4 files changed, 84 insertions, 4 deletions

diff --git a/include/libbb.h b/include/libbb.h
index f79b69365..f0f54ef82 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -814,9 +814,9 @@ void smart_ulltoa5(unsigned long long ul, char buf[5], const char *scale) FAST_F
 const char *make_human_readable_str(unsigned long long size,
                 unsigned long block_size, unsigned long display_unit) FAST_FUNC;
 /* Put a string of hex bytes ("1b2e66fe"...), return advanced pointer */
-char *bin2hex(char *buf, const char *cp, int count) FAST_FUNC;
+char *bin2hex(char *dst, const char *src, int count) FAST_FUNC;
 /* Reverse */
-char* hex2bin(char *dst, const char *str, int count) FAST_FUNC;
+char* hex2bin(char *dst, const char *src, int count) FAST_FUNC;
 
 /* Generate a UUID */
 void generate_uuid(uint8_t *buf) FAST_FUNC;
diff --git a/networking/udhcp/common.c b/networking/udhcp/common.c
index 70e34614c..ba41905cc 100644
--- a/networking/udhcp/common.c
+++ b/networking/udhcp/common.c
@@ -59,6 +59,7 @@ const struct dhcp_optflag dhcp_optflags[] = {
         { OPTION_U16                              , 0x84 }, /* DHCP_VLAN_ID       */
         { OPTION_U8                               , 0x85 }, /* DHCP_VLAN_PRIORITY */
 #endif
+        { OPTION_6RD                              , 0xd4 }, /* DHCP_6RD           */
         { OPTION_STATIC_ROUTES                    , 0xf9 }, /* DHCP_MS_STATIC_ROUTES */
         { OPTION_STRING                           , 0xfc }, /* DHCP_WPAD          */
 
@@ -126,6 +127,7 @@ const char dhcp_option_strings[] ALIGN1 =
         "vlanid" "\0"      /* DHCP_VLAN_ID        */
         "vlanpriority" "\0"/* DHCP_VLAN_PRIORITY  */
 #endif
+        "ip6rd" "\0"       /* DHCP_6RD            */
         "msstaticroutes""\0"/* DHCP_MS_STATIC_ROUTES */
         "wpad" "\0"        /* DHCP_WPAD           */
         ;
@@ -154,6 +156,7 @@ const uint8_t dhcp_option_lengths[] ALIGN1 = {
         [OPTION_S32] =     4,
         /* Just like OPTION_STRING, we use minimum length here */
         [OPTION_STATIC_ROUTES] = 5,
+        [OPTION_6RD] =    22,  /* ignored by udhcp_str2optset */
 };
 
 
diff --git a/networking/udhcp/common.h b/networking/udhcp/common.h
index 786266810..da0bd38d1 100644
--- a/networking/udhcp/common.h
+++ b/networking/udhcp/common.h
@@ -88,6 +88,7 @@ enum {
         OPTION_S32,
         OPTION_BIN,
         OPTION_STATIC_ROUTES,
+        OPTION_6RD,
 #if ENABLE_FEATURE_UDHCP_RFC3397
         OPTION_DNS_STRING,  /* RFC1035 compressed domain name list */
         OPTION_SIP_SERVERS,
diff --git a/networking/udhcp/dhcpc.c b/networking/udhcp/dhcpc.c
index ddfe3ccc0..311d4867a 100644
--- a/networking/udhcp/dhcpc.c
+++ b/networking/udhcp/dhcpc.c
@@ -100,6 +100,7 @@ static const uint8_t len_of_option_as_string[] = {
         [OPTION_IP              ] = sizeof("255.255.255.255 "),
         [OPTION_IP_PAIR         ] = sizeof("255.255.255.255 ") * 2,
         [OPTION_STATIC_ROUTES   ] = sizeof("255.255.255.255/32 255.255.255.255 "),
+        [OPTION_6RD             ] = sizeof("32 128 ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff 255.255.255.255 "),
         [OPTION_STRING          ] = 1,
 #if ENABLE_FEATURE_UDHCP_RFC3397
         [OPTION_DNS_STRING      ] = 1, /* unused */
@@ -123,6 +124,24 @@ static int sprint_nip(char *dest, const char *pre, const uint8_t *ip)
         return sprintf(dest, "%s%u.%u.%u.%u", pre, ip[0], ip[1], ip[2], ip[3]);
 }
 
