mirrors/cosmopolitan
1
0
Fork 0
mirror of https://github.com/jart/cosmopolitan.git synced 2025-05-23 05:42:29 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions 1

Added getnameinfo with only name lookup (#172)

Browse source 
Added necessary constants (DNS_TYPE_PTR, NI_NUMERICHOST etc.).
Implementation of getnameinfo is similar to getaddrinfo, with internal
functions:

* ResolveDnsReverse: performs rDNS query and parses the PTR record
* ResolveHostsReverse: reads /etc/hosts to map hostname to
  address

Earlier, the HOSTS.txt would only need to be sorted at loading time,
because the only kind of lookup was name -> address. Now since address
-> name lookups are also possible, so the HostsTxt struct, the sorting
method (and the related tests) was changed to reflect this.
This commit is contained in:
Gautham 2021-06-10 08:05:44 +05:30 • committed by GitHub
parent 05350eca60
commit 248c6d54bb
No known key found for this signature in database
GPG key ID: 4AEE18F83AFDEB23
12 changed files with 334 additions and 10 deletions
Download patch file Download diff file Expand all files Collapse all files

44
libc/dns/resolvehostsreverse.c Normal file
View file

@ -0,0 +1,44 @@
#include "libc/alg/alg.h"
#include "libc/dns/consts.h"
#include "libc/dns/dns.h"
#include "libc/dns/hoststxt.h"
#include "libc/sock/sock.h"
#include "libc/str/str.h"
#include "libc/sysv/consts/af.h"
#include "libc/sysv/errfuns.h"
static int hoststxtcmpaddr(const uint8_t *ip1, const struct HostsTxtEntry *he2) {
uint32_t v1 = *((uint32_t *)ip1), v2 = *((uint32_t *)he2->ip);
return (v1 == v2 ? 0 : (v1 > v2 ? 1 : -1));
}
/**
* Finds name associated with address in HOSTS.TXT table.
*
* @param ht can be GetHostsTxt()
* @param af can be AF_INET
* @param ip is IP address in binary (sin_addr)
* @param buf is buffer to store the name
* @param bufsize is length of buf
*
* @return 1 if found, 0 if not found, or -1 w/ errno
* @error EAFNOSUPPORT
*/
int ResolveHostsReverse(const struct HostsTxt *ht, int af, const uint8_t *ip,
char *buf, size_t bufsize) {
struct HostsTxtEntry *entry;
if (af != AF_INET && af != AF_UNSPEC) return eafnosupport();
if (!ht->entries.p) return -1;
if (ht->sorted_by != HOSTSTXT_SORTEDBYADDR)
SortHostsTxt(ht, HOSTSTXT_SORTEDBYADDR);
entry = bsearch(ip, ht->entries.p, ht->entries.i,
sizeof(struct HostsTxtEntry), (void *)hoststxtcmpaddr);
if (entry) {
strncpy(buf, &ht->strings.p[entry->name], bufsize);
return 1;
}
return 0;
}