Adds a few tweaks to mirror

Author: tomnomnom

mirror/main.go

@@ -18,7 +18,7 @@ func main() {
 
 	var input io.Reader
 	input = strings.NewReader(strings.Join(flag.Args(), "\n"))
-	if flag.Arg(0) == "" {
+	if flag.NArg() == 0 {
 		input = os.Stdin
 	}
 
@@ -27,29 +27,39 @@ func main() {
 	for sc.Scan() {
 		u, err := url.Parse(sc.Text())
 		if err != nil {
-			fmt.Println(err)
-			return
+			fmt.Fprintln(os.Stderr, err)
+			continue
 		}
 
 		resp, err := http.Get(u.String())
 		if err != nil {
-			fmt.Println(err)
-			return
+			fmt.Fprintln(os.Stderr, err)
+			continue
 		}
 
 		defer resp.Body.Close()
 
 		b, err := ioutil.ReadAll(resp.Body)
 		if err != nil {
-			fmt.Println(err)
-			return
+			fmt.Fprintln(os.Stderr, err)
+			continue
 		}
 		body := string(b)
 
 		for k, vv := range u.Query() {
 			for _, v := range vv {
 
+				// short strings are so likely to show up in the response
+				// that it's best just to skip over them to avoid too many
+				// false positives. There should be a flag to control this.
+				if len(v) < 4 {
+					continue
+				}
+
 				// a fairly shonky way to get a few chars of context either side of the match
+				// but it helps avoid trying to find the locations of all the matches in the
+				// body, and then getting the context on either side, with all the bounds
+				// checking etc that would need to be done for that.
 				re, err := regexp.Compile("(.{0,6}" + regexp.QuoteMeta(v) + ".{0,6})")
 				if err != nil {
 					fmt.Fprintf(os.Stderr, "regexp compile error: %s", err)
@@ -58,7 +68,7 @@ func main() {
 				matches := re.FindAllStringSubmatch(body, -1)
 
 				for _, m := range matches {
-					fmt.Printf("%s: query string key '%s' with value '%s' reflected in response body (...%s...)\n", u, k, v, m[0])
+					fmt.Printf("%s: '%s=%s' reflected in response body (...%s...)\n", u, k, v, m[0])
 				}
 			}