add nex protocol support

client.go

@@ -12,6 +12,7 @@ import (
 	"tildegit.org/tjp/sliderule/gemini"
 	"tildegit.org/tjp/sliderule/gopher"
 	"tildegit.org/tjp/sliderule/internal/types"
+	"tildegit.org/tjp/sliderule/nex"
 	"tildegit.org/tjp/sliderule/spartan"
 )
 
@@ -50,6 +51,7 @@ func NewClient(tlsConf *tls.Config) Client {
 			"spartan": spartan.NewClient(),
 			"http":    hc,
 			"https":   hc,
+			"nex":     nex.Client{},
 		},
 		MaxRedirects: DefaultMaxRedirects,
 	}

contrib/cgi/nex.go

@@ -0,0 +1,10 @@
+package cgi
+
+import (
+	"tildegit.org/tjp/sliderule"
+	"tildegit.org/tjp/sliderule/nex"
+)
+
+func NexCGIDirectory(fsroot, urlroot, cmd string) sliderule.Handler {
+	return cgiDirectory(nex.ServerProtocol, fsroot, urlroot, cmd)
+}

contrib/fs/nex.go

@@ -0,0 +1,48 @@
+package fs
+
+import (
+	"text/template"
+
+	sr "tildegit.org/tjp/sliderule"
+	"tildegit.org/tjp/sliderule/nex"
+)
+
+// NexFileHandler builds a handler which serves up files from a file system.
+//
+// It only serves responses for paths which correspond to files, not directories.
+func NexFileHandler(fsroot, urlroot string) sr.Handler {
+	return fileHandler(nex.ServerProtocol, fsroot, urlroot)
+}
+
+// NexDirectoryDefault serves up default files for directory path requests.
+//
+// If any of the supported filenames are found in the requested directory, the
+// contents of that file is returned as the nex response.
+//
+// It returns nil for any paths which don't correspond to a directory.
+func NexDirectoryDefault(fsroot, urlroot string, filenames ...string) sr.Handler {
+	return directoryDefault(nex.ServerProtocol, fsroot, urlroot, false, filenames...)
+}
+
+// NexDirectoryListing produces a listing of the contents of any requested directories.
+//
+// It returns a nil response for any paths which don't correspond to a filesystem directory.
+//
+// When it encounters a directory path which doesn't end in a trailing slash (/) it returns
+// a nil response. Trailing slashes are necessary for relative links to work properly.
+//
+// The template may be nil, in which case DefaultNexDirectoryList is used instead. The
+// template is then processed with RenderDirectoryListing.
+func NexDirectoryListing(fsroot, urlroot string, tmpl *template.Template) sr.Handler {
+	if tmpl == nil {
+		tmpl = DefaultNexDirectoryList
+	}
+	return directoryListing(nex.ServerProtocol, fsroot, urlroot, "", false, tmpl)
+}
+
+var DefaultNexDirectoryList = template.Must(template.New("nex_dirlist").Parse(`
+{{ .DirName }} directory:
+{{ range .Entries }}
+=> ./{{ .Name }}{{ if .IsDir }}/{{ end -}}
+{{ end }}
+`[1:]))

nex/client.go

@@ -0,0 +1,61 @@
+package nex
+
+import (
+	"bytes"
+	"errors"
+	"io"
+	"net"
+	neturl "net/url"
+
+	"tildegit.org/tjp/sliderule/internal/types"
+)
+
+// Client is used for sending nex requests and reading responses.
+//
+// It carries no state and is reusable simultaneously by multiple goroutines.
+//
+// The zero value is immediately usable.
+type Client struct{}
+
+// RoundTrip sends a single nex request and returns its response.
+func (c Client) RoundTrip(request *types.Request) (*types.Response, error) {
+	if request.Scheme != "nex" && request.Scheme != "" {
+		return nil, errors.New("non-nex protocols not supported")
+	}
+
+	host := request.Host
+	if _, port, _ := net.SplitHostPort(host); port == "" {
+		host = net.JoinHostPort(host, "1900")
+	}
+
+	conn, err := net.Dial("tcp", host)
+	if err != nil {
+		return nil, err
+	}
+	defer conn.Close()
+
+	request.RemoteAddr = conn.RemoteAddr()
+	request.TLSState = nil
+
+	if _, err := conn.Write([]byte(request.Path + "\n")); err != nil {
+		return nil, err
+	}
+
+	response, err := io.ReadAll(conn)
+	if err != nil {
+		return nil, err
+	}
+
+	return &types.Response{Body: bytes.NewBuffer(response)}, nil
+}
+
+// Fetch builds and sends a nex request, and returns the response.
+func (c Client) Fetch(url string) (*types.Response, error) {
+	u, err := neturl.Parse(url)
+	if err != nil {
+		return nil, err
+	}
+	return c.RoundTrip(&types.Request{URL: u})
+}
+
+func (c Client) IsRedirect(response *types.Response) bool { return false }

