optimize 16- and 32-bit moves

function                                             old     new   delta
udhcpd_main                                         1239    1257     +18
udhcp_add_simple_option                               93      92      -1
buffer_read_le_u32                                    19      18      -1
unpack_gz_stream_with_info                           526     520      -6
dnsd_main                                           1470    1463      -7
udhcp_run_script                                    1208    1186     -22
send_ACK                                             255     229     -26
arping_main                                         1661    1623     -38
send_offer                                           470     428     -42
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/8 up/down: 18/-143)          Total: -125 bytes

1 files changed, 16 insertions, 7 deletions

diff --git a/networking/arping.c b/networking/arping.c
index e4429973b..e7b842f5b 100644
--- a/networking/arping.c
+++ b/networking/arping.c
@@ -153,6 +153,15 @@ static bool recv_pack(unsigned char *buf, int len, struct sockaddr_ll *FROM)
         struct arphdr *ah = (struct arphdr *) buf;
         unsigned char *p = (unsigned char *) (ah + 1);
         struct in_addr src_ip, dst_ip;
+        /* moves below assume in_addr is 4 bytes big, ensure that */
+        struct BUG_in_addr_must_be_4 {
+                char BUG_in_addr_must_be_4[
+                        sizeof(struct in_addr) == 4 ? 1 : -1
+                ];
+                char BUG_s_addr_must_be_4[
+                        sizeof(src_ip.s_addr) == 4 ? 1 : -1
+                ];
+        };
 
         /* Filter out wild packets */
         if (FROM->sll_pkttype != PACKET_HOST
@@ -171,13 +180,13 @@ static bool recv_pack(unsigned char *buf, int len, struct sockaddr_ll *FROM)
 
         /* Protocol must be IP. */
         if (ah->ar_pro != htons(ETH_P_IP)
-                || (ah->ar_pln != 4)
-                || (ah->ar_hln != me.sll_halen)
-                || (len < (int)(sizeof(*ah) + 2 * (4 + ah->ar_hln))))
+         || (ah->ar_pln != 4)
+         || (ah->ar_hln != me.sll_halen)
+         || (len < (int)(sizeof(*ah) + 2 * (4 + ah->ar_hln))))
                 return false;
 
-        memcpy(&src_ip, p + ah->ar_hln, 4);
-        memcpy(&dst_ip, p + ah->ar_hln + 4 + ah->ar_hln, 4);
+        move_from_unaligned32(src_ip.s_addr, p + ah->ar_hln);
+        move_from_unaligned32(dst_ip.s_addr, p + ah->ar_hln + 4 + ah->ar_hln);
 
         if (dst.s_addr != src_ip.s_addr)
                 return false;
@@ -200,7 +209,7 @@ static bool recv_pack(unsigned char *buf, int len, struct sockaddr_ll *FROM)
                    dst_ip/dst_hw do not matter.
                  */
                 if ((memcmp(p, &me.sll_addr, me.sll_halen) == 0)
-                        || (src.s_addr && src.s_addr != dst_ip.s_addr))
+                 || (src.s_addr && src.s_addr != dst_ip.s_addr))
                         return false;
         }
         if (!(option_mask32 & QUIET)) {
@@ -306,7 +315,7 @@ int arping_main(int argc UNUSED_PARAM, char **argv)
         /* if (!inet_aton(target, &dst)) - not needed */ {
                 len_and_sockaddr *lsa;
                 lsa = xhost_and_af2sockaddr(target, 0, AF_INET);
-                memcpy(&dst, &lsa->u.sin.sin_addr.s_addr, 4);
+                dst = lsa->u.sin.sin_addr;
                 if (ENABLE_FEATURE_CLEAN_UP)
                         free(lsa);
         }