dhcp works in qemu with dedicated dhcp server on the subnetwork

no382001 · no382001 · commit bc437e0d8d03 · 2025-06-05T23:21:47.000+02:00
diff --git a/Dockerfile b/Dockerfile
@@ -0,0 +1,17 @@
+FROM debian:bookworm-slim
+
+RUN apt-get update && apt-get install -y \
+    build-essential \
+    nasm \
+    qemu-system-x86 \
+    gdb \
+    clang-format \
+    tcpdump \
+    dnsmasq \
+    bridge-utils \
+    iproute2 \
+    net-tools \
+    procps \
+    && rm -rf /var/lib/apt/lists/*
+
+WORKDIR /workspace
diff --git a/Makefile b/Makefile
@@ -1,5 +1,5 @@
-C_SOURCES = $(wildcard kernel/*.c drivers/*.c cpu/*.c libc/*.c apps/*.c net/*.c)
-HEADERS = $(wildcard kernel/*.h drivers/*.h cpu/*.h libc/*.h apps/*.h net/*.h)
+C_SOURCES = $(wildcard kernel/*.c drivers/*.c cpu/*.c libc/*.c apps/*.c net/*.c fs/*.c)
+HEADERS = $(wildcard kernel/*.h drivers/*.h cpu/*.h libc/*.h apps/*.h net/*.h fs/*.h)
 
 BUILD_DIR = _build
 OBJ = $(patsubst %.c, $(BUILD_DIR)/%.o, $(C_SOURCES)) $(BUILD_DIR)/cpu/interrupt.o $(BUILD_DIR)/cpu/task_switch.o
@@ -10,11 +10,11 @@ LD = ld -m elf_i386
 CFLAGSNO = -fno-pie -nostdlib -fno-builtin -nodefaultlibs -nostartfiles -Wno-error=comment -Wno-error=unused-variable -Wno-error=unused-parameter #-Wno-error=pointer-arith
 USAN = -fsanitize=undefined -fno-sanitize=shift
 CFLAGS = -g -O0 -m32 -fno-pie -ffreestanding -nostdlib -fno-builtin -nodefaultlibs -nostartfiles -Werror -Wpedantic -Wall -Wextra -I$(shell pwd)
-NETWORKING = -netdev tap,id=my_tap0,ifname=tap0 -device rtl8139,netdev=my_tap0
+NETWORKING = -netdev tap,id=net0,ifname=tap0,script=no,downscript=no -device rtl8139,netdev=net0
 QEMU_FLAGS=-no-shutdown -no-reboot
 RUN = qemu-system-i386  --enable-kvm $(QEMU_FLAGS) -m 4 -serial stdio -kernel $(BUILD_DIR)/kernel.elf -drive file=disk/fat16.img,format=raw -d int,cpu_reset,guest_errors -D qemu.log -trace kvm* -D kvm_trace.log
 
-$(shell mkdir -p $(BUILD_DIR)/boot $(BUILD_DIR)/kernel $(BUILD_DIR)/drivers $(BUILD_DIR)/cpu $(BUILD_DIR)/libc $(BUILD_DIR)/apps $(BUILD_DIR)/net)
+$(shell mkdir -p $(BUILD_DIR)/boot $(BUILD_DIR)/kernel $(BUILD_DIR)/drivers $(BUILD_DIR)/cpu $(BUILD_DIR)/libc $(BUILD_DIR)/apps $(BUILD_DIR)/net $(BUILD_DIR)/fs)
 
 all: format bits $(BUILD_DIR)/kernel.elf disk/fat16.img
 
@@ -34,6 +34,8 @@ net: all
 	$(RUN) $(NETWORKING)
 run: all
 	$(RUN)
+vnc : all
+	$(RUN) $(NETWORKING) -vnc :1
 
 #################
 disk/fat16.img:
diff --git a/README.md b/README.md
@@ -0,0 +1,10 @@
+```bash
+docker build -t kernel-dev .
+
+sudo docker run -it --privileged --cap-add=NET_ADMIN \
+    -v $(pwd):/workspace \
+    -p 5901:5901 \
+    kernel-dev bash
+
+vncviewer localhost:5901$
+```
diff --git a/TODO b/TODO
@@ -72,4 +72,12 @@ TODO:
   [ ] thread the ehternet packets
   [ ] add some log groups for debugging
   [ ] write a readme and collect main features and quirks 
-  [ ] ip packets are inefficient, it works but...
+  [ ] ip packets are inefficient, it works but...
+  [ ] vfs based on 9p
+  [ ] sockets, for udp
+
+
+`
+brctl show  
+sudo brctl addif virbr0 tap0
+`
diff --git a/apps/vga_demo_terminal.h b/apps/vga_demo_terminal.h
@@ -1,8 +1,8 @@
 #pragma once
 
