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mdns: Support mdns query for IPV6
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@pymumu
pymumu committed Jan 6, 2024
1 parent 94460d1 commit 526274b
Showing 1 changed file with 176 additions and 69 deletions.
245 changes: 176 additions & 69 deletions src/dns_server.c
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Original file line number Diff line number Diff line change
Expand Up @@ -4138,14 +4138,168 @@ static int _dns_server_process_ptrs(struct dns_request *request)
return -1;
}

static void _dns_server_set_request_mdns(struct dns_request *request)
{
if (dns_conf_mdns_lookup != 1) {
return;
}

request->is_mdns_lookup = 1;
}

static int _dns_server_parser_addr_from_apra(const char *arpa, unsigned char *addr, int *addr_len, int max_addr_len)
{
int high, low;
char *endptr = NULL;

if (arpa == NULL || addr == NULL || addr_len == NULL || max_addr_len < 4) {
return -1;
}

int ret = sscanf(arpa, "%hhd.%hhd.%hhd.%hhd.in-addr.arpa", &addr[3], &addr[2], &addr[1], &addr[0]);
if (ret == 4 && strstr(arpa, ".in-addr.arpa") != NULL) {
*addr_len = 4;
return 0;
}

if (max_addr_len != 16) {
return -1;
}

for (int i = 15; i >= 0; i--) {
low = strtol(arpa, &endptr, 16);
if (endptr == NULL || *endptr != '.' || *endptr == '\0') {
return -1;
}

arpa = endptr + 1;
high = strtol(arpa, &endptr, 16);
if (endptr == NULL || *endptr != '.' || *endptr == '\0') {
return -1;
}

arpa = endptr + 1;
addr[i] = (high << 4) | low;
}

if (strstr(arpa, "ip6.arpa") == NULL) {
return -1;
}

*addr_len = 16;

return 0;
}

static int _dns_server_ip_get_addr_from_ifaddrs(struct ifaddrs *ifaddr, unsigned char *addr, int *maskbit,
int *addr_len)
{
unsigned char *netmask = NULL;
unsigned char *netaddr = NULL;
int prefix_len = 0;

switch (ifaddr->ifa_addr->sa_family) {
case AF_INET: {
struct sockaddr_in *addr_in = NULL;
struct sockaddr_in *netmask_in = NULL;
addr_in = (struct sockaddr_in *)ifaddr->ifa_addr;
netmask_in = (struct sockaddr_in *)ifaddr->ifa_netmask;
netaddr = (unsigned char *)&(addr_in->sin_addr.s_addr);
netmask = (unsigned char *)&(netmask_in->sin_addr.s_addr);
*addr_len = 4;
} break;
case AF_INET6: {
struct sockaddr_in6 *addr_in6 = NULL;
struct sockaddr_in6 *netmask_in6 = NULL;
addr_in6 = (struct sockaddr_in6 *)ifaddr->ifa_addr;
netmask_in6 = (struct sockaddr_in6 *)ifaddr->ifa_netmask;
if (IN6_IS_ADDR_V4MAPPED(&addr_in6->sin6_addr)) {
netaddr = addr_in6->sin6_addr.s6_addr + 12;
netmask = netmask_in6->sin6_addr.s6_addr + 12;
*addr_len = 4;
} else {
netaddr = addr_in6->sin6_addr.s6_addr;
netmask = netmask_in6->sin6_addr.s6_addr;
*addr_len = 16;
}
} break;
default:
return -1;
break;
}

for (int i = 0; i < *addr_len; i++) {
if (netmask[i] == 0xff) {
prefix_len += 8;
} else {
unsigned char mask = netmask[i];
while (mask) {
mask <<= 1;
prefix_len++;
}
break;
}
}

memcpy(addr, netaddr, *addr_len);
*maskbit = prefix_len;

return 0;
}

static int _dns_server_ip_is_subnet(unsigned char *addr, int mask, unsigned char *sub_addr, int addr_len)
{
if (addr_len != 4 && addr_len != 16) {
return -1;
}

if (mask > addr_len * 8) {
return -1;
}

if (memcmp(addr, sub_addr, mask / 8) != 0) {
return -1;
}

if (mask % 8 != 0) {
if ((addr[mask / 8] & (0xff << (8 - mask % 8))) != (sub_addr[mask / 8] & (0xff << (8 - mask % 8)))) {
return -1;
}
}

return 0;
}

static int _dns_server_process_private_ptr(unsigned char *addr, int addr_len)
{
if (addr_len == 4) {
if (addr[0] == 10 || (addr[0] == 172 && addr[1] >= 16 && addr[1] <= 31) || (addr[0] == 192 && addr[1] == 168)) {
return 0;
}
} else if (addr_len == 16) {
if (addr[0] == 0xfe && addr[1] == 0x80) {
return 0;
}
}

return -1;
}

static int _dns_server_process_local_ptr(struct dns_request *request)
{
struct ifaddrs *ifaddr = NULL;
struct ifaddrs *ifa = NULL;
unsigned char *addr = NULL;
char reverse_addr[DNS_MAX_CNAME_LEN] = {0};
unsigned char ptr_addr[16];
int ptr_addr_len = 0;
unsigned char addr[16];
int addr_len = 0;
int maskbit = 0;
int found = 0;

if (_dns_server_parser_addr_from_apra(request->domain, ptr_addr, &ptr_addr_len, sizeof(ptr_addr)) != 0) {
return -1;
}

