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Replace incoming EDNS0_OPTION_NOMDEVICEID and EDNS0_OPTION_NOMCPEID options.

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This commit is contained in:
Simon Kelley
2016-02-28 21:48:34 +00:00
parent 22fe2fd038
commit c7f3bd2ac8
5 changed files with 37 additions and 14 deletions
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43
src/edns0.c
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@@ -96,7 +96,7 @@ unsigned char *find_pseudoheader(struct dns_header *header, size_t plen, size_t
}
size_t add_pseudoheader(struct dns_header *header, size_t plen, unsigned char *limit,
unsigned short udp_sz, int optno, unsigned char *opt, size_t optlen, int set_do)
unsigned short udp_sz, int optno, unsigned char *opt, size_t optlen, int set_do, int replace)
{
unsigned char *lenp, *datap, *p, *udp_len, *buff = NULL;
int rdlen = 0, is_sign, is_last;
@@ -120,7 +120,7 @@ size_t add_pseudoheader(struct dns_header *header, size_t plen, unsigned char *l
if (set_do)
{
p -=2;
p -= 2;
flags |= 0x8000;
PUTSHORT(flags, p);
}
@@ -136,13 +136,36 @@ size_t add_pseudoheader(struct dns_header *header, size_t plen, unsigned char *l
return plen;
/* check if option already there */
for (i = 0; i + 4 < rdlen; i += len + 4)
for (i = 0; i + 4 < rdlen;)
{
GETSHORT(code, p);
GETSHORT(len, p);
/* malformed option, delete the whole OPT RR and start again. */
if (i + len > rdlen)
{
rdlen = 0;
islast = 0;
break;
}
if (code == optno)
return plen;
p += len;
{
if (!replace)
return plen;
/* delete option if we're to replace it. */
p -= 4;
rdlen -= len + 4;
memcpy(p, p+len+4, rdlen - i);
PUTSHORT(rdlen, lenp);
lenp -= 2;
}
else
{
p += len;
i += len + 4;
}
}
/* If we're going to extend the RR, it has to be the last RR in the packet */
@@ -203,7 +226,7 @@ size_t add_pseudoheader(struct dns_header *header, size_t plen, unsigned char *l
size_t add_do_bit(struct dns_header *header, size_t plen, unsigned char *limit)
{
return add_pseudoheader(header, plen, (unsigned char *)limit, PACKETSZ, 0, NULL, 0, 1);
return add_pseudoheader(header, plen, (unsigned char *)limit, PACKETSZ, 0, NULL, 0, 1, 0);
}
static unsigned char char64(unsigned char c)
@@ -235,7 +258,7 @@ static size_t add_dns_client(struct dns_header *header, size_t plen, unsigned ch
encoder(mac+3, encode+4);
encode[8] = 0;
}
plen = add_pseudoheader(header, plen, limit, PACKETSZ, EDNS0_OPTION_NOMDEVICEID, (unsigned char *)encode, strlen(encode), 0);
plen = add_pseudoheader(header, plen, limit, PACKETSZ, EDNS0_OPTION_NOMDEVICEID, (unsigned char *)encode, strlen(encode), 0, 1);
}
return plen;
@@ -248,7 +271,7 @@ static size_t add_mac(struct dns_header *header, size_t plen, unsigned char *lim
unsigned char mac[DHCP_CHADDR_MAX];
if ((maclen = find_mac(l3, mac, 1, now)) != 0)
plen = add_pseudoheader(header, plen, limit, PACKETSZ, EDNS0_OPTION_MAC, mac, maclen, 0);
plen = add_pseudoheader(header, plen, limit, PACKETSZ, EDNS0_OPTION_MAC, mac, maclen, 0, 0);
return plen;
}
@@ -337,7 +360,7 @@ static size_t add_source_addr(struct dns_header *header, size_t plen, unsigned c
struct subnet_opt opt;
len = calc_subnet_opt(&opt, source);
return add_pseudoheader(header, plen, (unsigned char *)limit, PACKETSZ, EDNS0_OPTION_CLIENT_SUBNET, (unsigned char *)&opt, len, 0);
return add_pseudoheader(header, plen, (unsigned char *)limit, PACKETSZ, EDNS0_OPTION_CLIENT_SUBNET, (unsigned char *)&opt, len, 0, 0);
}
int check_source(struct dns_header *header, size_t plen, unsigned char *pseudoheader, union mysockaddr *peer)
@@ -391,7 +414,7 @@ size_t add_edns0_config(struct dns_header *header, size_t plen, unsigned char *l
if (daemon->dns_client_id)
plen = add_pseudoheader(header, plen, limit, PACKETSZ, EDNS0_OPTION_NOMCPEID,
(unsigned char *)daemon->dns_client_id, strlen(daemon->dns_client_id), 0);
(unsigned char *)daemon->dns_client_id, strlen(daemon->dns_client_id), 0, 1);
if (option_bool(OPT_CLIENT_SUBNET))
{