From e5905c4b84d4fb90aefcd96ee618411ebfac663d Mon Sep 17 00:00:00 2001
From: tomspiderlabs <128755403+tomspiderlabs@users.noreply.github.com>
Date: Thu, 23 Mar 2023 23:39:38 +0000
Subject: [PATCH] Added control character check

Added control character check, returning -1 (to "err") if control characters are present.
---
 lib/fields.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/lib/fields.c b/lib/fields.c
index 640be931f..fb51b5829 100644
--- a/lib/fields.c
+++ b/lib/fields.c
@@ -21,9 +21,9 @@
  *
  * The supplied field is scanned for non-printable and other illegal
  * characters.
- *  + -1 is returned if an illegal character is present.
- *  +  1 is returned if no illegal characters are present, but the field
- *       contains a non-printable character.
+ *  + -1 is returned if an illegal or control character is present.
+ *  +  1 is returned if no illegal or control characters are present,
+ *       but the field contains a non-printable character.
  *  +  0 is returned otherwise.
  */
 int valid_field (const char *field, const char *illegal)
@@ -45,10 +45,13 @@ int valid_field (const char *field, const char *illegal)
 	}
 
 	if (0 == err) {
-		/* Search if there are some non-printable characters */
+		/* Search if there are non-printable or control characters */
 		for (cp = field; '\0' != *cp; cp++) {
 			if (!isprint (*cp)) {
 				err = 1;
+			}
+			if (!iscntrl (*cp)) {
+				err = -1;
 				break;
 			}
 		}
From 2eaea70111f65b16d55998386e4ceb4273c19eb4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Christian=20G=C3=B6ttsche?= <cgzones@googlemail.com>
Date: Fri, 31 Mar 2023 14:46:50 +0200
Subject: [PATCH] Overhaul valid_field()

e5905c4b ("Added control character check") introduced checking for
control characters but had the logic inverted, so it rejects all
characters that are not control ones.

Cast the character to `unsigned char` before passing to the character
checking functions to avoid UB.

Use strpbrk(3) for the illegal character test and return early.
---
 lib/fields.c | 24 ++++++++++--------------
 1 file changed, 10 insertions(+), 14 deletions(-)

diff --git a/lib/fields.c b/lib/fields.c
index fb51b5829..539292485 100644
--- a/lib/fields.c
+++ b/lib/fields.c
@@ -37,26 +37,22 @@ int valid_field (const char *field, const char *illegal)
 
 	/* For each character of field, search if it appears in the list
 	 * of illegal characters. */
+	if (illegal && NULL != strpbrk (field, illegal)) {
+		return -1;
+	}
+
+	/* Search if there are non-printable or control characters */
 	for (cp = field; '\0' != *cp; cp++) {
-		if (strchr (illegal, *cp) != NULL) {
+		unsigned char c = *cp;
+		if (!isprint (c)) {
+			err = 1;
+		}
+		if (iscntrl (c)) {
 			err = -1;
 			break;
 		}
 	}
 
-	if (0 == err) {
-		/* Search if there are non-printable or control characters */
-		for (cp = field; '\0' != *cp; cp++) {
-			if (!isprint (*cp)) {
-				err = 1;
-			}
-			if (!iscntrl (*cp)) {
-				err = -1;
-				break;
-			}
-		}
-	}
-
 	return err;
 }