1 files changed, 103 insertions, 0 deletions
diff --git a/internal/router/info_refs.go b/internal/router/info_refs.go
new file mode 100644
index 000000000..b3cab9a50
--- /dev/null
+++ b/internal/router/info_refs.go
@@ -0,0 +1,103 @@
+package router
+
+import (
+	"fmt"
+	"io"
+	"net/http"
+	"os"
+	"os/exec"
+	"syscall"
+
+	"gitlab.com/gitlab-org/gitaly/internal/helper"
+
+	"github.com/gorilla/mux"
+)
+
+const (
+	gitalyRepoPathHeader = "Gitaly-Repo-Path"
+	gitlabIdHeader       = "Gitaly-GL-Id"
+)
+
+func GetInfoRefs(w http.ResponseWriter, r *http.Request) {
+	vars := mux.Vars(r)
+	rpc := vars["service"]
+
+	glId := r.Header.Get(gitlabIdHeader)
+	if glId == "" {
+		helper.Fail500(w, r, fmt.Errorf("GetInfoRefs: %s header was not found", gitlabIdHeader))
+		return
+	}
+	repoPath := r.Header.Get(gitalyRepoPathHeader)
+	if repoPath == "" {
+		helper.Fail500(w, r, fmt.Errorf("GetInfoRefs: %s header was not found", gitalyRepoPathHeader))
+		return
+	}
+
+	// Prepare our Git subprocess
+	cmd := gitCommand(glId, "git", rpc, "--stateless-rpc", "--advertise-refs", repoPath)
+
+	stdout, err := cmd.StdoutPipe()
+	if err != nil {
+		helper.Fail500(w, r, fmt.Errorf("GetInfoRefs: stdout: %v", err))
+		return
+	}
+	defer stdout.Close()
+
+	if err := cmd.Start(); err != nil {
+		helper.Fail500(w, r, fmt.Errorf("GetInfoRefs: start %v: %v", cmd.Args, err))
+		return
+	}
+	defer helper.CleanUpProcessGroup(cmd) // Ensure brute force subprocess clean-up
+
+	// Start writing the response
+	w.Header().Set("Content-Type", fmt.Sprintf("application/x-git-%s-advertisement", rpc))
+	w.Header().Set("Cache-Control", "no-cache")
+	w.WriteHeader(200) // Don't bother with HTTP 500 from this point on, just return
+
+	if err := pktLine(w, fmt.Sprintf("# service=git-%s\n", rpc)); err != nil {
+		helper.LogError(r, fmt.Errorf("GetInfoRefs: pktLine: %v", err))
+		return
+	}
+
+	if err := pktFlush(w); err != nil {
+		helper.LogError(r, fmt.Errorf("GetInfoRefs: pktFlush: %v", err))
+		return
+	}
+
+	if _, err := io.Copy(w, stdout); err != nil {
+		helper.LogError(r, fmt.Errorf("GetInfoRefs: copy output of %v: %v", cmd.Args, err))
+		return
+	}
+
+	if err := cmd.Wait(); err != nil {
+		helper.LogError(r, fmt.Errorf("GetInfoRefs: wait for %v: %v", cmd.Args, err))
+		return
+	}
+}
+
+func gitCommand(glId string, name string, args ...string) *exec.Cmd {
+	cmd := exec.Command(name, args...)
+	// Start the command in its own process group (nice for signalling)
+	cmd.SysProcAttr = &syscall.SysProcAttr{Setpgid: true}
+	// Explicitly set the environment for the Git command
+	cmd.Env = []string{
+		fmt.Sprintf("HOME=%s", os.Getenv("HOME")),
+		fmt.Sprintf("PATH=%s", os.Getenv("PATH")),
+		fmt.Sprintf("LD_LIBRARY_PATH=%s", os.Getenv("LD_LIBRARY_PATH")),
+		fmt.Sprintf("GL_ID=%s", glId),
+		fmt.Sprintf("GL_PROTOCOL=http"),
+	}
+	// If we don't do something with cmd.Stderr, Git errors will be lost
+	cmd.Stderr = os.Stderr
+	return cmd
+}
+
+func pktLine(w io.Writer, s string) error {
+	_, err := fmt.Fprintf(w, "%04x%s", len(s)+4, s)
+	return err
+}
+
+func pktFlush(w io.Writer) error {
+	_, err := fmt.Fprint(w, "0000")
+	return err
+}