U-Boot does not support IP fragmentation on TX (and unless
CONFIG_IP_DEFRAG is set, neither on RX). So the blocks we send must
fit in a single ethernet packet.
Currently, if tftpblocksize is set to something like 5000 and I
tftpput a large enough file, U-Boot crashes because we overflow
net_tx_packet (which only has room for 1500 bytes plus change).
Similarly, if tftpblocksize is set to something larger than what we
can actually receive (e.g. 50000, with NET_MAXDEFRAG being 16384), any
tftp get just hangs because we never receive any packets.
Signed-off-by: Rasmus Villemoes <rasmus.villem...@prevas.dk>
---
net/tftp.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 46 insertions(+)
diff --git a/net/tftp.c b/net/tftp.c
index e5e140bcd5..60e1273332 100644
--- a/net/tftp.c
+++ b/net/tftp.c
@@ -708,8 +708,52 @@ static int tftp_init_load_addr(void)
return 0;
}
+static int saved_tftp_block_size_option;
+static void sanitize_tftp_block_size_option(enum proto_t protocol)
+{
+ int cap, max_defrag;
+
+ switch (protocol) {
+ case TFTPGET:
+ max_defrag = config_opt_enabled(CONFIG_IP_DEFRAG,
CONFIG_NET_MAXDEFRAG, 0);
+ if (max_defrag) {
+ /* Account for IP, UDP and TFTP headers. */
+ cap = max_defrag - (20 + 8 + 4);
+ /* RFC2348 sets a hard upper limit. */
+ cap = min(cap, 65464);
+ break;
+ }
+ /*
+ * If not CONFIG_IP_DEFRAG, cap at the same value as
+ * for tftp put, namely normal MTU minus protocol
+ * overhead.
+ */
+ /* fall through */
+ case TFTPPUT:
+ default:
+ /*
+ * U-Boot does not support IP fragmentation on TX, so
+ * this must be small enough that it fits normal MTU
+ * (and small enough that it fits net_tx_packet which
+ * has room for PKTSIZE_ALIGN bytes).
+ */
+ cap = 1468;
+ }
+ if (tftp_block_size_option > cap) {
+ printf("Capping tftp block size option to %d (was %d)\n",
+ cap, tftp_block_size_option);
+ saved_tftp_block_size_option = tftp_block_size_option;
+ tftp_block_size_option = cap;
+ }
+}
+
void tftp_start(enum proto_t protocol)
{
+ if (saved_tftp_block_size_option) {
+ tftp_block_size_option = saved_tftp_block_size_option;
+ saved_tftp_block_size_option = 0;
+ }
+
if (IS_ENABLED(CONFIG_NET_TFTP_VARS)) {
char *ep; /* Environment pointer */
@@ -747,6 +791,8 @@ void tftp_start(enum proto_t protocol)
}
}
+ sanitize_tftp_block_size_option(protocol);
+
debug("TFTP blocksize = %i, TFTP windowsize = %d timeout = %ld ms\n",
tftp_block_size_option, tftp_window_size_option, timeout_ms);
--
2.37.2