-#include "drivers/fat16.h"
 #include "drivers/keyboard.h"
 #include "drivers/screen.h"
+#include "fs/fat16.h"
 #include "libc/bdf.h"
 
 typedef struct {
diff --git a/dhcp.sh b/dhcp.sh
@@ -0,0 +1,5 @@
+ip tuntap add dev tap0 mode tap
+ip addr add 192.168.100.1/24 dev tap0
+ip link set tap0 up
+
+dnsmasq --interface=tap0 --dhcp-range=192.168.100.10,192.168.100.50,12h --log-dhcp --no-daemon &
diff --git a/fs/fat16.c b/fs/fat16.c
diff --git a/fs/fat16.h b/fs/fat16.h
diff --git a/kernel/kernel.c b/kernel/kernel.c
@@ -84,22 +84,27 @@ void kernel_main(void) {
 
   uint8_t mac_addr[] = {0};
   get_mac_addr(mac_addr);
-  /*
-   */
-
-  /*
-  ethernet_send_packet(mac_addr, (void *)str, strlen(str), 0x0021);
-  ip_send_packet(ip_addr, (void *)str, strlen(str));
-  */
 
   // this does not work i cant seem to set up the network on wsl2 qemu
   // the packet looks okay, but i cant reach the dhcp server
-  /*
+
+  // maybe put this in a state machine?
   dhcp_discover();
-  while (gethostaddr((char *)mac_addr) == 0){};
-  */
+  extern int is_ip_allocated;
+  extern int is_ip_offered;
+
+  while (!is_ip_offered) {
+  }
+
+  while (!is_ip_allocated) {
+    sleep(1000);
+    extern uint32_t prev_requested_ip;
+    dhcp_request((uint8_t *)&prev_requested_ip);
+  }
+  extern uint8_t my_ip[4];
+  serial_debug("we got a dynamic ip!  %d.%d.%d.%d", my_ip[0], my_ip[1],
+               my_ip[2], my_ip[3]);
 
-  // udp_send_packet(ip_addr, 1234, 1153, str, strlen(str));
   while (1) {
     ;
   }
diff --git a/libc/bdf.h b/libc/bdf.h
@@ -1,5 +1,5 @@
 #pragma once
-#include "drivers/fat16.h"
+#include "fs/fat16.h"
 
 #define MAX_GLYPHS 256
 #define GLYPH_HEIGHT 16
diff --git a/libc/types.h b/libc/types.h
@@ -3,5 +3,5 @@
 #include <stddef.h>
 #include <stdint.h>
 
-#define low_16(address) (uint16_t)((address) & 0xFFFF)
+#define low_16(address) (uint16_t)((address)&0xFFFF)
 #define high_16(address) (uint16_t)(((address) >> 16) & 0xFFFF)
diff --git a/net/arp.c b/net/arp.c
@@ -5,7 +5,8 @@
 #include "network.h"
 #include "rtl8139.h"
 
-/**/
+/*
+ */
 #undef serial_debug
 #define serial_debug(...)
 
@@ -59,8 +60,10 @@ void arp_handle_packet(arp_packet_t *arp_packet) {
           arp_packet->dst_hardware_addr[2], arp_packet->dst_hardware_addr[3]);
     }
   } else if (ntohs(arp_packet->opcode) == ARP_REPLY) {
+    serial_debug("arp reply");
     // reply
   } else {
+    serial_debug("arp not for us");
     return; // not for us
   }
   uint8_t _[6] = {0};
diff --git a/net/dhcp.c b/net/dhcp.c
@@ -6,15 +6,19 @@
 #include "rtl8139.h"
 #include "udp.h"
 
+/*
+ */
 #undef serial_debug
 #define serial_debug(...)
 
