udhcpc: support for -O <option>.

Two important notes:
* nissrv and nisdomain are not requested by default anymore!
* inconsistency between "XXXsvr" and "XXsrv" in option names resolved,
  all are "XXXsrv" now.

function                                             old     new   delta
udhcpc_main                                         2494    2600    +106
packed_usage                                       23023   23067     +44
add_requests                                          91     119     +28
static.udhcpc_longopts                               209     226     +17
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 4/0 up/down: 195/0)             Total: 195 bytes

5 files changed, 97 insertions, 78 deletions

diff --git a/include/usage.h b/include/usage.h
index f6506b4f8..12d2cefd9 100644
--- a/include/usage.h
+++ b/include/usage.h
@@ -3840,7 +3840,7 @@ USE_FEATURE_RUN_PARTS_FANCY("\n	-l	Prints names of all matching files even when
 
 #define udhcpc_trivial_usage \
        "[-Cfbnqtv] [-c CID] [-V VCLS] [-H HOSTNAME] [-i INTERFACE]\n" \
-       "        [-p pidfile] [-r IP] [-s script]"
+       "        [-p pidfile] [-r IP] [-s script] [-O dhcp-option]..."
 #define udhcpc_full_usage \
         USE_GETOPT_LONG( \
        "        -V,--vendorclass=CLASSID        Vendor class identifier" \
@@ -3860,6 +3860,7 @@ USE_FEATURE_RUN_PARTS_FANCY("\n	-l	Prints names of all matching files even when
        "\n      -n,--now        Exit with failure if lease is not immediately obtained" \
        "\n      -q,--quit       Quit after obtaining lease" \
        "\n      -R,--release    Release IP on quit" \
+       "\n      -O,--request-option=OPT Request DHCP option OPT from server" \
         USE_FEATURE_UDHCPC_ARPING( \
        "\n      -a,--arping     Use arping to validate offered address" \
         ) \
@@ -3882,6 +3883,7 @@ USE_FEATURE_RUN_PARTS_FANCY("\n	-l	Prints names of all matching files even when
        "\n      -n              Exit with failure if lease is not immediately obtained" \
        "\n      -q              Quit after obtaining lease" \
        "\n      -R              Release IP on quit" \
+       "\n      -O OPT          Request DHCP option OPT from server" \
         USE_FEATURE_UDHCPC_ARPING( \
        "\n      -a              Use arping to validate offered address" \
         ) \
diff --git a/networking/udhcp/clientpacket.c b/networking/udhcp/clientpacket.c
index 406fe340a..54f3f0e49 100644
--- a/networking/udhcp/clientpacket.c
+++ b/networking/udhcp/clientpacket.c
@@ -57,13 +57,18 @@ static void init_packet(struct dhcpMessage *packet, char type)
  * goes towards the head of the packet. */
 static void add_requests(struct dhcpMessage *packet)
 {
+        uint8_t c;
         int end = end_option(packet->options);
         int i, len = 0;
 
         packet->options[end + OPT_CODE] = DHCP_PARAM_REQ;
-        for (i = 0; dhcp_options[i].code; i++)
-                if (dhcp_options[i].flags & OPTION_REQ)
-                        packet->options[end + OPT_DATA + len++] = dhcp_options[i].code;
+        for (i = 0; (c = dhcp_options[i].code) != 0; i++) {
+                if (dhcp_options[i].flags & OPTION_REQ
+                 || (client_config.opt_mask[c >> 3] & (1 << (c & 7)))
+                ) {
+                        packet->options[end + OPT_DATA + len++] = c;
+                }
+        }
         packet->options[end + OPT_LEN] = len;
         packet->options[end + OPT_DATA + len] = DHCP_END;
 
