udhcp: add inline docs; small code shrink

function                                             old     new   delta
send_packet                                          103      87     -16
udhcpc_main                                         2359    2323     -36

1 files changed, 14 insertions, 9 deletions

diff --git a/networking/udhcp/dhcpc.c b/networking/udhcp/dhcpc.c
index 8985cc705..2d48980d9 100644
--- a/networking/udhcp/dhcpc.c
+++ b/networking/udhcp/dhcpc.c
@@ -452,7 +452,7 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv)
                 }
 
                 /* select() didn't timeout, something did happen. */
-                /* Is is a packet? */
+                /* Is it a packet? */
                 if (listen_mode != LISTEN_NONE && FD_ISSET(sockfd, &rfds)) {
                         int len;
                         /* A packet is ready, read it */
@@ -474,7 +474,7 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv)
                                 continue;
 
                         if (packet.xid != xid) {
-                                DEBUG("Ignoring XID %x (our xid is %x)",
+                                DEBUG("Ignoring xid %x (our xid is %x)",
                                         (unsigned)packet.xid, (unsigned)xid);
                                 continue;
                         }
@@ -524,17 +524,24 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv)
                                                 bb_error_msg("no lease time with ACK, using 1 hour lease");
                                                 lease_seconds = 60 * 60;
                                         } else {
-                                                /* can be misaligned, thus memcpy */
-                                                memcpy(&lease_seconds, temp, 4);
+                                                /* it IS unaligned sometimes, don't "optimize" */
+                                                lease_seconds = get_unaligned_u32p((uint32_t*)temp);
                                                 lease_seconds = ntohl(lease_seconds);
                                                 lease_seconds &= 0x0fffffff; /* paranoia: must not be prone to overflows */
                                                 if (lease_seconds < 10) /* and not too small */
                                                         lease_seconds = 10;
                                         }
-//FIXME: why do we check ARP only after we've got DHCPACK?
-//Shouldn't we do it immediately after DHCPOFFER?
 #if ENABLE_FEATURE_UDHCPC_ARPING
                                         if (opt & OPT_a) {
+/* RFC 2131 3.1 paragraph 5:
+ * "The client receives the DHCPACK message with configuration
+ * parameters. The client SHOULD perform a final check on the
+ * parameters (e.g., ARP for allocated network address), and notes
+ * the duration of the lease specified in the DHCPACK message. At this
+ * point, the client is configured. If the client detects that the
+ * address is already in use (e.g., through the use of ARP),
+ * the client MUST send a DHCPDECLINE message to the server and restarts
+ * the configuration process..." */
                                                 if (!arpping(packet.yiaddr,
                                                             (uint32_t) 0,
                                                             client_config.arp,
@@ -542,8 +549,6 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv)
                                                 ) {
                                                         bb_info_msg("offered address is in use "
                                                                 "(got ARP reply), declining");
-//NB: not clear whether it should be unicast or bcast.
-//Currently it is a bcast. Why?
                                                         send_decline(xid, server_addr, packet.yiaddr);
 
                                                         if (state != REQUESTING)
@@ -568,7 +573,7 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv)
                                         }
                                         requested_ip = packet.yiaddr;
                                         udhcp_run_script(&packet,
-                                                   ((state == RENEWING || state == REBINDING) ? "renew" : "bound"));
+                                                        ((state == RENEWING || state == REBINDING) ? "renew" : "bound"));
 
                                         state = BOUND;
                                         change_listen_mode(LISTEN_NONE);