nex/protocol.go

@@ -0,0 +1,23 @@
+package nex
+
+import (
+	"io"
+	"net/url"
+
+	"tildegit.org/tjp/sliderule/internal/types"
+)
+
+type proto struct{}
+
+func (p proto) TemporaryRedirect(u *url.URL) *types.Response { return nil }
+func (p proto) PermanentRedirect(u *url.URL) *types.Response { return nil }
+
+func (p proto) TemporaryServerError(err error) *types.Response { return StringResponse(err.Error()) }
+func (p proto) PermanentServerError(err error) *types.Response { return StringResponse(err.Error()) }
+func (p proto) CGIFailure(err error) *types.Response           { return StringResponse(err.Error()) }
+
+func (p proto) Success(_ string, body io.Reader) *types.Response { return Response(body) }
+
+func (p proto) ParseResponse(input io.Reader) (*types.Response, error) { return Response(input), nil }
+
+var ServerProtocol types.ServerProtocol = proto{}

nex/request.go

@@ -0,0 +1,28 @@
+package nex
+
+import (
+	"bufio"
+	"io"
+	"net/url"
+	"strings"
+
+	"tildegit.org/tjp/sliderule/internal/types"
+)
+
+// ParseRequest reads a nex request from an io.Reader.
+func ParseRequest(rdr io.Reader) (*types.Request, error) {
+	line, err := bufio.NewReader(rdr).ReadString('\n')
+	if err != nil {
+		return nil, err
+	}
+	line = strings.TrimSuffix(line, "\n")
+	line = strings.TrimSuffix(line, "\r")
+
+	return &types.Request{
+		URL: &url.URL{
+			Scheme:   "nex",
+			Path:     line,
+			OmitHost: true,
+		},
+	}, nil
+}

nex/response.go

@@ -0,0 +1,18 @@
+package nex
+
+import (
+	"bytes"
+	"io"
+
+	"tildegit.org/tjp/sliderule/internal/types"
+)
+
+// Response builds a nex Response from an io.Reader.
+func Response(body io.Reader) *types.Response {
+	return &types.Response{Body: body}
+}
+
+// StringResponse builds a nex Response from a string.
+func StringResponse(body string) *types.Response {
+	return Response(bytes.NewBufferString(body))
+}

nex/serve.go

@@ -0,0 +1,91 @@
+package nex
+
+import (
+	"bytes"
+	"context"
+	"crypto/tls"
+	"fmt"
+	"io"
+	"net"
+
+	"tildegit.org/tjp/sliderule/internal"
+	"tildegit.org/tjp/sliderule/internal/types"
+	"tildegit.org/tjp/sliderule/logging"
+)
+
+type nexServer struct {
+	internal.Server
+	handler types.Handler
+}
+
+func (ns nexServer) Protocol() string { return "NEX" }
+
+// NewServer builds a new nex server
+func NewServer(
+	ctx context.Context,
+	hostname string,
+	network string,
+	address string,
+	handler types.Handler,
+	baseLog logging.Logger,
+) (types.Server, error) {
+	ns := &nexServer{handler: handler}
+
+	hostname = internal.JoinDefaultPort(hostname, "1900")
+	address = internal.JoinDefaultPort(address, "1900")
+
+	var err error
+	ns.Server, err = internal.NewServer(ctx, hostname, network, address, baseLog, ns.handleConn)
+	if err != nil {
+		return nil, err
+	}
+
+	return ns, err
+}
+
+func NewTLSServer(
+	ctx context.Context,
+	hostname string,
+	network string,
+	address string,
+	handler types.Handler,
+	baseLog logging.Logger,
+	tlsConfig *tls.Config,
+) (types.Server, error) {
+	ns, err := NewServer(ctx, hostname, network, address, handler, baseLog)
+	if err != nil {
+		return nil, err
+	}
+
+	ns.(*nexServer).Listener = tls.NewListener(ns.(*nexServer).Listener, tlsConfig)
+	return ns, nil
+}
+
+func (ns *nexServer) handleConn(conn net.Conn) {
+	request, err := ParseRequest(conn)
+	if err != nil {
+		_, _ = fmt.Fprint(conn, err.Error()+"\n")
+	}
+
+	request.Server = ns
+	request.RemoteAddr = conn.RemoteAddr()
+
+	if tlsconn, ok := conn.(*tls.Conn); ok {
+		state := tlsconn.ConnectionState()
+		request.TLSState = &state
+	}
+
+	defer func() {
+		if r := recover(); r != nil {
+			_ = ns.LogError("msg", "panic in handler", "err", r)
+			_, _ = fmt.Fprint(conn, "Error handling request.\n")
+		}
+	}()
+	response := ns.handler.Handle(ns.Ctx, request)
+	if response == nil {
+		response = Response(bytes.NewBufferString("Document not found."))
+	}
+
+	defer response.Close()
+	_, _ = io.Copy(conn, response.Body)
+}