udhcpc6: make -O OPT work

Patch is based on work by tiggerswelt.net.

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 109 insertions, 41 deletions

diff --git a/networking/udhcp/d6_dhcpc.c b/networking/udhcp/d6_dhcpc.c
index ef9b9a5f2..f6d3fb98b 100644
--- a/networking/udhcp/d6_dhcpc.c
+++ b/networking/udhcp/d6_dhcpc.c
@@ -2,26 +2,49 @@
 /*
  * DHCPv6 client.
  *
- * 2011-11.
- * WARNING: THIS CODE IS INCOMPLETE. IT IS NOWHERE NEAR
- * TO BE READY FOR PRODUCTION USE.
+ * WARNING: THIS CODE IS INCOMPLETE.
  *
- * Copyright (C) 2011 Denys Vlasenko.
+ * Copyright (C) 2011-2017 Denys Vlasenko.
  *
  * Licensed under GPLv2, see file LICENSE in this source tree.
  */
 
 //config:config UDHCPC6
-//config:       bool "udhcpc6 (DHCPv6 client, NOT READY)"
+//config:       bool "udhcpc6 (DHCPv6 client, EXPERIMENTAL)"
 //config:       default n  # not yet ready
 //config:       depends on FEATURE_IPV6
 //config:       help
 //config:         udhcpc6 is a DHCPv6 client
+//config:
+//config:config FEATURE_UDHCPC6_RFC3646
+//config:       bool "Support RFC 3646 (DNS server and search list)"
+//config:       default y
+//config:       depends on UDHCPC6
+//config:       help
+//config:         List of DNS servers and domain search list can be requested with
+//config:         "-O dns" and "-O search". If server gives these values,
+//config:         they will be set in environment variables "dns" and "search".
+//config:
+//config:config FEATURE_UDHCPC6_RFC4704
+//config:       bool "Support RFC 4704 (Client FQDN)"
+//config:       default y
+//config:       depends on UDHCPC6
+//config:       help
+//config:         You can request FQDN to be given by server using "-O fqdn".
+//config:
+//config:config FEATURE_UDHCPC6_RFC4833
+//config:       bool "Support RFC 4833 (Timezones)"
+//config:       default y
+//config:       depends on UDHCPC6
+//config:       help
+//config:         You can request POSIX timezone with "-O tz" and timezone name
+//config:         with "-O timezone".
 
 //applet:IF_UDHCPC6(APPLET(udhcpc6, BB_DIR_USR_BIN, BB_SUID_DROP))
 
 //kbuild:lib-$(CONFIG_UDHCPC6) += d6_dhcpc.o d6_packet.o d6_socket.o common.o socket.o signalpipe.o
-
+//kbuild:lib-$(CONFIG_FEATURE_UDHCPC6_RFC3646) += domain_codec.o
+//kbuild:lib-$(CONFIG_FEATURE_UDHCPC6_RFC4704) += domain_codec.o
 
 #include <syslog.h>
 /* Override ENABLE_FEATURE_PIDFILE - ifupdown needs our pidfile to always exist */
@@ -37,6 +60,34 @@
 
 /* "struct client_config_t client_config" is in bb_common_bufsiz1 */
 
+static const struct dhcp_optflag d6_optflags[] = {
+#if ENABLE_FEATURE_UDHCPC6_RFC3646
+        { OPTION_6RD | OPTION_LIST        | OPTION_REQ, D6_OPT_DNS_SERVERS },
+        { OPTION_DNS_STRING | OPTION_LIST | OPTION_REQ, D6_OPT_DOMAIN_LIST },
+#endif
+#if ENABLE_FEATURE_UDHCPC6_RFC4704
+        { OPTION_DNS_STRING,                            D6_OPT_CLIENT_FQDN },
+#endif
+#if ENABLE_FEATURE_UDHCPC6_RFC4833
+        { OPTION_STRING,                                D6_OPT_TZ_POSIX },
+        { OPTION_STRING,                                D6_OPT_TZ_NAME },
+#endif
+        { 0, 0 }
+};
+/* Must match d6_optflags[] order */
+static const char d6_option_strings[] ALIGN1 =
+#if ENABLE_FEATURE_UDHCPC6_RFC3646
+        "dns" "\0"      /* D6_OPT_DNS_SERVERS */
+        "search" "\0"   /* D6_OPT_DOMAIN_LIST */
+#endif
+#if ENABLE_FEATURE_UDHCPC6_RFC4704
+        "fqdn" "\0"     /* D6_OPT_CLIENT_FQDN */
+#endif
+#if ENABLE_FEATURE_UDHCPC6_RFC4833
+        "tz" "\0"       /* D6_OPT_TZ_POSIX */
+        "timezone" "\0" /* D6_OPT_TZ_NAME */
+#endif
+        "\0";
 
