add fqdn_check()

2 files changed, 35 insertions, 0 deletions

diff --git a/src/dns.c b/src/dns.c
index 50db12c..647c1b2 100644
--- a/src/dns.c
+++ b/src/dns.c
@@ -228,6 +228,35 @@ int fqdn_to_qname( char* _source, int _sourcelen, char* _sink ,int _sinklen )
 	return i+2;
 }
 
+int fqdn_check ( char* _source, int _sourcelen ) {
+	int i;
+	char c;
+
+	if ( !_source || _sourcelen <= 0 )
+		return -1;
+
+	for( i=0; i<_sourcelen; i++ ) {
+		c = _source[i];
+		if (!c)
+			break;
+		if (
+			!(c>='0' && c<='9') &&
+			!(c>='A' && c<='Z') &&
+			!(c>='a' && c<='z') &&
+			!(c== '-') && !(c=='_') && !(c=='.')
+			) {
+			return i+1;
+		}
+	}
+
+	if ( _source[ i-1 ] != '.' )
+		return i;
+	if ( _source[ 0 ] == '-' )
+		return 1;
+
+	return 0;
+}
+
 int qname_to_fqdn( char* _source, int _sourcelen, char* _sink, int _sinklen )
 {
 	unsigned int next_dot;
diff --git a/src/dns.h b/src/dns.h
index 7357bf0..7d51b0e 100644
--- a/src/dns.h
+++ b/src/dns.h
@@ -198,6 +198,12 @@ int dns_parse_packet ( char* _buffer, int _bufflen, dns_message_t* _msg );
 int fqdn_to_qname( char* _source, int _sourcelen, char* _sink, int _sinklen );
 
 /**
+ * Check FQDN validity
+ * Returns: 0 when valid, <0 for string errors, position > 0 of invalid character
+ */
+int fqdn_check ( char* _source, int _sourcelen );
+
+/**
  * Convert a QNAME back to a FQDN, reversing fqdn_to_qname( )
  * returns: length of string in _sink, < 0 on failure
  * _sink may still be altered in failed attempts, but not terminated.