基于PLC1850平台的UDP报文接收与发送
一、UDP报文格式
源端口（2个字节）：发送报文的进程的16位端口号。
目的端口（2个字节）：目的设备上的接收进程的16位端口号。
长度（2个字节）：整个UDP数据报的长度，包括首都和数据字段。
校验和（2个字节）：提供错误检测功能的16位校验和，为可选项。
数据（可变长度）：要发送已封存应用报文。
2、UDP封装
3、UDP校验和计算
UDP校验和是所计算字段的16位反码和的反码，用IP数据报的某些字段组成一个伪首部，再与UDP报文合在一起计算校验和。因此，校验和是对伪首部、UDP首部和UDP数据的计算结果。如果需要，数据后面可能会填以数值为0的字节，使得数据字节数为两字节的整数倍。
4、发送UDP报文
通过java语言编写一个UDP数据报发送个LPC1850平台，程序代码如下：
1 /** 2 * @Author CFF 3 * @Date:Created in 22:45 2019/4/20 4 */ 5 import java.net.DatagramSocket; 6 import java.net.DatagramPacket; 7 import java.net.InetAddress; 8 9 public class udp { 10 public static void main(String[] args ) throws Exception { 11 String content = "ABCDEFGHIJ"; 12 byte [] sentBuf = content .getBytes( "GBK" ); 13 DatagramSocket client = new DatagramSocket(); 14 InetAddress destinationAddress =InetAddress. getByName ( "192.168.1.190" ); 15 int port =2425; 16 DatagramPacket sendPacket = new DatagramPacket( sentBuf , sentBuf.length , destinationAddress , port ); 17 client .send(sendPacket); 18 client .close(); 19 } 20 }
5、LPC1850代码
LPC1850 Internet初始化主函数，代码如下：
1 #include "LPC18xx.h" 2 #include "led.h" 3 4 5 extern void taskEth (void); 6 7 int main(void) 8 { 9 SystemInit(); 10 11 ledInit(); 12 SysTick_Config(GetCoreClock() / 1000); 13 14 taskEth(); 15 16 while (1); 17 } 18 19 void SysTick_Handler(void) 20 { 21 static int counter = 0; 22 23 counter++; 24 if (counter >= 100) 25 { 26 counter = 0; 27 ledRolling(); 28 } 29 }
EthTask.c代码如下：
1 #include <stdlib.h> 2 #include <lpc18xx.h> 3 #include "lpc18xx_emac.h" 4 #include "lpc18xx_debug.h" 5 6 extern uint32_t ipatol(char * p_input); 7 extern void ipInit(uint8_t * mac, uint32_t ip); 8 extern uint32_t ipRcvMacFrame(uint8_t * block, uint32_t frameLen); 9 10 uint8_t gFlag = 0; 11 12 uint8_t g_emacBuffer[2048]; 13 14 uint8_t g_ethMac[6]; 15 16 // EMAC½Ó¿Ú½ÓÊÕµ½Êý¾Ý£¬Í¨ÖªÓ¦ÓòãµÄ»Øµ÷º¯Êý¡£ 17 void ethReadReadyCb() 18 { 19 gFlag = 1; 20 } 21 22 void taskEth (void) 23 { 24 uint32_t len; 25 26 g_ethMac[0] = 0x11; 27 g_ethMac[1] = 0x1F; 28 g_ethMac[2] = 0xE0; 29 g_ethMac[3] = 0x12; 30 g_ethMac[4] = 0x1E; 31 g_ethMac[5] = 0x0F; 32 33 debugComInit(); 34 uartPrint("uart init\r\n"); 35 36 while (ethInit(ethReadReadyCb, g_ethMac) == 0); 37 38 uartPrint("eth init complete\r\n"); 39 // ΪÒÔÌ«Íø½Ó¿ÚÖ¸¶¨MACµØÖ·ºÍIPµØÖ· 40 ipInit(g_ethMac, 0xBE01A8C0); // 192.168.1.190 41 42 while (1) 43 { 44 if (!gFlag) 45 { 46 continue; 47 } 48 49 len = ethRead(g_emacBuffer, 2048); 50 if (len) 51 { 52 ipRcvMacFrame((uint8_t *)g_emacBuffer, len); 53 } 54 gFlag = 0; 55 } 56 }
ip.c代码如下：
1 #include <stdint.h> 2 #include <string.h> 3 #include <stdlib.h> 4 #include "lpc18xx_emac.h" 5 #include "lpc18xx_debug.h" 6 //#include "shell.h" 7 8 #define MAC_TYPE_IP 0x0800 //ipÀàÐÍ 9 #define MAC_TYPE_ARP 0x0806 //macÀàÐÍ 10 11 #define ARP_REQ 0x0001 //ARPÇëÇó 12 #define ARP_RSP 0x0002 //ARPÏìÓ¦ 13 14 #define ICMP_ECHO_REQUEST 8 // message is an echo request 15 #define ICMP_ECHO_REPLY 0 // message is an echo reply 16 17 #define PROT_ICMP 1 // Internet Control Message Protocol 18 #define PROT_TCP 6 // Transmission Control Protocol 19 #define PROT_UDP 17 // User Datagram Protocol 20 21 #define DONT_FRAGMENT 0x4000 //fragment 22 #define MORE_FRAGMENT 0x2000 23 #define FRAGMENT_OFFSET 0x1FFF 24 25 uint8_t * UDPChecksum; 26 uint8_t g_ethMacAddr[6]; 27 uint32_t g_ethIpAddr; 28 29 uint32_t g_ipSndBuffer[64]; 30 31 uint16_t g_ipIdentifier = 0; 32 33 // ½«×Ö´ÓÖ÷»úÐòתΪÍøÂçÐò 34 uint16_t htons(uint16_t word) 35 { 36 return ((word >> 8) & 0x00FF) | ((word << 