diff options
Diffstat (limited to 'networking/udhcp/common.c')
| -rw-r--r-- | networking/udhcp/common.c | 15 |
1 files changed, 13 insertions, 2 deletions
diff --git a/networking/udhcp/common.c b/networking/udhcp/common.c index bc41c8d4d..680852ce4 100644 --- a/networking/udhcp/common.c +++ b/networking/udhcp/common.c @@ -142,7 +142,7 @@ const char dhcp_option_strings[] ALIGN1 = * udhcp_str2optset: to determine how many bytes to allocate. * xmalloc_optname_optval: to estimate string length * from binary option length: (option[LEN] / dhcp_option_lengths[opt_type]) - * is the number of elements, multiply in by one element's string width + * is the number of elements, multiply it by one element's string width * (len_of_option_as_string[opt_type]) and you know how wide string you need. */ const uint8_t dhcp_option_lengths[] ALIGN1 = { @@ -162,7 +162,18 @@ 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 */ + [OPTION_6RD] = 12, /* ignored by udhcp_str2optset */ + /* The above value was chosen as follows: + * len_of_option_as_string[] for this option is >60: it's a string of the form + * "32 128 ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff 255.255.255.255 ". + * Each additional ipv4 address takes 4 bytes in binary option and appends + * another "255.255.255.255 " 16-byte string. We can set [OPTION_6RD] = 4 + * but this severely overestimates string length: instead of 16 bytes, + * it adds >60 for every 4 bytes in binary option. + * We cheat and declare here that option is in units of 12 bytes. + * This adds more than 60 bytes for every three ipv4 addresses - more than enough. + * (Even 16 instead of 12 should work, but let's be paranoid). + */ }; |