.countFailure(upstream)
// if we've tried long enough, break
if !h.LoadBalancing.tryAgain(h.ctx, start, retries, proxyErr, r) {
return true, proxyErr
}
return false, proxyErr
}
// prepareRequest clones req so that it can be safely modified without
// changing the original request or introducing data races. It then
// modifies it so that it is ready to be proxied, except for directing
// to a specific upstream. This method adjusts headers and other relevant
// properties of the cloned request and should be done just once (before
// proxying) regardless of proxy retries. This assumes that no mutations
// of the cloned request are performed by h during or after proxying.
func (h Handler) prepareRequest(req *http.Request, repl *caddy.Replacer) (*http.Request, error) {
req = cloneRequest(req)
// if enabled, perform rewrites on the cloned request; if
// the method is GET or HEAD, prevent the request body
// from being copied to the upstream
if h.Rewrite != nil {
changed := h.Rewrite.Rewrite(req, repl)
if changed && (h.Rewrite.Method == "GET" || h.Rewrite.Method == "HEAD") {
req.ContentLength = 0
req.Body = nil
}
}
// if enabled, buffer client request; this should only be
// enabled if the upstream requires it and does not work
// with "slow clients" (gunicorn, etc.) - this obviously
// has a perf overhead and makes the proxy at risk of
// exhausting memory and more susceptible to slowloris
// attacks, so it is strongly recommended to only use this
// feature if absolutely required, if read timeouts are
// set, and if body size is limited
if h.RequestBuffers != 0 && req.Body != nil {
var readBytes int64
req.Body, readBytes = h.bufferedBody(req.Body, h.RequestBuffers)
if h.RequestBuffers == -1 {
req.ContentLength = readBytes
req.Header.Set("Content-Length", strconv.FormatInt(req.ContentLength, 10))
}
}
if req.ContentLength == 0 {
req.Body = nil // Issue golang/go#16036: nil Body for http.Transport retries
}
req.Close = false
// if User-Agent is not set by client, then explicitly
// disable it so it's not set to default value by std lib
if _, ok := req.Header["User-Agent"]; !ok {
req.Header.Set("User-Agent", "")
}
// Indicate if request has been conveyed in early data.
// RFC 8470: "An intermediary that forwards a request prior to the
// completion of the TLS handshake with its client MUST send it with
// the Early-Data header field set to “1” (i.e., it adds it if not
// present in the request). An intermediary MUST use the Early-Data
// header field if the request might have been subject to a replay and
// might already have been forwarded by it or another instance
// (see Section 6.2)."
if req.TLS != nil && !req.TLS.HandshakeComplete {
req.Header.Set("Early-Data", "1")
}
reqUpType := upgradeType(req.Header)
removeConnectionHeaders(req.Header)
// Remove hop-by-hop headers to the backend. Especially
// important is "Connection" because we want a persistent
// connection, regardless of what the client sent to us.
// Issue golang/go#46313: don't skip if field is empty.
for _, h := range hopHeaders {
// Issue golang/go#21096: tell backend applications that care about trailer support
// that we support trailers. (We do, but we don't go out of our way to
// advertise that unless the incoming client request thought it was worth
// mentioning.)
if h == "Te" && httpguts.HeaderValuesContainsToken(req.Header["Te"], "trailers") {
req.Header.Set("Te", "trailers")
continue
}
req.Header.Del(h)
}
// After stripping all the hop-by-hop connection headers above, add back any
// necessary for protocol upgrades, such as for websockets.
