internal/httpd/smart.go

  1// Package httpd serves the HTTP listener: anonymous smart-HTTP git reads for
  2// public repositories, and (from M5) the web UI. There is no authentication
  3// on this listener by design — private repositories answer 404 everywhere,
  4// and pushes are refused with a pkt-line ERR so no git version ever falls
  5// back to asking for credentials.
  6package httpd
  7
  8import (
  9	"compress/gzip"
 10	"fmt"
 11	"io"
 12	"net/http"
 13	"os"
 14	"os/exec"
 15	"strings"
 16
 17	"gitbay.org/gitbay/internal/config"
 18	"gitbay.org/gitbay/internal/control"
 19	"gitbay.org/gitbay/internal/store"
 20)
 21
 22type Server struct {
 23	cfg      config.Config
 24	st       *store.Store
 25	apiLimit *apiLimiter
 26}
 27
 28func New(cfg config.Config, st *store.Store) *Server {
 29	return &Server{cfg: cfg, st: st, apiLimit: newAPILimiter(cfg.Limits.APIRate)}
 30}
 31
 32// receivePackRefusal exists only to fail legibly if a client POSTs without
 33// reading the advertisement first.
 34func (s *Server) receivePackRefusal(w http.ResponseWriter, r *http.Request) {
 35	http.Error(w, s.pushRefusalMessage(r.PathValue("owner"), r.PathValue("repo")), http.StatusForbidden)
 36}
 37
 38// publicRepo resolves owner/name and returns it only if it exists and is
 39// public. Every failure mode is the same 404.
 40func (s *Server) publicRepo(owner, name string) (store.Repo, bool) {
 41	repo, err := s.st.RepoByPath(owner + "/" + name)
 42	if err != nil || repo.Visibility != "public" {
 43		return store.Repo{}, false
 44	}
 45	return repo, true
 46}
 47
 48func pktLine(w io.Writer, s string) {
 49	fmt.Fprintf(w, "%04x%s", len(s)+4, s)
 50}
 51
 52func pktFlush(w io.Writer) { io.WriteString(w, "0000") }
 53
 54func (s *Server) pushRefusalMessage(owner, repo string) string {
 55	host := strings.TrimSuffix(strings.TrimPrefix(strings.TrimPrefix(s.cfg.Server.SiteURL, "https://"), "http://"), "/")
 56	name := strings.TrimSuffix(repo, ".git")
 57	return fmt.Sprintf("pushes to this forge go over SSH: git remote set-url --push origin git@%s:%s/%s.git", host, owner, name)
 58}
 59
 60func (s *Server) infoRefs(w http.ResponseWriter, r *http.Request) {
 61	owner, name := r.PathValue("owner"), r.PathValue("repo")
 62	repo, ok := s.publicRepo(owner, name)
 63	if !ok {
 64		http.NotFound(w, r)
 65		return
 66	}
 67	switch service := r.URL.Query().Get("service"); service {
 68	case "git-upload-pack":
 69		w.Header().Set("Content-Type", "application/x-git-upload-pack-advertisement")
 70		w.Header().Set("Cache-Control", "no-cache")
 71		pktLine(w, "# service=git-upload-pack\n")
 72		pktFlush(w)
 73		dir := control.RepoDir(s.cfg.Server.Root, repo.OwnerName, repo.Name)
 74		cmd := exec.CommandContext(r.Context(), "git", "upload-pack", "--stateless-rpc", "--advertise-refs", dir)
 75		cmd.Env = append(os.Environ(), gitProtocolEnv(r)...)
 76		cmd.Stdout = w
 77		cmd.Run()
 78	case "git-receive-pack":
 79		// HTTP 200 with a pkt-line ERR: every git version renders this as
 80		// "fatal: remote error: ..." and never falls back to credential
 81		// prompting the way a 401/403 would.
 82		w.Header().Set("Content-Type", "application/x-git-receive-pack-advertisement")
 83		w.Header().Set("Cache-Control", "no-cache")
 84		pktLine(w, "# service=git-receive-pack\n")
 85		pktFlush(w)
 86		pktLine(w, "ERR "+s.pushRefusalMessage(owner, name)+"\n")
 87	default:
 88		// Dumb-protocol clients are not supported.
 89		http.NotFound(w, r)
 90	}
 91}
 92
 93func (s *Server) uploadPack(w http.ResponseWriter, r *http.Request) {
 94	repo, ok := s.publicRepo(r.PathValue("owner"), r.PathValue("repo"))
 95	if !ok {
 96		http.NotFound(w, r)
 97		return
 98	}
 99	body := io.Reader(r.Body)
100	if r.Header.Get("Content-Encoding") == "gzip" {
101		gz, err := gzip.NewReader(body)
102		if err != nil {
103			http.Error(w, "bad gzip body", http.StatusBadRequest)
104			return
105		}
106		defer gz.Close()
107		body = gz
108	}
109	w.Header().Set("Content-Type", "application/x-git-upload-pack-result")
110	w.Header().Set("Cache-Control", "no-cache")
111	dir := control.RepoDir(s.cfg.Server.Root, repo.OwnerName, repo.Name)
112	cmd := exec.CommandContext(r.Context(), "git", "upload-pack", "--stateless-rpc", dir)
113	cmd.Env = append(os.Environ(), gitProtocolEnv(r)...)
114	cmd.Stdin = body
115	cmd.Stdout = w
116	cmd.Run()
117}
118
119// gitProtocolEnv forwards the client's protocol negotiation header so
120// protocol v2 works over stateless HTTP.
121func gitProtocolEnv(r *http.Request) []string {
122	if p := r.Header.Get("Git-Protocol"); p != "" {
123		return []string{"GIT_PROTOCOL=" + p}
124	}
125	return nil
126}