package main import ( "flag" "fmt" "html" "io" "mime" "net/http" "net/url" "os" "strconv" "strings" "git.curoverse.com/arvados.git/sdk/go/arvadosclient" "git.curoverse.com/arvados.git/sdk/go/auth" "git.curoverse.com/arvados.git/sdk/go/httpserver" "git.curoverse.com/arvados.git/sdk/go/keepclient" ) type handler struct{} var ( clientPool = arvadosclient.MakeClientPool() trustAllContent = false attachmentOnlyHost = "" ) func init() { flag.StringVar(&attachmentOnlyHost, "attachment-only-host", "", "Accept credentials, and add \"Content-Disposition: attachment\" response headers, for requests at this hostname:port. Prohibiting inline display makes it possible to serve untrusted and non-public content from a single origin, i.e., without wildcard DNS or SSL.") flag.BoolVar(&trustAllContent, "trust-all-content", false, "Serve non-public content from a single origin. Dangerous: read docs before using!") } // return a UUID or PDH if s begins with a UUID or URL-encoded PDH; // otherwise return "". func parseCollectionIDFromDNSName(s string) string { // Strip domain. if i := strings.IndexRune(s, '.'); i >= 0 { s = s[:i] } // Names like {uuid}--collections.example.com serve the same // purpose as {uuid}.collections.example.com but can reduce // cost/effort of using [additional] wildcard certificates. if i := strings.Index(s, "--"); i >= 0 { s = s[:i] } if arvadosclient.UUIDMatch(s) { return s } if pdh := strings.Replace(s, "-", "+", 1); arvadosclient.PDHMatch(pdh) { return pdh } return "" } var urlPDHDecoder = strings.NewReplacer(" ", "+", "-", "+") // return a UUID or PDH if s is a UUID or a PDH (even if it is a PDH // with "+" replaced by " " or "-"); otherwise return "". func parseCollectionIDFromURL(s string) string { if arvadosclient.UUIDMatch(s) { return s } if pdh := urlPDHDecoder.Replace(s); arvadosclient.PDHMatch(pdh) { return pdh } return "" } func (h *handler) ServeHTTP(wOrig http.ResponseWriter, r *http.Request) { var statusCode = 0 var statusText string remoteAddr := r.RemoteAddr if xff := r.Header.Get("X-Forwarded-For"); xff != "" { remoteAddr = xff + "," + remoteAddr } w := httpserver.WrapResponseWriter(wOrig) defer func() { if statusCode == 0 { statusCode = w.WroteStatus() } else if w.WroteStatus() == 0 { w.WriteHeader(statusCode) } else if w.WroteStatus() != statusCode { httpserver.Log(r.RemoteAddr, "WARNING", fmt.Sprintf("Our status changed from %d to %d after we sent headers", w.WroteStatus(), statusCode)) } if statusText == "" { statusText = http.StatusText(statusCode) } httpserver.Log(remoteAddr, statusCode, statusText, w.WroteBodyBytes(), r.Method, r.Host, r.URL.Path, r.URL.RawQuery) }() if r.Method != "GET" && r.Method != "POST" { statusCode, statusText = http.StatusMethodNotAllowed, r.Method return } arv := clientPool.Get() if arv == nil { statusCode, statusText = http.StatusInternalServerError, "Pool failed: "+clientPool.Err().Error() return } defer clientPool.Put(arv) pathParts := strings.Split(r.URL.Path[1:], "/") var targetID string var targetPath []string var tokens []string var reqTokens []string var pathToken bool var attachment bool credentialsOK := trustAllContent if r.Host != "" && r.Host == attachmentOnlyHost { credentialsOK = true attachment = true } else if r.FormValue("disposition") == "attachment" { attachment = true } if targetID = parseCollectionIDFromDNSName(r.Host); targetID != "" { // http://ID.collections.example/PATH... credentialsOK = true targetPath = pathParts } else if len(pathParts) >= 2 && strings.HasPrefix(pathParts[0], "c=") { // /c=ID/PATH... targetID = parseCollectionIDFromURL(pathParts[0][2:]) targetPath = pathParts[1:] } else if len(pathParts) >= 3 && pathParts[0] == "collections" { if len(pathParts) >= 5 && pathParts[1] == "download" { // /collections/download/ID/TOKEN/PATH... targetID = pathParts[2] tokens = []string{pathParts[3]} targetPath = pathParts[4:] pathToken = true } else { // /collections/ID/PATH... targetID = pathParts[1] tokens = anonymousTokens targetPath = pathParts[2:] } } else { statusCode = http.StatusNotFound return } if t := r.FormValue("api_token"); t != "" { // The client provided an explicit token in the query // string, or a form in POST body. We must put the // token in an HttpOnly cookie, and redirect to the // same URL with the query param redacted and method = // GET. if !credentialsOK { // It is not safe to copy the provided token // into a cookie unless the current vhost // (origin) serves only a single collection or // we are in trustAllContent mode. statusCode = http.StatusBadRequest return } // The HttpOnly