-char ip_addr[4];
+extern uint8_t my_ip[4];
 int is_ip_allocated = 0;
+int is_ip_offered = 0;
 uint32_t dhcp_server_ip = 0;
+uint32_t prev_requested_ip = 0;
 
 int gethostaddr(char *addr) {
-  memcpy(addr, ip_addr, 4);
+  memcpy(addr, my_ip, 4);
   return is_ip_allocated;
 }
 
@@ -76,8 +80,7 @@ void dhcp_discover() {
 }
 
 void dhcp_request(uint8_t *requested_ip) {
-  uint8_t dst_ip[4] = {255, 255, 255, 255};
-
+  uint8_t dst_ip[4] = {255, 255, 255, 255}; // need to broadcast
   dhcp_packet_t packet = {0};
 
   packet.op = BOOTREQUEST;
@@ -86,6 +89,7 @@ void dhcp_request(uint8_t *requested_ip) {
   packet.hops = 0;
   packet.xid = htonl(DHCP_TRANSACTION_IDENTIFIER);
   packet.flags = htons(0x8000); // broadcast flag
+
   get_mac_addr(packet.client_hardware_addr);
 
   uint8_t *options = packet.options;
@@ -125,6 +129,7 @@ void dhcp_request(uint8_t *requested_ip) {
       DHCP_OPT_ROUTER,      // router
       DHCP_OPT_DNS          // DNS server
   };
+
   options =
       add_dhcp_option(options, DHCP_OPT_PARAM_REQ_LIST, sizeof(params), params);
 
@@ -167,34 +172,49 @@ void *get_dhcp_option(dhcp_packet_t *packet, uint8_t type) {
 
 void dhcp_handle_packet(dhcp_packet_t *packet) {
   if (packet->op != DHCP_REPLY) {
+    serial_debug("not a reply! its %x", packet->op);
     return;
   }
 
   if (ntohl(packet->xid) != DHCP_TRANSACTION_IDENTIFIER) {
+    serial_debug("not our xid!");
     return;
   }
 
   uint8_t *type_ptr = get_dhcp_option(packet, DHCP_OPT_MSG_TYPE);
   if (!type_ptr) {
+    serial_debug("invalid msg type!");
     return;
   }
 
   uint8_t msg_type = *type_ptr;
 
   switch (msg_type) {
   case DHCP_MSG_OFFER: {
+    is_ip_offered = 1;
+    memcpy(&prev_requested_ip, &packet->your_ip, 4);
+    serial_debug("offer! of %d.%d.%d.%d", ((uint8_t *)&packet->your_ip)[0],
+                 ((uint8_t *)&packet->your_ip)[1],
+                 ((uint8_t *)&packet->your_ip)[2],
+                 ((uint8_t *)&packet->your_ip)[3]);
 
     uint8_t *server_id = get_dhcp_option(packet, 54); // 54 = Server ID
     if (server_id) {
       memcpy(&dhcp_server_ip, server_id, 4);
+      serial_debug("dhcp server: %d.%d.%d.%d", server_id[0], server_id[1],
+                   server_id[2], server_id[3]);
     }
 
     dhcp_request((uint8_t *)&packet->your_ip);
   } break;
 
   case DHCP_MSG_ACK:
-    memcpy(ip_addr, &packet->your_ip, 4);
+    if (is_ip_allocated) {
+      break;
+    }
+    memcpy(my_ip, &packet->your_ip, 4);
     is_ip_allocated = 1;
+    serial_debug("we got an ip!");
 
     // process other configuration options (subnet, router, DNS)
     uint8_t *subnet_mask = get_dhcp_option(packet, DHCP_OPT_SUBNET_MASK);
@@ -216,8 +236,10 @@ void dhcp_handle_packet(dhcp_packet_t *packet) {
     break;
 
   case DHCP_MSG_NAK:
+    serial_debug("nack!");
     // start over with DISCOVER
     is_ip_allocated = 0;
+    is_ip_offered = 0;
     dhcp_discover();
     break;
   }
diff --git a/net/dhcp.h b/net/dhcp.h
@@ -54,7 +54,7 @@ typedef struct dhcp_packet {
 
 int gethostaddr(char *addr);
 void dhcp_discover();
-void dhcp_request(uint8_t *request_ip);
+void dhcp_request(uint8_t *requested_ip);
 void dhcp_handle_packet(dhcp_packet_t *packet);
 void *get_dhcp_options(dhcp_packet_t *packet, uint8_t type);
 void make_dhcp_packet(dhcp_packet_t *packet, uint8_t msg_type,
diff --git a/net/icmp.c b/net/icmp.c
@@ -4,8 +4,10 @@
 #include "libc/mem.h"
 #include "network.h"
 
+/*
 #undef serial_debug
 #define serial_debug(...)
+*/
 
 static uint16_t icmp_calculate_checksum(void *buffer, uint16_t size) {
   uint32_t sum = 0;
diff --git a/net/ip.c b/net/ip.c
@@ -5,10 +5,12 @@
 #include "libc/string.h"
 #include "network.h"
 
+/*
+ */
 #undef serial_debug
 #define serial_debug(...)
 
