[tls] Concatenate received non-data records before processing

Allow non-data records to be split across multiple received I/O
buffers, to accommodate large certificate chains.

Reported-by: Nicola Volpini <Nicola.Volpini@kambi.com>
Tested-by: Nicola Volpini <Nicola.Volpini@kambi.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/core/iobuf.c

@@ -158,3 +158,45 @@ int iob_ensure_headroom ( struct io_buffer *iobuf, size_t len ) {
 	return -ENOBUFS;
 }
 
+/**
+ * Concatenate I/O buffers into a single buffer
+ *
+ * @v list	List of I/O buffers
+ * @ret iobuf	Concatenated I/O buffer, or NULL on allocation failure
+ *
+ * After a successful concatenation, the list will be empty.
+ */
+struct io_buffer * iob_concatenate ( struct list_head *list ) {
+	struct io_buffer *iobuf;
+	struct io_buffer *tmp;
+	struct io_buffer *concatenated;
+	size_t len = 0;
+
+	/* If the list contains only a single entry, avoid an
+	 * unnecessary additional allocation.
+	 */
+	if ( list_is_singular ( list ) ) {
+		iobuf = list_first_entry ( list, struct io_buffer, list );
+		INIT_LIST_HEAD ( list );
+		return iobuf;
+	}
+
+	/* Calculate total length */
+	list_for_each_entry ( iobuf, list, list )
+		len += iob_len ( iobuf );
+
+	/* Allocate new I/O buffer */
+	concatenated = alloc_iob_raw ( len, __alignof__ ( *iobuf ), 0 );
+	if ( ! concatenated )
+		return NULL;
+
+	/* Move data to new I/O buffer */
+	list_for_each_entry_safe ( iobuf, tmp, list, list ) {
+		list_del ( &iobuf->list );
+		memcpy ( iob_put ( concatenated, iob_len ( iobuf ) ),
+			 iobuf->data, iob_len ( iobuf ) );
+		free_iob ( iobuf );
+	}
+
+	return concatenated;
+}

src/include/ipxe/iobuf.h

@@ -216,5 +216,6 @@ extern struct io_buffer * __malloc alloc_iob ( size_t len );
 extern void free_iob ( struct io_buffer *iobuf );
 extern void iob_pad ( struct io_buffer *iobuf, size_t min_len );
 extern int iob_ensure_headroom ( struct io_buffer *iobuf, size_t len );
+extern struct io_buffer * iob_concatenate ( struct list_head *list );
 
 #endif /* _IPXE_IOBUF_H */

src/net/tls.c

@@ -105,10 +105,6 @@ FILE_LICENCE ( GPL2_OR_LATER );
 #define EINFO_EINVAL_MAC						\
 	__einfo_uniqify ( EINFO_EINVAL, 0x0d,				\
 			  "Invalid MAC" )
-#define EINVAL_NON_DATA __einfo_error ( EINFO_EINVAL_NON_DATA )
-#define EINFO_EINVAL_NON_DATA						\
-	__einfo_uniqify ( EINFO_EINVAL, 0x0e,				\
-			  "Overlength non-data record" )
 #define EIO_ALERT __einfo_error ( EINFO_EIO_ALERT )
 #define EINFO_EIO_ALERT							\
 	__einfo_uniqify ( EINFO_EINVAL, 0x01,				\
@@ -137,6 +133,10 @@ FILE_LICENCE ( GPL2_OR_LATER );
 #define EINFO_ENOMEM_RX_DATA						\
 	__einfo_uniqify ( EINFO_ENOMEM, 0x07,				\
 			  "Not enough space for received data" )
+#define ENOMEM_RX_CONCAT __einfo_error ( EINFO_ENOMEM_RX_CONCAT )
+#define EINFO_ENOMEM_RX_CONCAT						\
+	__einfo_uniqify ( EINFO_ENOMEM, 0x08,				\
+			  "Not enough space to concatenate received data" )
 #define ENOTSUP_CIPHER __einfo_error ( EINFO_ENOTSUP_CIPHER )
 #define EINFO_ENOTSUP_CIPHER						\
 	__einfo_uniqify ( EINFO_ENOTSUP, 0x01,				\
@@ -1743,14 +1743,12 @@ static int tls_new_record ( struct tls_session *tls, unsigned int type,
 		return 0;
 	}
 
-	/* For all other records, fail unless we have exactly one I/O buffer */
-	iobuf = list_first_entry ( rx_data, struct io_buffer, list );
-	assert ( iobuf != NULL );
-	list_del ( &iobuf->list );
-	if ( ! list_empty ( rx_data ) ) {
-		DBGC ( tls, "TLS %p overlength non-data record\n", tls );
-		free_iob ( iobuf );
-		return -EINVAL_NON_DATA;
+	/* For all other records, merge into a single I/O buffer */
+	iobuf = iob_concatenate ( rx_data );
+	if ( ! iobuf ) {
+		DBGC ( tls, "TLS %p could not concatenate non-data record "
+		       "type %d\n", tls, type );
+		return -ENOMEM_RX_CONCAT;
 	}
 
 	/* Determine handler */