net: TFTP: variables cleanup and addition

TFTP source and destination port variable names are
'tftpsrcp' and 'tftpdstp' in the code, but 'tftpsrcport'
and 'tftpdstport' in the README file. Fix the README.

Add environment variable 'tftptimeoutcountmax'. As per the
comments about the global variable tftp_timeout_count_max,
make sure tftptimeoutcountmax is nonnegative.

Introduce configuration option CONFIG_NET_TFTP_VARS,
which controls whether environment variables tftpblocksize,
tftptimeout, and tftptimoueoutcountmax are read by the TFTP
client code. CONFIG_NET_TFTP_VARS defaults to y but can be
set to n by targets with to tight size contraints.

Make bf527-ezkit set CONFIG_NET_TFTP_VARS to n to keep the
target size below limit.

2 files changed, 25 insertions, 2 deletions

diff --git a/net/Kconfig b/net/Kconfig
index 77a2f7e07e..a44a783cae 100644
--- a/net/Kconfig
+++ b/net/Kconfig
@@ -22,4 +22,14 @@ config NETCONSOLE
 	  Support the 'nc' input/output device for networked console.
 	  See README.NetConsole for details.
 
+config NET_TFTP_VARS
+	bool "Control TFTP timeout and count through environment"
+	default y
+	help
+	  If set, allows controlling the TFTP timeout through the
+	  environment variable tftptimeout, and the TFTP maximum
+	  timeout count through the variable tftptimeoutcountmax.
+	  If unset, timeout and maximum are hard-defined as 1 second
+	  and 10 timouts per TFTP transfer.
+
 endif   # if NET
diff --git a/net/tftp.c b/net/tftp.c
index 1a5113179a..f2889fe4c9 100644
--- a/net/tftp.c
+++ b/net/tftp.c
@@ -602,7 +602,7 @@ static void tftp_handler(uchar *pkt, unsigned dest, struct in_addr sip,
 		}
 
 		tftp_prev_block = tftp_cur_block;
-		timeout_count_max = TIMEOUT_COUNT;
+		timeout_count_max = tftp_timeout_count_max;
 		net_set_timeout_handler(timeout_ms, tftp_timeout_handler);
 
 		store_block(tftp_cur_block - 1, pkt + 2, len);
@@ -697,12 +697,14 @@ static void tftp_timeout_handler(void)
 
 void tftp_start(enum proto_t protocol)
 {
+#if CONFIG_NET_TFTP_VARS
 	char *ep;             /* Environment pointer */
 
 	/*
 	 * Allow the user to choose TFTP blocksize and timeout.
 	 * TFTP protocol has a minimal timeout of 1 second.
 	 */
+
 	ep = getenv("tftpblocksize");
 	if (ep != NULL)
 		tftp_block_size_option = simple_strtol(ep, NULL, 10);
@@ -717,6 +719,17 @@ void tftp_start(enum proto_t protocol)
 		timeout_ms = 1000;
 	}
 
+	ep = getenv("tftptimeoutcountmax");
+	if (ep != NULL)
+		tftp_timeout_count_max = simple_strtol(ep, NULL, 10);
+
+	if (tftp_timeout_count_max < 0) {
+		printf("TFTP timeout count max (%d ms) negative, set to 0\n",
+		       tftp_timeout_count_max);
+		tftp_timeout_count_max = 0;
+	}
+#endif
+
 	debug("TFTP blocksize = %i, timeout = %ld ms\n",
 	      tftp_block_size_option, timeout_ms);
 
@@ -842,7 +855,7 @@ void tftp_start_server(void)
 
 	puts("Loading: *\b");
 
-	timeout_count_max = TIMEOUT_COUNT;
+	timeout_count_max = tftp_timeout_count_max;
 	timeout_count = 0;
 	timeout_ms = TIMEOUT;
 	net_set_timeout_handler(timeout_ms, tftp_timeout_handler);