if (getifaddrs(&ifaddr) == -1) {
return -1;
}
Expand All @@ -4156,48 +4310,28 @@ static int _dns_server_process_local_ptr(struct dns_request *request)
continue;
}

switch (ifa->ifa_addr->sa_family) {
case AF_INET: {
struct sockaddr_in *addr_in = NULL;
addr_in = (struct sockaddr_in *)ifa->ifa_addr;
addr = (unsigned char *)&(addr_in->sin_addr.s_addr);
snprintf(reverse_addr, sizeof(reverse_addr), "%d.%d.%d.%d.in-addr.arpa", addr[3], addr[2], addr[1],
addr[0]);
} break;
case AF_INET6: {
struct sockaddr_in6 *addr_in6 = NULL;
addr_in6 = (struct sockaddr_in6 *)ifa->ifa_addr;
if (IN6_IS_ADDR_V4MAPPED(&addr_in6->sin6_addr)) {
addr = addr_in6->sin6_addr.s6_addr + 12;
snprintf(reverse_addr, sizeof(reverse_addr), "%d.%d.%d.%d.in-addr.arpa", addr[3], addr[2], addr[1],
addr[0]);
} else {
addr = addr_in6->sin6_addr.s6_addr;
snprintf(reverse_addr, sizeof(reverse_addr),
"%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x.%x."
"%x.ip6.arpa",
addr[15] & 0xF, (addr[15] >> 4) & 0xF, addr[14] & 0xF, (addr[14] >> 4) & 0xF, addr[13] & 0xF,
(addr[13] >> 4) & 0xF, addr[12] & 0xF, (addr[12] >> 4) & 0xF, addr[11] & 0xF,
(addr[11] >> 4) & 0xF, addr[10] & 0xF, (addr[10] >> 4) & 0xF, addr[9] & 0xF,
(addr[9] >> 4) & 0xF, addr[8] & 0xF, (addr[8] >> 4) & 0xF, addr[7] & 0xF, (addr[7] >> 4) & 0xF,
addr[6] & 0xF, (addr[6] >> 4) & 0xF, addr[5] & 0xF, (addr[5] >> 4) & 0xF, addr[4] & 0xF,
(addr[4] >> 4) & 0xF, addr[3] & 0xF, (addr[3] >> 4) & 0xF, addr[2] & 0xF, (addr[2] >> 4) & 0xF,
addr[1] & 0xF, (addr[1] >> 4) & 0xF, addr[0] & 0xF, (addr[0] >> 4) & 0xF);
}
} break;
default:
addr_len = sizeof(addr);
if (_dns_server_ip_get_addr_from_ifaddrs(ifa, addr, &maskbit, &addr_len) != 0) {
continue;
}

if (addr_len != ptr_addr_len) {
continue;
break;
}

if (strncmp(request->domain, reverse_addr, DNS_MAX_CNAME_LEN) == 0) {
if (_dns_server_ip_is_subnet(addr, addr_len * 8, ptr_addr, ptr_addr_len) == 0) {
found = 1;
break;
}

if (_dns_server_ip_is_subnet(addr, maskbit, ptr_addr, ptr_addr_len) == 0) {
_dns_server_set_request_mdns(request);
goto errout;
}
}

/* Determine if the smartdns service is in effect. */
if (strncmp(request->domain, "0.0.0.0.in-addr.arpa", DNS_MAX_CNAME_LEN - 1) == 0) {
if (found == 0 && strncmp(request->domain, "0.0.0.0.in-addr.arpa", DNS_MAX_CNAME_LEN - 1) == 0) {
found = 1;
}

Expand All @@ -4206,6 +4340,12 @@ static int _dns_server_process_local_ptr(struct dns_request *request)
found = 1;
}

if (found == 0 && _dns_server_process_private_ptr(ptr_addr, ptr_addr_len) == 0) {
request->has_soa = 1;
_dns_server_setup_soa(request);
goto clear;
}

if (found == 0) {
goto errout;
}
Expand Down Expand Up @@ -4244,7 +4384,7 @@ static int _dns_server_process_local_ptr(struct dns_request *request)

request->has_ptr = 1;
safe_strncpy(request->ptr_hostname, full_hostname, DNS_MAX_CNAME_LEN);

clear:
freeifaddrs(ifaddr);
return 0;
errout:
Expand Down Expand Up @@ -4281,35 +4421,6 @@ static int _dns_server_get_local_ttl(struct dns_request *request)
return DNS_SERVER_ADDR_TTL;
}

static void _dns_server_set_request_mdns(struct dns_request *request)
{
if (dns_conf_mdns_lookup != 1) {
return;
}

request->is_mdns_lookup = 1;
}

static int _dns_server_process_private_ptr(struct dns_request *request)
{
int a, b, c, d;
int ret = sscanf(request->domain, "%d.%d.%d.%d.in-addr.arpa", &a, &b, &c, &d);
if (ret != 4) {
return -1;
}

if (d == 10 || (d == 172 && c >= 16 && c <= 31) || (d == 192 && c == 168)) {
if (dns_conf_mdns_lookup == 0) {
request->has_soa = 1;
_dns_server_setup_soa(request);
return 0;
}
_dns_server_set_request_mdns(request);
}

return -1;
}

static int _dns_server_process_ptr(struct dns_request *request)
{
if (_dns_server_process_ptrs(request) == 0) {
Expand All @@ -4320,10 +4431,6 @@ static int _dns_server_process_ptr(struct dns_request *request)
goto reply_exit;
}

if (_dns_server_process_private_ptr(request) == 0) {
goto reply_exit;
}

return -1;

reply_exit:
Expand Down

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