flag is necessary to prevent // JavaScript code (included in, or loaded by, a page // in the collection being served) from employing the // user's token beyond reading other files in the same // domain, i.e., same collection. // // The 303 redirect is necessary in the case of a GET // request to avoid exposing the token in the Location // bar, and in the case of a POST request to avoid // raising warnings when the user refreshes the // resulting page. http.SetCookie(w, &http.Cookie{ Name: "arvados_api_token", Value: auth.EncodeTokenCookie([]byte(t)), Path: "/", HttpOnly: true, }) redir := (&url.URL{Host: r.Host, Path: r.URL.Path}).String() w.Header().Add("Location", redir) statusCode, statusText = http.StatusSeeOther, redir w.WriteHeader(statusCode) io.WriteString(w, `Continue`) return } if tokens == nil && strings.HasPrefix(targetPath[0], "t=") { // http://ID.example/t=TOKEN/PATH... // /c=ID/t=TOKEN/PATH... // // This form must only be used to pass scoped tokens // that give permission for a single collection. See // FormValue case above. tokens = []string{targetPath[0][2:]} pathToken = true targetPath = targetPath[1:] } if tokens == nil { if credentialsOK { reqTokens = auth.NewCredentialsFromHTTPRequest(r).Tokens } tokens = append(reqTokens, anonymousTokens...) } if len(targetPath) > 0 && targetPath[0] == "_" { // If a collection has a directory called "t=foo" or // "_", it can be served at // //collections.example/_/t=foo/ or // //collections.example/_/_/ respectively: // //collections.example/t=foo/ won't work because // t=foo will be interpreted as a token "foo". targetPath = targetPath[1:] } tokenResult := make(map[string]int) collection := make(map[string]interface{}) found := false for _, arv.ApiToken = range tokens { err := arv.Get("collections", targetID, nil, &collection) if err == nil { // Success found = true break } if srvErr, ok := err.(arvadosclient.APIServerError); ok { switch srvErr.HttpStatusCode { case 404, 401: // Token broken or insufficient to // retrieve collection tokenResult[arv.ApiToken] = srvErr.HttpStatusCode continue } } // Something more serious is wrong statusCode, statusText = http.StatusInternalServerError, err.Error() return } if !found { if pathToken || !credentialsOK { // Either the URL is a "secret sharing link" // that didn't work out (and asking the client // for additional credentials would just be // confusing), or we don't even accept // credentials at this path. statusCode = http.StatusNotFound return } for _, t := range reqTokens { if tokenResult[t] == 404 { // The client provided valid token(s), but the // collection was not found. statusCode = http.StatusNotFound return } } // The client's token was invalid (e.g., expired), or // the client didn't even provide one. Propagate the // 401 to encourage the client to use a [different] // token. // // TODO(TC): This response would be confusing to // someone trying (anonymously) to download public // data that has been deleted. Allow a referrer to // provide this context somehow? w.Header().Add("WWW-Authenticate", "Basic realm=\"collections\"") statusCode = http.StatusUnauthorized return } filename := strings.Join(targetPath, "/") kc, err := keepclient.MakeKeepClient(arv) if err != nil { statusCode, statusText = http.StatusInternalServerError, err.Error() return } rdr, err := kc.CollectionFileReader(collection, filename) if os.IsNotExist(err) { statusCode = http.StatusNotFound return } else if err != nil { statusCode, statusText = http.StatusBadGateway, err.Error() return } defer rdr.Close() // One or both of these can be -1 if not found: basenamePos := strings.LastIndex(filename, "/") extPos := strings.LastIndex(filename, ".") if extPos > basenamePos { // Now extPos is safely >= 0. if t := mime.TypeByExtension(filename[extPos:]); t != "" { w.Header().Set("Content-Type", t) } } if rdr, ok := rdr.(keepclient.ReadCloserWithLen); ok { w.Header().Set("Content-Length", fmt.Sprintf("%d", rdr.Len())) } disposition := "inline" if attachment { disposition = "attachment" } if strings.ContainsRune(r.RequestURI, '?') { // Help the UA realize that the filename is just // "filename.txt", not // "filename.txt?disposition=attachment". // // TODO(TC): Follow advice at RFC 6266 appendix D if basenamePos < 0 { basenamePos = 0 } disposition += "; filename=" + strconv.QuoteToASCII(filename[basenamePos:]) } if disposition != "inline" { w.Header().Set("Content-Disposition", disposition) } w.WriteHeader(http.StatusOK) _, err = io.Copy(w, rdr) if err != nil { statusCode, statusText = http.StatusBadGateway, err.Error() } }