if reqUpType != "" {
req.Header.Set("Connection", "Upgrade")
req.Header.Set("Upgrade", reqUpType)
}
// Set up the PROXY protocol info
address := caddyhttp.GetVar(req.Context(), caddyhttp.ClientIPVarKey).(string)
addrPort, err := netip.ParseAddrPort(address)
if err != nil {
// OK; probably didn't have a port
addr, err := netip.ParseAddr(address)
if err != nil {
// Doesn't seem like a valid ip address at all
} else {
// Ok, only the port was missing
addrPort = netip.AddrPortFrom(addr, 0)
}
}
proxyProtocolInfo := ProxyProtocolInfo{AddrPort: addrPort}
caddyhttp.SetVar(req.Context(), proxyProtocolInfoVarKey, proxyProtocolInfo)
// Add the supported X-Forwarded-* headers
err = h.addForwardedHeaders(req)
if err != nil {
return nil, err
}
return req, nil
}
// addForwardedHeaders adds the de-facto standard X-Forwarded-*
// headers to the request before it is sent upstream.
//
// These headers are security sensitive, so care is taken to only
// use existing values for these headers from the incoming request
// if the client IP is trusted (i.e. coming from a trusted proxy
// sitting in front of this server). If the request didn't have
// the headers at all, then they will be added with the values
// that we can glean from the request.
func (h Handler) addForwardedHeaders(req *http.Request) error {
// Parse the remote IP, ignore the error as non-fatal,
// but the remote IP is required to continue, so we
// just return early. This should probably never happen
// though, unless some other module manipulated the request's
// remote address and used an invalid value.
clientIP, _, err := net.SplitHostPort(req.RemoteAddr)
if err != nil {
// Remove the `X-Forwarded-*` headers to avoid upstreams
// potentially trusting a header that came from the client
req.Header.Del("X-Forwarded-For")
req.Header.Del("X-Forwarded-Proto")
req.Header.Del("X-Forwarded-Host")
return nil
}
// Client IP may contain a zone if IPv6, so we need
// to pull that out before parsing the IP
clientIP, _, _ = strings.Cut(clientIP, "%")
ipAddr, err := netip.ParseAddr(clientIP)
if err != nil {
return fmt.Errorf("invalid IP address: '%s': %v", clientIP, err)
}
// Check if the client is a trusted proxy
trusted := caddyhttp.GetVar(req.Context(), caddyhttp.TrustedProxyVarKey).(bool)
for _, ipRange := range h.trustedProxies {
if ipRange.Contains(ipAddr) {
trusted = true
break
}
}
// If we aren't the first proxy, and the proxy is trusted,
// retain prior X-Forwarded-For information as a comma+space
// separated list and fold multiple headers into one.
clientXFF := clientIP
prior, ok, omit := allHeaderValues(req.Header, "X-Forwarded-For")
if trusted && ok && prior != "" {
clientXFF = prior + ", " + clientXFF
}
if !omit {
req.Header.Set("X-Forwarded-For", clientXFF)
}
// Set X-Forwarded-Proto; many backend apps expect this,
// so that they can properly craft URLs with the right
// scheme to match the original request
proto := "https"
if req.TLS == nil {
proto = "http"
}
prior, ok, omit = lastHeaderValue(req.Header, "X-Forwarded-Proto")
if trusted && ok && prior != "" {
proto = prior
}
if !omit {
req.Header.Set("X-Forwarded-Proto", proto)
}
// Set X-Forwarded-Host; often this is redundant because
// we pass through the request Host as-is, but in situations
// where we proxy over HTTPS, the user may need to override
// Host themselves, so it's helpful to send the original too.
host := req.Host
prior, ok, omit = lastHeaderValue(req.Header, "X-Forwarded-Host")
if trusted && ok && prior != "" {
host = prior
}
if !omit {
req.Header.Set("X-Forwarded-Host", host)
}
return nil
}
// reverseProxy performs a round-trip to the given backend and processes the response with the client.
