From 1043f1a0471757fb46350494aff32114b5e2574b Mon Sep 17 00:00:00 2001
From: Damien George <damien.p.george@gmail.com>
Date: Sat, 1 Jun 2019 15:58:23 +1000
Subject: [PATCH] lib/netutils: Add DHCP server component.
---
lib/netutils/dhcpserver.c | 304 ++++++++++++++++++++++++++++++++++++++
lib/netutils/dhcpserver.h | 49 ++++++
2 files changed, 353 insertions(+)
create mode 100644 lib/netutils/dhcpserver.c
create mode 100644 lib/netutils/dhcpserver.h
diff --git a/lib/netutils/dhcpserver.c b/lib/netutils/dhcpserver.c
new file mode 100644
index 000000000..476eb3d69
--- /dev/null
+++ b/lib/netutils/dhcpserver.c
@@ -0,0 +1,304 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2018-2019 Damien P. George
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+// For DHCP specs see:
+// https://www.ietf.org/rfc/rfc2131.txt
+// https://tools.ietf.org/html/rfc2132 -- DHCP Options and BOOTP Vendor Extensions
+
+#include <stdio.h>
+#include <string.h>
+#include "py/mperrno.h"
+#include "py/mphal.h"
+
+#if MICROPY_PY_LWIP
+
+#include "lib/netutils/dhcpserver.h"
+#include "lwip/udp.h"
+
+#define DHCPDISCOVER (1)
+#define DHCPOFFER (2)
+#define DHCPREQUEST (3)
+#define DHCPDECLINE (4)
+#define DHCPACK (5)
+#define DHCPNACK (6)
+#define DHCPRELEASE (7)
+#define DHCPINFORM (8)
+
+#define DHCP_OPT_PAD (0)
+#define DHCP_OPT_SUBNET_MASK (1)
+#define DHCP_OPT_ROUTER (3)
+#define DHCP_OPT_DNS (6)
+#define DHCP_OPT_HOST_NAME (12)
+#define DHCP_OPT_REQUESTED_IP (50)
+#define DHCP_OPT_IP_LEASE_TIME (51)
+#define DHCP_OPT_MSG_TYPE (53)
+#define DHCP_OPT_SERVER_ID (54)
+#define DHCP_OPT_PARAM_REQUEST_LIST (55)
+#define DHCP_OPT_MAX_MSG_SIZE (57)
+#define DHCP_OPT_VENDOR_CLASS_ID (60)
+#define DHCP_OPT_CLIENT_ID (61)
+#define DHCP_OPT_END (255)
+
+#define PORT_DHCP_SERVER (67)
+#define PORT_DHCP_CLIENT (68)
+
+#define DEFAULT_DNS MAKE_IP4(8, 8, 8, 8)
+#define DEFAULT_LEASE_TIME_S (24 * 60 * 60) // in seconds
+
+#define MAC_LEN (6)
+#define MAKE_IP4(a, b, c, d) ((a) << 24 | (b) << 16 | (c) << 8 | (d))
+
+typedef struct {
+ uint8_t op; // message opcode
+ uint8_t htype; // hardware address type
+ uint8_t hlen; // hardware address length
+ uint8_t hops;
+ uint32_t xid; // transaction id, chosen by client
+ uint16_t secs; // client seconds elapsed
+ uint16_t flags;
+ uint8_t ciaddr[4]; // client IP address
+ uint8_t yiaddr[4]; // your IP address
+ uint8_t siaddr[4]; // next server IP address
+ uint8_t giaddr[4]; // relay agent IP address
+ uint8_t chaddr[16]; // client hardware address
+ uint8_t sname[64]; // server host name
+ uint8_t file[128]; // boot file name
+ uint8_t options[312]; // optional parameters, variable, starts with magic
+} dhcp_msg_t;
+
+static int dhcp_socket_new_dgram(struct udp_pcb **udp, void *cb_data, udp_recv_fn cb_udp_recv) {
+ // family is AF_INET
+ // type is SOCK_DGRAM
+
+ *udp = udp_new();
+ if (*udp == NULL) {
+ return -MP_ENOMEM;
+ }
+
+ // Register callback
+ udp_recv(*udp, cb_udp_recv, (void*)cb_data);
+
+ return 0; // success
+}
+
+static void dhcp_socket_free(struct udp_pcb **udp) {
+ if (*udp != NULL) {
+ udp_remove(*udp);
