328 lines
8.5 KiB
C
328 lines
8.5 KiB
C
#include "DHCP_Server.h"
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#include <stdio.h>
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#include <string.h>
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#include <errno.h>
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#include <cyw43_config.h>
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#include <lwip/udp.h>
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#include <lwip/ip_addr.h>
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#include "DHCP_Config.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 MAC_LEN (6)
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struct dhcp_server_lease_t {
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uint8_t mac[6];
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uint16_t expiry;
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};
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struct dhcp_server_t {
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ip_addr_t ip;
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ip_addr_t nm;
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struct dhcp_server_lease_t lease[DHCPS_MAX_IP];
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struct udp_pcb *pcb;
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} dhcp_server;
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struct dhcp_msg_t {
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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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};
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#define DHCP_MSG_MIN_SIZE (240 + 3)
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static void dhcp_socket_sendto(struct netif *nif, const void *buf, size_t len, uint32_t ip, uint16_t port)
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{
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if(len > 0xffff)
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{
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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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{
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puts("Pbuf allocation error");
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return;
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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(ip_2_ip4(&dest), ip >> 24 & 0xff, ip >> 16 & 0xff, ip >> 8 & 0xff, ip & 0xff);
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err_t err;
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if(nif != NULL)
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{
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err = udp_sendto_if(dhcp_server.pcb, p, &dest, port, nif);
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}
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else
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{
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err = udp_sendto(dhcp_server.pcb, p, &dest, port);
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}
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pbuf_free(p);
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if(err != ERR_OK)
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{
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printf("Error sending DHCP packets : %d\n", err);
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}
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}
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static uint8_t *opt_find(uint8_t *opt, uint8_t cmd)
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{
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for(int i = 0; i < 308 && opt[i] != DHCP_OPT_END; )
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{
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if (opt[i] == cmd)
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{
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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, const void *data)
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{
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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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{
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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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{
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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 __unused, struct udp_pcb *upcb __unused, struct pbuf *p, const ip_addr_t *src_addr __unused, u16_t src_port __unused)
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{
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// This is around 548 bytes
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struct dhcp_msg_t dhcp_msg;
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if(p->tot_len < DHCP_MSG_MIN_SIZE)
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{
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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_MSG_MIN_SIZE)
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{
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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, &ip4_addr_get_u32(ip_2_ip4(&dhcp_server.ip)), 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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uint8_t *msgtype = opt_find(opt, DHCP_OPT_MSG_TYPE);
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if(msgtype == NULL)
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{
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// A DHCP package without MSG_TYPE?
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goto ignore_request;
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}
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switch(msgtype[2])
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{
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case DHCPDISCOVER:
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{
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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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{
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if(memcmp(dhcp_server.lease[i].mac, dhcp_msg.chaddr, MAC_LEN) == 0)
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{
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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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{
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// Look for a free IP address
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if (memcmp(dhcp_server.lease[i].mac, "\x00\x00\x00\x00\x00\x00", MAC_LEN) == 0)
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{
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// IP available
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yi = i;
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}
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uint32_t expiry = dhcp_server.lease[i].expiry << 16 | 0xffff;
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if((int32_t)(expiry - cyw43_hal_ticks_ms()) < 0)
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{
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// IP expired, reuse it
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memset(dhcp_server.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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{
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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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{
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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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{
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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, &ip4_addr_get_u32(ip_2_ip4(&dhcp_server.ip)), 3) != 0)
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{
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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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{
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// Should be NACK
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goto ignore_request;
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}
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if(memcmp(dhcp_server.lease[yi].mac, dhcp_msg.chaddr, MAC_LEN) == 0)
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{
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// MAC match, ok to use this IP address
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}
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else if(memcmp(dhcp_server.lease[yi].mac, "\x00\x00\x00\x00\x00\x00", MAC_LEN) == 0)
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{
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// IP unused, ok to use this IP address
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memcpy(dhcp_server.lease[yi].mac, dhcp_msg.chaddr, MAC_LEN);
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}
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else
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{
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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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dhcp_server.lease[yi].expiry = (cyw43_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("DHCP Server: 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, &ip4_addr_get_u32(ip_2_ip4(&dhcp_server.ip)));
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opt_write_n(&opt, DHCP_OPT_SUBNET_MASK, 4, &ip4_addr_get_u32(ip_2_ip4(&dhcp_server.nm)));
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opt_write_n(&opt, DHCP_OPT_ROUTER, 4, &ip4_addr_get_u32(ip_2_ip4(&dhcp_server.ip))); // aka gateway; can have multiple addresses
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opt_write_n(&opt, DHCP_OPT_DNS, 4, &ip4_addr_get_u32(ip_2_ip4(&dhcp_server.ip))); // this server is the dns
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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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struct netif *nif = ip_current_input_netif();
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dhcp_socket_sendto(nif, &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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int dhcp_server_init(void)
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{
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dhcp_server.ip.addr = DHCP_SERVER_IP;
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dhcp_server.nm.addr = DHCP_SERVER_MASK;
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memset(dhcp_server.lease, 0, sizeof(dhcp_server.lease));
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dhcp_server.pcb = udp_new();
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if(dhcp_server.pcb == NULL)
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{
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puts("Error creating DHCP server");
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return PICO_ERROR_GENERIC;
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}
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// Register callback
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udp_recv(dhcp_server.pcb, dhcp_server_process, NULL);
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err_t err = udp_bind(dhcp_server.pcb, IP_ANY_TYPE, PORT_DHCP_SERVER);
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if(err != ERR_OK)
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{
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printf("Error binding DHCP server : %d\n", err);
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return err;
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}
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return PICO_OK;
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}
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void dhcp_server_exit(void)
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{
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if(dhcp_server.pcb != NULL)
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{
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udp_remove(dhcp_server.pcb);
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dhcp_server.pcb = NULL;
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}
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}
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