// (This method is mostly the beginning of what was borrowed from the net/http/httputil package in the
// Go standard library which was used as the foundation.)
func (h *Handler) reverseProxy(rw http.ResponseWriter, req *http.Request, origReq *http.Request, repl *caddy.Replacer, di DialInfo, next caddyhttp.Handler) error {
_ = di.Upstream.Host.countRequest(1)
//nolint:errcheck
defer di.Upstream.Host.countRequest(-1)
// point the request to this upstream
h.directRequest(req, di)
server := req.Context().Value(caddyhttp.ServerCtxKey).(*caddyhttp.Server)
shouldLogCredentials := server.Logs != nil && server.Logs.ShouldLogCredentials
// Forward 1xx status codes, backported from https://github.com/golang/go/pull/53164
trace := &httptrace.ClientTrace{
Got1xxResponse: func(code int, header textproto.MIMEHeader) error {
h := rw.Header()
copyHeader(h, http.Header(header))
rw.WriteHeader(code)
// Clear headers coming from the backend
// (it's not automatically done by ResponseWriter.WriteHeader() for 1xx responses)
for k := range header {
delete(h, k)
}
return nil
},
}
req = req.WithContext(httptrace.WithClientTrace(req.Context(), trace))
// if FlushInterval is explicitly configured to -1 (i.e. flush continuously to achieve
// low-latency streaming), don't let the transport cancel the request if the client
// disconnects: user probably wants us to finish sending the data to the upstream
// regardless, and we should expect client disconnection in low-latency streaming
// scenarios (see issue #4922)
if h.FlushInterval == -1 {
req = req.WithContext(context.WithoutCancel(req.Context()))
}
// do the round-trip; emit debug log with values we know are
// safe, or if there is no error, emit fuller log entry
start := time.Now()
res, err := h.Transport.RoundTrip(req)
duration := time.Since(start)
logger := h.logger.With(
zap.String("upstream", di.Upstream.String()),
zap.Duration("duration", duration),
zap.Object("request", caddyhttp.LoggableHTTPRequest{
Request: req,
ShouldLogCredentials: shouldLogCredentials,
}),
)
if err != nil {
logger.Debug("upstream roundtrip", zap.Error(err))
return err
}
logger.Debug("upstream roundtrip",
zap.Object("headers", caddyhttp.LoggableHTTPHeader{
Header: res.Header,
ShouldLogCredentials: shouldLogCredentials,
}),
zap.Int("status", res.StatusCode))
// duration until upstream wrote response headers (roundtrip duration)
repl.Set("http.reverse_proxy.upstream.latency", duration)
repl.Set("http.reverse_proxy.upstream.latency_ms", duration.Seconds()*1e3) // multiply seconds to preserve decimal (see #4666)
// update circuit breaker on current conditions
if di.Upstream.cb != nil {
di.Upstream.cb.RecordMetric(res.StatusCode, duration)
}
// perform passive health checks (if enabled)
if h.HealthChecks != nil && h.HealthChecks.Passive != nil {
// strike if the status code matches one that is "bad"
for _, badStatus := range h.HealthChecks.Passive.UnhealthyStatus {
if caddyhttp.StatusCodeMatches(res.StatusCode, badStatus) {
h.countFailure(di.Upstream)
}
}
// strike if the roundtrip took too long
if h.HealthChecks.Passive.UnhealthyLatency > 0 &&
duration >= time.Duration(h.HealthChecks.Passive.UnhealthyLatency) {
h.countFailure(di.Upstream)
}
}
// if enabled, buffer the response body
if h.ResponseBuffers != 0 {
res.Body, _ = h.bufferedBody(res.Body, h.ResponseBuffers)
}
// see if any response handler is configured for this response from the backend
for i, rh := range h.HandleResponse {
if rh.Match != nil && !rh.Match.Match(res.StatusCode, res.Header) {
continue
}
// if configured to only change the status code,
// do that then continue regular proxy response
if statusCodeStr := rh.StatusCode.String(); statusCodeStr != "" {
statusCode, err := strconv.Atoi(repl.ReplaceAll(statusCodeStr, ""))
if err != nil {
return caddyhttp.Error(http.StatusInternalServerError, err)
}
if statusCode != 0 {
res.StatusCode = statusCode
}
break
}
// set up the replacer so that parts of the original response can be
// used for routing decisions
for field, value := range res.Header {
repl.Set("http.reverse_proxy.header."+field, strings.Join(value, ","))
}
repl.Set("http.reverse_proxy.status_code", res.StatusCode)
repl.Set("http.reverse_proxy.status_text", res.Status)
logger.Debug("handling response", zap.Int("handler", i))
// we make some data available via request context to child routes
// so that they may inherit some options and functions from the
// handler, and be able to copy the response.
