[iscsi] Rewrite unrelicensable portions of iscsi.c

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/net/tcp/iscsi.c

  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  * 02110-1301, USA.
+ *
+ * You can also choose to distribute this program under the terms of
+ * the Unmodified Binary Distribution Licence (as given in the file
+ * COPYING.UBDL), provided that you have satisfied its requirements.
  */
 
-FILE_LICENCE ( GPL2_OR_LATER );
+FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 
 #include <stddef.h>
 #include <string.h>
 #include <stdlib.h>
 #include <stdio.h>
+#include <ctype.h>
 #include <errno.h>
 #include <assert.h>
 #include <byteswap.h>
 #define EPROTO_INVALID_LARGE_BINARY \
 	__einfo_error ( EINFO_EPROTO_INVALID_LARGE_BINARY )
 #define EINFO_EPROTO_INVALID_LARGE_BINARY \
-	__einfo_uniqify ( EINFO_EPROTO, 0x03, "Invalid large binary" )
+	__einfo_uniqify ( EINFO_EPROTO, 0x03, "Invalid large binary value" )
 #define EPROTO_INVALID_CHAP_RESPONSE \
 	__einfo_error ( EINFO_EPROTO_INVALID_CHAP_RESPONSE )
 #define EINFO_EPROTO_INVALID_CHAP_RESPONSE \
 	return xfer_deliver_iob ( &iscsi->socket, iobuf );
 }
 
-/**
- * Calculate maximum length of decoded large binary value
- *
- * @v encoded		Encoded large binary value
- * @v max_raw_len	Maximum length of raw data
- */
-static inline size_t
-iscsi_large_binary_decoded_max_len ( const char *encoded ) {
-	return ( strlen ( encoded ) ); /* Decoding never expands data */
-}
-
 /**
  * Decode large binary value
  *
  */
 static int iscsi_large_binary_decode ( const char *encoded, uint8_t *raw ) {
 
-	if ( encoded[0] != '0' )
-		return -EPROTO_INVALID_LARGE_BINARY;
-
-	switch ( encoded[1] ) {
-	case 'x' :
-	case 'X' :
-		return base16_decode ( ( encoded + 2 ), raw );
-	case 'b' :
-	case 'B' :
-		return base64_decode ( ( encoded + 2 ), raw );
-	default:
-		return -EPROTO_INVALID_LARGE_BINARY;
+	/* Check for initial '0x' or '0b' and decode as appropriate */
+	if ( *(encoded++) == '0' ) {
+		switch ( tolower ( *(encoded++) ) ) {
+		case 'x' :
+			return base16_decode ( encoded, raw );
+		case 'b' :
+			return base64_decode ( encoded, raw );
+		}
 	}
+
+	return -EPROTO_INVALID_LARGE_BINARY;
 }
 
 /**
  */
 static int iscsi_handle_chap_c_value ( struct iscsi_session *iscsi,
 				       const char *value ) {
-	uint8_t buf[ iscsi_large_binary_decoded_max_len ( value ) ];
+	uint8_t buf[ strlen ( value ) ]; /* Decoding never expands data */
 	unsigned int i;
-	size_t len;
+	int len;
 	int rc;
 
 	/* Process challenge */
-	rc = iscsi_large_binary_decode ( value, buf );
-	if ( rc < 0 ) {
+	len = iscsi_large_binary_decode ( value, buf );
+	if ( len < 0 ) {
+		rc = len;
 		DBGC ( iscsi, "iSCSI %p invalid CHAP challenge \"%s\": %s\n",
 		       iscsi, value, strerror ( rc ) );
 		return rc;
 	}
-	len = rc;
 	chap_update ( &iscsi->chap, buf, len );
 
 	/* Build CHAP response */
  */
 static int iscsi_handle_chap_r_value ( struct iscsi_session *iscsi,
 				       const char *value ) {
-	uint8_t buf[ iscsi_large_binary_decoded_max_len ( value ) ];
-	size_t len;
+	uint8_t buf[ strlen ( value ) ]; /* Decoding never expands data */
+	int len;
 	int rc;
 
 	/* Generate CHAP response for verification */
 	chap_respond ( &iscsi->chap );
 
 	/* Process response */
-	rc = iscsi_large_binary_decode ( value, buf );
-	if ( rc < 0 ) {
+	len = iscsi_large_binary_decode ( value, buf );
+	if ( len < 0 ) {
+		rc = len;
 		DBGC ( iscsi, "iSCSI %p invalid CHAP response \"%s\": %s\n",
 		       iscsi, value, strerror ( rc ) );
 		return rc;
 	}
-	len = rc;
 
 	/* Check CHAP response */
-	if ( len != iscsi->chap.response_len ) {
+	if ( len != ( int ) iscsi->chap.response_len ) {
 		DBGC ( iscsi, "iSCSI %p invalid CHAP response length\n",
 		       iscsi );
 		return -EPROTO_INVALID_CHAP_RESPONSE;