7 files changed, 60 insertions, 5 deletions

diff --git a/examples/fileserver/main.go b/examples/fileserver/main.go
index d7f628b..b38ae76 100644
--- a/examples/fileserver/main.go
+++ b/examples/fileserver/main.go
@@ -23,7 +23,7 @@ func main() {
 	// build the request handler
 	fileSystem := os.DirFS(".")
 	// Fallthrough tries each handler in succession until it gets something other than "51 Not Found"
-	handler := gemini.Fallthrough(
+	handler := gemini.FallthroughHandler(
 		// first see if they're fetching a directory and we have <dir>/index.gmi
 		fs.DirectoryDefault(fileSystem, "index.gmi"),
 		// next (still if they requested a directory) build a directory listing response
diff --git a/gemini/client.go b/gemini/client.go
index 53c8b71..aca4576 100644
--- a/gemini/client.go
+++ b/gemini/client.go
@@ -28,6 +28,9 @@ func NewClient(tlsConf *tls.Config) Client {
 //
 // It also populates the TLSState and RemoteAddr fields on the request - the only field
 // it needs populated beforehand is the URL.
+//
+// This method will not automatically follow redirects or cache permanent failures or
+// redirects.
 func (client Client) RoundTrip(request *Request) (*Response, error) {
 	if request.Scheme != "gemini" && request.Scheme != "" {
 		return nil, errors.New("non-gemini protocols not supported")
@@ -57,8 +60,8 @@ func (client Client) RoundTrip(request *Request) (*Response, error) {
 		return nil, err
 	}
 
-	// read and store the request body in full or we may miss doing so before the
-	// connection gets closed.
+	// read and store the request body in full or we may miss doing so before
+	// closing the connection
 	bodybuf, err := io.ReadAll(response.Body)
 	if err != nil {
 		return nil, err
diff --git a/gemini/handler.go b/gemini/handler.go
index ded77a5..0f48e62 100644
--- a/gemini/handler.go
+++ b/gemini/handler.go
@@ -6,7 +6,7 @@ import "context"
 //
 // A Handler MUST NOT return a nil response. Errors should be returned in the form
 // of error responses (4x, 5x, 6x response status). If the Handler should not be
-// responsible for the requested resource it can return a "51 Not Found" response.
+// responsible for the requested resource it can return a 51 response.
 type Handler func(context.Context, *Request) *Response
 
 // Middleware is a handle decorator.
@@ -15,7 +15,11 @@ type Handler func(context.Context, *Request) *Response
 // transform the request or response in some way.
 type Middleware func(Handler) Handler
 
-func Fallthrough(handlers ...Handler) Handler {
+// FallthroughHandler builds a handler which tries multiple child handlers.
+//
+// The returned handler will invoke each of the passed child handlers in order,
+// stopping when it receives a response with status other than 51.
+func FallthroughHandler(handlers ...Handler) Handler {
 	return func(ctx context.Context, req *Request) *Response {
 		for _, handler := range handlers {
 			response := handler(ctx, req)
@@ -27,3 +31,24 @@ func Fallthrough(handlers ...Handler) Handler {
 		return NotFound("Resource does not exist.")
 	}
 }
+
+// Filter wraps a handler with a predicate which determines whether to run the handler.
+//
+// When the predicate function returns false, the Filter returns the provided failure
+// response. The failure argument may be nil, in which case a "51 Resource does not exist."
+// response will be used.
+func Filter(
+	predicate func(context.Context, *Request) bool,
+	handler Handler,
+	failure *Response,
+) Handler {
+	if failure == nil {
+		failure = NotFound("Resource does not exist.")
+	}
+	return func(ctx context.Context, req *Request) *Response {
+		if !predicate(ctx, req) {
+			return failure
+		}
+		return handler(ctx, req)
+	}
+}
diff --git a/gemini/request.go b/gemini/request.go
index 43ee69b..933281b 100644
--- a/gemini/request.go
+++ b/gemini/request.go
@@ -14,10 +14,26 @@ var InvalidRequestLineEnding = errors.New("invalid request line ending")
 
 // Request represents a request over the gemini protocol.
 type Request struct {
+	// URL is the specific URL being fetched by the request.
 	*url.URL
 
+	// Server is the server which received the request.
+	//
+	// This is only populated in gemini servers.
+	// It is unused on the client end.
 	Server     *Server
+
+	// RemoteAddr is the address of the other side of the connection.
+	//
+	// This will be the server address for clients, or the connecting
+	// client's address in servers.
+	//
+	// Be aware though that proxies (and reverse proxies) can confuse this.
 	RemoteAddr net.Addr
+
+	// TLSState contains information about the TLS encryption over the connection.
+	//
+	// This includes peer certificates and version information.
 	TLSState   *tls.ConnectionState
 }
 
diff --git a/gemini/response.go b/gemini/response.go
index 1fa64cf..5b5ced4 100644
--- a/gemini/response.go
+++ b/gemini/response.go
@@ -114,6 +114,8 @@ type Response struct {
 	Meta string
 
 	// Body is the response body, if any.
+	//
+	// It is not guaranteed to be readable more than once.
 	Body io.Reader
 
 	reader io.Reader
diff --git a/gemini/serve.go b/gemini/serve.go
index abf127e..f9a8a1c 100644
--- a/gemini/serve.go
+++ b/gemini/serve.go
@@ -8,6 +8,7 @@ import (
 	"sync"
 )
 
+// Server listens on a network and serves the gemini protocol.
 type Server struct {
 	ctx      context.Context
 	network  string
@@ -18,6 +19,7 @@ type Server struct {
 	handler  Handler
 }
 
+// NewServer builds a server.
 func NewServer(
 	ctx context.Context,
 	tlsConfig *tls.Config,
@@ -46,6 +48,10 @@ func NewServer(
 //
 // This function will allocate resources which are not cleaned up until
 // Close() is called.
+//
+// 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.
 func (s *Server) Serve() error {
 	s.wg.Add(1)
 	defer s.wg.Done()
diff --git a/gemini/tls.go b/gemini/tls.go
index 3cdf93b..5b35fb6 100644
--- a/gemini/tls.go
+++ b/gemini/tls.go
@@ -2,6 +2,9 @@ package gemini
 
 import "crypto/tls"
 
+// FileTLS builds a TLS configuration from paths to a certificate and key file.
+//
+// It sets parameters on the configuration to make it suitable for use with gemini.
 func FileTLS(certfile string, keyfile string) (*tls.Config, error) {
 	cert, err := tls.LoadX509KeyPair(certfile, keyfile)
 	if err != nil {