 #if ENABLE_LONG_OPTS
 static const char udhcpc6_longopts[] ALIGN1 =
@@ -88,14 +139,7 @@ enum {
         IF_FEATURE_UDHCP_PORT(   OPT_P = 1 << OPTBIT_P,)
 };
 
-static const char opt_req[] = {
-        (D6_OPT_ORO >> 8), (D6_OPT_ORO & 0xff),
-        0, 6,
-        (D6_OPT_DNS_SERVERS >> 8), (D6_OPT_DNS_SERVERS & 0xff),
-        (D6_OPT_DOMAIN_LIST >> 8), (D6_OPT_DOMAIN_LIST & 0xff),
-        (D6_OPT_CLIENT_FQDN >> 8), (D6_OPT_CLIENT_FQDN & 0xff),
-};
-
+#if ENABLE_FEATURE_UDHCPC6_RFC4704
 static const char opt_fqdn_req[] = {
         (D6_OPT_CLIENT_FQDN >> 8), (D6_OPT_CLIENT_FQDN & 0xff),
         0, 2, /* optlen */
@@ -105,6 +149,7 @@ static const char opt_fqdn_req[] = {
         /* N=0: server SHOULD perform updates (PTR RR only in our case, since S=0) */
         0 /* empty DNS-encoded name */
 };
+#endif
 
 /*** Utility functions ***/
 
@@ -152,10 +197,12 @@ static char** new_env(void)
 /* put all the parameters into the environment */
 static void option_to_env(uint8_t *option, uint8_t *option_end)
 {
-        char *dlist;
+#if ENABLE_FEATURE_UDHCPC6_RFC3646
+        int addrs, option_offset;
+#endif
         /* "length minus 4" */
         int len_m4 = option_end - option - 4;
-        int addrs, option_offset;
+
         while (len_m4 >= 0) {
                 uint32_t v32;
                 char ipv6str[sizeof("ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff")];
@@ -237,7 +284,10 @@ static void option_to_env(uint8_t *option, uint8_t *option_end)
                         sprint_nip6(ipv6str, option + 4 + 4 + 1);
                         *new_env() = xasprintf("ipv6prefix=%s/%u", ipv6str, (unsigned)(option[4 + 4]));
                         break;
-                case D6_OPT_DNS_SERVERS:
+#if ENABLE_FEATURE_UDHCPC6_RFC3646
+                case D6_OPT_DNS_SERVERS: {
+                        char *dlist;
+
                         /* Make sure payload-size is a multiple of 16 */
                         if ((option[3] & 0x0f) != 0)
                                 break;
@@ -259,13 +309,21 @@ static void option_to_env(uint8_t *option, uint8_t *option_end)
                         }
 
                         break;
-                case D6_OPT_DOMAIN_LIST:
+                }
+                case D6_OPT_DOMAIN_LIST: {
+                        char *dlist;
+
                         dlist = dname_dec(option + 4, (option[2] << 8) | option[3], "search=");
                         if (!dlist)
                                 break;
                         *new_env() = dlist;
                         break;
-                case D6_OPT_CLIENT_FQDN:
+                }
+#endif
+#if ENABLE_FEATURE_UDHCPC6_RFC4704
+                case D6_OPT_CLIENT_FQDN: {
+                        char *dlist;
+
                         if (option[3] == 0)
                                 break;
                         /* Work around broken ISC DHCPD6.
@@ -284,6 +342,9 @@ static void option_to_env(uint8_t *option, uint8_t *option_end)
                                 break;
                         *new_env() = dlist;
                         break;
+                }
+#endif
+#if ENABLE_FEATURE_UDHCPC6_RFC4833
                 /* RFC 4833 Timezones */
                 case D6_OPT_TZ_POSIX:
                         *new_env() = xasprintf("tz=%.*s", (int)option[3], (char*)option + 4);
@@ -291,6 +352,7 @@ static void option_to_env(uint8_t *option, uint8_t *option_end)
                 case D6_OPT_TZ_NAME:
                         *new_env() = xasprintf("tz_name=%.*s", (int)option[3], (char*)option + 4);
                         break;
+#endif
                 }
                 len_m4 -= 4 + option[3];
                 option += 4 + option[3];
@@ -363,17 +425,33 @@ static uint8_t *init_d6_packet(struct d6_packet *packet, char type, uint32_t xid
 
