120 lines
3.2 KiB
C
120 lines
3.2 KiB
C
#include "../hammer.h"
|
|
|
|
bool is_zero(parse_result_t *p) {
|
|
if (TT_UINT != p->ast->token_type)
|
|
return 0;
|
|
return (0 == p->ast->uint);
|
|
}
|
|
|
|
/**
|
|
* A label can't be more than 63 characters.
|
|
*/
|
|
bool validate_label(parse_result_t *p) {
|
|
if (TT_SEQ != p->ast->token_type)
|
|
return 0;
|
|
return (64 > p->ast->seq->used);
|
|
}
|
|
|
|
/**
|
|
* Every DNS message should have QDCOUNT entries in the question
|
|
* section, and ANCOUNT+NSCOUNT+ARCOUNT resource records.
|
|
*
|
|
*/
|
|
bool validate_dns(parse_result_t *p) {
|
|
if (TT_SEQ != p->ast->token_type)
|
|
return 0;
|
|
// The header holds the counts as its last 4 elements.
|
|
parsed_token_t *header = p->ast->seq->elements[0];
|
|
size_t qd = header->seq->elements[8];
|
|
size_t an = header->seq->elements[9];
|
|
size_t ns = header->seq->elements[10];
|
|
size_t ar = header->seq->elements[11];
|
|
parsed_token_t *questions = p->ast->seq->elements[1];
|
|
if (questions->seq->used != qd)
|
|
return false;
|
|
parsed_token_t *rrs = p->ast->seq->elements[2];
|
|
if (an+ns+ar != rrs->seq->used)
|
|
return false;
|
|
}
|
|
|
|
parser_t init_parser() {
|
|
static parser_t *dns_message = NULL;
|
|
if (dns_message)
|
|
return dns_message;
|
|
|
|
const parser_t *dns_header = sequence(bits(16, false), // ID
|
|
bits(1, false), // QR
|
|
bits(4, false), // opcode
|
|
bits(1, false), // AA
|
|
bits(1, false), // TC
|
|
bits(1, false), // RD
|
|
bits(1, false), // RA
|
|
ignore(attr_bool(bits(3, false), is_zero)), // Z
|
|
bits(4, false), // RCODE
|
|
uint16(), // QDCOUNT
|
|
uint16(), // ANCOUNT
|
|
uint16(), // NSCOUNT
|
|
uint16(), // ARCOUNT
|
|
NULL);
|
|
|
|
const parser_t *dns_question = sequence(length_value(uint8(), uint8()), // QNAME
|
|
uint16(), // QTYPE
|
|
uint16(), // QCLASS
|
|
NULL);
|
|
|
|
const parser_t *letter = choice(range('a', 'z'),
|
|
range('A', 'Z'),
|
|
NULL);
|
|
|
|
const parser_t *let_dig = choice(letter,
|
|
range('0', '9'),
|
|
NULL);
|
|
|
|
const parser_t *ldh_str = many1(choice(let_dig,
|
|
ch('-'),
|
|
NULL));
|
|
|
|
const parser_t *label = attr_bool(sequence(letter,
|
|
optional(sequence(optional(ldh_str),
|
|
let_dig,
|
|
NULL)),
|
|
NULL),
|
|
validate_label);
|
|
|
|
/**
|
|
* You could write it like this ...
|
|
* parser_t *indirect_subdomain = indirect();
|
|
* const parser_t *subdomain = choice(label,
|
|
* sequence(indirect_subdomain,
|
|
* ch('.'),
|
|
* label,
|
|
* NULL),
|
|
* NULL);
|
|
* bind_indirect(indirect_subdomain, subdomain);
|
|
*
|
|
* ... but this is easier and equivalent
|
|
*/
|
|
|
|
parser_t *subdomain = sepBy1(label, ch('.'));
|
|
|
|
const parser_t *domain = choice(subdomain,
|
|
ch(' '),
|
|
NULL);
|
|
|
|
const parser_t *dns_rr = sequence(domain, // NAME
|
|
uint16(), // TYPE
|
|
uint16(), // CLASS
|
|
uint32(), // TTL
|
|
length_value(uint16(), uint8()) // RDLENGTH+RDATA
|
|
NULL);
|
|
|
|
|
|
dns_message = attr_bool(sequence(dns_header,
|
|
many(dns_question),
|
|
many(dns_rr),
|
|
end_p(),
|
|
NULL),
|
|
validate_dns);
|
|
|
|
return dns_message;
|
|
}
|