// we use the original request here, so that any routes from 'next'
// see the original request rather than the proxy cloned request.
hrc := &handleResponseContext{
handler: h,
response: res,
start: start,
logger: logger,
}
ctx := origReq.Context()
ctx = context.WithValue(ctx, proxyHandleResponseContextCtxKey, hrc)
// pass the request through the response handler routes
routeErr := rh.Routes.Compile(next).ServeHTTP(rw, origReq.WithContext(ctx))
// close the response body afterwards, since we don't need it anymore;
// either a route had 'copy_response' which already consumed the body,
// or some other terminal handler ran which doesn't need the response
// body after that point (e.g. 'file_server' for X-Accel-Redirect flow),
// or we fell through to subsequent handlers past this proxy
// (e.g. forward auth's 2xx response flow).
if !hrc.isFinalized {
res.Body.Close()
}
// wrap any route error in roundtripSucceeded so caller knows that
// the roundtrip was successful and to not retry
if routeErr != nil {
return roundtripSucceeded{routeErr}
}
// we're done handling the response, and we don't want to
// fall through to the default finalize/copy behaviour
return nil
}
// copy the response body and headers back to the upstream client
return h.finalizeResponse(rw, req, res, repl, start, logger)
}
// finalizeResponse prepares and copies the response.
func (h *Handler) finalizeResponse(
rw http.ResponseWriter,
req *http.Request,
res *http.Response,
repl *caddy.Replacer,
start time.Time,
logger *zap.Logger,
) error {
// deal with 101 Switching Protocols responses: (WebSocket, h2c, etc)
if res.StatusCode == http.StatusSwitchingProtocols {
var wg sync.WaitGroup
h.handleUpgradeResponse(logger, &wg, rw, req, res)
wg.Wait()
return nil
}
removeConnectionHeaders(res.Header)
for _, h := range hopHeaders {
res.Header.Del(h)
}
// apply any response header operations
if h.Headers != nil && h.Headers.Response != nil {
if h.Headers.Response.Require == nil ||
h.Headers.Response.Require.Match(res.StatusCode, res.Header) {
h.Headers.Response.ApplyTo(res.Header, repl)
}
}
copyHeader(rw.Header(), res.Header)
// The "Trailer" header isn't included in the Transport's response,
// at least for *http.Transport. Build it up from Trailer.
announcedTrailers := len(res.Trailer)
if announcedTrailers > 0 {
trailerKeys := make([]string, 0, len(res.Trailer))
for k := range res.Trailer {
trailerKeys = append(trailerKeys, k)
}
rw.Header().Add("Trailer", strings.Join(trailerKeys, ", "))
}
rw.WriteHeader(res.StatusCode)
if h.VerboseLogs {
logger.Debug("wrote header")
}
err := h.copyResponse(rw, res.Body, h.flushInterval(req, res), logger)
errClose := res.Body.Close() // close now, instead of defer, to populate res.Trailer
if h.VerboseLogs || errClose != nil {
logger.Debug("closed response body from upstream", zap.Error(errClose))
}
if err != nil {
// we're streaming the response and we've already written headers, so
// there's nothing an error handler can do to recover at this point;
// we'll just log the error and abort the stream here and panic just as
// the standard lib's proxy to propagate the stream error.
