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udhcpc[6]: when renewing, send 1 packet (not 3), on failure go back to BOUND

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This restores old behavior where we slept for 1/2 of lease, then tried renewing,
thel slept for 1/4 and tried again, etc. But now we will NOT be listening to
all packets for 1/2 of lease time, processing (rejecting) everyone else's
DHCP traffic.
We'll go back to bound state, where we have no listening socket at all.

function                                             old     new   delta
udhcpc6_main                                        2600    2655     +55
udhcpc_main                                         2608    2625     +17
.rodata                                           103250  103249      -1
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/1 up/down: 72/-1)              Total: 71 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2021-06-03 09:20:45 +02:00
parent 01daecca1d
commit 1c7253726f
2 changed files with 54 additions and 44 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

43
networking/udhcp/d6_dhcpc.c
View File

@ -1420,7 +1420,7 @@ int udhcpc6_main(int argc UNUSED_PARAM, char **argv)
retval = 1; retval = 1;
goto ret; goto ret;
} }
/* wait before trying again */ /* Wait before trying again */
timeout = tryagain_timeout; timeout = tryagain_timeout;
packet_num = 0; packet_num = 0;
continue; continue;
@ -1442,14 +1442,14 @@ int udhcpc6_main(int argc UNUSED_PARAM, char **argv)
/* 1/2 lease passed, enter renewing state */ /* 1/2 lease passed, enter renewing state */
client_data.state = RENEWING; client_data.state = RENEWING;
client_data.first_secs = 0; /* make secs field count from 0 */ client_data.first_secs = 0; /* make secs field count from 0 */
change_listen_mode(LISTEN_KERNEL); got_SIGUSR1:
log1s("entering renew state"); log1s("entering renew state");
change_listen_mode(LISTEN_KERNEL);
/* fall right through */ /* fall right through */
case RENEW_REQUESTED: /* manual (SIGUSR1) renew */ case RENEW_REQUESTED: /* in manual (SIGUSR1) renew */
case_RENEW_REQUESTED:
case RENEWING: case RENEWING:
if (packet_num < 3) { if (packet_num == 0) {
/* send an unicast renew request */ /* Send an unicast renew request */
/* Sometimes observed to fail (EADDRNOTAVAIL) to bind /* Sometimes observed to fail (EADDRNOTAVAIL) to bind
* a new UDP socket for sending inside send_renew. * a new UDP socket for sending inside send_renew.
* I hazard to guess existing listening socket * I hazard to guess existing listening socket
@ -1463,13 +1463,18 @@ int udhcpc6_main(int argc UNUSED_PARAM, char **argv)
else else
send_d6_renew(xid, &srv6_buf, requested_ipv6); send_d6_renew(xid, &srv6_buf, requested_ipv6);
timeout = discover_timeout; timeout = discover_timeout;
/* ^^^ used to be = lease_remaining / 2 - WAY too long */
packet_num++; packet_num++;
continue; continue;
} /* else: we had sent one packet, but got no reply */
log1s("no response to renew");
if (lease_remaining > 30) {
/* Some lease time remains, try to renew later */
change_listen_mode(LISTEN_NONE);
goto BOUND_for_half_lease;
} }
/* Timed out, enter rebinding state */ /* Enter rebinding state */
log1s("entering rebinding state");
client_data.state = REBINDING; client_data.state = REBINDING;
log1s("entering rebinding state");
/* Switch to bcast receive */ /* Switch to bcast receive */
change_listen_mode(LISTEN_RAW); change_listen_mode(LISTEN_RAW);
packet_num = 0; packet_num = 0;
@ -1509,8 +1514,14 @@ int udhcpc6_main(int argc UNUSED_PARAM, char **argv)
/* Is it a signal? */ /* Is it a signal? */
switch (udhcp_sp_read()) { switch (udhcp_sp_read()) {
case SIGUSR1: case SIGUSR1:
if (client_data.state <= REQUESTING)
/* Initial negotiations in progress, do not disturb */
break;
if (lease_remaining > 30) /* if renew fails, do not go back to BOUND */
lease_remaining = 30;
client_data.first_secs = 0; /* make secs field count from 0 */ client_data.first_secs = 0; /* make secs field count from 0 */
bb_simple_info_msg("performing DHCP renew"); packet_num = 0;
switch (client_data.state) { switch (client_data.state) {
/* Try to renew/rebind */ /* Try to renew/rebind */
@ -1519,21 +1530,19 @@ int udhcpc6_main(int argc UNUSED_PARAM, char **argv)
case REBINDING: case REBINDING:
change_listen_mode(LISTEN_KERNEL); change_listen_mode(LISTEN_KERNEL);
client_data.state = RENEW_REQUESTED; client_data.state = RENEW_REQUESTED;
goto case_RENEW_REQUESTED; goto got_SIGUSR1;
/* Start things over */ /* Two SIGUSR1 received, start things over */
case RENEW_REQUESTED: /* two or more SIGUSR1 received */ case RENEW_REQUESTED:
change_listen_mode(LISTEN_NONE); change_listen_mode(LISTEN_NONE);
d6_run_script_no_option("deconfig"); d6_run_script_no_option("deconfig");
/* Wake from SIGUSR2-induced deconfigured state */
default: default:
/* case REQUESTING: */
/* case RELEASED: */ /* case RELEASED: */
/* case INIT_SELECTING: */
change_listen_mode(LISTEN_NONE); change_listen_mode(LISTEN_NONE);
} }
client_data.state = INIT_SELECTING; client_data.state = INIT_SELECTING;
packet_num = 0;
/* Kill any timeouts, user wants this to hurry along */ /* Kill any timeouts, user wants this to hurry along */
timeout = 0; timeout = 0;
continue; continue;
@ -1830,7 +1839,7 @@ int udhcpc6_main(int argc UNUSED_PARAM, char **argv)
} }
#endif #endif
// BOUND_for_half_lease: BOUND_for_half_lease:
timeout = (unsigned)lease_remaining / 2; timeout = (unsigned)lease_remaining / 2;
client_data.state = BOUND; client_data.state = BOUND;
packet_num = 0; packet_num = 0;