+ *udp = NULL;
+ }
+}
+
+static int dhcp_socket_bind(struct udp_pcb **udp, uint32_t ip, uint16_t port) {
+ ip_addr_t addr;
+ IP4_ADDR(&addr, ip >> 24 & 0xff, ip >> 16 & 0xff, ip >> 8 & 0xff, ip & 0xff);
+ // TODO convert lwIP errors to errno
+ return udp_bind(*udp, &addr, port);
+}
+
+static int dhcp_socket_sendto(struct udp_pcb **udp, const void *buf, size_t len, uint32_t ip, uint16_t port) {
+ if (len > 0xffff) {
+ len = 0xffff;
+ }
+
+ struct pbuf *p = pbuf_alloc(PBUF_TRANSPORT, len, PBUF_RAM);
+ if (p == NULL) {
+ return -MP_ENOMEM;
+ }
+
+ memcpy(p->payload, buf, len);
+
+ ip_addr_t dest;
+ IP4_ADDR(&dest, ip >> 24 & 0xff, ip >> 16 & 0xff, ip >> 8 & 0xff, ip & 0xff);
+ err_t err = udp_sendto(*udp, p, &dest, port);
+
+ pbuf_free(p);
+
+ if (err != ERR_OK) {
+ return err;
+ }
+
+ return len;
+}
+
+static uint8_t *opt_find(uint8_t *opt, uint8_t cmd) {
+ for (int i = 0; i < 308 && opt[i] != DHCP_OPT_END;) {
+ if (opt[i] == cmd) {
+ return &opt[i];
+ }
+ i += 2 + opt[i + 1];
+ }
+ return NULL;
+}
+
+static void opt_write_n(uint8_t **opt, uint8_t cmd, size_t n, void *data) {
+ uint8_t *o = *opt;
+ *o++ = cmd;
+ *o++ = n;
+ memcpy(o, data, n);
+ *opt = o + n;
+}
+
+static void opt_write_u8(uint8_t **opt, uint8_t cmd, uint8_t val) {
+ uint8_t *o = *opt;
+ *o++ = cmd;
+ *o++ = 1;
+ *o++ = val;
+ *opt = o;
+}
+
+static void opt_write_u32(uint8_t **opt, uint8_t cmd, uint32_t val) {
+ uint8_t *o = *opt;
+ *o++ = cmd;
+ *o++ = 4;
+ *o++ = val >> 24;
+ *o++ = val >> 16;
+ *o++ = val >> 8;
+ *o++ = val;
+ *opt = o;
+}
+
+static void dhcp_server_process(void *arg, struct udp_pcb *upcb, struct pbuf *p, const ip_addr_t *src_addr, u16_t src_port) {
+ dhcp_server_t *d = arg;
+ (void)upcb;
+ (void)src_addr;
+ (void)src_port;
+
+ // This is around 548 bytes
+ dhcp_msg_t dhcp_msg;
+
+ #define DHCP_MIN_SIZE (240 + 3)
+ if (p->tot_len < DHCP_MIN_SIZE) {
+ goto ignore_request;
+ }
+
+ size_t len = pbuf_copy_partial(p, &dhcp_msg, sizeof(dhcp_msg), 0);
+ if (len < DHCP_MIN_SIZE) {
+ goto ignore_request;
+ }
+
+ dhcp_msg.op = DHCPOFFER;
+ memcpy(&dhcp_msg.yiaddr, &d->ip.addr, 4);
+
+ uint8_t *opt = (uint8_t*)&dhcp_msg.options;
+ opt += 4; // assume magic cookie: 99, 130, 83, 99
+
+ switch (opt[2]) {
+ case DHCPDISCOVER: {
+ int yi = DHCPS_MAX_IP;
+ for (int i = 0; i < DHCPS_MAX_IP; ++i) {
+ if (memcmp(d->lease[i].mac, dhcp_msg.chaddr, MAC_LEN) == 0) {
+ // MAC match, use this IP address
+ yi = i;
+ break;
+ }
+ if (yi == DHCPS_MAX_IP) {
+ // Look for a free IP address
+ if (memcmp(d->lease[i].mac, "\x00\x00\x00\x00\x00\x00", MAC_LEN) == 0) {
+ // IP available
+ yi = i;
+ }
+ uint32_t expiry = d->lease[i].expiry << 16 | 0xffff;
+ if ((int32_t)(expiry - mp_hal_ticks_ms()) < 0) {
+ // IP expired, reuse it
+ memset(d->lease[i].mac, 0, MAC_LEN);
+ yi = i;
+ }
+ }
+ }
+ if (yi == DHCPS_MAX_IP) {
+ // No more IP addresses left
+ goto ignore_request;
+ }
+ dhcp_msg.yiaddr[3] = DHCPS_BASE_IP + yi;
+ opt_write_u8(&opt, DHCP_OPT_MSG_TYPE, DHCPOFFER);
+ break;
+ }
+
+ case DHCPREQUEST: {
+ uint8_t *o = opt_find(opt, DHCP_OPT_REQUESTED_IP);
