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#include <stdio.h>
#include <string.h>
#include <core.h>
#include "pxe.h"
#include "lwip/api.h"
#include "lwip/dns.h"
/* DNS CLASS values we care about */
#define CLASS_IN 1
/* DNS TYPE values we care about */
#define TYPE_A 1
#define TYPE_CNAME 5
/*
* The DNS header structure
*/
struct dnshdr {
uint16_t id;
uint16_t flags;
/* number of entries in the question section */
uint16_t qdcount;
/* number of resource records in the answer section */
uint16_t ancount;
/* number of name server resource records in the authority records section*/
uint16_t nscount;
/* number of resource records in the additional records section */
uint16_t arcount;
} __attribute__ ((packed));
/*
* The DNS query structure
*/
struct dnsquery {
uint16_t qtype;
uint16_t qclass;
} __attribute__ ((packed));
/*
* The DNS Resource recodes structure
*/
struct dnsrr {
uint16_t type;
uint16_t class;
uint32_t ttl;
uint16_t rdlength; /* The lenght of this rr data */
char rdata[];
} __attribute__ ((packed));
uint32_t dns_server[DNS_MAX_SERVERS] = {0, };
/*
* parse the ip_str and return the ip address with *res.
* return true if the whole string was consumed and the result
* was valid.
*
*/
static bool parse_dotquad(const char *ip_str, uint32_t *res)
{
const char *p = ip_str;
uint8_t part = 0;
uint32_t ip = 0;
int i;
for (i = 0; i < 4; i++) {
while (is_digit(*p)) {
part = part * 10 + *p - '0';
p++;
}
if (i != 3 && *p != '.')
return false;
ip = (ip << 8) | part;
part = 0;
p++;
}
p--;
*res = htonl(ip);
return *p == '\0';
}
/*
* Actual resolver function.
*
* Points to a null-terminated in _name_ and returns the ip addr in
* _ip_ if it exists and can be found. If _ip_ = 0 on exit, the
* lookup failed. _name_ will be updated
*/
__export uint32_t pxe_dns(const char *name)
{
err_t err;
struct ip_addr ip;
char fullname[512];
/*
* Return failure on an empty input... this can happen during
* some types of URL parsing, and this is the easiest place to
* check for it.
*/
if (!name || !*name)
return 0;
/* If it is a valid dot quad, just return that value */
if (parse_dotquad(name, &ip.addr))
return ip.addr;
/* Make sure we have at least one valid DNS server */
if (!dns_getserver(0).addr)
return 0;
/* Is it a local (unqualified) domain name? */
if (!strchr(name, '.') && LocalDomain[0]) {
snprintf(fullname, sizeof fullname, "%s.%s", name, LocalDomain);
name = fullname;
}
err = netconn_gethostbyname(name, &ip);
if (err)
return 0;
return ip.addr;
}
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