From 7d3124fb4ba8c2c18b1c2d992c01167a13386815 Mon Sep 17 00:00:00 2001
From: "Joseph C. Lehner" <joseph.c.lehner@gmail.com>
Date: Wed, 26 Jul 2023 11:38:39 +0200
Subject: [PATCH] Drain NMRP rx buffer before TFTP upload

More debug log spam
---
 nmrp.c  | 29 +++++++++++++++++++++++++++++
 nmrpd.h |  3 +++
 tftp.c  | 11 ++++++++---
 3 files changed, 40 insertions(+), 3 deletions(-)

diff --git a/nmrp.c b/nmrp.c
index 230c7b5..ae69a8c 100644
--- a/nmrp.c
+++ b/nmrp.c
@@ -348,6 +348,32 @@ static void sigh(int sig)
 	g_interrupted = 1;
 }
 
+static void nmrp_drain(void* arg)
+{
+	// between nmrpflash sending the TFTP WRQ packet, and the router
+	// responding with ACK(0)/OACK, some devices send extraneous
+	// CONF_REQ and/or TFTP_UL_REQ packets.
+	//
+	// we drain the NMRP receive buffer here, otherwise it might seem
+	// as if these packets arrived *after* the TFTP upload.
+
+	struct nmrp_pkt rx;
+	int i = 0;
+
+	while (pkt_recv((struct ethsock*)arg, &rx) == 0) {
+		if (rx.msg.code != NMRP_C_CONF_REQ && rx.msg.code != NMRP_C_TFTP_UL_REQ) {
+			if (verbosity > 1) {
+				printf("Drained unexpected packet type %s\n", msg_code_str(rx.msg.code));
+			}
+		}
+		++i;
+	}
+
+	if (verbosity > 1) {
+		printf("Drained %d packet(s) from rx buffer\n", i);
+	}
+}
+
 static const char *spinner = "\\|/-";
 
 int nmrp_do(struct nmrpd_args *args)
@@ -564,6 +590,9 @@ int nmrp_do(struct nmrpd_args *args)
 	ulreqs = 0;
 	ka_reqs = 0;
 
+	args->on_tftp_ack0_callback = &nmrp_drain;
+	args->on_tftp_ack0_arg = sock;
+
 	while (!g_interrupted) {
 		if (expect != NMRP_C_NONE && rx.msg.code != expect) {
 			fprintf(stderr, "Received %s while waiting for %s!\n",
diff --git a/nmrpd.h b/nmrpd.h
index f7ca57b..3aaebe0 100644
--- a/nmrpd.h
+++ b/nmrpd.h
@@ -112,6 +112,9 @@ struct nmrpd_args {
 	uint16_t port;
 	const char *region;
 	off_t offset;
+
+	void (*on_tftp_ack0_callback)(void*);
+	void* on_tftp_ack0_arg;
 };
 
 const char *leafname(const char *path);
diff --git a/tftp.c b/tftp.c
index 5ce15db..c30042d 100644
--- a/tftp.c
+++ b/tftp.c
@@ -328,8 +328,8 @@ ssize_t tftp_put(struct nmrpd_args *args)
 	char rx[2048], tx[2048];
 	const char *file_remote = args->file_remote;
 	char *val, *end;
-	bool rollover;
-	const unsigned rx_timeout = MAX(args->rx_timeout / (args->blind ? 50 : 5), 2000);
+	bool rollover, tftp_ack0_callback_called;
+	const unsigned rx_timeout = MIN(args->rx_timeout / (args->blind ? 50 : 5), 2000);
 	const unsigned max_timeouts = args->blind ? 3 : 5;
 #ifndef NMRPFLASH_WINDOWS
 	int enabled = 1;
@@ -393,7 +393,6 @@ ssize_t tftp_put(struct nmrpd_args *args)
 		}
 
 		if (bind(sock, (struct sockaddr*)&addr, sizeof(addr)) != 0) {
-			printf("errno=%d\n", errno);
 			sock_perror("bind");
 			goto cleanup;
 		}
@@ -415,6 +414,7 @@ ssize_t tftp_put(struct nmrpd_args *args)
 	rollover = false;
 	/* Not really, but this way the loop sends our WRQ before receiving */
 	timeouts = 1;
+	tftp_ack0_callback_called = false;
 
 	pkt_mkwrq(tx, file_remote, TFTP_BLKSIZE);
 
@@ -440,6 +440,11 @@ ssize_t tftp_put(struct nmrpd_args *args)
 					}
 				}
 			}
+
+			if (!ackblock && args->on_tftp_ack0_callback && !tftp_ack0_callback_called) {
+				args->on_tftp_ack0_callback(args->on_tftp_ack0_arg);
+				tftp_ack0_callback_called = true;
+			}
 		}
 
 		if (timeouts || ackblock == block) {