mirror of
https://github.com/gitpod-io/gitpod.git
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132 lines
3.6 KiB
Go
132 lines
3.6 KiB
Go
// Copyright (c) 2021 Gitpod GmbH. All rights reserved.
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// Licensed under the GNU Affero General Public License (AGPL).
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// See License.AGPL.txt in the project root for license information.
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package workspacedownload
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import (
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"fmt"
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"net/http"
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"net/http/httputil"
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"net/url"
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"strings"
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"github.com/caddyserver/caddy/v2"
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"github.com/caddyserver/caddy/v2/caddyconfig/caddyfile"
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"github.com/caddyserver/caddy/v2/caddyconfig/httpcaddyfile"
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"github.com/caddyserver/caddy/v2/modules/caddyhttp"
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)
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const (
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frontendDevModule = "gitpod.frontend_dev"
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devURLHeaderName = "X-Frontend-Dev-URL"
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)
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func init() {
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caddy.RegisterModule(Config{})
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httpcaddyfile.RegisterHandlerDirective(frontendDevModule, parseCaddyfile)
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}
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// Config implements an HTTP handler that extracts gitpod headers
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type Config struct {
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}
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// CaddyModule returns the Caddy module information.
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func (Config) CaddyModule() caddy.ModuleInfo {
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return caddy.ModuleInfo{
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ID: "http.handlers.frontend_dev",
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New: func() caddy.Module { return new(Config) },
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}
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}
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// ServeHTTP implements caddyhttp.MiddlewareHandler.
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func (m Config) ServeHTTP(w http.ResponseWriter, r *http.Request, next caddyhttp.Handler) error {
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devURLStr := r.Header.Get(devURLHeaderName)
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if devURLStr == "" {
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caddy.Log().Sugar().Errorf("dev URL header empty")
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return caddyhttp.Error(http.StatusInternalServerError, fmt.Errorf("unexpected error forwarding to dev URL"))
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}
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devURL, err := url.Parse(devURLStr)
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if err != nil {
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caddy.Log().Sugar().Errorf("Cannot parse dev URL")
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return caddyhttp.Error(http.StatusInternalServerError, fmt.Errorf("unexpected error forwarding to dev URL"))
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}
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targetQuery := devURL.RawQuery
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director := func(req *http.Request) {
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req.URL.Scheme = devURL.Scheme
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req.URL.Host = devURL.Host
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req.Host = devURL.Host // override host header so target proxy can handle this request properly
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req.URL.Path, req.URL.RawPath = joinURLPath(devURL, req.URL)
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if targetQuery == "" || req.URL.RawQuery == "" {
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req.URL.RawQuery = targetQuery + req.URL.RawQuery
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} else {
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req.URL.RawQuery = targetQuery + "&" + req.URL.RawQuery
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}
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if _, ok := req.Header["User-Agent"]; !ok {
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// explicitly disable User-Agent so it's not set to default value
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req.Header.Set("User-Agent", "")
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}
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}
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proxy := httputil.ReverseProxy{Director: director}
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proxy.ServeHTTP(w, r)
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return nil
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}
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func joinURLPath(a, b *url.URL) (path, rawpath string) {
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if a.RawPath == "" && b.RawPath == "" {
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return singleJoiningSlash(a.Path, b.Path), ""
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}
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// Same as singleJoiningSlash, but uses EscapedPath to determine
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// whether a slash should be added
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apath := a.EscapedPath()
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bpath := b.EscapedPath()
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aslash := strings.HasSuffix(apath, "/")
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bslash := strings.HasPrefix(bpath, "/")
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switch {
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case aslash && bslash:
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return a.Path + b.Path[1:], apath + bpath[1:]
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case !aslash && !bslash:
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return a.Path + "/" + b.Path, apath + "/" + bpath
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}
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return a.Path + b.Path, apath + bpath
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}
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func singleJoiningSlash(a, b string) string {
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aslash := strings.HasSuffix(a, "/")
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bslash := strings.HasPrefix(b, "/")
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switch {
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case aslash && bslash:
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return a + b[1:]
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case !aslash && !bslash:
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return a + "/" + b
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}
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return a + b
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}
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// UnmarshalCaddyfile implements Caddyfile.Unmarshaler.
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func (m *Config) UnmarshalCaddyfile(d *caddyfile.Dispenser) error {
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return nil
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}
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func parseCaddyfile(h httpcaddyfile.Helper) (caddyhttp.MiddlewareHandler, error) {
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m := new(Config)
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err := m.UnmarshalCaddyfile(h.Dispenser)
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if err != nil {
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return nil, err
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}
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return m, nil
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}
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// Interface guards
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var (
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_ caddyhttp.MiddlewareHandler = (*Config)(nil)
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_ caddyfile.Unmarshaler = (*Config)(nil)
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)
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