+ if (o == NULL) {
+ // Should be NACK
+ goto ignore_request;
+ }
+ if (memcmp(o + 2, &d->ip.addr, 3) != 0) {
+ // Should be NACK
+ goto ignore_request;
+ }
+ uint8_t yi = o[5] - DHCPS_BASE_IP;
+ if (yi >= DHCPS_MAX_IP) {
+ // Should be NACK
+ goto ignore_request;
+ }
+ if (memcmp(d->lease[yi].mac, dhcp_msg.chaddr, MAC_LEN) == 0) {
+ // MAC match, ok to use this IP address
+ } else if (memcmp(d->lease[yi].mac, "\x00\x00\x00\x00\x00\x00", MAC_LEN) == 0) {
+ // IP unused, ok to use this IP address
+ memcpy(d->lease[yi].mac, dhcp_msg.chaddr, MAC_LEN);
+ } else {
+ // IP already in use
+ // Should be NACK
+ goto ignore_request;
+ }
+ d->lease[yi].expiry = (mp_hal_ticks_ms() + DEFAULT_LEASE_TIME_S * 1000) >> 16;
+ dhcp_msg.yiaddr[3] = DHCPS_BASE_IP + yi;
+ opt_write_u8(&opt, DHCP_OPT_MSG_TYPE, DHCPACK);
+ printf("DHCPS: client connected: MAC=%02x:%02x:%02x:%02x:%02x:%02x IP=%u.%u.%u.%u\n",
+ dhcp_msg.chaddr[0], dhcp_msg.chaddr[1], dhcp_msg.chaddr[2], dhcp_msg.chaddr[3], dhcp_msg.chaddr[4], dhcp_msg.chaddr[5],
+ dhcp_msg.yiaddr[0], dhcp_msg.yiaddr[1], dhcp_msg.yiaddr[2], dhcp_msg.yiaddr[3]);
+ break;
+ }
+
+ default:
+ goto ignore_request;
+ }
+
+ opt_write_n(&opt, DHCP_OPT_SERVER_ID, 4, &d->ip.addr);
+ opt_write_n(&opt, DHCP_OPT_SUBNET_MASK, 4, &d->nm.addr);
+ opt_write_n(&opt, DHCP_OPT_ROUTER, 4, &d->ip.addr); // aka gateway; can have mulitple addresses
+ opt_write_u32(&opt, DHCP_OPT_DNS, DEFAULT_DNS); // can have mulitple addresses
+ opt_write_u32(&opt, DHCP_OPT_IP_LEASE_TIME, DEFAULT_LEASE_TIME_S);
+ *opt++ = DHCP_OPT_END;
+ dhcp_socket_sendto(&d->udp, &dhcp_msg, opt - (uint8_t*)&dhcp_msg, 0xffffffff, PORT_DHCP_CLIENT);
+
+ignore_request:
+ pbuf_free(p);
+}
+
+void dhcp_server_init(dhcp_server_t *d, ip_addr_t *ip, ip_addr_t *nm) {
+ ip_addr_copy(d->ip, *ip);
+ ip_addr_copy(d->nm, *nm);
+ memset(d->lease, 0, sizeof(d->lease));
+ if (dhcp_socket_new_dgram(&d->udp, d, dhcp_server_process) != 0) {
+ return;
+ }
+ dhcp_socket_bind(&d->udp, 0, PORT_DHCP_SERVER);
+}
+
+void dhcp_server_deinit(dhcp_server_t *d) {
+ dhcp_socket_free(&d->udp);
+}
+
+#endif // MICROPY_PY_LWIP
diff --git a/lib/netutils/dhcpserver.h b/lib/netutils/dhcpserver.h
new file mode 100644
index 000000000..2349d2ea4
--- /dev/null
+++ b/lib/netutils/dhcpserver.h
@@ -0,0 +1,49 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2018-2019 Damien P. George
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+#ifndef MICROPY_INCLUDED_LIB_NETUTILS_DHCPSERVER_H
+#define MICROPY_INCLUDED_LIB_NETUTILS_DHCPSERVER_H
+
+#include "lwip/ip_addr.h"
+
+#define DHCPS_BASE_IP (16)
+#define DHCPS_MAX_IP (8)
+
+typedef struct _dhcp_server_lease_t {
+ uint8_t mac[6];
+ uint16_t expiry;
+} dhcp_server_lease_t;
+
+typedef struct _dhcp_server_t {
+ ip_addr_t ip;
+ ip_addr_t nm;
+ dhcp_server_lease_t lease[DHCPS_MAX_IP];
+ struct udp_pcb *udp;
+} dhcp_server_t;
+
+void dhcp_server_init(dhcp_server_t *d, ip_addr_t *ip, ip_addr_t *nm);
+void dhcp_server_deinit(dhcp_server_t *d);
+
+#endif // MICROPY_INCLUDED_LIB_NETUTILS_DHCPSERVER_H
--
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