diff --git a/networking/udhcp/dhcpc.c b/networking/udhcp/dhcpc.c
index d8077f7e8..69c35ca50 100644
--- a/networking/udhcp/dhcpc.c
+++ b/networking/udhcp/dhcpc.c
@@ -133,6 +133,7 @@ int udhcpc_main(int argc, char **argv)
 {
         uint8_t *temp, *message;
         char *str_c, *str_V, *str_h, *str_F, *str_r, *str_T, *str_A, *str_t;
+        llist_t *list_O = NULL;
 #if ENABLE_FEATURE_UDHCPC_ARPING
         char *str_W;
 #endif
@@ -183,28 +184,29 @@ int udhcpc_main(int argc, char **argv)
         };
 #if ENABLE_GETOPT_LONG
         static const char udhcpc_longopts[] ALIGN1 =
-                "clientid\0"      Required_argument "c"
-                "clientid-none\0" No_argument       "C"
-                "vendorclass\0"   Required_argument "V"
-                "foreground\0"    No_argument       "f"
-                "background\0"    No_argument       "b"
-                "hostname\0"      Required_argument "H"
-                "fqdn\0"          Required_argument "F"
-                "interface\0"     Required_argument "i"
-                "now\0"           No_argument       "n"
-                "pidfile\0"       Required_argument "p"
-                "quit\0"          No_argument       "q"
-                "release\0"       No_argument       "R"
-                "request\0"       Required_argument "r"
-                "script\0"        Required_argument "s"
-                "timeout\0"       Required_argument "T"
-                "version\0"       No_argument       "v"
-                "retries\0"       Required_argument "t"
-                "tryagain\0"      Required_argument "A"
-                "syslog\0"        No_argument       "S"
+                "clientid\0"       Required_argument "c"
+                "clientid-none\0"  No_argument       "C"
+                "vendorclass\0"    Required_argument "V"
+                "foreground\0"     No_argument       "f"
+                "background\0"     No_argument       "b"
+                "hostname\0"       Required_argument "H"
+                "fqdn\0"           Required_argument "F"
+                "interface\0"      Required_argument "i"
+                "now\0"            No_argument       "n"
+                "pidfile\0"        Required_argument "p"
+                "quit\0"           No_argument       "q"
+                "release\0"        No_argument       "R"
+                "request\0"        Required_argument "r"
+                "script\0"         Required_argument "s"
+                "timeout\0"        Required_argument "T"
+                "version\0"        No_argument       "v"
+                "retries\0"        Required_argument "t"
+                "tryagain\0"       Required_argument "A"
+                "syslog\0"         No_argument       "S"
 #if ENABLE_FEATURE_UDHCPC_ARPING
-                "arping\0"        No_argument       "a"
+                "arping\0"         No_argument       "a"
 #endif
+                "request-option\0" Required_argument "O"
                 ;
 #endif
         /* Default options. */
@@ -212,16 +214,18 @@ int udhcpc_main(int argc, char **argv)
         client_config.script = DEFAULT_SCRIPT;
 
         /* Parse command line */
-        opt_complementary = "c--C:C--c"; // mutually exclusive
+        opt_complementary = "c--C:C--c:O::"; // Cc: mutually exclusive; O: list
 #if ENABLE_GETOPT_LONG
         applet_long_options = udhcpc_longopts;
 #endif
         opt = getopt32(argv, "c:CV:fbH:h:F:i:np:qRr:s:T:t:vSA:"
                 USE_FEATURE_UDHCPC_ARPING("aW:")
-                , &str_c, &str_V, &str_h, &str_h, &str_F,
-                &client_config.interface, &client_config.pidfile, &str_r,
-                &client_config.script, &str_T, &str_t, &str_A
+                "O:"
+                , &str_c, &str_V, &str_h, &str_h, &str_F
+                , &client_config.interface, &client_config.pidfile, &str_r
+                , &client_config.script, &str_T, &str_t, &str_A
                 USE_FEATURE_UDHCPC_ARPING(, &str_W)
+                , &list_O
                 );
 
         if (opt & OPT_c)
@@ -268,11 +272,18 @@ int udhcpc_main(int argc, char **argv)
                 puts("version "BB_VER);
                 return 0;
         }
-
         if (opt & OPT_S) {
                 openlog(applet_name, LOG_PID, LOG_LOCAL0);
                 logmode |= LOGMODE_SYSLOG;
         }
+        while (list_O) {
+                int n = index_in_strings(dhcp_option_strings, list_O->data);
+                if (n < 0)
+                        bb_error_msg_and_die("unknown option '%s'", list_O->data);
+                n = dhcp_options[n].code;
+                client_config.opt_mask[n >> 3] |= 1 << (n & 7);
+                list_O = list_O->link;
+        }
 
