krz/gitbay

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