Add support for titan:// to the gemini server

Titan is a gemini add-on protocol so it really didn't make sense to
build it out in a separate package. The most significant difference in
titan for the purposes of implementation here is that requests can have
bodies following the URL line.

Since gus.Request is a struct, the only way to smuggle in the new field
(a reader for the body) was to stash it in the context.

3 files changed, 110 insertions, 32 deletions

diff --git a/gemini/request.go b/gemini/request.go
index ced7d0b..5220952 100644
--- a/gemini/request.go
+++ b/gemini/request.go
@@ -13,8 +13,15 @@ import (
 var InvalidRequestLineEnding = errors.New("invalid request line ending")
 
 // ParseRequest parses a single gemini request from a reader.
+//
+// If the reader argument is a *bufio.Reader, it will only read a single line from it.
 func ParseRequest(rdr io.Reader) (*gus.Request, error) {
-	line, err := bufio.NewReader(rdr).ReadString('\n')
+	bufrdr, ok := rdr.(*bufio.Reader)
+	if !ok {
+		bufrdr = bufio.NewReader(rdr)
+	}
+
+	line, err := bufrdr.ReadString('\n')
 	if err != io.EOF && err != nil {
 		return nil, err
 	}
diff --git a/gemini/roundtrip_test.go b/gemini/roundtrip_test.go
index 4bac239..4f48e47 100644
--- a/gemini/roundtrip_test.go
+++ b/gemini/roundtrip_test.go
@@ -9,56 +9,84 @@ import (
 	"net/url"
 	"testing"
 
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
 	"tildegit.org/tjp/gus"
 	"tildegit.org/tjp/gus/gemini"
 )
 
 func TestRoundTrip(t *testing.T) {
 	tlsConf, err := gemini.FileTLS("./testdata/server.crt", "./testdata/server.key")
-	if err != nil {
-		t.Fatalf("FileTLS(): %s", err.Error())
-	}
+	require.Nil(t, err)
 
 	handler := func(ctx context.Context, req *gus.Request) *gus.Response {
 		return gemini.Success("text/gemini", bytes.NewBufferString("you've found my page"))
 	}
 
 	server, err := gemini.NewServer(context.Background(), nil, tlsConf, "tcp", "127.0.0.1:0", handler)
-	if err != nil {
-		t.Fatalf("NewServer(): %s", err.Error())
-	}
+	require.Nil(t, err)
 
 	go server.Serve()
 	defer server.Close()
 
 	u, err := url.Parse(fmt.Sprintf("gemini://%s/test", server.Address()))
-	if err != nil {
-		t.Fatalf("url.Parse: %s", err.Error())
-	}
+	require.Nil(t, err)
 
 	cli := gemini.NewClient(testClientTLS())
 	response, err := cli.RoundTrip(&gus.Request{URL: u})
-	if err != nil {
-		t.Fatalf("RoundTrip(): %s", err.Error())
-	}
+	require.Nil(t, err)
 
-	if response.Status != gemini.StatusSuccess {
-		t.Errorf("response status: expected %d, got %d", gemini.StatusSuccess, response.Status)
-	}
-	if response.Meta != "text/gemini" {
-		t.Errorf("response meta: expected \"text/gemini\", got %q", response.Meta)
-	}
+	assert.Equal(t, gemini.StatusSuccess, response.Status)
+	assert.Equal(t, "text/gemini", response.Meta)
 
-	if response.Body == nil {
-		t.Fatal("succcess response has nil body")
-	}
+	require.NotNil(t, response.Body)
 	body, err := io.ReadAll(response.Body)
-	if err != nil {
-		t.Fatalf("ReadAll: %s", err.Error())
-	}
-	if string(body) != "you've found my page" {
-		t.Errorf("response body: expected \"you've found my page\", got %q", string(body))
+	require.Nil(t, err)
+
+	assert.Equal(t, "you've found my page", string(body))
+}
+
+func TestTitanRequest(t *testing.T) {
+	tlsConf, err := gemini.FileTLS("./testdata/server.crt", "./testdata/server.key")
+	require.Nil(t, err)
+
+	invoked := false
+	handler := func(ctx context.Context, request *gus.Request) *gus.Response {
+		invoked = true
+
+		body := ctx.Value(gemini.TitanRequestBody)
+		if !assert.NotNil(t, body) {
+			return gemini.Success("", nil)
+		}
+
+		bodyBytes, err := io.ReadAll(body.(io.Reader))
+		require.Nil(t, err)
+
+		assert.Equal(t, "the request body\n", string(bodyBytes))
+		return gemini.Success("", nil)
 	}
+
+	server, err := gemini.NewServer(context.Background(), nil, tlsConf, "tcp", "127.0.0.1:0", handler)
+	require.Nil(t, err)
+
+	go server.Serve()
+	defer server.Close()
+
+	conn, err := tls.Dial(server.Network(), server.Address(), testClientTLS())
+	require.Nil(t, err)
+
+	_, err = fmt.Fprintf(
+		conn,
+		"titan://%s/foobar;size=17;mime=text/plain\r\nthe request body\n",
+		server.Address(),
+	)
+	require.Nil(t, err)
+
+	_, err = io.ReadAll(conn)
+	require.Nil(t, err)
+
+	assert.True(t, invoked)
 }
 