         if (read_interface(client_config.interface, &client_config.ifindex,
                            NULL, client_config.arp))
diff --git a/networking/udhcp/dhcpc.h b/networking/udhcp/dhcpc.h
index c0172a84f..e818896c9 100644
--- a/networking/udhcp/dhcpc.h
+++ b/networking/udhcp/dhcpc.h
@@ -30,6 +30,7 @@ struct client_config_t {
         uint8_t *fqdn;                  /* Optional fully qualified domain name to use */
         int ifindex;                    /* Index number of the interface to use */
         uint8_t arp[6];                 /* Our arp address */
+        uint8_t opt_mask[256 / 8];      /* Bitmask of options to send (-O option) */
 };
 
 #define client_config (*(struct client_config_t*)&bb_common_bufsiz1)
diff --git a/networking/udhcp/options.c b/networking/udhcp/options.c
index c224f3670..12e566210 100644
--- a/networking/udhcp/options.c
+++ b/networking/udhcp/options.c
@@ -11,49 +11,49 @@
 
 /* Supported options are easily added here */
 const struct dhcp_option dhcp_options[] = {
-        /* flags                                     code */
-        { OPTION_IP | OPTION_REQ,                    0x01 }, /* DHCP_SUBNET        */
-        { OPTION_S32,                                0x02 }, /* DHCP_TIME_OFFSET   */
-        { OPTION_IP | OPTION_LIST | OPTION_REQ,      0x03 }, /* DHCP_ROUTER        */
-        { OPTION_IP | OPTION_LIST,                   0x04 }, /* DHCP_TIME_SERVER   */
-        { OPTION_IP | OPTION_LIST,                   0x05 }, /* DHCP_NAME_SERVER   */
-        { OPTION_IP | OPTION_LIST | OPTION_REQ,      0x06 }, /* DHCP_DNS_SERVER    */
-        { OPTION_IP | OPTION_LIST,                   0x07 }, /* DHCP_LOG_SERVER    */
-        { OPTION_IP | OPTION_LIST,                   0x08 }, /* DHCP_COOKIE_SERVER */
-        { OPTION_IP | OPTION_LIST,                   0x09 }, /* DHCP_LPR_SERVER    */
-        { OPTION_STRING | OPTION_REQ,                0x0c }, /* DHCP_HOST_NAME     */
-        { OPTION_U16,                                0x0d }, /* DHCP_BOOT_SIZE     */
-        { OPTION_STRING | OPTION_LIST | OPTION_REQ,  0x0f }, /* DHCP_DOMAIN_NAME   */
-        { OPTION_IP,                                 0x10 }, /* DHCP_SWAP_SERVER   */
-        { OPTION_STRING,                             0x11 }, /* DHCP_ROOT_PATH     */
-        { OPTION_U8,                                 0x17 }, /* DHCP_IP_TTL        */
-        { OPTION_U16,                                0x1a }, /* DHCP_MTU           */
-        { OPTION_IP | OPTION_REQ,                    0x1c }, /* DHCP_BROADCAST     */
-        { OPTION_STRING | OPTION_REQ,                0x28 }, /* DHCP_NTP_SERVER    */
-        { OPTION_IP | OPTION_LIST | OPTION_REQ,      0x29 }, /* DHCP_WINS_SERVER   */
-        { OPTION_IP | OPTION_LIST | OPTION_REQ,      0x2a }, /* DHCP_REQUESTED_IP  */
-        { OPTION_IP | OPTION_LIST,                   0x2c }, /* DHCP_LEASE_TIME    */
-        { OPTION_IP,                                 0x32 }, /* DHCP_OPTION_OVER   */
-        { OPTION_U32,                                0x33 }, /* DHCP_MESSAGE_TYPE  */
-        { OPTION_U8,                                 0x35 }, /* DHCP_SERVER_ID     */
-        { OPTION_IP,                                 0x36 }, /* DHCP_PARAM_REQ     */
-        { OPTION_STRING,                             0x38 }, /* DHCP_MESSAGE       */
-        { OPTION_STRING,                             0x3C }, /* DHCP_VENDOR        */
-        { OPTION_STRING,                             0x3D }, /* DHCP_CLIENT_ID     */
