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Continuing with DNS. Added some checks to attr_bool, and explained checks in docs.

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This commit is contained in:
Meredith L. Patterson 2012-05-24 11:01:18 +02:00
parent 05ef58b958
commit 947b67b5a5
3 changed files with 86 additions and 23 deletions
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65
examples/dns.c
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@ -1,16 +1,48 @@
#include "../hammer.h"
bool is_zero(parse_result_t *p) {
if (TT_UINT != p->ast->token_type)
return 0;
return (0 == p->ast->uint);
}
bool validate_dns(parse_result_t *p) {
/**
* 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);
}
int main(int argc, char **argv) {
/**
* 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;
}
const parser_t dns_header = sequence(bits(16, false), // ID
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
@ -42,11 +74,12 @@ int main(int argc, char **argv) {
ch('-'),
NULL));
const parser_t *label = sequence(letter,
optional(sequence(optional(ldh_str),
let_dig,
NULL)),
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 ...
@ -76,10 +109,12 @@ int main(int argc, char **argv) {
NULL);
const parser_t *dns_message = attr_bool(sequence(dns_header,
dns_question,
many(dns_rr),
end_p(),
NULL),
validate_dns);
dns_message = attr_bool(sequence(dns_header,
many(dns_question),
many(dns_rr),
end_p(),
NULL),
validate_dns);
return dns_message;
}