1 files changed, 53 insertions, 0 deletions
diff --git a/libnet/dns.c b/libnet/dns.c
new file mode 100644
index 0000000..b35eb72
--- /dev/null
+++ b/libnet/dns.c
@@ -0,0 +1,53 @@
+// MIT License, Copyright (c) 2020 Marvin Borner
+
+#include <def.h>
+#include <mem.h>
+#include <random.h>
+#include <socket.h>
+#include <str.h>
+
+static u32 dns_ip_addr = ip(1, 1, 1, 1);
+
+struct dns_packet {
+	u16 qid;
+	u16 flags;
+	u16 questions;
+	u16 answers;
+	u16 authorities;
+	u16 additional;
+	u8 data[];
+} __attribute__((packed));
+
+static void dns_make_packet(struct dns_packet *packet, const char *name, const char *tld)
+{
+	packet->qid = htons(rand());
+	packet->flags = htons(0x0100); // Standard query
+	packet->questions = htons(1);
+	packet->answers = htons(0);
+	packet->authorities = htons(0);
+	packet->additional = htons(0);
+
+	packet->data[0] = (u8)strlen(name);
+	memcpy(&packet->data[1], name, (u8)strlen(name));
+	packet->data[(u8)strlen(name) + 1] = (u8)strlen(tld);
+	memcpy(&packet->data[(u8)strlen(name) + 2], tld, (u8)strlen(tld));
+	packet->data[(u8)strlen(name) + (u8)strlen(tld) + 2] = 0x00; // Name end
+	packet->data[(u8)strlen(name) + (u8)strlen(tld) + 4] = 0x01; // A
+	packet->data[(u8)strlen(name) + (u8)strlen(tld) + 6] = 0x01; // IN
+}
+
+void dns_request(const char *name, const char *tld)
+{
+	struct socket *socket = net_open(S_UDP);
+	if (socket)
+		socket->src_port = 50053;
+	if (!socket || !net_connect(socket, dns_ip_addr, 53))
+		return;
+
+	u32 length = sizeof(struct dns_packet) + strlen(name) + strlen(tld) + 7; // TODO: 7 :)
+	struct dns_packet *packet = malloc(length);
+	memset(packet, 0, length);
+	dns_make_packet(packet, name, tld);
+	net_send(socket, packet, length);
+	free(packet);
+}