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This commit is contained in:
Justine Tunney 2020-12-01 03:43:40 -08:00
parent 3e4fd4b0ad
commit e44a0cf6f8
256 changed files with 23100 additions and 2294 deletions
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27
libc/dns/resolvedns.c
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@ -34,6 +34,8 @@
#include "libc/sysv/consts/sock.h"
#include "libc/sysv/errfuns.h"
#define kMsgMax 512
/**
* Queries Domain Name System for address associated with name.
*
@ -48,10 +50,15 @@
*/
int resolvedns(const struct ResolvConf *resolvconf, int af, const char *name,
struct sockaddr *addr, uint32_t addrsize) {
size_t msgsize;
int res, fd, rc, rc2;
struct sockaddr_in *addr4;
struct DnsQuestion question;
uint16_t rtype, rclass, rdlength;
uint8_t *p, *pe, *outmsg, *inmsg;
struct DnsHeader header, response;
if (af != AF_INET && af != AF_UNSPEC) return eafnosupport();
if (!resolvconf->nameservers.i) return 0;
struct DnsHeader header;
struct DnsQuestion question;
memset(&header, 0, sizeof(header));
header.id = rand32();
header.bf1 = 1; /* recursion desired */
@ -59,28 +66,21 @@ int resolvedns(const struct ResolvConf *resolvconf, int af, const char *name,
question.qname = name;
question.qtype = DNS_TYPE_A;
question.qclass = DNS_CLASS_IN;
const size_t kMsgMax = 512;
uint8_t *outmsg = NULL;
uint8_t *inmsg = NULL;
size_t msgsize;
int res = -1;
int rc, rc2;
res = -1;
if ((outmsg = malloc(kMsgMax)) && (inmsg = malloc(kMsgMax)) &&
(rc = serializednsheader(outmsg, kMsgMax, header)) != -1 &&
(rc2 = serializednsquestion(outmsg + rc, kMsgMax - rc, question)) != -1) {
msgsize = rc + rc2;
int fd;
if ((fd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) != -1 &&
sendto(fd, outmsg, msgsize, 0, (void *)&resolvconf->nameservers.p[0],
sizeof(resolvconf->nameservers.p[0])) == msgsize) {
struct DnsHeader response;
if ((rc = recv(fd, inmsg, kMsgMax, 0)) != -1 &&
(rc2 = deserializednsheader(&response, inmsg, rc)) != -1 &&
response.id == header.id) {
res = 0;
if (response.ancount) {
uint8_t *p = inmsg + rc2;
uint8_t *pe = inmsg + rc;
p = inmsg + rc2;
pe = inmsg + rc;
while (p < pe && response.qdcount) {
p += strnlen((char *)p, pe - p) + 1 + 4;
response.qdcount--;
@ -92,7 +92,6 @@ int resolvedns(const struct ResolvConf *resolvconf, int af, const char *name,
p += strnlen((char *)p, pe - p) + 1;
}
if (p + 2 + 2 + 4 + 2 < pe) {
uint16_t rtype, rclass, rdlength;
rtype = READ16BE(p), p += 2;
rclass = READ16BE(p), p += 2;
/* ttl */ p += 4;
@ -102,7 +101,7 @@ int resolvedns(const struct ResolvConf *resolvconf, int af, const char *name,
res = 1;
if (addrsize) {
if (addrsize >= kMinSockaddr4Size) {
struct sockaddr_in *addr4 = (struct sockaddr_in *)addr;
addr4 = (struct sockaddr_in *)addr;
addr4->sin_family = AF_INET;
memcpy(&addr4->sin_addr.s_addr, p, 4);
} else {