1+ use std:: convert:: TryInto ;
2+
3+ #[ derive( Debug ) ]
4+ pub enum Opt < ' a > {
5+ Malformed ( u8 , & ' a [ u8 ] ) ,
6+ Unknown ( u8 , & ' a [ u8 ] ) ,
7+ //Pad, // #0
8+
9+ /// Subnet mask, encoded as an address
10+ SubnetMask ( [ u8 ; 4 ] ) ,
11+ /// Timezone seconds east of UTC
12+ TimeOffset ( i32 ) ,
13+ /// A list of routers
14+ Routers ( & ' a [ [ u8 ; 4 ] ] ) ,
15+ /// A list of ?NTP time servers
16+ TimeServers ( & ' a [ [ u8 ; 4 ] ] ) ,
17+ /// A list of IEN-116 name servers
18+ NameServersIen116 ( & ' a [ [ u8 ; 4 ] ] ) ,
19+ /// #6 A list of DNS name servers
20+ NameServersDns ( & ' a [ [ u8 ; 4 ] ] ) ,
21+
22+ /// #12 Client hostname
23+ HostName ( & ' a [ u8 ] ) ,
24+ /// #15 Domain Name
25+ DomainName ( & ' a [ u8 ] ) ,
26+
27+ /// #42 Vendor-specific
28+ VendorSpecific ( & ' a [ u8 ] ) ,
29+
30+ /// #50 Allows client to request a specific IP address
31+ RequestedIpAddress ( [ u8 ; 4 ] ) ,
32+
33+ /// #52 Specifies that `file` or `sname` (or both) also contain options
34+ ///
35+ /// 1 = only `file`
36+ /// 2 = only `sname`
37+ /// 3 = both
38+ OptionOverload ( u8 ) ,
39+
40+ /// #53
41+ DhcpMessageType ( u8 ) ,
42+
43+ /// #54 IPv4 address of the server that sent this offer/ack
44+ ServerIdentifier ( [ u8 ; 4 ] ) ,
45+
46+ /// #56 - Human-readable (ASCII) text error message for DHCPNAK
47+ Message ( & ' a [ u8 ] ) ,
48+
49+ /// #61 - An opaque blob client identifier
50+ ClientIdentifier ( & ' a [ u8 ] ) ,
51+ }
52+ macro_rules! enc_dec_option {
53+ ( $in_data: ident ;
54+ $(
55+ $idx: literal $name: ident( $valname: ident ) : $dec: expr => $enc: expr ;
56+ ) *
57+ ) => {
58+ impl <' a> Opt <' a> {
59+ pub fn decode( code: u8 , $in_data: & ' a [ u8 ] ) -> Self {
60+ match code {
61+ 0 => unreachable!( ) ,
62+ $(
63+ $idx => if let Some ( v) = $dec { Opt :: $name( v) } else { Opt :: Malformed ( code, $in_data) } ,
64+ ) *
65+ _ => Opt :: Unknown ( code, $in_data)
66+ }
67+ }
68+ pub fn encode( & self , mut push: impl FnMut ( u8 , & [ u8 ] ) ) {
69+ fn flatten( data: & [ [ u8 ; 4 ] ] ) -> & [ u8 ] {
70+ // SAFE: Same alignment, correct length
71+ unsafe { :: core:: slice:: from_raw_parts( data. as_ptr( ) as * const u8 , data. len( ) * 4 ) }
72+ }
73+ match self {
74+ Opt :: Malformed ( _op, _data) => {
75+ // Ignore malformed data
76+ }
77+ Opt :: Unknown ( op, data) => push( * op, data) ,
78+ $(
79+ Opt :: $name( $valname) => push( $idx, $enc) ,
80+ ) *
81+ }
82+ }
83+ }
84+ }
85+ }
86+ fn get_u8_4 ( data : & [ u8 ] ) -> Option < & [ u8 ; 4 ] > {
87+ data. try_into ( ) . ok ( )
88+ }
89+ fn get_u8_4_seq ( data : & [ u8 ] ) -> Option < & [ [ u8 ; 4 ] ] > {
90+ if data. len ( ) % 4 == 0 {
91+ // SAFE: Same alignment, and length is aligned to 4
92+ Some ( unsafe { :: core:: slice:: from_raw_parts ( data. as_ptr ( ) as * const [ u8 ; 4 ] , data. len ( ) / 4 ) } )
93+ }
94+ else {
95+ None
96+ }
97+ }
98+ enc_dec_option ! { d;
99+ // 0 Pad (not encoded)
100+ 1 SubnetMask ( data) : get_u8_4( d) . copied( ) => data;
101+ 2 TimeOffset ( ofs) : get_u8_4( d) . map( |v| i32 :: from_be_bytes( * v) ) => & ofs. to_le_bytes( ) ;
102+ 3 Routers ( addrs) : get_u8_4_seq( d) => flatten( addrs) ;
103+ 4 TimeServers ( addrs) : get_u8_4_seq( d) => flatten( addrs) ;
104+ 5 NameServersIen116 ( addrs) : get_u8_4_seq( d) => flatten( addrs) ;
105+ 6 NameServersDns ( addrs) : get_u8_4_seq( d) => flatten( addrs) ;
106+ 12 HostName ( name) : Some ( d) => name;
107+ 15 DomainName ( name) : Some ( d) => name;
108+ 42 VendorSpecific ( data) : Some ( d) => data;
109+ 50 RequestedIpAddress ( addr) : get_u8_4( d) . copied( ) => addr;
110+ 52 OptionOverload ( v) : match d { & [ v] => Some ( v) , _ => None } => & [ * v] ;
111+ 53 DhcpMessageType ( v) : match d { & [ v] => Some ( v) , _ => None } => & [ * v] ;
112+ 54 ServerIdentifier ( data) : get_u8_4( d) . copied( ) => data;
113+ 56 Message ( msg) : Some ( d) => msg;
114+ 61 ClientIdentifier ( blob) : Some ( d) => blob;
115+ // 255 End (not encoded)
116+ }
117+
118+ #[ derive( Debug ) ] // TODO: Implement using clone+run
119+ pub struct OptionsIter < ' a > ( pub & ' a [ u8 ] ) ;
120+ impl < ' a > Iterator for OptionsIter < ' a > {
121+ type Item = Opt < ' a > ;
122+ fn next ( & mut self ) -> Option < Self :: Item > {
123+ match self . 0 {
124+ [ ] => None ,
125+ // Padding: Handled specially
126+ [ 0 , tail @ ..] => {
127+ self . 0 = tail;
128+ //Some(Opt::Pad)
129+ self . next ( )
130+ } ,
131+ // End
132+ [ 255 , ..] => None ,
133+ [ _] => {
134+ self . 0 = & [ ] ;
135+ None
136+ } ,
137+ & [ code, len, ref tail @ ..] => {
138+ let Some ( ( data, tail) ) = tail. split_at_checked ( len as usize ) else {
139+ self . 0 = & [ ] ;
140+ return None ;
141+ } ;
142+ self . 0 = tail;
143+ Some ( Opt :: decode ( code, data) )
144+ }
145+ }
146+ }
147+ }
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