utils.go

package gemini

import (
	"fmt"
	"net"
	urlpkg "net/url"
	"path"
	"sort"
	"strings"
)

// cleanPath returns the canonical path for p, eliminating . and .. elements.
func cleanPath(p string) string {
	if p == "" {
		return "/"
	}
	if p[0] != '/' {
		p = "/" + p
	}
	np := path.Clean(p)
	// path.Clean removes trailing slash except for root;
	// put the trailing slash back if necessary.
	if p[len(p)-1] == '/' && np != "/" {
		// Fast path for common case of p being the string we want:
		if len(p) == len(np)+1 && strings.HasPrefix(p, np) {
			np = p
		} else {
			np += "/"
		}
	}
	return np
}

// stripHostPort returns h without any trailing ":<port>".
func stripHostPort(h string) string {
	// If no port on host, return unchanged
	if strings.IndexByte(h, ':') == -1 {
		return h
	}
	host, _, err := net.SplitHostPort(h)
	if err != nil {
		return h // on error, return unchanged
	}
	return host
}

// Redirect to a fixed URL
type redirectHandler struct {
	url  string
	code uint8
}

func (rh *redirectHandler) ServeGemini(w ResponseWriter, r *Request) {
	Redirect(w, r, rh.url, rh.code)
}

// RedirectHandler returns a request handler that redirects
// each request it receives to the given url using the given
// status code.
//
// The provided code should be in the 3xx range and is usually
// StatusMovedPermanently, StatusFound or StatusSeeOther.
func RedirectHandler(url string, code uint8) Handler {
	return &redirectHandler{url, code}
}

// Redirect replies to the request with a redirect to url,
// which may be a path relative to the request path.
//
// The provided code should be in the 3xx range and is usually
// StatusMovedPermanently, StatusFound or StatusSeeOther.
//
// If the Content-Type header has not been set, Redirect sets it
// to "text/html; charset=utf-8" and writes a small HTML body.
// Setting the Content-Type header to any value, including nil,
// disables that behavior.
func Redirect(w ResponseWriter, r *Request, url string, code uint8) {
	if u, err := urlpkg.Parse(url); err == nil {
		// If url was relative, make its path absolute by
		// combining with request path.
		// The client would probably do this for us,
		// but doing it ourselves is more reliable.
		// See RFC 7231, section 7.1.2
		if u.Scheme == "" && u.Host == "" {
			oldpath := r.URL.Path
			if oldpath == "" { // should not happen, but avoid a crash if it does
				oldpath = "/"
			}

			// no leading gemini://server
			if url == "" || url[0] != '/' {
				// make relative path absolute
				olddir, _ := path.Split(oldpath)
				url = olddir + url
			}

			var query string
			if i := strings.Index(url, "?"); i != -1 {
				url, query = url[:i], url[i:]
			}

			// clean up but preserve trailing slash
			trailing := strings.HasSuffix(url, "/")
			url = path.Clean(url)
			if trailing && !strings.HasSuffix(url, "/") {
				url += "/"
			}
			url += query
		}
	}

	w.WriteHeader(code, "") // TODO: вместо пустых кавычек должен передаваться тип
}

// NotFoundHandler returns a simple request handler
// that replies to each request with a ``404 page not found'' reply.
func NotFoundHandler() Handler { return HandlerFunc(NotFound) }

func NotFound(w ResponseWriter, r *Request) { Error(w, "404 page not found", StatusNotFound) }

// Error replies to the request with the specified error message and Gemini code.
// It does not otherwise end the request; the caller should ensure no further
// writes are done to w.
// The error message should be plain text.
func Error(w ResponseWriter, error string, code uint8) {
	w.WriteHeader(code, error) // TODO: проверить пустые кавычки
}

func appendSorted(es []muxEntry, e muxEntry) []muxEntry {
	n := len(es)
	i := sort.Search(n, func(i int) bool {
		return len(es[i].pattern) < len(e.pattern)
	})
	if i == n {
		return append(es, e)
	}
	// we now know that i points at where we want to insert
	es = append(es, muxEntry{}) // try to grow the slice in place, any entry works.
	copy(es[i+1:], es[i:])      // Move shorter entries down
	es[i] = e
	return es
}

func checkWriteHeaderCode(code int) {
	// Issue 22880: require valid WriteHeader status codes.
	// For now we only enforce that it's two digits.
	if code < 10 || code > 99 {
		panic(fmt.Sprintf("invalid WriteHeader code %v", code))
	}
}