Initial Commit

internal/router/logging.go

@@ -0,0 +1,74 @@
+/*
+ * Seashell - SSH server with virtual hosts and username-based routing
+ *
+ * Copyright (C) 2024 Elara6331 <elara@elara.ws>
+ *
+ * This file is part of Seashell.
+ *
+ * Seashell is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * Seashell is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with Seashell.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package router
+
+import (
+	"log/slog"
+	"time"
+
+	"github.com/gliderlabs/ssh"
+	"go.elara.ws/seashell/internal/sshctx"
+)
+
+// Logging returns a middleware that logs incoming session details,
+// and closed connections, as well as any error that may have caused
+// the connection to close.
+func Logging(log *slog.Logger) Middleware {
+	return func(next Handler) Handler {
+		return func(sess ssh.Session, arg string) error {
+			user, _ := sshctx.GetUser(sess.Context())
+			route := sess.Context().Value(routeKey{}).(route)
+
+			log.Info(
+				"Incoming user session",
+				slog.String("user", user.Name),
+				slog.String("route", route.name),
+				slog.String("arg", arg),
+				slog.String("addr", sess.RemoteAddr().String()),
+			)
+
+			start := time.Now()
+			err := next(sess, arg)
+			duration := time.Since(start)
+
+			if err != nil {
+				log.Error(
+					"Connection closed",
+					slog.String("user", user.Name),
+					slog.String("route", route.name),
+					slog.Duration("duration", duration),
+					slog.String("addr", sess.RemoteAddr().String()),
+					slog.Any("error", err),
+				)
+			} else {
+				log.Info(
+					"Connection closed",
+					slog.String("user", user.Name),
+					slog.String("route", route.name),
+					slog.Duration("duration", duration),
+				)
+			}
+
+			return err
+		}
+	}
+}

internal/router/router.go

@@ -0,0 +1,122 @@
+/*
+ * Seashell - SSH server with virtual hosts and username-based routing
+ *
+ * Copyright (C) 2024 Elara6331 <elara@elara.ws>
+ *
+ * This file is part of Seashell.
+ *
+ * Seashell is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * Seashell is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with Seashell.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package router
+
+import (
+	"errors"
+	"fmt"
+	"regexp"
+
+	"github.com/gliderlabs/ssh"
+	"go.elara.ws/seashell/internal/sshctx"
+)
+
+// ErrUnauthorized represents an unauthorized access error.
+var ErrUnauthorized = errors.New("you are not authorized to access this resource")
+
+// Handler defines a function type to handle SSH sessions.
+type Handler func(sess ssh.Session, arg string) error
+
+// Middleware defines a function type for middleware.
+type Middleware func(next Handler) Handler
+
+// Router manages routing and middleware for SSH sessions.
+type Router struct {
+	routes      map[string]route
+	middlewares []Middleware
+}
+
+// route represents a single route configuration.
+type route struct {
+	name    string
+	handler Handler
+	regex   *regexp.Regexp
+}
+
+// New creates and returns a new [Router] instance.
+func New() *Router {
+	return &Router{routes: map[string]route{}}
+}
+
+// Use adds a middleware to the router.
+func (r *Router) Use(m Middleware) {
+	r.middlewares = append(r.middlewares, m)
+}
+
+// Handle registers a new route with the given name and pattern.
+func (r *Router) Handle(name, pattern string, h Handler) error {
+	re, err := regexp.Compile(pattern)
+	if err != nil {
+		return err
+	}
+	r.routes[pattern] = route{
+		name:    name,
+		handler: h,
+		regex:   re,
+	}
+	return nil
+}
+
+// routeKey is a context key for storing route information.
+type routeKey struct{}
+
+// Handler handles an SSH session, routing it to the appropriate handler.
+func (r *Router) Handler(sess ssh.Session) {
+	arg, _ := sshctx.GetArg(sess.Context())
+
+	for _, ro := range r.routes {
+		matches := ro.regex.FindStringSubmatch(arg)
+		if matches == nil {
+			continue
+		}
+
+		sess.Context().SetValue(routeKey{}, ro)
+
+		var cleanArg string
+		if idx := ro.regex.SubexpIndex("arg"); idx != -1 {
+			cleanArg = matches[idx]
+		} else if len(matches) >= 2 {
+			cleanArg = matches[1]
+		} else {
+			cleanArg = arg
+		}
+
+		handler := ro.handler
+		for _, middleware := range r.middlewares {
+			handler = middleware(handler)
+		}
+
+		err := handler(sess, cleanArg)
+		if err != nil {
+			writeError(sess, err.Error())
+		}
+
+		return
+	}
+
+	writeError(sess, "no matching route found for %q", arg)
+}
+
+// writeError writes a formatted error message to the SSH session.
+func writeError(sess ssh.Session, format string, v ...any) {
+	fmt.Fprintf(sess.Stderr(), "\x1b[31;1m[ERROR]\x1b[0m "+format+"\r\n", v...)
+}