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	Resend DHCPREQUEST in case server does not respond - sdhcp - simple dhcp client
	git clone git://git.codemadness.org/sdhcp
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	---
	commit 5506c81d9930e68cfb29960a4211454fd46262b9
	parent 80bdf55532fadbf9398ce7e12fe494282f45f394
	Author: Michael Forney <[email protected]>
	Date: Wed, 14 Nov 2018 18:40:39 -0800

	Resend DHCPREQUEST in case server does not respond

	The delays were chosen to follow section 4.1 of RFC 2131.

	Diffstat:
	M sdhcp.c \| 29 +++++++++++++++++++----------

	1 file changed, 19 insertions(+), 10 deletions(-)
	---
	diff --git a/sdhcp.c b/sdhcp.c
	@@ -386,7 +386,7 @@ calctimeout(int n, struct itimerspec *ts)
	static void
	run(void)
	{
	- int forked = 0;
	+ int forked = 0, t;
	struct itimerspec timeout = { 0 };

	Init:
	@@ -399,8 +399,6 @@ Selecting:
	for (;;) {
	switch (dhcprecv()) {
	case DHCPoffer:
	- timeout.it_value.tv_sec = 0;
	- settimeout(0, &timeout);
	memcpy(client, bp.yiaddr, sizeof(client));
	optget(&bp, server, ODserverid, sizeof(server));
	optget(&bp, mask, OBmask, sizeof(mask));
	@@ -418,15 +416,26 @@ Selecting:
	}
	}
	Requesting:
	- dhcpsend(DHCPrequest, Broadcast);
	- for (;;) {
	- switch (dhcprecv()) {
	- case DHCPack:
	- goto Bound;
	- case DHCPnak:
	- goto Init;
	+ for (t = 4; t <= 64; t *= 2) {
	+ dhcpsend(DHCPrequest, Broadcast);
	+ timeout.it_value.tv_sec = t;
	+ settimeout(0, &timeout);
	+ for (;;) {
	+ switch (dhcprecv()) {
	+ case DHCPack:
	+ goto Bound;
	+ case DHCPnak:
	+ goto Init;
	+ case Timeout0:
	+ break;
	+ default:
	+ continue;
	+ }
	+ break;
	}
	}
	+ /* no response from DHCPREQUEST after several attempts, go to INIT */
	+ goto Init;
	Bound:
	acceptlease();
	fputs("Congrats! You should be on the 'net.\n", stdout);