wireless: escape_ssid should handle non-printables

Also use common backslash sequences like \t, \n, \r, and \\ as well as \0.
Signed-off-by: John W. Linville <linville@tuxdriver.com>

net/wireless/lib80211.c

@@ -6,6 +6,7 @@
  */
 
 #include <linux/module.h>
+#include <linux/ctype.h>
 #include <linux/ieee80211.h>
 
 #include <net/lib80211.h>
@@ -20,19 +21,31 @@ MODULE_LICENSE("GPL");
 
 const char *escape_ssid(const char *ssid, u8 ssid_len)
 {
-	static char escaped[IEEE80211_MAX_SSID_LEN * 2 + 1];
+	static char escaped[IEEE80211_MAX_SSID_LEN * 4 + 1];
 	const char *s = ssid;
 	char *d = escaped;
 
 	ssid_len = min_t(u8, ssid_len, IEEE80211_MAX_SSID_LEN);
 	while (ssid_len--) {
-		if (*s == '\0') {
+		if (isprint(*s)) {
+			*d++ = *s++;
+			continue;
+		}
+
 		*d++ = '\\';
+		if (*s == '\0')
 			*d++ = '0';
+		else if (*s == '\n')
+			*d++ = 'n';
+		else if (*s == '\r')
+			*d++ = 'r';
+		else if (*s == '\t')
+			*d++ = 't';
+		else if (*s == '\\')
+			*d++ = '\\';
+		else
+			d += snprintf(d, 3, "%03o", *s);
 		s++;
-		} else {
-			*d++ = *s++;
-		}
 	}
 	*d = '\0';
 	return escaped;