// Command jslibscan is a reference mitmux plugin - a Retire.js-style
// passive scanner for known-vulnerable JavaScript library versions.
// Unlike authcheck and paramminer, this one never sends anything: it
// only reads response bodies already captured by ordinary proxying and
// checks any JS library version string it can find against a small
// built-in table of known-bad ranges, tagging a match "jslibscan:hit".
// Demonstrating a purely passive plugin (subscribe, inspect, tag - no
// repeat calls at all) alongside the two active ones is deliberate: it's
// the simplest possible plugin shape, and the one least likely to
// surprise anyone running it against traffic they can't afford to probe.
//
// The built-in table is a small, illustrative starting set (five
// libraries, one well-known vulnerable-version threshold each) - NOT a
// maintained vulnerability feed. Real Retire.js pulls from a
// continuously updated JSON database with dozens of libraries and many
// more precise version ranges; replicating that here would mean
// committing to keep it current, which this reference plugin doesn't.
// Extending libraries is adding one entry to the libraries slice below.
//
// Speaks the wire protocol directly, no internal/ipc import - see
// plugins/authcheck's package doc for why, and PLUGINS.md for the
// protocol.
package main

import (
	"encoding/json"
	"flag"
	"fmt"
	"log"
	"net"
	"os"
	"path/filepath"
	"regexp"
	"strconv"
	"strings"
)

type request struct {
	Type      string `json:"type"`
	ID        int64  `json:"id,omitempty"`
	TagPlugin string `json:"tag_plugin,omitempty"`
	Tag       string `json:"tag,omitempty"`
	TagData   string `json:"tag_data,omitempty"`
}

type summary struct {
	ID     int64  `json:"id"`
	Source string `json:"source"`
}

type entryDetail struct {
	summary
	ResponseRaw []byte `json:"response_raw"`
}

type response struct {
	Type   string       `json:"type"`
	New    *summary     `json:"new,omitempty"`
	Detail *entryDetail `json:"detail,omitempty"`
	Error  string       `json:"error,omitempty"`
}

type client struct {
	conn net.Conn
	enc  *json.Encoder
	dec  *json.Decoder
}

func dial(path string) (*client, error) {
	conn, err := net.Dial("unix", path)
	if err != nil {
		return nil, err
	}
	return &client{conn: conn, enc: json.NewEncoder(conn), dec: json.NewDecoder(conn)}, nil
}

func (c *client) call(req request) (response, error) {
	if err := c.enc.Encode(req); err != nil {
		return response{}, err
	}
	var resp response
	if err := c.dec.Decode(&resp); err != nil {
		return response{}, err
	}
	if resp.Type == "error" {
		return response{}, fmt.Errorf("%s", resp.Error)
	}
	return resp, nil
}

func defaultSocketPath() string {
	if rt := os.Getenv("XDG_RUNTIME_DIR"); rt != "" {
		return filepath.Join(rt, "mitmux.sock")
	}
	cfg, err := os.UserConfigDir()
	if err != nil {
		return "mitmux.sock"
	}
	return filepath.Join(cfg, "mitmux", "mitmux.sock")
}

// library is one entry in the built-in illustrative table: match finds
// a version string for the library (its first capture group is the
// dotted version number, e.g. "3.4.1"), and any version strictly below
// fixedIn is flagged.
type library struct {
	name    string
	match   *regexp.Regexp
	fixedIn [3]int
	advice  string
}

// The 0-to-15-character non-greedy gap between a library's name and its
// version digits (rather than a fixed one-character separator) is
// deliberate - confirmed directly, not assumed: real-world version
// strings show up as "jQuery v1.8.3" (space-then-"v", two separator
// characters, not one), "jquery-3.4.1.min.js" (filename form), and
// "jquery.min.js?v=1.11.0" (cache-busting query string) alike. Kept
// bounded and non-greedy rather than wide open, so it can't walk past
// the library's own version into an unrelated number elsewhere on the
// page.
var libraries = []library{
	{
		name:    "jQuery",
		match:   regexp.MustCompile(`(?i)jquery.{0,15}?(\d+\.\d+\.\d+)`),
		fixedIn: [3]int{3, 5, 0},
		advice:  "known cross-site scripting vulnerability in HTML parsing/prefiltering fixed in 3.5.0",
	},
	{
		name:    "Lodash",
		match:   regexp.MustCompile(`(?i)lodash.{0,15}?(\d+\.\d+\.\d+)`),
		fixedIn: [3]int{4, 17, 21},
		advice:  "known prototype pollution / command injection vulnerabilities fixed in 4.17.21",
	},
	{
		name:    "Handlebars",
		match:   regexp.MustCompile(`(?i)handlebars.{0,15}?(\d+\.\d+\.\d+)`),
		fixedIn: [3]int{4, 7, 7},
		advice:  "known prototype pollution vulnerability fixed in 4.7.7",
	},
	{
		name:    "Moment.js",
		match:   regexp.MustCompile(`(?i)moment(?:\.js)?.{0,15}?(\d+\.\d+\.\d+)`),
		fixedIn: [3]int{2, 29, 4},
		advice:  "known path traversal / ReDoS vulnerabilities fixed in 2.29.4",
	},
	{
		name:    "AngularJS",
		match:   regexp.MustCompile(`(?i)angular(?:js|\.js)?.{0,15}?(1\.\d+\.\d+)`),
		fixedIn: [3]int{1, 8, 3},
		advice:  "AngularJS 1.x reached end of life; known sandbox-escape/XSS issues, no fixes past 1.8.3",
	},
}

