udhcpc: add -o "do not request options by default" switch

(by L. Gabriel Somlo <somlo AT cmu.edu>)

function                                             old     new   delta
udhcpc_main                                         2513    2554     +41
static.udhcpc_longopts                               226     247     +21
add_param_req_option                                 119     132     +13
packed_usage                                       23952   23964     +12
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 4/0 up/down: 87/0)               Total: 87 bytes

4 files changed, 20 insertions, 8 deletions

diff --git a/networking/udhcp/clientpacket.c b/networking/udhcp/clientpacket.c
index 29d0d9a..f826c1b 100644
--- a/networking/udhcp/clientpacket.c
+++ b/networking/udhcp/clientpacket.c
@@ -62,17 +62,20 @@ static void add_param_req_option(struct dhcpMessage *packet)
 	int end = end_option(packet->options);
 	int i, len = 0;
 
-	packet->options[end + OPT_CODE] = DHCP_PARAM_REQ;
 	for (i = 0; (c = dhcp_options[i].code) != 0; i++) {
-		if ((dhcp_options[i].flags & OPTION_REQ)
+		if (((dhcp_options[i].flags & OPTION_REQ)
+                     && !client_config.no_default_options)
 		 || (client_config.opt_mask[c >> 3] & (1 << (c & 7)))
 		) {
 			packet->options[end + OPT_DATA + len] = c;
 			len++;
 		}
 	}
-	packet->options[end + OPT_LEN] = len;
-	packet->options[end + OPT_DATA + len] = DHCP_END;
+	if (len) {
+		packet->options[end + OPT_CODE] = DHCP_PARAM_REQ;
+		packet->options[end + OPT_LEN] = len;
+		packet->options[end + OPT_DATA + len] = DHCP_END;
+	}
 }
 
 
@@ -107,7 +110,9 @@ int send_discover(uint32_t xid, uint32_t requested)
 	/* Explicitly saying that we want RFC-compliant packets helps
 	 * some buggy DHCP servers to NOT send bigger packets */
 	add_simple_option(packet.options, DHCP_MAX_SIZE, htons(576));
+
 	add_param_req_option(&packet);
+
 	bb_info_msg("Sending discover...");
 	return udhcp_send_raw_packet(&packet, INADDR_ANY, CLIENT_PORT, INADDR_BROADCAST,
 			SERVER_PORT, MAC_BCAST_ADDR, client_config.ifindex);
@@ -125,8 +130,8 @@ int send_selecting(uint32_t xid, uint32_t server, uint32_t requested)
 
 	add_simple_option(packet.options, DHCP_REQUESTED_IP, requested);
 	add_simple_option(packet.options, DHCP_SERVER_ID, server);
-
 	add_param_req_option(&packet);
+
 	addr.s_addr = requested;
 	bb_info_msg("Sending select for %s...", inet_ntoa(addr));
 	return udhcp_send_raw_packet(&packet, INADDR_ANY, CLIENT_PORT, INADDR_BROADCAST,
diff --git a/networking/udhcp/dhcpc.c b/networking/udhcp/dhcpc.c
index bc06761..fb328cb 100644
--- a/networking/udhcp/dhcpc.c
+++ b/networking/udhcp/dhcpc.c
@@ -182,6 +182,7 @@ int udhcpc_main(int argc ATTRIBUTE_UNUSED, char **argv)
 		OPT_W = 1 << 21,
 #endif
 		OPT_P = 1 << 22,
+		OPT_o = 1 << 23,
 	};
 #if ENABLE_GETOPT_LONG
 	static const char udhcpc_longopts[] ALIGN1 =
@@ -211,6 +212,7 @@ int udhcpc_main(int argc ATTRIBUTE_UNUSED, char **argv)
 #if ENABLE_FEATURE_UDHCP_PORT
 		"client-port\0"	   Required_argument "P"
 #endif
+		"no-default-options\0" No_argument   "o"
 		;
 #endif
 	/* Default options. */
@@ -230,7 +232,7 @@ int udhcpc_main(int argc ATTRIBUTE_UNUSED, char **argv)
 	opt = getopt32(argv, "c:CV:fbH:h:F:i:np:qRr:s:T:t:vSA:"
 		USE_FEATURE_UDHCPC_ARPING("aW:")
 		USE_FEATURE_UDHCP_PORT("P:")
-		"O:"
+		"O:o"
 		, &str_c, &str_V, &str_h, &str_h, &str_F
 		, &client_config.interface, &client_config.pidfile, &str_r
 		, &client_config.script
@@ -291,6 +293,8 @@ int udhcpc_main(int argc ATTRIBUTE_UNUSED, char **argv)
 		SERVER_PORT = CLIENT_PORT - 1;
 	}
 #endif
+	if (opt & OPT_o)
+		client_config.no_default_options = 1;
 	while (list_O) {
 		int n = index_in_strings(dhcp_option_strings, list_O->data);
 		if (n < 0)
diff --git a/networking/udhcp/dhcpc.h b/networking/udhcp/dhcpc.h
index d0fde73..c8acd49 100644
--- a/networking/udhcp/dhcpc.h
+++ b/networking/udhcp/dhcpc.h
@@ -21,6 +21,7 @@ struct client_config_t {
 	char release_on_quit;           /* Perform release on quit */
 	char abort_if_no_lease;         /* Abort if no lease */
 	char background_if_no_lease;    /* Fork to background if no lease */
+	char no_default_options;        /* Do not include default optins in request */
 	const char *interface;          /* The name of the interface to use */
 	char *pidfile;                  /* Optionally store the process ID */
 	const char *script;             /* User script to run at dhcp events */
diff --git a/networking/udhcp/files.c b/networking/udhcp/files.c
index 6a93bd0..043a95b 100644
--- a/networking/udhcp/files.c
+++ b/networking/udhcp/files.c
@@ -396,6 +396,7 @@ void write_leases(void)
 	close(fp);
 
 	if (server_config.notify_file) {
+// TODO: vfork-based child creation
 		char *cmd = xasprintf("%s %s", server_config.notify_file, server_config.lease_file);
 		system(cmd);
 		free(cmd);
@@ -406,7 +407,7 @@ void write_leases(void)
 void read_leases(const char *file)
 {
 	int fp;
-	unsigned int i = 0;
+	unsigned i;
 	struct dhcpOfferedAddr lease;
 
 	fp = open_or_warn(file, O_RDONLY);
@@ -414,6 +415,7 @@ void read_leases(const char *file)
 		return;
 	}
 
+	i = 0;
 	while (i < server_config.max_leases
 	 && full_read(fp, &lease, sizeof(lease)) == sizeof(lease)
 	) {
@@ -422,7 +424,7 @@ void read_leases(const char *file)
 		if (y >= server_config.start_ip && y <= server_config.end_ip) {
 			lease.expires = ntohl(lease.expires);
 			if (!server_config.remaining)
-				lease.expires -= time(0);
+				lease.expires -= time(NULL);
 			if (!(add_lease(lease.chaddr, lease.yiaddr, lease.expires))) {
 				bb_error_msg("too many leases while loading %s", file);
 				break;