Fix issue #33, respond to NS requests

This commit is contained in:
Erik Ekman 2008-09-09 20:55:13 +00:00
parent d40c464ac1
commit 4c805fef6a
4 changed files with 98 additions and 0 deletions

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@ -19,6 +19,8 @@ CHANGES:
- Added capability to forward DNS queries outside tunnel domain to
a nameserver on localhost. Use -b port to enable.
- iodine client now shuts down if it detects a server restart.
- iodined now replies to NS request on its own domain, fixes issue #33.
The destination IP address is sent as reply.
2008-08-06: 0.4.2 "Opened Zone"
- Applied a few small patches from Maxim Bourmistrov and Gregor Herrmann

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@ -98,6 +98,85 @@ dns_encode(char *buf, size_t buflen, struct query *q, qr_t qr, char *data, size_
return len;
}
int
dns_encode_ns_response(char *buf, size_t buflen, struct query *q, char *topdomain)
{
HEADER *header;
int len;
short name;
short topname;
short nsname;
char *domain;
int domain_len;
char *p;
memset(buf, 0, buflen);
header = (HEADER*)buf;
header->id = htons(q->id);
header->qr = 1;
header->opcode = 0;
header->aa = 1;
header->tc = 0;
header->rd = 0;
header->ra = 0;
p = buf + sizeof(HEADER);
header->qdcount = htons(1);
header->ancount = htons(1);
header->arcount = htons(1);
/* pointer to start of name */
name = 0xc000 | ((p - buf) & 0x3fff);
domain = strstr(q->name, topdomain);
if (domain) {
domain_len = (int) (domain - q->name);
} else {
return -1;
}
/* pointer to start of topdomain */
topname = 0xc000 | ((p - buf + domain_len) & 0x3fff);
/* Query section */
putname(&p, sizeof(q->name), q->name); /* Name */
putshort(&p, q->type); /* Type */
putshort(&p, C_IN); /* Class */
/* Answer section */
putshort(&p, name); /* Name */
putshort(&p, q->type); /* Type */
putshort(&p, C_IN); /* Class */
putlong(&p, 0x3ea7d011); /* TTL */
putshort(&p, 5); /* Data length */
/* pointer to ns.topdomain */
nsname = 0xc000 | ((p - buf) & 0x3fff);
putbyte(&p, 2);
putbyte(&p, 'n');
putbyte(&p, 's');
putshort(&p, topname); /* Name Server */
/* Additional data (A-record of NS server) */
putshort(&p, nsname); /* Name Server */
putshort(&p, T_A); /* Type */
putshort(&p, C_IN); /* Class */
putlong(&p, 0x3ea7d011); /* TTL */
putshort(&p, 4); /* Data length */
/* ugly hack to output IP address */
domain = (char *) &q->destination;
putbyte(&p, *domain++);
putbyte(&p, *domain++);
putbyte(&p, *domain++);
putbyte(&p, *domain);
len = p - buf;
return len;
}
short
dns_get_id(char *packet, size_t packetlen)
{

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@ -25,6 +25,7 @@ typedef enum {
} qr_t;
int dns_encode(char *, size_t, struct query *, qr_t, char *, size_t);
int dns_encode_ns_response(char *buf, size_t buflen, struct query *q, char *topdomain);
short dns_get_id(char *packet, size_t packetlen);
int dns_decode(char *, size_t, struct query *, qr_t, char *, size_t);

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@ -333,6 +333,19 @@ handle_null_request(int tun_fd, int dns_fd, struct query *q, int domain_len)
}
}
static void
handle_ns_request(int dns_fd, struct query *q)
{
char buf[64*1024];
int len;
len = dns_encode_ns_response(buf, sizeof(buf), q, topdomain);
if (sendto(dns_fd, buf, len, 0, (struct sockaddr*)&q->from, q->fromlen) <= 0) {
warn("ns reply send error");
}
}
static void
forward_query(int bind_fd, struct query *q)
{
@ -443,6 +456,9 @@ tunnel_dns(int tun_fd, int dns_fd, int bind_fd)
case T_NULL:
handle_null_request(tun_fd, dns_fd, &q, domain_len);
break;
case T_NS:
handle_ns_request(dns_fd, &q);
break;
default:
break;
}