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// Package proxy provides functionality for configuring and using a proxy server.
package proxy
import (
"fmt"
"net/http"
"net/http/httputil"
"net/url"
"sync"
"time"
"gitlab.com/gitlab-org/gitlab/workhorse/internal/helper"
"gitlab.com/gitlab-org/gitlab/workhorse/internal/helper/nginx"
)
const (
// matches the default size used in httputil.ReverseProxy
bufferPoolSize = 32 * 1024
)
var (
defaultTarget = helper.URLMustParse("http://localhost")
// pool is a buffer pool that is shared across all Proxy instances to maximize buffer reuse.
pool = newBufferPool()
)
// Proxy represents a proxy configuration with various settings.
type Proxy struct {
Version string
reverseProxy *httputil.ReverseProxy
AllowResponseBuffering bool
customHeaders map[string]string
forceTargetHostHeader bool
}
// WithCustomHeaders is a function that returns a configuration function to set custom headers for a proxy.
func WithCustomHeaders(customHeaders map[string]string) func(*Proxy) {
return func(proxy *Proxy) {
proxy.customHeaders = customHeaders
}
}
// WithForcedTargetHostHeader is a function that returns a configuration function to force the target host header for a proxy.
func WithForcedTargetHostHeader() func(*Proxy) {
return func(proxy *Proxy) {
proxy.forceTargetHostHeader = true
}
}
// NewProxy creates a new Proxy instance with the provided options.
func NewProxy(myURL *url.URL, version string, roundTripper http.RoundTripper, options ...func(*Proxy)) *Proxy {
p := Proxy{Version: version, AllowResponseBuffering: true, customHeaders: make(map[string]string)}
if myURL == nil {
myURL = defaultTarget
}
u := *myURL // Make a copy of p.URL
u.Path = ""
p.reverseProxy = httputil.NewSingleHostReverseProxy(&u)
p.reverseProxy.Transport = roundTripper
p.reverseProxy.BufferPool = pool
chainDirector(p.reverseProxy, func(r *http.Request) {
r.Header.Set("Gitlab-Workhorse", p.Version)
r.Header.Set("Gitlab-Workhorse-Proxy-Start", fmt.Sprintf("%d", time.Now().UnixNano()))
for k, v := range p.customHeaders {
r.Header.Set(k, v)
}
})
for _, option := range options {
option(&p)
}
if p.forceTargetHostHeader {
// because of https://github.com/golang/go/issues/28168, the
// upstream won't receive the expected Host header unless this
// is forced in the Director func here
chainDirector(p.reverseProxy, func(request *http.Request) {
// send original host along for the upstream
// to know it's being proxied under a different Host
// (for redirects and other stuff that depends on this)
request.Header.Set("X-Forwarded-Host", request.Host)
request.Header.Set("Forwarded", fmt.Sprintf("host=%s", request.Host))
// override the Host with the target
request.Host = request.URL.Host
})
}
return &p
}
func chainDirector(rp *httputil.ReverseProxy, nextDirector func(*http.Request)) {
previous := rp.Director
rp.Director = func(r *http.Request) {
previous(r)
nextDirector(r)
}
}
func (p *Proxy) ServeHTTP(w http.ResponseWriter, r *http.Request) {
if p.AllowResponseBuffering {
nginx.AllowResponseBuffering(w)
}
// If the ultimate client disconnects when the response isn't fully written
// to them yet, httputil.ReverseProxy panics with a net/http.ErrAbortHandler
// error. We can catch and discard this to keep the error log clean
defer func() {
if err := recover(); err != nil {
if err != http.ErrAbortHandler {
panic(err)
}
}
}()
p.reverseProxy.ServeHTTP(w, r)
}
type bufferPool struct {
pool sync.Pool
}
func newBufferPool() *bufferPool {
return &bufferPool{
pool: sync.Pool{
New: func() any {
return make([]byte, bufferPoolSize)
},
},
}
}
func (bp *bufferPool) Get() []byte {
return bp.pool.Get().([]byte)
}
func (bp *bufferPool) Put(v []byte) {
bp.pool.Put(v) //lint:ignore SA6002 we either allocate manually to satisfy the linter or let the compiler allocate for us and silence the linter
}
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