-        { OPTION_STRING,                             0x42 }, /* "tftp"             */
-        { OPTION_STRING,                             0x43 }, /* "bootfile"         */
-        { OPTION_STRING,                             0x4D }, /* "userclass"        */
+        /* flags                                    code */
+        { OPTION_IP                   | OPTION_REQ, 0x01 }, /* DHCP_SUBNET        */
+        { OPTION_S32                              , 0x02 }, /* DHCP_TIME_OFFSET   */
+        { OPTION_IP | OPTION_LIST     | OPTION_REQ, 0x03 }, /* DHCP_ROUTER        */
+        { OPTION_IP | OPTION_LIST                 , 0x04 }, /* DHCP_TIME_SERVER   */
+        { OPTION_IP | OPTION_LIST                 , 0x05 }, /* DHCP_NAME_SERVER   */
+        { OPTION_IP | OPTION_LIST     | OPTION_REQ, 0x06 }, /* DHCP_DNS_SERVER    */
+        { OPTION_IP | OPTION_LIST                 , 0x07 }, /* DHCP_LOG_SERVER    */
+        { OPTION_IP | OPTION_LIST                 , 0x08 }, /* DHCP_COOKIE_SERVER */
+        { OPTION_IP | OPTION_LIST                 , 0x09 }, /* DHCP_LPR_SERVER    */
+        { OPTION_STRING               | OPTION_REQ, 0x0c }, /* DHCP_HOST_NAME     */
+        { OPTION_U16                              , 0x0d }, /* DHCP_BOOT_SIZE     */
+        { OPTION_STRING | OPTION_LIST | OPTION_REQ, 0x0f }, /* DHCP_DOMAIN_NAME   */
+        { OPTION_IP                               , 0x10 }, /* DHCP_SWAP_SERVER   */
+        { OPTION_STRING                           , 0x11 }, /* DHCP_ROOT_PATH     */
+        { OPTION_U8                               , 0x17 }, /* DHCP_IP_TTL        */
+        { OPTION_U16                              , 0x1a }, /* DHCP_MTU           */
+        { OPTION_IP                   | OPTION_REQ, 0x1c }, /* DHCP_BROADCAST     */
+        { OPTION_STRING                           , 0x28 }, /* nisdomain          */
+        { OPTION_IP | OPTION_LIST                 , 0x29 }, /* nissrv             */
+        { OPTION_IP | OPTION_LIST     | OPTION_REQ, 0x2a }, /* DHCP_NTP_SERVER    */
+        { OPTION_IP | OPTION_LIST                 , 0x2c }, /* DHCP_WINS_SERVER   */
+        { OPTION_IP                               , 0x32 }, /* DHCP_REQUESTED_IP  */
+        { OPTION_U32                              , 0x33 }, /* DHCP_LEASE_TIME    */
+        { OPTION_U8                               , 0x35 }, /* dhcptype           */
+        { OPTION_IP                               , 0x36 }, /* DHCP_SERVER_ID     */
+        { OPTION_STRING                           , 0x38 }, /* DHCP_MESSAGE       */
+        { OPTION_STRING                           , 0x3C }, /* DHCP_VENDOR        */
+        { OPTION_STRING                           , 0x3D }, /* DHCP_CLIENT_ID     */
+        { OPTION_STRING                           , 0x42 }, /* tftp               */
+        { OPTION_STRING                           , 0x43 }, /* bootfile           */
+        { OPTION_STRING                           , 0x4D }, /* userclass          */
 #if ENABLE_FEATURE_RFC3397
-        { OPTION_STR1035 | OPTION_LIST | OPTION_REQ, 0x77 }, /* "search"           */
+        { OPTION_STR1035 | OPTION_LIST            , 0x77 }, /* search             */
 #endif
         /* MSIE's "Web Proxy Autodiscovery Protocol" support */
-        { OPTION_STRING,                             0xfc }, /* "wpad"             */
+        { OPTION_STRING                           , 0xfc }, /* wpad               */
 
