Allow user to specify hostnames as argv

LICENSE

@@ -1,5 +1,5 @@
 MIT License
-Copyright (c) 2017 Stephen McQuay
+Copyright (c) 2018 Stephen McQuay
 
 Permission is hereby granted, free of charge, to any person obtaining a copy of
 this software and associated documentation files (the "Software"), to deal in

README.md

@@ -9,6 +9,15 @@ $ echo | openssl s_client -connect $hostname:$port 2> /dev/null | openssl x509 -
 
 ## example usage
 
+```bash
+$ certexp google.com amazon.com imap.gmail.com:993
+google.com:443           2018-03-07 13:01:00 +0000 UTC
+imap.gmail.com:993       2018-03-07 13:02:00 +0000 UTC
+amazon.com:443           2018-09-21 23:59:59 +0000 UTC
+```
+
+or to stdin:
+
 ```bash
 $ cat sites.txt
 apple.com

main.go

@@ -18,24 +18,13 @@ var conc = flag.Int("workers", 8, "number of fetches to perform concurrently")
 
 func main() {
 	flag.Parse()
+
 	work := make(chan job)
-	go func() {
+	if len(flag.Args()) > 0 {
-		s := bufio.NewScanner(os.Stdin)
+		go fromArgs(work, flag.Args())
-		for s.Scan() {
+	} else {
-			line := s.Text()
+		go fromStdin(work)
-			if line == "" {
+	}
-				continue
-			}
-
-			host, port := line, "443"
-			if h, p, err := net.SplitHostPort(line); err == nil {
-				host, port = h, p
-			}
-
-			work <- job{host, port}
-		}
-		close(work)
-	}()
 
 	wg := sync.WaitGroup{}
 	sema := make(chan bool, *conc)
@@ -59,6 +48,33 @@ func main() {
 	wg.Wait()
 }
 
+func parseLine(line string) job {
+	host, port := line, "443"
+	if h, p, err := net.SplitHostPort(line); err == nil {
+		host, port = h, p
+	}
+	return job{host, port}
+}
+
+func fromArgs(work chan job, args []string) {
+	for _, arg := range args {
+		work <- parseLine(arg)
+	}
+	close(work)
+}
+
+func fromStdin(work chan job) {
+	s := bufio.NewScanner(os.Stdin)
+	for s.Scan() {
+		line := s.Text()
+		if line == "" {
+			continue
+		}
+		work <- parseLine(line)
+	}
+	close(work)
+}
+
 type job struct {
 	host string
 	port string