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.villemoes@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);