55
networking/udhcp/dhcpc.c
View File

@ -1480,7 +1480,7 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv)
retval = 1; retval = 1;
goto ret; goto ret;
} }
/* wait before trying again */ /* Wait before trying again */
timeout = tryagain_timeout; timeout = tryagain_timeout;
packet_num = 0; packet_num = 0;
continue; continue;
@ -1502,14 +1502,14 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv)
/* 1/2 lease passed, enter renewing state */ /* 1/2 lease passed, enter renewing state */
client_data.state = RENEWING; client_data.state = RENEWING;
client_data.first_secs = 0; /* make secs field count from 0 */ client_data.first_secs = 0; /* make secs field count from 0 */
change_listen_mode(LISTEN_KERNEL); got_SIGUSR1:
log1s("entering renew state"); log1s("entering renew state");
change_listen_mode(LISTEN_KERNEL);
/* fall right through */ /* fall right through */
case RENEW_REQUESTED: /* manual (SIGUSR1) renew */ case RENEW_REQUESTED: /* in manual (SIGUSR1) renew */
case_RENEW_REQUESTED:
case RENEWING: case RENEWING:
if (packet_num < 3) { if (packet_num == 0) {
/* send an unicast renew request */ /* Send an unicast renew request */
/* Sometimes observed to fail (EADDRNOTAVAIL) to bind /* Sometimes observed to fail (EADDRNOTAVAIL) to bind
* a new UDP socket for sending inside send_renew. * a new UDP socket for sending inside send_renew.
* I hazard to guess existing listening socket * I hazard to guess existing listening socket
@ -1520,7 +1520,6 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv)
*/ */
if (send_renew(xid, server_addr, requested_ip) >= 0) { if (send_renew(xid, server_addr, requested_ip) >= 0) {
timeout = discover_timeout; timeout = discover_timeout;
/* ^^^ used to be = lease_remaining / 2 - WAY too long */
packet_num++; packet_num++;
continue; continue;
} }
@ -1529,15 +1528,16 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv)
* which gave us bogus server ID 1.1.1.1 * which gave us bogus server ID 1.1.1.1
* which wasn't reachable (and probably did not exist). * which wasn't reachable (and probably did not exist).
*/ */
} /* else: we had sent one packet, but got no reply */
log1s("no response to renew");
if (lease_remaining > 30) {
/* Some lease time remains, try to renew later */
change_listen_mode(LISTEN_NONE);
goto BOUND_for_half_lease;
} }
//TODO: if 3 renew's failed (no reply) but remaining lease is large enough, /* Enter rebinding state */
//it might make sense to go back to BOUND and try later? a-la
// if (lease_remaining > 30) change_listen_mode(LISTEN_NONE) + goto BOUND_for_half_lease;
//If we do that, "packet_num < 3" test below might be superfluous
//(lease_remaining will run out anyway)
/* Timed out or error, enter rebinding state */
log1s("entering rebinding state");
client_data.state = REBINDING; client_data.state = REBINDING;
log1s("entering rebinding state");
/* Switch to bcast receive */ /* Switch to bcast receive */
