Move add_requests() from dhcpmsg.c to options.c. Fixes a layering violation.

Document an ugly-as-hell code bit in ifchange.c.
Add some debugging messages for the netlink response code.
Clean headers a bit more.

ndhc/dhcpmsg.c

@@ -99,22 +99,6 @@ static void init_packet(struct dhcpMessage *packet, char type)
     add_option_string(packet->options, (unsigned char *)&vendor_id);
 }
 
-/* Add a paramater request list for stubborn DHCP servers. Pull the data
- * from the struct in options.c. Don't do bounds checking here because it
- * goes towards the head of the packet. */
-static void add_requests(struct dhcpMessage *packet)
-{
-    int end = end_option(packet->options);
-    int i, len = 0;
-
-    packet->options[end + OPT_CODE] = DHCP_PARAM_REQ;
-    for (i = 0; options[i].code; i++)
-        if (options[i].flags & OPTION_REQ)
-            packet->options[end + OPT_DATA + len++] = options[i].code;
-    packet->options[end + OPT_LEN] = len;
-    packet->options[end + OPT_DATA + len] = DHCP_END;
-}
-
 #define MAC_BCAST_ADDR  (unsigned char *) "\xff\xff\xff\xff\xff\xff"
 /* Wrapper that broadcasts a raw dhcp packet on the bound interface. */
 static int bcast_raw_packet(struct dhcpMessage *packet)

ndhc/ifchange.c

@@ -69,7 +69,7 @@ static int fill_options(char *dest, unsigned char *option,
 
     if (!option)
         return -1;
-    int len = option[OPT_LEN - 2];
+    int len = option[-1]; // XXX: WTF ugly as all hell
 
     odest = dest;
 

ndhc/netlink.c

@@ -132,6 +132,7 @@ static void nl_handlemsg(struct nlmsghdr *msg, unsigned int len,
                                 if (cs->dhcpState == DS_BOUND) {
                                     /* arp_check_gw(cs); */
                                 } else if (cs->dhcpState != DS_INIT_SELECTING) {
+                                    log_line("nl: taking down interface");
                                     // Same as packet.c: line 258
                                     ifchange(NULL, IFCHANGE_DECONFIG);
                                     cs->dhcpState = DS_INIT_SELECTING;

ndhc/options.c

@@ -13,6 +13,12 @@
 #include "log.h"
 #include "malloc.h"
 
+enum {
+    OPT_CODE = 0,
+    OPT_LEN  = 1,
+    OPT_DATA = 2
+};
+
 /* supported options are easily added here */
 struct dhcp_option options[] = {
     /* name[10]     flags                                   code */
@@ -242,3 +248,19 @@ struct option_set *find_option(struct option_set *opt_list, char code)
 		return opt_list;
 	return NULL;
 }
+
+/* Add a paramater request list for stubborn DHCP servers. Pull the data
+ * from the struct in options.c. Don't do bounds checking here because it
+ * goes towards the head of the packet. */
+void add_requests(struct dhcpMessage *packet)
+{
+    int end = end_option(packet->options);
+    int i, len = 0;
+
+    packet->options[end + OPT_CODE] = DHCP_PARAM_REQ;
+    for (i = 0; options[i].code; i++)
+        if (options[i].flags & OPTION_REQ)
+            packet->options[end + OPT_DATA + len++] = options[i].code;
+    packet->options[end + OPT_LEN] = len;
+    packet->options[end + OPT_DATA + len] = DHCP_END;
+}

ndhc/options.h

@@ -68,12 +68,6 @@ enum {
 #define OPTION_REQ	0x10 /* have the client request this option */
 #define OPTION_LIST	0x20 /* There can be a list of 1 or more of these */
 
-enum {
-    OPT_CODE = 0,
-    OPT_LEN  = 1,
-    OPT_DATA = 2
-};
-
 struct dhcp_option {
 	char name[10];
 	char flags;
@@ -103,4 +97,6 @@ int add_option_string(unsigned char *optionptr, unsigned char *string);
 int add_simple_option(unsigned char *optionptr, unsigned char code, uint32_t data);
 struct option_set *find_option(struct option_set *opt_list, char code);
 
+void add_requests(struct dhcpMessage *packet);
+
 #endif