         /* Options below have no match in dhcp_option_strings[],
          * are not passed to dhcpc scripts, and cannot be specified
          * with "option XXX YYY" syntax in dhcpd config file. */
 
-        { OPTION_U16,                                0x39 }, /* DHCP_MAX_SIZE      */
+        { OPTION_U16                              , 0x39 }, /* DHCP_MAX_SIZE      */
         { } /* zeroed terminating entry */
 };
 
@@ -64,28 +64,28 @@ const char dhcp_option_strings[] ALIGN1 =
         "subnet" "\0"      /* DHCP_SUBNET         */
         "timezone" "\0"    /* DHCP_TIME_OFFSET    */
         "router" "\0"      /* DHCP_ROUTER         */
-        "timesvr" "\0"     /* DHCP_TIME_SERVER    */
-        "namesvr" "\0"     /* DHCP_NAME_SERVER    */
+        "timesrv" "\0"     /* DHCP_TIME_SERVER    */
+        "namesrv" "\0"     /* DHCP_NAME_SERVER    */
         "dns" "\0"         /* DHCP_DNS_SERVER     */
-        "logsvr" "\0"      /* DHCP_LOG_SERVER     */
-        "cookiesvr" "\0"   /* DHCP_COOKIE_SERVER  */
-        "lprsvr" "\0"      /* DHCP_LPR_SERVER     */
+        "logsrv" "\0"      /* DHCP_LOG_SERVER     */
+        "cookiesrv" "\0"   /* DHCP_COOKIE_SERVER  */
+        "lprsrv" "\0"      /* DHCP_LPR_SERVER     */
         "hostname" "\0"    /* DHCP_HOST_NAME      */
         "bootsize" "\0"    /* DHCP_BOOT_SIZE      */
         "domain" "\0"      /* DHCP_DOMAIN_NAME    */
-        "swapsvr" "\0"     /* DHCP_SWAP_SERVER    */
+        "swapsrv" "\0"     /* DHCP_SWAP_SERVER    */
         "rootpath" "\0"    /* DHCP_ROOT_PATH      */
         "ipttl" "\0"       /* DHCP_IP_TTL         */
         "mtu" "\0"         /* DHCP_MTU            */
         "broadcast" "\0"   /* DHCP_BROADCAST      */
-        "nisdomain" "\0"   /* DHCP_NTP_SERVER     */
-        "nissrv" "\0"      /* DHCP_WINS_SERVER    */
-        "ntpsrv" "\0"      /* DHCP_REQUESTED_IP   */
-        "wins" "\0"        /* DHCP_LEASE_TIME     */
-        "requestip" "\0"   /* DHCP_OPTION_OVER    */
-        "lease" "\0"       /* DHCP_MESSAGE_TYPE   */
-        "dhcptype" "\0"    /* DHCP_SERVER_ID      */
-        "serverid" "\0"    /* DHCP_PARAM_REQ      */
+        "nisdomain" "\0"   /*                     */
+        "nissrv" "\0"      /*                     */
+        "ntpsrv" "\0"      /* DHCP_NTP_SERVER     */
+        "wins" "\0"        /* DHCP_WINS_SERVER    */
+        "requestip" "\0"   /* DHCP_REQUESTED_IP   */
+        "lease" "\0"       /* DHCP_LEASE_TIME     */
+        "dhcptype" "\0"    /*                     */
+        "serverid" "\0"    /* DHCP_SERVER_ID      */
         "message" "\0"     /* DHCP_MESSAGE        */
         "vendorclass" "\0" /* DHCP_VENDOR         */
         "clientid" "\0"    /* DHCP_CLIENT_ID      */