+static int sprint_nip6(char *dest, const char *pre, const uint8_t *ip)
+{
+        char hexstrbuf[16 * 2];
+        bin2hex(hexstrbuf, (void*)ip, 16);
+        return sprintf(dest, "%s"
+                "%.4s:%.4s:%.4s:%.4s:%.4s:%.4s:%.4s:%.4s",
+                pre,
+                hexstrbuf + 0 * 4,
+                hexstrbuf + 1 * 4,
+                hexstrbuf + 2 * 4,
+                hexstrbuf + 3 * 4,
+                hexstrbuf + 4 * 4,
+                hexstrbuf + 5 * 4,
+                hexstrbuf + 6 * 4,
+                hexstrbuf + 7 * 4
+        );
+}
+
 /* really simple implementation, just count the bits */
 static int mton(uint32_t mask)
 {
@@ -147,7 +166,8 @@ static NOINLINE char *xmalloc_optname_optval(uint8_t *option, const struct dhcp_
 
         type = optflag->flags & OPTION_TYPE_MASK;
         optlen = dhcp_option_lengths[type];
-        upper_length = len_of_option_as_string[type] * ((unsigned)len / (unsigned)optlen);
+        upper_length = len_of_option_as_string[type]
+                * ((unsigned)(len + optlen - 1) / (unsigned)optlen);
 
         dest = ret = xmalloc(upper_length + strlen(opt_name) + 2);
         dest += sprintf(ret, "%s=", opt_name);
@@ -232,6 +252,62 @@ static NOINLINE char *xmalloc_optname_optval(uint8_t *option, const struct dhcp_
 
                         return ret;
                 }
+                case OPTION_6RD: {
+                        /* Option binary format (see RFC 5969):
+                         * 0                   1                   2                   3
+                         * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+                         * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+                         * |  OPTION_6RD   | option-length |  IPv4MaskLen  |  6rdPrefixLen |
+                         * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+                         * |                                                               |
+                         * |                           6rdPrefix                           |
+                         * |                          (16 octets)                          |
+                         * |                                                               |
+                         * |                                                               |
+                         * |                                                               |
+                         * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+                         * |                     6rdBRIPv4Address(es)                      |
+                         * .                                                               .
+                         * .                                                               .
+                         * .                                                               .
+                         * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+                         *
+                         * We convert it to a string
+                         * "IPv4MaskLen 6rdPrefixLen 6rdPrefix 6rdBRIPv4Address..."
+                         */
+
+                        /* Sanity check: ensure that our length is at least 22 bytes, that
+                         * IPv4MaskLen <= 32,
+                         * 6rdPrefixLen <= 128,
+                         * 6rdPrefixLen + (32 - IPv4MaskLen) <= 128
+                         * (2nd condition need no check - it follows from 1st and 3rd).
+                         * If any of these requirements is not fulfilled, return with empty
+                         * value.
+                         */
+                        if (len >= 22
+                         && option[0] <= 32
+                         && (option[1] + 32 - option[0]) <= 128
+                        ) {
+                                /* IPv4MaskLen */
+                                dest += sprintf(dest, "%u ", *option++);
+                                /* 6rdPrefixLen */
+                                dest += sprintf(dest, "%u ", *option++);
+                                /* 6rdPrefix */
+                                dest += sprint_nip6(dest, "", option);
+                                option += 16;
+                                len -= 1 + 1 + 16;
+                                /* 6rdBRIPv4Address(es) */
+                                while (1) {
+                                        dest += sprint_nip(dest, " ", option);
+                                        option += 4;
+                                        len -= 4;
+                                        if (len < 0)
+                                                break;
+                                }
+                        }
+
+                        return ret;
+                }
 #if ENABLE_FEATURE_UDHCP_RFC3397
                 case OPTION_DNS_STRING:
                         /* unpack option into dest; use ret for prefix (i.e., "optname=") */
@@ -394,7 +470,7 @@ static char **fill_envp(struct dhcp_packet *packet)
                         len = temp[-OPT_DATA + OPT_LEN];
                         *curr = xmalloc(sizeof("optNNN=") + 1 + len*2);
                         ofs = sprintf(*curr, "opt%u=", i);
-                        bin2hex(*curr + ofs, (void*) temp, len)[0] = '\0';
+                        *bin2hex(*curr + ofs, (void*) temp, len) = '\0';
                         putenv(*curr++);
                 }
                 i++;