change_listen_mode(LISTEN_RAW); change_listen_mode(LISTEN_RAW);
packet_num = 0; packet_num = 0;
@ -1575,31 +1575,34 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv)
/* Is it a signal? */ /* Is it a signal? */
switch (udhcp_sp_read()) { switch (udhcp_sp_read()) {
case SIGUSR1: case SIGUSR1:
if (client_data.state <= REQUESTING)
/* Initial negotiations in progress, do not disturb */
break;
if (lease_remaining > 30) /* if renew fails, do not go back to BOUND */
lease_remaining = 30;
client_data.first_secs = 0; /* make secs field count from 0 */ client_data.first_secs = 0; /* make secs field count from 0 */
bb_simple_info_msg("performing DHCP renew"); packet_num = 0;
switch (client_data.state) { switch (client_data.state) {
/* Try to renew/rebind */ /* Try to renew/rebind */
case BOUND: case BOUND:
case RENEWING: case RENEWING:
case REBINDING: case REBINDING:
change_listen_mode(LISTEN_KERNEL);
client_data.state = RENEW_REQUESTED; client_data.state = RENEW_REQUESTED;
goto case_RENEW_REQUESTED; goto got_SIGUSR1;
/* Start things over */ /* Two SIGUSR1 received, start things over */
case RENEW_REQUESTED: /* two or more SIGUSR1 received */ case RENEW_REQUESTED:
change_listen_mode(LISTEN_NONE); change_listen_mode(LISTEN_NONE);
udhcp_run_script(NULL, "deconfig"); udhcp_run_script(NULL, "deconfig");
/* Wake from SIGUSR2-induced deconfigured state */
default: default:
/* case REQUESTING: */
/* case RELEASED: */ /* case RELEASED: */
/* case INIT_SELECTING: */
change_listen_mode(LISTEN_NONE); change_listen_mode(LISTEN_NONE);
} }
client_data.state = INIT_SELECTING; client_data.state = INIT_SELECTING;
packet_num = 0;
/* Kill any timeouts, user wants this to hurry along */ /* Kill any timeouts, user wants this to hurry along */
timeout = 0; timeout = 0;
continue; continue;
@ -1723,10 +1726,9 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv)
strcpy(server_str, inet_ntoa(temp_addr)); strcpy(server_str, inet_ntoa(temp_addr));
temp_addr.s_addr = packet.yiaddr; temp_addr.s_addr = packet.yiaddr;
temp = udhcp_get_option32(&packet, DHCP_LEASE_TIME);
if (!temp) {
lease_remaining = 60 * 60; lease_remaining = 60 * 60;
} else { temp = udhcp_get_option32(&packet, DHCP_LEASE_TIME);
if (temp) {
uint32_t lease; uint32_t lease;
/* it IS unaligned sometimes, don't "optimize" */ /* it IS unaligned sometimes, don't "optimize" */
move_from_unaligned32(lease, temp); move_from_unaligned32(lease, temp);
@ -1798,8 +1800,7 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv)
opt = ((opt & ~OPT_b) | OPT_f); opt = ((opt & ~OPT_b) | OPT_f);
} }
#endif #endif
BOUND_for_half_lease:
// BOUND_for_half_lease:
timeout = (unsigned)lease_remaining / 2; timeout = (unsigned)lease_remaining / 2;
client_data.state = BOUND; client_data.state = BOUND;
/* make future renew packets use different xid */ /* make future renew packets use different xid */