 func testClientTLS() *tls.Config {
diff --git a/gemini/serve.go b/gemini/serve.go
index cd51370..dd7ad52 100644
--- a/gemini/serve.go
+++ b/gemini/serve.go
@@ -1,16 +1,26 @@
 package gemini
 
 import (
+	"bufio"
 	"context"
 	"crypto/tls"
+	"errors"
 	"io"
 	"net"
+	"strconv"
+	"strings"
 	"sync"
 
 	"tildegit.org/tjp/gus"
 	"tildegit.org/tjp/gus/logging"
 )
 
+// TitanRequestBody is the key set in a handler's context for titan requests.
+//
+// When this key is present in the context (request.URL.Scheme will be "titan"), the
+// corresponding value is a *bufio.Reader from which the request body can be read.
+const TitanRequestBody = "titan_request_body"
+
 type server struct {
 	ctx      context.Context
 	errorLog logging.Logger
@@ -59,6 +69,10 @@ func NewServer(
 // It will respect cancellation of the context the server was created with,
 // but be aware that Close() must still be called in that case to avoid
 // dangling goroutines.
+//
+// On titan protocol requests, it sets a key/value pair in the context. The
+// key is TitanRequestBody, and the value is a *bufio.Reader from which the
+// request body can be read.
 func (s *server) Serve() error {
 	s.wg.Add(1)
 	defer s.wg.Done()
@@ -74,7 +88,7 @@ func (s *server) Serve() error {
 			if s.Closed() {
 				err = nil
 			} else {
-			s.errorLog.Log("msg", "accept_error", "error", err)
+				s.errorLog.Log("msg", "accept_error", "error", err)
 			}
 
 			return err
@@ -112,11 +126,12 @@ func (s *server) handleConn(conn net.Conn) {
 	defer s.wg.Done()
 	defer conn.Close()
 
+	buf := bufio.NewReader(conn)
+
 	var response *gus.Response
-	req, err := ParseRequest(conn)
+	req, err := ParseRequest(buf)
 	if err != nil {
 		response = BadRequest(err.Error())
-		return
 	} else {
 		req.Server = s
 		req.RemoteAddr = conn.RemoteAddr()
@@ -125,13 +140,25 @@ func (s *server) handleConn(conn net.Conn) {
 			req.TLSState = &state
 		}
 
-		response = s.handler(s.ctx, req)
+		ctx := s.ctx
+		if req.Scheme == "titan" {
+			len, err := sizeParam(req.Path)
+			if err == nil {
+				ctx = context.WithValue(
+					ctx,
+					"titan_request_body",
+					io.LimitReader(buf, int64(len)),
+				)
+			}
+		}
+
+		response = s.handler(ctx, req)
 		if response == nil {
 			response = NotFound("Resource does not exist.")
 		}
-		defer response.Close()
 	}
 
+	defer response.Close()
 	_, _ = io.Copy(conn, NewResponseReader(response))
 }
 
@@ -152,3 +179,19 @@ func (s *server) Closed() bool {
 		return false
 	}
 }
+
+func sizeParam(path string) (int, error) {
+	_, rest, found := strings.Cut(path, ";")
+	if !found {
+		return 0, errors.New("no params in path")
+	}
+
+	for _, piece := range strings.Split(rest, ";") {
+		key, val, _ := strings.Cut(piece, "=")
+		if key == "size" {
+			return strconv.Atoi(val)
+		}
+	}
+
+	return 0, errors.New("no size param found")
+}