From: Francois-Xavier Le Bail <fx.lebail@yahoo.com>
Date: Mon, 9 Nov 2015 14:59:58 +0000 (+0100)
Subject: CDP: Filter out non-printable characters
X-Git-Tag: tcpdump-4.8.0~77
X-Git-Url: https://git.tcpdump.org/tcpdump/commitdiff_plain/4df36ab95d6e23ac109a186c22e2ba60f628c36a

CDP: Filter out non-printable characters

Add a fn_print_char() to do filtering.
---

diff --git a/netdissect.h b/netdissect.h
index 47624d19..b2f824d3 100644
--- a/netdissect.h
+++ b/netdissect.h
@@ -310,6 +310,7 @@ struct netdissect_options {
 extern void ts_print(netdissect_options *, const struct timeval *);
 extern void relts_print(netdissect_options *, int);
 
+extern void fn_print_char(netdissect_options *, u_char);
 extern int fn_print(netdissect_options *, const u_char *, const u_char *);
 extern int fn_printn(netdissect_options *, const u_char *, u_int, const u_char *);
 extern int fn_printzp(netdissect_options *, const u_char *, u_int, const u_char *);
diff --git a/print-cdp.c b/print-cdp.c
index 96ef143b..cd544ef5 100644
--- a/print-cdp.c
+++ b/print-cdp.c
@@ -169,9 +169,11 @@ cdp_print(netdissect_options *ndo,
 			ND_PRINT((ndo, "\n\t  "));
 			for (i=0;i<len;i++) {
 			    j = *(tptr+i);
-			    ND_PRINT((ndo, "%c", j));
-			    if (j == 0x0a) /* lets rework the version string to get a nice indentation */
-				ND_PRINT((ndo, "\t  "));
+			    if (j == '\n') /* lets rework the version string to
+					      get a nice indentation */
+				ND_PRINT((ndo, "\n\t  "));
+			    else
+				fn_print_char(ndo, j);
 			}
 			break;
 		    case 0x06: /* Platform */
diff --git a/util-print.c b/util-print.c
index f11155ad..bcb14337 100644
--- a/util-print.c
+++ b/util-print.c
@@ -66,6 +66,23 @@ int32_t thiszone;		/* seconds offset from gmt to local time */
 
 #define TOKBUFSIZE 128
 
+/*
+ * Print out a character, filtering out the non-printable ones
+ */
+void
+fn_print_char(netdissect_options *ndo, u_char c)
+{
+	if (!ND_ISASCII(c)) {
+		c = ND_TOASCII(c);
+		ND_PRINT((ndo, "M-"));
+	}
+	if (!ND_ISPRINT(c)) {
+		c ^= 0x40;	/* DEL to ?, others to alpha */
+		ND_PRINT((ndo, "^"));
+	}
+	ND_PRINT((ndo, "%c", c));
+}
+
 /*
  * Print out a null-terminated filename (or other ascii string).
  * If ep is NULL, assume no truncation check is needed.