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) */