// see issue https://github.com/caddyserver/caddy/issues/5951
logger.Warn("aborting with incomplete response", zap.Error(err))
// no extra logging from stdlib
panic(http.ErrAbortHandler)
}
if len(res.Trailer) > 0 {
// Force chunking if we saw a response trailer.
// This prevents net/http from calculating the length for short
// bodies and adding a Content-Length.
//nolint:bodyclose
http.NewResponseController(rw).Flush()
}
// total duration spent proxying, including writing response body
repl.Set("http.reverse_proxy.upstream.duration", time.Since(start))
repl.Set("http.reverse_proxy.upstream.duration_ms", time.Since(start).Seconds()*1e3)
if len(res.Trailer) == announcedTrailers {
copyHeader(rw.Header(), res.Trailer)
return nil
}
for k, vv := range res.Trailer {
k = http.TrailerPrefix + k
for _, v := range vv {
rw.Header().Add(k, v)
}
}
if h.VerboseLogs {
logger.Debug("response finalized")
}
return nil
}
// tryAgain takes the time that the handler was initially invoked,
// the amount of retries already performed, as well as any error
// currently obtained, and the request being tried, and returns
// true if another attempt should be made at proxying the request.
// If true is returned, it has already blocked long enough before
// the next retry (i.e. no more sleeping is needed). If false is
// returned, the handler should stop trying to proxy the request.
func (lb LoadBalancing) tryAgain(ctx caddy.Context, start time.Time, retries int, proxyErr error, req *http.Request) bool {
// no retries are configured
if lb.TryDuration == 0 && lb.Retries == 0 {
return false
}
// if we've tried long enough, break
if lb.TryDuration > 0 && time.Since(start) >= time.Duration(lb.TryDuration) {
return false
}
// if we've reached the retry limit, break
if lb.Retries > 0 && retries >= lb.Retries {
return false
}
// if the error occurred while dialing (i.e. a connection
// could not even be established to the upstream), then it
// should be safe to retry, since without a connection, no
// HTTP request can be transmitted; but if the error is not
// specifically a dialer error, we need to be careful
if proxyErr != nil {
_, isDialError := proxyErr.(DialError)
herr, isHandlerError := proxyErr.(caddyhttp.HandlerError)
// if the error occurred after a connection was established,
// we have to assume the upstream received the request, and
// retries need to be carefully decided, because some requests
// are not idempotent
if !isDialError && !(isHandlerError && errors.Is(herr, errNoUpstream)) {
if lb.RetryMatch == nil && req.Method != "GET" {
// by default, don't retry requests if they aren't GET
return false
}
if !lb.RetryMatch.AnyMatch(req) {
return false
}
}
}
// fast path; if the interval is zero, we don't need to wait
if lb.TryInterval == 0 {
return true
}
// otherwise, wait and try the next available host
timer := time.NewTimer(time.Duration(lb.TryInterval))
select {
case <-timer.C:
return true
case <-ctx.Done():
if !timer.Stop() {
// if the timer has been stopped then read from the channel
<-timer.C
}
return false
}
}
// directRequest modifies only req.URL so that it points to the upstream
// in the given DialInfo. It must modify ONLY the request URL.
func (Handler) directRequest(req *http.Request, di DialInfo) {
// we need a host, so set the upstream's host address
reqHost := di.Address
// if the port equates to the scheme, strip the port because
// it's weird to make a request like http://example.com:80/.
if (req.URL.Scheme == "http" && di.Port == "80") ||
(req.URL.Scheme == "https" && di.Port == "443") {
reqHost = di.Host
}
req.URL.Host = reqHost
}
func (h Handler) provisionUpstream(upstream *Upstream) {
// create or get the host representation for this upstream
upstream.fillHost()
// give it the circuit breaker, if any
upstream.cb = h.CB
// if the passive health checker has a non-zero UnhealthyRequestCount
// but the upstream has no MaxRequests set (they are the same thing,
// but the passive health checker is a default value for upstreams
// without MaxRequests), copy the value into this upstream, since the
// value in the upstream (MaxRequests) is what is used during
// availability checks
if h.HealthChecks != nil &&
h.HealthChecks.Passive != nil &&
h.HealthChecks.Passive.UnhealthyRequestCount > 0 &&
upstream.MaxRequests == 0 {
upstream.MaxRequests = h.HealthChecks.Passive.UnhealthyRequestCount
}
// upstreams need independent access to the passive
// health check policy because passive health checks
// run without access to h.
