wget: use monotonic_sec instead of gettimeofday

zcip: use monotonic_us instead of gettimeofday
udhcpcd: simpler, shorter random_xid()

function                                             old     new   delta
monotonic_sec                                          -      41     +41
find_pair                                            164     180     +16
run_list_real                                       2018    2028     +10
cmp_main                                             547     555      +8
collect_ctx                                          112     119      +7
singlemount                                         4544    4549      +5
time_main                                           1124    1128      +4
static.start_sec                                       -       4      +4
static.lastupdate_sec                                  -       4      +4
sock                                                   -       4      +4
read_package_field                                   253     257      +4
pick                                                  38      40      +2
get_next_line                                        145     147      +2
count_lines                                           59      61      +2
process_stdin                                        435     433      -2
xstrtoul_range_sfx                                   229     226      -3
static.initialized                                     4       1      -3
dhcprelay_main                                      1125    1122      -3
catcher                                              380     377      -3
arping_main                                         1969    1966      -3
s                                                      8       4      -4
cfg                                                    4       -      -4
static.lastupdate                                      8       -      -8
start                                                  8       -      -8
random_xid                                            95      33     -62
.rodata                                           129114  129050     -64
zcip_main                                           1731    1576    -155
progressmeter                                       1035     867    -168
------------------------------------------------------------------------------
(add/remove: 4/3 grow/shrink: 10/11 up/down: 113/-490)       Total: -377 bytes

2 files changed, 6 insertions, 12 deletions

diff --git a/networking/udhcp/clientpacket.c b/networking/udhcp/clientpacket.c
index 69d7f2d38..af97962a0 100644
--- a/networking/udhcp/clientpacket.c
+++ b/networking/udhcp/clientpacket.c
@@ -25,19 +25,13 @@
 
 
 /* Create a random xid */
-unsigned long random_xid(void)
+unsigned random_xid(void)
 {
-        static int initialized;
+        static smallint initialized;
+
         if (!initialized) {
-                unsigned long seed;
-
-                if (open_read_close("/dev/urandom", &seed, sizeof(seed)) < 0) {
-                        bb_info_msg("Cannot load seed "
-                                "from /dev/urandom: %s", strerror(errno));
-                        seed = time(0);
-                }
-                srand(seed);
-                initialized++;
+                srand(monotonic_us());
+                initialized = 1;
         }
         return rand();
 }
diff --git a/networking/udhcp/dhcpc.h b/networking/udhcp/dhcpc.h
index 4ddd12120..fa091bf72 100644
--- a/networking/udhcp/dhcpc.h
+++ b/networking/udhcp/dhcpc.h
@@ -38,7 +38,7 @@ extern struct client_config_t client_config;
 
 /*** clientpacket.h ***/
 
-unsigned long random_xid(void);
+unsigned random_xid(void);
 int send_discover(unsigned long xid, unsigned long requested);
 int send_selecting(unsigned long xid, unsigned long server, unsigned long requested);
 int send_renew(unsigned long xid, unsigned long server, unsigned long ciaddr);