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lib/netutils: Add DHCP server component.
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‎lib/netutils/dhcpserver.c‎

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

‎lib/netutils/dhcpserver.h‎

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/*
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* This file is part of the MicroPython project, http://micropython.org/
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*
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* The MIT License (MIT)
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*
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* Copyright (c) 2018-2019 Damien P. George
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
9+
* of this software and associated documentation files (the "Software"), to deal
10+
* in the Software without restriction, including without limitation the rights
11+
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
12+
* copies of the Software, and to permit persons to whom the Software is
13+
* furnished to do so, subject to the following conditions:
14+
*
15+
* The above copyright notice and this permission notice shall be included in
16+
* all copies or substantial portions of the Software.
17+
*
18+
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
19+
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
20+
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
21+
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
22+
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
23+
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
24+
* THE SOFTWARE.
25+
*/
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#ifndef MICROPY_INCLUDED_LIB_NETUTILS_DHCPSERVER_H
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#define MICROPY_INCLUDED_LIB_NETUTILS_DHCPSERVER_H
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#include "lwip/ip_addr.h"
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#define DHCPS_BASE_IP (16)
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#define DHCPS_MAX_IP (8)
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typedef struct _dhcp_server_lease_t {
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uint8_t mac[6];
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uint16_t expiry;
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} dhcp_server_lease_t;
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typedef struct _dhcp_server_t {
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ip_addr_t ip;
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ip_addr_t nm;
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dhcp_server_lease_t lease[DHCPS_MAX_IP];
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struct udp_pcb *udp;
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} dhcp_server_t;
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void dhcp_server_init(dhcp_server_t *d, ip_addr_t *ip, ip_addr_t *nm);
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void dhcp_server_deinit(dhcp_server_t *d);
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#endif // MICROPY_INCLUDED_LIB_NETUTILS_DHCPSERVER_H

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