udhcpc: shrink

udhcpc: guard against zero lease time

function                                             old     new   delta
timeout                                                4       -      -4
server_addr                                            4       -      -4
requested_ip                                           4       -      -4
perform_release                                      134     112     -22
udhcpc_main                                         2511    2485     -26
------------------------------------------------------------------------------
(add/remove: 0/3 grow/shrink: 0/2 up/down: 0/-60)             Total: -60 bytes

3 files changed, 36 insertions, 21 deletions

diff --git a/include/platform.h b/include/platform.h
index 0e0ccaf90..21224fabf 100644
--- a/include/platform.h
+++ b/include/platform.h
@@ -135,7 +135,18 @@
 #define SWAP_LE64(x) (x)
 #endif
 
+/* ---- Unaligned access ------------------------------------ */
+
+/* parameter is supposed to be an uint32_t* ptr */
+#if defined(i386) || defined(__x86_64__) /* + other arches? */
+#define get_unaligned_u32p(u32p) (*(u32p))
+#else
+/* performs reasonably well (gcc usually inlines memcpy here) */
+#define get_unaligned_u32p(u32p) ({ uint32_t __t; memcpy(&__t, (u32p), 4); __t; })
+#endif
+
 /* ---- Networking ------------------------------------------ */
+
 #ifndef __APPLE__
 # include <arpa/inet.h>
 # ifndef __socklen_t_defined
@@ -146,6 +157,7 @@ typedef int socklen_t;
 #endif
 
 /* ---- Compiler dependent settings ------------------------- */
+
 #if (defined __digital__ && defined __unix__) || defined __APPLE__
 # undef HAVE_MNTENT_H
 # undef HAVE_SYS_STATFS_H
@@ -163,9 +175,10 @@ __extension__ typedef unsigned long long __u64;
 #endif
 
 /*----- Kernel versioning ------------------------------------*/
+
 #define KERNEL_VERSION(a,b,c) (((a) << 16) + ((b) << 8) + (c))
 
-/* ---- miscellaneous --------------------------------------- */
+/* ---- Miscellaneous --------------------------------------- */
 
 #if defined(__GNU_LIBRARY__) && __GNU_LIBRARY__ < 5 && \
 	!defined(__dietlibc__) && \
diff --git a/networking/udhcp/dhcpc.c b/networking/udhcp/dhcpc.c
index fef8632f6..f1aa36fe6 100644
--- a/networking/udhcp/dhcpc.c
+++ b/networking/udhcp/dhcpc.c
@@ -18,9 +18,6 @@
 #include "options.h"
 
 
-static int timeout; /* = 0. Must be signed */
-static uint32_t requested_ip; /* = 0 */
-static uint32_t server_addr;
 static int sockfd = -1;
 
 #define LISTEN_NONE 0
@@ -28,6 +25,14 @@ static int sockfd = -1;
 #define LISTEN_RAW 2
 static smallint listen_mode;
 
+#define INIT_SELECTING  0
+#define REQUESTING      1
+#define BOUND           2
+#define RENEWING        3
+#define REBINDING       4
+#define INIT_REBOOT     5
+#define RENEW_REQUESTED 6
+#define RELEASED        7
 static smallint state;
 
 /* struct client_config_t client_config is in bb_common_bufsiz1 */
@@ -71,7 +76,7 @@ static void perform_renew(void)
 
 
 /* perform a release */
-static void perform_release(void)
+static void perform_release(uint32_t requested_ip, uint32_t server_addr)
 {
 	char buffer[sizeof("255.255.255.255")];
 	struct in_addr temp_addr;
@@ -90,7 +95,6 @@ static void perform_release(void)
 
 	change_listen_mode(LISTEN_NONE);
 	state = RELEASED;
-	timeout = INT_MAX;
 }
 
 
@@ -140,9 +144,12 @@ int udhcpc_main(int argc ATTRIBUTE_UNUSED, char **argv)
 	int tryagain_timeout = 20;
 	int discover_timeout = 3;
 	int discover_retries = 3;
+	uint32_t server_addr = server_addr; /* for compiler */
+	uint32_t requested_ip = 0;
 	uint32_t xid = 0;
 	uint32_t lease_seconds = 0; /* can be given as 32-bit quantity */
 	int packet_num;
+	int timeout; /* must be signed */
 	unsigned already_waited_sec;
 	unsigned opt;
 	int max_fd;
@@ -332,6 +339,7 @@ int udhcpc_main(int argc ATTRIBUTE_UNUSED, char **argv)
 	udhcp_run_script(NULL, "deconfig");
 	change_listen_mode(LISTEN_RAW);
 	packet_num = 0;
+	timeout = 0;
 	already_waited_sec = 0;
 
 	/* Main event loop. select() waits on signal pipe and possibly
@@ -510,8 +518,8 @@ int udhcpc_main(int argc ATTRIBUTE_UNUSED, char **argv)
 						continue;
 						/* still selecting - this server looks bad */
 					}
-					/* can be misaligned, thus memcpy */
-					memcpy(&server_addr, temp, 4);
+					/* it IS unaligned sometimes, don't "optimize" */
+					server_addr = get_unaligned_u32p((uint32_t*)temp);
 					xid = packet.xid;
 					requested_ip = packet.yiaddr;
 
@@ -535,7 +543,9 @@ int udhcpc_main(int argc ATTRIBUTE_UNUSED, char **argv)
 						/* can be misaligned, thus memcpy */
 						memcpy(&lease_seconds, temp, 4);
 						lease_seconds = ntohl(lease_seconds);
-						lease_seconds &= 0x0fffffff; /* paranoia: must not be negative */
+						lease_seconds &= 0x0fffffff; /* paranoia: must not be prone to overflows */
+						if (lease_seconds < 10) /* and not too small */
+							lease_seconds = 10;
 					}
 #if ENABLE_FEATURE_UDHCPC_ARPING
 					if (opt & OPT_a) {
@@ -576,7 +586,7 @@ int udhcpc_main(int argc ATTRIBUTE_UNUSED, char **argv)
 					change_listen_mode(LISTEN_NONE);
 					if (client_config.quit_after_lease) {
 						if (client_config.release_on_quit)
-							perform_release();
+							perform_release(requested_ip, server_addr);
 						goto ret0;
 					}
 					if (!client_config.foreground)
@@ -618,12 +628,13 @@ int udhcpc_main(int argc ATTRIBUTE_UNUSED, char **argv)
 				timeout = 0;
 				break;
 			case SIGUSR2:
-				perform_release();
+				perform_release(requested_ip, server_addr);
+				timeout = INT_MAX;
 				break;
 			case SIGTERM:
 				bb_info_msg("Received SIGTERM");
 				if (client_config.release_on_quit)
-					perform_release();
+					perform_release(requested_ip, server_addr);
 				goto ret0;
 			}
 		}
diff --git a/networking/udhcp/dhcpc.h b/networking/udhcp/dhcpc.h
index 9331466e1..97d3b3c9d 100644
--- a/networking/udhcp/dhcpc.h
+++ b/networking/udhcp/dhcpc.h
@@ -8,15 +8,6 @@
 # pragma GCC visibility push(hidden)
 #endif
 
-#define INIT_SELECTING	0
-#define REQUESTING	1
-#define BOUND		2
-#define RENEWING	3
-#define REBINDING	4
-#define INIT_REBOOT	5
-#define RENEW_REQUESTED 6
-#define RELEASED	7
-
 struct client_config_t {
 	/* TODO: combine flag fields into single "unsigned opt" */
 	/* (can be set directly to the result of getopt32) */