if h.HealthChecks != nil {
upstream.healthCheckPolicy = h.HealthChecks.Passive
}
}
// bufferedBody reads originalBody into a buffer with maximum size of limit (-1 for unlimited),
// then returns a reader for the buffer along with how many bytes were buffered. Always close
// the return value when done with it, just like if it was the original body! If limit is 0
// (which it shouldn't be), this function returns its input; i.e. is a no-op, for safety.
func (h Handler) bufferedBody(originalBody io.ReadCloser, limit int64) (io.ReadCloser, int64) {
if limit == 0 {
return originalBody, 0
}
var written int64
buf := bufPool.Get().(*bytes.Buffer)
buf.Reset()
if limit > 0 {
n, err := io.CopyN(buf, originalBody, limit)
if (err != nil && err != io.EOF) || n == limit {
return bodyReadCloser{
Reader: io.MultiReader(buf, originalBody),
buf: buf,
body: originalBody,
}, n
}
} else {
written, _ = io.Copy(buf, originalBody)
}
originalBody.Close() // no point in keeping it open
return bodyReadCloser{
Reader: buf,
buf: buf,
}, written
}
// cloneRequest makes a semi-deep clone of origReq.
//
// Most of this code is borrowed from the Go stdlib reverse proxy,
// but we make a shallow-ish clone the request (deep clone only
// the headers and URL) so we can avoid manipulating the original
// request when using it to proxy upstream. This prevents request
// corruption and data races.
func cloneRequest(origReq *http.Request) *http.Request {
req := new(http.Request)
*req = *origReq
if origReq.URL != nil {
newURL := new(url.URL)
*newURL = *origReq.URL
if origReq.URL.User != nil {
newURL.User = new(url.Userinfo)
*newURL.User = *origReq.URL.User
}
// sanitize the request URL; we expect it to not contain the
// scheme and host since those should be determined by r.TLS
// and r.Host respectively, but some clients may include it
// in the request-line, which is technically valid in HTTP,
// but breaks reverseproxy behaviour, overriding how the
// dialer will behave. See #4237 for context.
newURL.Scheme = ""
newURL.Host = ""
req.URL = newURL
}
if origReq.Header != nil {
req.Header = origReq.Header.Clone()
}
if origReq.Trailer != nil {
req.Trailer = origReq.Trailer.Clone()
}
return req
}
func copyHeader(dst, src http.Header) {
for k, vv := range src {
for _, v := range vv {
dst.Add(k, v)
}
}
}
// allHeaderValues gets all values for a given header field,
// joined by a comma and space if more than one is set. If the
// header field is nil, then the omit is true, meaning some
// earlier logic in the server wanted to prevent this header from
// getting written at all. If the header is empty, then ok is
// false. Callers should still check that the value is not empty
// (the header field may be set but have an empty value).
func allHeaderValues(h http.Header, field string) (value string, ok bool, omit bool) {
values, ok := h[http.CanonicalHeaderKey(field)]
if ok && values == nil {
return "", true, true
}
if len(values) == 0 {
return "", false, false
}
return strings.Join(values, ", "), true, false
}
// lastHeaderValue gets the last value for a given header field
// if more than one is set. If the header field is nil, then
// the omit is true, meaning some earlier logic in the server
// wanted to prevent this header from getting written at all.