-uint8_t my_ip[] = {10, 0, 2, 14};
+uint8_t my_ip[] = {0, 0, 0, 0};
 
 void get_ip_str(char *ip_str, uint8_t *ip) {
   char temp[4];
diff --git a/net/network.c b/net/network.c
@@ -6,6 +6,8 @@
 #include "libc/mem.h"
 #include "rtl8139.h"
 
+/*
+ */
 #undef serial_debug
 #define serial_debug(...)
 
@@ -41,33 +43,33 @@ void ethernet_handle_packet(ethernet_frame_t *packet, int len) {
 
   uint8_t our_mac[6] = {0};
   get_mac_addr(our_mac);
-
-  // !!!
-  for (int i = 0; i < 6; i++) {
-    if (packet->dst_mac_addr[i] != our_mac[i] &&
-        !(packet->dst_mac_addr[0] == 0xFF && packet->dst_mac_addr[1] == 0xFF &&
-          packet->dst_mac_addr[2] == 0xFF && packet->dst_mac_addr[3] == 0xFF &&
-          packet->dst_mac_addr[4] == 0xFF && packet->dst_mac_addr[5] == 0xFF)) {
-      // serial_debug("not for us tho, ignoring...");
-      /*
-      serial_debug(
-        "not for us! from: %x:%x:%x:%x:%x:%x to:   %x:%x:%x:%x:%x:%x",
-        packet->src_mac_addr[0], packet->src_mac_addr[1],
-        packet->src_mac_addr[2], packet->src_mac_addr[3],
-        packet->src_mac_addr[4], packet->src_mac_addr[5],
-        packet->dst_mac_addr[0], packet->dst_mac_addr[1],
-        packet->dst_mac_addr[2], packet->dst_mac_addr[3],
-        packet->dst_mac_addr[4], packet->dst_mac_addr[5]);
-      */
-      return; // not for us
-    }
+  serial_debug(
+      " dst=%02x:%02x:%02x:%02x:%02x:%02x src=%02x:%02x:%02x:%02x:%02x:%02x",
+      packet->dst_mac_addr[0], packet->dst_mac_addr[1], packet->dst_mac_addr[2],
+      packet->dst_mac_addr[3], packet->dst_mac_addr[4], packet->dst_mac_addr[5],
+      packet->src_mac_addr[0], packet->src_mac_addr[1], packet->src_mac_addr[2],
+      packet->src_mac_addr[3], packet->src_mac_addr[4],
+      packet->src_mac_addr[5]);
+
+  serial_debug("our_mac=%02x:%02x:%02x:%02x:%02x:%02x", our_mac[0], our_mac[1],
+               our_mac[2], our_mac[3], our_mac[4], our_mac[5]);
+
+  bool is_broadcast =
+      (packet->dst_mac_addr[0] == 0xFF && packet->dst_mac_addr[1] == 0xFF &&
+       packet->dst_mac_addr[2] == 0xFF && packet->dst_mac_addr[3] == 0xFF &&
+       packet->dst_mac_addr[4] == 0xFF && packet->dst_mac_addr[5] == 0xFF);
+
+  bool is_for_us = memcmp(packet->dst_mac_addr, our_mac, 6) == 0;
+
+  if (!is_broadcast && !is_for_us) {
+    serial_debug("not for us");
+    return; // not for us
   }
 
   serial_debug("type: %x, length: %d", type, len);
 
   // ARP packet
   if (type == ETHERNET_TYPE_ARP) {
-    serial_debug("arp packet)");
     arp_handle_packet((void *)packet->data);
     return;
   } else
diff --git a/net/network.h b/net/network.h
@@ -11,8 +11,8 @@ typedef struct ethernet_frame {
   uint8_t src_mac_addr[6];
   uint16_t type;
   uint8_t data[];
-} __attribute__((
-    packed)) ethernet_frame_t; // just give this down to evey handle_fn
+} __attribute__((packed))
+ethernet_frame_t; // just give this down to evey handle_fn
 
 int ethernet_send_packet(uint8_t *dst_mac_addr, uint8_t *data, int len,
                          uint16_t protocol);
diff --git a/net/rtl8139.c b/net/rtl8139.c
diff --git a/net/udp.c b/net/udp.c
diff --git a/setup_network.sh b/setup_network.sh
