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Terrible implementation of DNS

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This commit is contained in:
Kevin Lange 2016-09-05 15:01:20 +09:00
parent ea45b87148
commit c9a85035ae
1 changed files with 59 additions and 32 deletions
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91
modules/net.c
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@ -12,6 +12,7 @@
#include <mod/net.h>
static hashmap_t * dns_cache;
static list_t * dns_waiters = NULL;
static hashmap_t *_tcp_sockets = NULL;
static hashmap_t *_udp_sockets = NULL;
@ -148,6 +149,35 @@ static struct dirent * readdir_netfs(fs_node_t *node, uint32_t index) {
return NULL;
}
size_t dns_name_to_normal_name(struct dns_packet * dns, size_t offset, char * buf) {
uint8_t * bytes = (uint8_t *)dns;
size_t i = 0;
while (1) {
uint8_t c = bytes[offset];
if (c == 0) break;
if (c >= 0xC0) {
uint16_t ref = ((c - 0xC0) << 8) + bytes[offset+1];
i += dns_name_to_normal_name(dns, ref, &buf[i]);
return i;
}
offset++;
for (size_t j = 0; j < c; j++) {
buf[i] = bytes[offset];
i++;
offset++;
}
buf[i] = '.';
i++;
buf[i] = '\0';
}
if (i == 0) return 0;
buf[i-1] = '\0';
return i-1;
}
size_t print_dns_name(fs_node_t * tty, struct dns_packet * dns, size_t offset) {
uint8_t * bytes = (uint8_t *)dns;
while (1) {
@ -319,8 +349,11 @@ static fs_node_t * finddir_netfs(fs_node_t * node, char * name) {
queries[0] = '\0';
char * subs[10]; /* 10 is probably not the best number. */
int argc = tokenize(xname, ".", subs);
int n = 0;
for (int i = 0; i < argc; ++i) {
sprintf(queries, "%c%s", strlen(subs[i]), subs[i]);
debug_print(WARNING, "dns [%d]%s", strlen(subs[i]), subs[i]);
sprintf(&queries[n], "%c%s", strlen(subs[i]), subs[i]);
n += strlen(&queries[n]);
}
int c = strlen(queries) + 1;
queries[c+0] = 0x00;
@ -330,15 +363,20 @@ static fs_node_t * finddir_netfs(fs_node_t * node, char * name) {
free(xname);
void * tmp = malloc(1024);
size_t packet_size = write_dns_packet(tmp, strlen(queries) + 4, (uint8_t *)queries);
size_t packet_size = write_dns_packet(tmp, c + 4, (uint8_t *)queries);
free(queries);
_netif.send_packet(tmp, packet_size);
free(tmp);
/* wait for response */
return NULL;
sleep_on(dns_waiters);
if (hashmap_has(dns_cache, name)) {
ip = ip_aton(hashmap_get(dns_cache, name));
debug_print(WARNING, " Now in cache: %s → %x", name, ip);
} else {
return NULL;
}
}
}
@ -386,7 +424,7 @@ static size_t write_dns_packet(uint8_t * buffer, size_t queries_len, uint8_t * q
.protocol = IPV4_PROT_UDP,
.checksum = 0, /* fill this in later */
.source = htonl(_netif.source),
.destination = htonl(ip_aton("192.167.1.1")),
.destination = htonl(ip_aton("10.0.2.3")),
};
uint16_t checksum = calculate_ipv4_checksum(&ipv4_out);
@ -700,10 +738,12 @@ static void net_handle_tcp(struct tcp_header * tcp, size_t length) {
static void net_handle_udp(struct udp_packet * udp, size_t length) {
// size_t data_length = length - sizeof(struct tcp_header);
debug_print(WARNING, "UDP response!");
/* Short-circuit DNS */
if (ntohs(udp->source_port) == 50053) {
parse_dns_response(debug_file, udp->payload);
if (ntohs(udp->source_port) == 53) {
debug_print(WARNING, "UDP response to DNS query!");
parse_dns_response(debug_file, udp);
return;
}
@ -831,6 +871,8 @@ void net_handler(void * data, char * name) {
placeholder_dhcp();
dns_waiters = list_create();
_tcp_sockets = hashmap_create_int(0xFF);
_udp_sockets = hashmap_create_int(0xFF);
@ -950,31 +992,7 @@ size_t write_dhcp_packet(uint8_t * buffer) {
}
static void parse_dns_response(fs_node_t * tty, void * last_packet) {
struct ethernet_packet * eth = (struct ethernet_packet *)last_packet;
uint16_t eth_type = ntohs(eth->type);
fprintf(tty, "Ethernet II, Src: (%2x:%2x:%2x:%2x:%2x:%2x), Dst: (%2x:%2x:%2x:%2x:%2x:%2x) [type=%4x)\n",
eth->source[0], eth->source[1], eth->source[2],
eth->source[3], eth->source[4], eth->source[5],
eth->destination[0], eth->destination[1], eth->destination[2],
eth->destination[3], eth->destination[4], eth->destination[5],
eth_type);
struct ipv4_packet * ipv4 = (struct ipv4_packet *)eth->payload;
uint32_t src_addr = ntohl(ipv4->source);
uint32_t dst_addr = ntohl(ipv4->destination);
uint16_t length = ntohs(ipv4->length);
char src_ip[16];
char dst_ip[16];
ip_ntoa(src_addr, src_ip);
ip_ntoa(dst_addr, dst_ip);
fprintf(tty, "IP packet [%s → %s] length=%d bytes\n",
src_ip, dst_ip, length);
struct udp_packet * udp = (struct udp_packet *)ipv4->payload;
struct udp_packet * udp = (struct udp_packet *)last_packet;
uint16_t src_port = ntohs(udp->source_port);
uint16_t dst_port = ntohs(udp->destination_port);
uint16_t udp_len = ntohs(udp->length);
@ -1003,6 +1021,9 @@ static void parse_dns_response(fs_node_t * tty, void * last_packet) {
fprintf(tty, "Answers:\n");
int answers = 0;
while (answers < dns_answers) {
char buf[1024];
size_t ret = dns_name_to_normal_name(dns, offset, buf);
debug_print(WARNING, "%d - %s", ret, buf);
offset = print_dns_name(tty, dns, offset);
uint16_t * d = (uint16_t *)&bytes[offset];
fprintf(tty, " - Type: %4x %4x; ", ntohs(d[0]), ntohs(d[1]));
@ -1019,6 +1040,10 @@ static void parse_dns_response(fs_node_t * tty, void * last_packet) {
char ip[16];
ip_ntoa(ntohl(i[0]), ip);
fprintf(tty, " Address: %s\n", ip);
debug_print(NOTICE, "Domain [%s] maps to [%s]", buf, ip);
if (!hashmap_has(dns_cache, buf)) {
hashmap_set(dns_cache, buf, strdup(ip));
}
} else {
if (ntohs(d[0]) == 5) {
fprintf(tty, "CNAME: ");
@ -1031,6 +1056,8 @@ static void parse_dns_response(fs_node_t * tty, void * last_packet) {
offset += _l;
answers++;
}
wakeup_queue(dns_waiters);
}
static fs_node_t * netfs_create(void) {