busybox: Support DHCP refresh without restarting the interface

When the kernel is started using ip=dhcp, we want a way to be able to run
the udhcp client within busybox and not reset the interface.

When using the '-D' option to udhcpc, the defconfig script will be skipped
allowing the refresh without changing the network settings.

Also provide an initscript that can be used to detect ip=dhcp on the
kernel command line, if detected it will refresh the lease and set the
proper resolve.conf and related files, but not reset the interface.

Original code in Wind River Linux by Greg Moffatt <greg.moffat@windriver.com>

Signed-off-by: Mark Hatle <mark.hatle@windriver.com>

1 files changed, 110 insertions, 0 deletions

diff --git a/meta/recipes-core/busybox/busybox-1.17.3/busybox-udhcpc-no_deconfig.patch b/meta/recipes-core/busybox/busybox-1.17.3/busybox-udhcpc-no_deconfig.patch
new file mode 100644
index 0000000000..cdf56b826c
--- /dev/null
+++ b/meta/recipes-core/busybox/busybox-1.17.3/busybox-udhcpc-no_deconfig.patch
@@ -0,0 +1,110 @@
+Add a new option -D to the udhcpc client that allows for
+dhcp renewal to occur without having to down the interface
+in the process.
+
+Signed-off-by: Greg Moffatt <greg.moffatt@windriver.com>
+
+Updated to latest Busybox 1.17.3
+
+Signed-off-by: Mark Hatle <mark.hatle@windriver.com>
+
+diff -ur busybox-1.17.3.orig/networking/udhcp/dhcpc.c busybox-1.17.3/networking/udhcp/dhcpc.c
+--- busybox-1.17.3.orig/networking/udhcp/dhcpc.c
++++ busybox-1.17.3/networking/udhcp/dhcpc.c
+@@ -35,6 +35,9 @@
+ #endif
+ #include <linux/filter.h>
+ 
++/* option whether to down the interface when reconfiguring */
++static int allow_deconfig = 1;
++
+ /* struct client_config_t client_config is in bb_common_bufsiz1 */
+ 
+ 
+@@ -709,7 +712,8 @@
+                state = RENEW_REQUESTED;
+                break;
+        case RENEW_REQUESTED: /* impatient are we? fine, square 1 */
+-               udhcp_run_script(NULL, "deconfig");
++               if (allow_deconfig)
++                       udhcp_run_script(NULL, "deconfig");
+        case REQUESTING:
+        case RELEASED:
+                change_listen_mode(LISTEN_RAW);
+@@ -733,7 +737,8 @@
+                bb_info_msg("Unicasting a release of %s to %s",
+                                inet_ntoa(temp_addr), buffer);
+                send_release(server_addr, requested_ip); /* unicast */
+-               udhcp_run_script(NULL, "deconfig");
++               if (allow_deconfig)
++                       udhcp_run_script(NULL, "deconfig");
+        }
+        bb_info_msg("Entering released state");
+ 
+@@ -836,6 +841,7 @@
+                OPT_o = 1 << 18,
+                OPT_x = 1 << 19,
+                OPT_f = 1 << 20,
++               OPT_D = 1 << 21,
+ /* The rest has variable bit positions, need to be clever */
+                OPTBIT_f = 20,
+                USE_FOR_MMU(             OPTBIT_b,)
+@@ -861,7 +867,7 @@
+ #endif
+                ;
+        IF_LONG_OPTS(applet_long_options = udhcpc_longopts;)
+-       opt = getopt32(argv, "c:CV:H:h:F:i:np:qRr:s:T:t:SA:O:ox:f"
++       opt = getopt32(argv, "c:CV:H:h:F:i:np:qRr:s:T:t:SA:O:ox:fD"
+                USE_FOR_MMU("b")
+                IF_FEATURE_UDHCPC_ARPING("a")
+                IF_FEATURE_UDHCP_PORT("P:")
+@@ -950,6 +956,9 @@
+                logmode |= LOGMODE_SYSLOG;
+        }
+ 
++       if (opt & OPT_D)
++               allow_deconfig = 0;
++
+        /* Make sure fd 0,1,2 are open */
+        bb_sanitize_stdio();
+        /* Equivalent of doing a fflush after every \n */
+@@ -964,7 +973,8 @@
+        srand(monotonic_us());
+ 
+        state = INIT_SELECTING;
+-       udhcp_run_script(NULL, "deconfig");
++       if (allow_deconfig)
++               udhcp_run_script(NULL, "deconfig");
+        change_listen_mode(LISTEN_RAW);
+        packet_num = 0;
+        timeout = 0;
+@@ -1100,7 +1110,8 @@
+                                }
+                                /* Timed out, enter init state */
+                                bb_info_msg("Lease lost, entering init state");
+-                               udhcp_run_script(NULL, "deconfig");
++                               if (allow_deconfig)
++                                       udhcp_run_script(NULL, "deconfig");
+                                state = INIT_SELECTING;
+                                /*timeout = 0; - already is */
+                                packet_num = 0;
+@@ -1246,7 +1257,8 @@
+                                                send_decline(xid, server_addr, packet.yiaddr);
+ 
+                                                if (state != REQUESTING)
+-                                                       udhcp_run_script(NULL, "deconfig");
++                                                       if (allow_deconfig)
++                                                               udhcp_run_script(NULL, "deconfig");
+                                                change_listen_mode(LISTEN_RAW);
+                                                state = INIT_SELECTING;
+                                                requested_ip = 0;
+@@ -1292,7 +1304,8 @@
+                                bb_info_msg("Received DHCP NAK");
+                                udhcp_run_script(&packet, "nak");
+                                if (state != REQUESTING)
+-                                       udhcp_run_script(NULL, "deconfig");
++                                       if (allow_deconfig)
++                                               udhcp_run_script(NULL, "deconfig");
+                                change_listen_mode(LISTEN_RAW);
+                                sleep(3); /* avoid excessive network traffic */
+                                state = INIT_SELECTING;