470bebe67
Denys Vlasenko
2017-06-27
Subject
udhcpc6: add comments about option 39, no code changes
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networking/udhcp/d6_common.h+36 -0
| @@ -87,6 +87,42 @@ struct d6_option { | |
| #define D6_OPT_IA_PD 25 | |
| #define D6_OPT_IAPREFIX 26 | |
| + | /* RFC 4704 "The DHCPv6 Client FQDN Option" |
| + | * uint16 option-code OPTION_CLIENT_FQDN (39) |
| + | * uint16 option-len 1 + length of domain name |
| + | * uint8 flags |
| + | * char[] domain-name partial or fully qualified domain name |
| + | * |
| + | * Flags format is |MBZ|N|O|S| |
| + | * The "S" bit indicates whether the server SHOULD or SHOULD NOT perform |
| + | * the AAAA RR (FQDN-to-address) DNS updates. A client sets the bit to |
| + | * 0 to indicate that the server SHOULD NOT perform the updates and 1 to |
| + | * indicate that the server SHOULD perform the updates. The state of |
| + | * the bit in the reply from the server indicates the action to be taken |
| + | * by the server; if it is 1, the server has taken responsibility for |
| + | * AAAA RR updates for the FQDN. |
| + | * The "O" bit indicates whether the server has overridden the client's |
| + | * preference for the "S" bit. A client MUST set this bit to 0. A |
| + | * server MUST set this bit to 1 if the "S" bit in its reply to the |
| + | * client does not match the "S" bit received from the client. |
| + | * The "N" bit indicates whether the server SHOULD NOT perform any DNS |
| + | * updates. A client sets this bit to 0 to request that the server |
| + | * SHOULD perform updates (the PTR RR and possibly the AAAA RR based on |
| + | * the "S" bit) or to 1 to request that the server SHOULD NOT perform |
| + | * any DNS updates. A server sets the "N" bit to indicate whether the |
| + | * server SHALL (0) or SHALL NOT (1) perform DNS updates. If the "N" |
| + | * bit is 1, the "S" bit MUST be 0. |
| + | * |
| + | * If a client knows only part of its name, it MAY send a name that is not |
| + | * fully qualified, indicating that it knows part of the name but does not |
| + | * necessarily know the zone in which the name is to be embedded. |
| + | * To send a fully qualified domain name, the Domain Name field is set |
| + | * to the DNS-encoded domain name including the terminating zero-length |
| + | * label. To send a partial name, the Domain Name field is set to the |
| + | * DNS-encoded domain name without the terminating zero-length label. |
| + | * A client MAY also leave the Domain Name field empty if it desires the |
| + | * server to provide a name. |
| + | */ |
| #define D6_OPT_CLIENT_FQDN 39 | |
| #define D6_OPT_TZ_POSIX 41 | |
networking/udhcp/d6_dhcpc.c+6 -2
| @@ -98,8 +98,12 @@ static const char opt_req[] = { | |
| static const char opt_fqdn_req[] = { | |
| (D6_OPT_CLIENT_FQDN >> 8), (D6_OPT_CLIENT_FQDN & 0xff), | |
| - | 0, 2, |
| - | 0, 0 |
| + | 0, 2, /* optlen */ |
| + | 0, /* flags: */ |
| + | /* S=0: server SHOULD NOT perform AAAA RR updates */ |
| + | /* O=0: client MUST set this bit to 0 */ |
| + | /* N=0: server SHOULD perform updates (PTR RR only in our case, since S=0) */ |
| + | 0 /* empty DNS-encoded name */ |
| }; | |
| /*** Utility functions ***/ | |