From 68400a25b7bcd817ff2a7c1f80fc7e76c26a606c Mon Sep 17 00:00:00 2001
From: Piper Pentagram <piper@pipi.sh>
Date: Tue, 8 Jul 2025 15:36:27 -0700
Subject: [PATCH] read the packets into packet structs

---
 include/dns_packet_buffer.h |  7 +++++--
 include/dns_request.h       |  5 ++++-
 include/udp_server.h        |  2 +-
 src/dns_packet_buffer.c     | 32 ++++++++++++++++++++++++++++++++
 src/dns_request.c           | 11 +++++++++++
 5 files changed, 53 insertions(+), 4 deletions(-)

diff --git a/include/dns_packet_buffer.h b/include/dns_packet_buffer.h
index f23287d..4539e02 100644
--- a/include/dns_packet_buffer.h
+++ b/include/dns_packet_buffer.h
@@ -1,13 +1,16 @@
 #pragma once
 #include <stddef.h>
 
-#define PACKET_BUFFER_SIZE 512
+#define PB_SIZE 512
+#define PB_OUT_OF_BOUNDS 9999;
 
 struct DNSPacketBuffer {
-    char buf[PACKET_BUFFER_SIZE];
+    char buf[PB_SIZE];
     size_t pos;
 };
 
 struct DNSPacketBuffer *new_dns_packet_buffer();
 
 struct DNSPacketHeader *dns_header(struct DNSPacketBuffer);
+
+char pb_read_byte(struct DNSPacketBuffer *);
diff --git a/include/dns_request.h b/include/dns_request.h
index aeecf54..e5705ff 100644
--- a/include/dns_request.h
+++ b/include/dns_request.h
@@ -1,7 +1,10 @@
 #pragma once
 
 #include "dns_packets.h"
+#include "dns_packet_buffer.h"
 
 struct DNSRequest {
-    struct DNSPacketHeader header;
+    struct DNSPacketHeader *header;
 };
+
+struct DNSRequest *new_dns_request(struct DNSPacketBuffer *pb);
diff --git a/include/udp_server.h b/include/udp_server.h
index cd63cfc..40276be 100644
--- a/include/udp_server.h
+++ b/include/udp_server.h
@@ -1,5 +1,5 @@
 #pragma once
 
-#define UDP_PORT 53
+#define UDP_PORT 1053
 
 int start_server();
diff --git a/src/dns_packet_buffer.c b/src/dns_packet_buffer.c
index 55fe986..7d7cd69 100644
--- a/src/dns_packet_buffer.c
+++ b/src/dns_packet_buffer.c
@@ -1,4 +1,5 @@
 #include "dns_packet_buffer.h"
+#include <stdio.h>
 #include <stdlib.h>
 
 struct DNSPacketBuffer *new_dns_packet_buffer()
@@ -12,3 +13,34 @@ struct DNSPacketHeader *dns_header(struct DNSPacketBuffer)
 {
 
 }
+
+
+// read a single byte and move the cursor one byte forward
+char pb_read_byte(struct DNSPacketBuffer *pb)
+{
+    char b = pb->buf[pb->pos];
+    pb->pos++;
+
+    if (pb->pos >= PB_SIZE) {
+       printf(
+           "WARN: pb_read_byte: advanced packetbuffer cursor pos to %lu, which is greater than the max %d",
+           pb->pos,
+           PB_SIZE
+        ); 
+    }
+
+    return b;
+}
+
+char pb_get_byte(struct DNSPacketBuffer *pb)
+{
+    if (pb->pos >= PB_SIZE) {
+       printf(
+           "WARN: pb_get_byte: accessing packetbuffer cursor pos %lu, which is greater than the max %d",
+           pb->pos,
+           PB_SIZE
+        ); 
+    }
+
+    return pb->buf[pb->pos];
+}
diff --git a/src/dns_request.c b/src/dns_request.c
index 243502c..b960d9d 100644
--- a/src/dns_request.c
+++ b/src/dns_request.c
@@ -1,3 +1,14 @@
+#include <stdlib.h>
+
 #include "dns_request.h"
 
 
+
+struct DNSRequest *new_dns_request(struct DNSPacketBuffer *pb)
+{
+    struct DNSRequest *req;
+    req = malloc(sizeof(struct DNSRequest));
+
+    req->header = (struct DNSPacketHeader *) pb->buf;
+    return req;
+}