// If the header is empty, then ok is false. Callers should
// still check that the value is not empty (the header field
// may be set but have an empty value).
func lastHeaderValue(h http.Header, field string) (value string, ok bool, omit bool) {
values, ok := h[http.CanonicalHeaderKey(field)]
if ok && values == nil {
return "", true, true
}
if len(values) == 0 {
return "", false, false
}
return values[len(values)-1], true, false
}
func upgradeType(h http.Header) string {
if !httpguts.HeaderValuesContainsToken(h["Connection"], "Upgrade") {
return ""
}
return strings.ToLower(h.Get("Upgrade"))
}
// removeConnectionHeaders removes hop-by-hop headers listed in the "Connection" header of h.
// See RFC 7230, section 6.1
func removeConnectionHeaders(h http.Header) {
for _, f := range h["Connection"] {
for _, sf := range strings.Split(f, ",") {
if sf = textproto.TrimString(sf); sf != "" {
h.Del(sf)
}
}
}
}
// statusError returns an error value that has a status code.
func statusError(err error) error {
// errors proxying usually mean there is a problem with the upstream(s)
statusCode := http.StatusBadGateway
// timeout errors have a standard status code (see issue #4823)
if err, ok := err.(net.Error); ok && err.Timeout() {
statusCode = http.StatusGatewayTimeout
}
// if the client canceled the request (usually this means they closed
// the connection, so they won't see any response), we can report it
// as a client error (4xx) and not a server error (5xx); unfortunately
// the Go standard library, at least at time of writing in late 2020,
// obnoxiously wraps the exported, standard context.Canceled error with
// an unexported garbage value that we have to do a substring check for:
// https://github.com/golang/go/blob/6965b01ea248cabb70c3749fd218b36089a21efb/src/net/net.go#L416-L430
if errors.Is(err, context.Canceled) || strings.Contains(err.Error(), "operation was canceled") {
// regrettably, there is no standard error code for "client closed connection", but
// for historical reasons we can use a code that a lot of people are already using;
// using 5xx is problematic for users; see #3748
statusCode = 499
}
return caddyhttp.Error(statusCode, err)
}
// LoadBalancing has parameters related to load balancing.
type LoadBalancing struct {
// A selection policy is how to choose an available backend.
// The default policy is random selection.
SelectionPolicyRaw json.RawMessage `json:"selection_policy,omitempty" caddy:"namespace=http.reverse_proxy.selection_policies inline_key=policy"`
// How many times to retry selecting available backends for each
// request if the next available host is down. If try_duration is
// also configured, then retries may stop early if the duration
// is reached. By default, retries are disabled (zero).
Retries int `json:"retries,omitempty"`
// How long to try selecting available backends for each request
// if the next available host is down. Clients will wait for up
// to this long while the load balancer tries to find an available
// upstream host. If retries is also configured, tries may stop
// early if the maximum retries is reached. By default, retries
// are disabled (zero duration).
TryDuration caddy.Duration `json:"try_duration,omitempty"`
// How long to wait between selecting the next host from the pool.
// Default is 250ms if try_duration is enabled, otherwise zero. Only
// relevant when a request to an upstream host fails. Be aware that
// setting this to 0 with a non-zero try_duration can cause the CPU
// to spin if all backends are down and latency is very low.
TryInterval caddy.Duration `json:"try_interval,omitempty"`
// A list of matcher sets that restricts with which requests retries are
// allowed. A request must match any of the given matcher sets in order
// to be retried if the connection to the upstream succeeded but the
// subsequent round-trip failed. If the connection to the upstream failed,
// a retry is always allowed. If unspecified, only GET requests will be
// allowed to be retried. Note that a retry is done with the next available
// host according to the load balancing policy.
