udhcpc: shrink code by setting xid more economically

function                                             old     new   delta
send_decline                                          90      82      -8
udhcpc_main                                         2649    2640      -9

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

diff --git a/networking/udhcp/dhcpc.c b/networking/udhcp/dhcpc.c
index 43d68234135bf352b97001b0a135f1d3ffa08c48..945600c6bfc8c09682bebb310e719981539c9746 100644 (file)
--- a/networking/udhcp/dhcpc.c
+++ b/networking/udhcp/dhcpc.c
@@ -726,7 +726,7 @@ static NOINLINE int send_renew(uint32_t xid, uint32_t server, uint32_t ciaddr)
 #if ENABLE_FEATURE_UDHCPC_ARPING
 /* Broadcast a DHCP decline message */
 /* NOINLINE: limit stack usage in caller */
-static NOINLINE int send_decline(uint32_t xid, uint32_t server, uint32_t requested)
+static NOINLINE int send_decline(/*uint32_t xid,*/ uint32_t server, uint32_t requested)
 {
        struct dhcp_packet packet;
 
@@ -735,12 +735,14 @@ static NOINLINE int send_decline(uint32_t xid, uint32_t server, uint32_t request
         */
        init_packet(&packet, DHCPDECLINE);
 
+#if 0
        /* RFC 2131 says DHCPDECLINE's xid is randomly selected by client,
         * but in case the server is buggy and wants DHCPDECLINE's xid
         * to match the xid which started entire handshake,
         * we use the same xid we used in initial DHCPDISCOVER:
         */
        packet.xid = xid;
+#endif
        /* DHCPDECLINE uses "requested ip", not ciaddr, to store offered IP */
        udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
 
@@ -1131,7 +1133,7 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv)
        int discover_retries = 3;
        uint32_t server_addr = server_addr; /* for compiler */
        uint32_t requested_ip = 0;
-       uint32_t xid = 0;
+       uint32_t xid = xid; /* for compiler */
        int packet_num;
        int timeout; /* must be signed */
        unsigned already_waited_sec;
@@ -1520,7 +1522,7 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv)
 
                switch (state) {
                case INIT_SELECTING:
-                       /* Must be a DHCPOFFER to one of our xid's */
+                       /* Must be a DHCPOFFER */
                        if (*message == DHCPOFFER) {
 /* What exactly is server's IP? There are several values.
  * Example DHCP offer captured with tchdump:
@@ -1600,7 +1602,7 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv)
                                        ) {
                                                bb_info_msg("Offered address is in use "
                                                        "(got ARP reply), declining");
-                                               send_decline(xid, server_addr, packet.yiaddr);
+                                               send_decline(/*xid,*/ server_addr, packet.yiaddr);
 
                                                if (state != REQUESTING)
                                                        udhcp_run_script(NULL, "deconfig");
@@ -1637,6 +1639,8 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv)
                                        opt = ((opt & ~OPT_b) | OPT_f);
                                }
 #endif
+                               /* make future renew packets use different xid */
+                               /* xid = random_xid(); ...but why bother? */
                                already_waited_sec = 0;
                                continue; /* back to main loop */
                        }