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

5 files changed, 23 insertions, 10 deletions

diff --git a/networking/ifupdown.c b/networking/ifupdown.c
index 7c31448e8..50b96261b 100644
--- a/networking/ifupdown.c
+++ b/networking/ifupdown.c
@@ -476,7 +476,8 @@ static const struct dhcp_client_t ext_dhcp_clients[] = {
                 "pump -i %iface% -k",
         },
         { "udhcpc",
-                "udhcpc -R -n -p /var/run/udhcpc.%iface%.pid -i %iface%[[ -H %hostname%]][[ -c %clientid%]][[ -s %script%]][[ -t %retries%]]",
+                "udhcpc -R -n -p /var/run/udhcpc.%iface%.pid -i %iface%[[ -H %hostname%]][[ -c %clientid%]]"
+                                "[[ -s %script%]][[ %udhcpc_opts%]]",
                 "kill `cat /var/run/udhcpc.%iface%.pid` 2>/dev/null",
         },
 };
@@ -507,7 +508,7 @@ static int dhcp_up(struct interface_defn_t *ifd, execfn *exec)
                 return 0;
 #endif
         return execute("udhcpc -R -n -p /var/run/udhcpc.%iface%.pid "
-                        "-i %iface%[[ -H %hostname%]][[ -c %clientid%]][[ -s %script%]][[ -t %retries%]]",
+                        "-i %iface%[[ -H %hostname%]][[ -c %clientid%]][[ -s %script%]][[ %udhcpc_opts%]]",
                         ifd, exec);
 }
 #else
diff --git a/networking/udhcp/clientpacket.c b/networking/udhcp/clientpacket.c
index 29d0d9a1d..f826c1b94 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 bc0676152..fb328cb03 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 d0fde7302..c8acd4982 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 6a93bd0e2..043a95bb0 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;