RetryMatchRaw caddyhttp.RawMatcherSets `json:"retry_match,omitempty" caddy:"namespace=http.matchers"`
SelectionPolicy Selector `json:"-"`
RetryMatch caddyhttp.MatcherSets `json:"-"`
}
// Selector selects an available upstream from the pool.
type Selector interface {
Select(UpstreamPool, *http.Request, http.ResponseWriter) *Upstream
}
// UpstreamSource gets the list of upstreams that can be used when
// proxying a request. Returned upstreams will be load balanced and
// health-checked. This should be a very fast function -- instant
// if possible -- and the return value must be as stable as possible.
// In other words, the list of upstreams should ideally not change much
// across successive calls. If the list of upstreams changes or the
// ordering is not stable, load balancing will suffer. This function
// may be called during each retry, multiple times per request, and as
// such, needs to be instantaneous. The returned slice will not be
// modified.
type UpstreamSource interface {
GetUpstreams(*http.Request) ([]*Upstream, error)
}
// Hop-by-hop headers. These are removed when sent to the backend.
// As of RFC 7230, hop-by-hop headers are required to appear in the
// Connection header field. These are the headers defined by the
// obsoleted RFC 2616 (section 13.5.1) and are used for backward
// compatibility.
var hopHeaders = []string{
"Alt-Svc",
"Connection",
"Proxy-Connection", // non-standard but still sent by libcurl and rejected by e.g. google
"Keep-Alive",
"Proxy-Authenticate",
"Proxy-Authorization",
"Te", // canonicalized version of "TE"
"Trailer", // not Trailers per URL above; https://www.rfc-editor.org/errata_search.php?eid=4522
"Transfer-Encoding",
"Upgrade",
}
// DialError is an error that specifically occurs
// in a call to Dial or DialContext.
type DialError struct{ error }
// TLSTransport is implemented by transports
// that are capable of using TLS.
type TLSTransport interface {
// TLSEnabled returns true if the transport
// has TLS enabled, false otherwise.
TLSEnabled() bool
// EnableTLS enables TLS within the transport
// if it is not already, using the provided
// value as a basis for the TLS config.
EnableTLS(base *TLSConfig) error
}
// roundtripSucceeded is an error type that is returned if the
// roundtrip succeeded, but an error occurred after-the-fact.
type roundtripSucceeded struct{ error }
// bodyReadCloser is a reader that, upon closing, will return
// its buffer to the pool and close the underlying body reader.
type bodyReadCloser struct {
io.Reader
buf *bytes.Buffer
body io.ReadCloser
}
func (brc bodyReadCloser) Close() error {
bufPool.Put(brc.buf)
if brc.body != nil {
return brc.body.Close()
}
return nil
}
// bufPool is used for buffering requests and responses.
var bufPool = sync.Pool{
New: func() any {
return new(bytes.Buffer)
},
}
// handleResponseContext carries some contextual information about the
// current proxy handling.
type handleResponseContext struct {
// handler is the active proxy handler instance, so that
// routes like copy_response may inherit some config
// options and have access to handler methods.
handler *Handler
// response is the actual response received from the proxy
// roundtrip, to potentially be copied if a copy_response
// handler is in the handle_response routes.
response *http.Response
// start is the time just before the proxy roundtrip was
// performed, used for logging.
start time.Time
// logger is the prepared logger which is used to write logs
// with the request, duration, and selected upstream attached.
logger *zap.Logger
// isFinalized is whether the response has been finalized,
// i.e. copied and closed, to make sure that it doesn't
// happen twice.
isFinalized bool
}
// proxyHandleResponseContextCtxKey is the context key for the active proxy handler
// so that handle_response routes can inherit some config options
// from the proxy handler.
const proxyHandleResponseContextCtxKey caddy.CtxKey = "reverse_proxy_handle_response_context"
// errNoUpstream occurs when there are no upstream available.
var errNoUpstream = fmt.Errorf("no upstreams available")
// Interface guards
var (
_ caddy.Provisioner = (*Handler)(nil)
_ caddy.CleanerUpper = (*Handler)(nil)
_ caddyhttp.MiddlewareHandler = (*Handler)(nil)
)