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dnsd: stop using oversized buffer. trim comment.

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This commit is contained in:
Denis Vlasenko 2009-04-12 19:03:01 +00:00
parent e12c90217b
commit ef1b439669
1 changed files with 10 additions and 17 deletions
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27
networking/dnsd.c
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@ -24,15 +24,10 @@
#define DEBUG 0 #define DEBUG 0
enum { enum {
/* Can tweak this */ /* can tweak this */
DEFAULT_TTL = 120, DEFAULT_TTL = 120,
/* Cannot get bigger packets than 512 per RFC1035. /* cannot get bigger packets than 512 per RFC1035. */
* In practice this can be set considerably smaller:
* Length of response packet is header (12B) + 2*type(4B) + 2*class(4B) +
* ttl(4B) + rlen(2B) + r (MAX_NAME_LEN = 21B) +
* 2*querystring (2 MAX_NAME_LEN = 42B), all together 90 Bytes
*/
MAX_PACK_LEN = 512, MAX_PACK_LEN = 512,
IP_STRING_LEN = sizeof(".xxx.xxx.xxx.xxx"), IP_STRING_LEN = sizeof(".xxx.xxx.xxx.xxx"),
MAX_NAME_LEN = IP_STRING_LEN - 1 + sizeof(".in-addr.arpa"), MAX_NAME_LEN = IP_STRING_LEN - 1 + sizeof(".in-addr.arpa"),
@ -225,9 +220,9 @@ OPCODE 0 standard query (QUERY)
2 server status request (STATUS) 2 server status request (STATUS)
AA Authoritative Answer - this bit is valid in responses. AA Authoritative Answer - this bit is valid in responses.
Responding name server is an authority for the domain name Responding name server is an authority for the domain name
in question section. Answer section may have multiple owner names in question section. Answer section may have multiple owner names
because of aliases. The AA bit corresponds to the name which matches because of aliases. The AA bit corresponds to the name which matches
the query name, or the first owner name in the answer section. the query name, or the first owner name in the answer section.
TC TrunCation - this message was truncated. TC TrunCation - this message was truncated.
RD Recursion Desired - this bit may be set in a query and RD Recursion Desired - this bit may be set in a query and
is copied into the response. If RD is set, it directs is copied into the response. If RD is set, it directs
@ -240,10 +235,10 @@ RCODE Response code.
0 No error condition 0 No error condition
1 Format error 1 Format error
2 Server failure - server was unable to process the query 2 Server failure - server was unable to process the query
due to a problem with the name server. due to a problem with the name server.
3 Name Error - meaningful only for responses from 3 Name Error - meaningful only for responses from
an authoritative name server. The referenced domain name an authoritative name server. The referenced domain name
does not exist. does not exist.
4 Not Implemented. 4 Not Implemented.
5 Refused. 5 Refused.
QDCOUNT number of entries in the question section. QDCOUNT number of entries in the question section.
@ -293,7 +288,7 @@ QTYPE a two octet type of the query.
255 a request for all records 255 a request for all records
QCLASS a two octet code that specifies the class of the query. QCLASS a two octet code that specifies the class of the query.
1 the Internet 1 the Internet
(others are historic only) (others are historic only)
255 any class 255 any class
4.1.3. Resource record format 4.1.3. Resource record format
@ -464,9 +459,7 @@ int dnsd_main(int argc UNUSED_PARAM, char **argv)
unsigned lsa_size; unsigned lsa_size;
int udps, opts; int udps, opts;
uint16_t port = 53; uint16_t port = 53;
/* Paranoid sizing: querystring x2 + ttl + outr_rlen + answstr */ uint8_t buf[MAX_PACK_LEN + 1];
/* I'd rather see process_packet() fixed instead... */
uint8_t buf[MAX_PACK_LEN * 2 + 4 + 2 + (MAX_NAME_LEN+1)];
opts = getopt32(argv, "vi:c:t:p:d", &listen_interface, &fileconf, &sttl, &sport); opts = getopt32(argv, "vi:c:t:p:d", &listen_interface, &fileconf, &sttl, &sport);
//if (opts & 0x1) // -v //if (opts & 0x1) // -v