type hit struct {
	Library      string `json:"library"`
	VersionFound string `json:"version_found"`
	FirstFixedIn string `json:"first_fixed_in"`
	Advisory     string `json:"advisory"`
}

func main() {
	socketPath := flag.String("socket", "", "daemon control socket path (default: same as mitmux itself)")
	pluginName := flag.String("name", "jslibscan", "name this plugin tags entries as")
	flag.Parse()

	path := *socketPath
	if path == "" {
		path = defaultSocketPath()
	}

	actor, err := dial(path)
	if err != nil {
		log.Fatalf("dial %s: %v", path, err)
	}
	defer actor.conn.Close()

	subConn, err := net.Dial("unix", path)
	if err != nil {
		log.Fatalf("dial %s (subscribe): %v", path, err)
	}
	defer subConn.Close()
	if err := json.NewEncoder(subConn).Encode(request{Type: "subscribe"}); err != nil {
		log.Fatalf("subscribe: %v", err)
	}

	log.Printf("jslibscan: watching live traffic on %s", path)
	dec := json.NewDecoder(subConn)
	for {
		var resp response
		if err := dec.Decode(&resp); err != nil {
			log.Fatalf("subscribe feed closed: %v", err)
		}
		if resp.Type != "new" || resp.New == nil {
			continue
		}
		// Not a correctness concern here the way it is for authcheck/
		// paramminer (this plugin never calls repeat, so there's no
		// loop risk) - just avoids redundant work rescanning response
		// bodies that are probably near-identical to an original
		// request's, which is what most of a wordlist-driven probe's
		// own resends look like.
		if resp.New.Source != "proxy" {
			continue
		}
		if err := scanEntry(actor, *pluginName, resp.New.ID); err != nil {
			log.Printf("entry #%d: %v", resp.New.ID, err)
		}
	}
}

func scanEntry(c *client, pluginName string, id int64) error {
	resp, err := c.call(request{Type: "get", ID: id})
	if err != nil {
		return fmt.Errorf("get: %w", err)
	}
	if resp.Detail == nil || len(resp.Detail.ResponseRaw) == 0 {
		return nil
	}
	body := string(resp.Detail.ResponseRaw)

	var hits []hit
	for _, lib := range libraries {
		m := lib.match.FindStringSubmatch(body)
		if m == nil {
			continue
		}
		found, ok := parseVersion(m[1])
		if !ok || !isBelow(found, lib.fixedIn) {
			continue
		}
		hits = append(hits, hit{
			Library:      lib.name,
			VersionFound: m[1],
			FirstFixedIn: joinVersion(lib.fixedIn),
			Advisory:     lib.advice,
		})
	}
	if len(hits) == 0 {
		return nil
	}

	data, err := json.Marshal(hits)
	if err != nil {
		return fmt.Errorf("marshal hits: %w", err)
	}
	if _, err := c.call(request{Type: "tag_entry", ID: id, TagPlugin: pluginName, Tag: "jslibscan:hit", TagData: string(data)}); err != nil {
		return fmt.Errorf("tag_entry: %w", err)
	}
	names := make([]string, len(hits))
	for i, h := range hits {
		names[i] = fmt.Sprintf("%s %s", h.Library, h.VersionFound)
	}
	log.Printf("#%d -> outdated JS librar(y/ies): %s", id, strings.Join(names, ", "))
	return nil
}

func parseVersion(s string) ([3]int, bool) {
	parts := strings.SplitN(s, ".", 3)
	if len(parts) != 3 {
		return [3]int{}, false
	}
	var v [3]int
	for i, p := range parts {
		n, err := strconv.Atoi(p)
		if err != nil {
			return [3]int{}, false
		}
		v[i] = n
	}
	return v, true
}

func isBelow(v, fixedIn [3]int) bool {
	for i := 0; i < 3; i++ {
		if v[i] != fixedIn[i] {
			return v[i] < fixedIn[i]
		}
	}
	return false // exactly equal to the fixed version - not vulnerable
}

func joinVersion(v [3]int) string {
	return fmt.Sprintf("%d.%d.%d", v[0], v[1], v[2])
}