 static uint8_t *add_d6_client_options(uint8_t *ptr)
 {
-        return ptr;
-        //uint8_t c;
-        //int i, end, len;
+        uint8_t *start = ptr;
+        unsigned option;
+
+        ptr += 4;
+        for (option = 1; option < 256; option++) {
+                if (client_config.opt_mask[option >> 3] & (1 << (option & 7))) {
+                        ptr[0] = (option >> 8);
+                        ptr[1] = option;
+                        ptr += 2;
+                }
+        }
 
-        /* Add a "param req" option with the list of options we'd like to have
-         * from stubborn DHCP servers. Pull the data from the struct in common.c.
-         * No bounds checking because it goes towards the head of the packet. */
-        //...
+        if ((ptr - start - 4) != 0) {
+                start[0] = (D6_OPT_ORO >> 8);
+                start[1] = D6_OPT_ORO;
+                start[2] = ((ptr - start - 4) >> 8);
+                start[3] = (ptr - start - 4);
+        } else
+                ptr = start;
 
+#if ENABLE_FEATURE_UDHCPC6_RFC4704
+        ptr = mempcpy(ptr, &opt_fqdn_req, sizeof(opt_fqdn_req));
+#endif
         /* Add -x options if any */
         //...
+
+        return ptr;
 }
 
 static int d6_mcast_from_client_config_ifindex(struct d6_packet *packet, uint8_t *end)
@@ -497,10 +575,6 @@ static NOINLINE int send_d6_discover(uint32_t xid, struct in6_addr *requested_ip
         }
         opt_ptr = mempcpy(opt_ptr, client6_data.ia_na, len);
 
-        /* Request additional options */
-        opt_ptr = mempcpy(opt_ptr, &opt_req, sizeof(opt_req));
-        opt_ptr = mempcpy(opt_ptr, &opt_fqdn_req, sizeof(opt_fqdn_req));
-
         /* Add options:
          * "param req" option according to -O, options specified with -x
          */
@@ -554,10 +628,6 @@ static NOINLINE int send_d6_select(uint32_t xid)
         /* IA NA (contains requested IP) */
         opt_ptr = mempcpy(opt_ptr, client6_data.ia_na, client6_data.ia_na->len + 2+2);
 
-        /* Request additional options */
-        opt_ptr = mempcpy(opt_ptr, &opt_req, sizeof(opt_req));
-        opt_ptr = mempcpy(opt_ptr, &opt_fqdn_req, sizeof(opt_fqdn_req));
-
         /* Add options:
          * "param req" option according to -O, options specified with -x
          */
@@ -1063,20 +1133,18 @@ int udhcpc6_main(int argc UNUSED_PARAM, char **argv)
                 char *optstr = llist_pop(&list_O);
                 unsigned n = bb_strtou(optstr, NULL, 0);
                 if (errno || n > 254) {
-                        n = udhcp_option_idx(optstr);
-                        n = dhcp_optflags[n].code;
+                        n = udhcp_option_idx(optstr, d6_option_strings);
+                        n = d6_optflags[n].code;
                 }
                 client_config.opt_mask[n >> 3] |= 1 << (n & 7);
         }
         if (!(opt & OPT_o)) {
-                /*
                 unsigned i, n;
-                for (i = 0; (n = dhcp_optflags[i].code) != 0; i++) {
-                        if (dhcp_optflags[i].flags & OPTION_REQ) {
+                for (i = 0; (n = d6_optflags[i].code) != 0; i++) {
+                        if (d6_optflags[i].flags & OPTION_REQ) {
                                 client_config.opt_mask[n >> 3] |= 1 << (n & 7);
                         }
                 }
-                */
         }
         while (list_x) {
                 char *optstr = llist_pop(&list_x);
@@ -1085,7 +1153,7 @@ int udhcpc6_main(int argc UNUSED_PARAM, char **argv)
                         *colon = ' ';
                 /* now it looks similar to udhcpd's config file line:
                  * "optname optval", using the common routine: */
-                udhcp_str2optset(optstr, &client_config.options);
+                udhcp_str2optset(optstr, &client_config.options, d6_optflags, d6_option_strings);
                 if (colon)
                         *colon = ':'; /* restore it for NOMMU reexec */
         }