8) & 0xFF00); 37 } 38 39 // ½«×Ö´ÓÍøÂçÐòתΪÖ÷»úÐò 40 uint16_t ntohs(uint16_t word) 41 { 42 return ((word >> 8) & 0x00FF) | ((word << 8) & 0xFF00); 43 } 44 45 46 uint16_t calcChecksum(uint16_t * buffer, uint32_t size) 47 { 48 uint32_t cksum; 49 50 cksum = 0; 51 52 while (size > 1) 53 { 54 cksum += *buffer++; 55 size -= sizeof(uint16_t); 56 } 57 58 if (size) 59 { 60 cksum += *(uint8_t*)buffer; 61 } 62 63 cksum = (cksum >> 16) + (cksum & 0xffff); 64 cksum += (cksum >>16); 65 66 return (uint16_t)(~cksum); 67 } 68 69 // ·¢ËÍARPÏìÓ¦ 70 void arpSndRsp(uint32_t dstIp, uint8_t * mac) 71 { 72 uint8_t * block; 73 //uint32_t blockLen; 74 75 block = (uint8_t *)g_ipSndBuffer; 76 77 memcpy(block, mac, 6); 78 79 memcpy(block + 6, g_ethMacAddr, 6); 80 81 // arp type 82 *(uint16_t *)&block[12] = htons(MAC_TYPE_ARP); 83 84 // --------- ARP ²ã 85 86 // Hardway type : Ethernet 87 block[14] = 0x00; 88 block[15] = 0x01; 89 90 // ip type 91 *(uint16_t *)&block[16] = htons(MAC_TYPE_IP); 92 93 // Hardway size 94 block[18] = 0x06; 95 96 // Protocal size 97 block[19] = 0x04; 98 99 // arp reply 100 *(uint16_t *)&block[20] = htons(ARP_RSP); 101 102 // Sender MAC address 103 memcpy(block + 22, g_ethMacAddr, 6); 104 105 // Sender IP address 106 *(uint32_t *)&block[28] = g_ethIpAddr; 107 108 // Target MAC address 109 memcpy(block + 32, mac, 6); 110 111 // Target IP address : 192.168.0.67 112 block[38] = (uint8_t)dstIp; 113 block[39] = (uint8_t)(dstIp >> 8); 114 block[40] = (uint8_t)(dstIp >> 16); 115 block[41] = (uint8_t)(dstIp >> 24); 116 117 // 18¸öÌî³ä×Ö½Ú 118 memset(block + 42, 0, 18); 119 120 ethWrite((uint8_t *)block, 60); 121 } 122 123 void arpRcv(uint8_t * block, uint32_t frameLen) 124 { 125 uint32_t srcIp, dstIp; 126 uint16_t msgType; 127 128 msgType = ntohs(*(uint16_t *)(block+6)); 129 130 srcIp = (uint32_t)*(uint16_t *)(block + 14); 131 srcIp|= ((uint32_t)*(uint16_t *)(block + 16)) << 16; 132 133 dstIp = (uint32_t)*(uint16_t *)(block + 24); 134 dstIp|= ((uint32_t)*(uint16_t *)(block + 26)) << 16; 135 136 if (dstIp != g_ethIpAddr) 137 { 138 return; 139 } 140 141 if (msgType == ARP_REQ) 142 { 143 arpSndRsp(srcIp, block + 8); 144 } 145 } 146 147 // ²»¹Ü³É¹¦Óë·ñ,¶¼ÓÉIP²ãÀ´ÊÍ·ÅÊý¾Ý°ü¡£ 148 void ipSnd(uint32_t dstIp, uint8_t * block, uint32_t len, uint8_t protoType, uint8_t * mac) 149 { 150 block-= 20; 151 len+= 20; 152 153 // ------------ IP ²ã 154 155 block[0] = 0x45; // IP V4. length 20(5*4) 156 157 block[1] = 0x00; // service 158 159 *(uint16_t *)&block[2] = htons(len); 160 161 *(uint16_t *)&block[4] = htons((uint16_t)g_ipIdentifier++); // identification 162 163 *(uint16_t *)&block[6] = 0x0040; // flag and fragment 164 165 block[8] = 128; // TTL 166 167 block[9] = protoType; 168 169 *(uint16_t *)&block[10] = 0; // УÑéºÍÏÈÌîÉÏ0 170 171 *(uint16_t *)&block[12] = (uint16_t)g_ethIpAddr; 172 *(uint16_t *)&block[14] = (uint16_t)(g_ethIpAddr >> 16); 173 174 *(uint16_t *)&block[16] = (uint16_t)dstIp; 175 *(uint16_t *)&block[18] = (uint16_t)(dstIp >> 16); 176 177 *(uint16_t *)&block[10] = calcChecksum((uint16_t *)block, 20); 178 179 // ------------ MAC ²ã 180 181 block-= 14; 182 len+= 14; 183 184 memcpy(block, mac , 6); 185 186 memcpy(block + 6, g_ethMacAddr, 6); 187 188 *(uint16_t *)&block[12] = htons(MAC_TYPE_IP); 189 190 if (len < 60) 191 { 192 // MACÖ¡Ì«¶Ì£¬²¹µ½×î¶Ì³¤¶È¡£ 193 memset(block + len, 0, 60 - len); 194 len = 60; 195 } 196 197 ethWrite((uint8_t *)block, len); 198 } 199 200 // ICMPÊÕµ½ÇëÇó£¬ÐèÒª»ØÏìÓ¦¡£ 201 void icmpRcvRequest(uint32_t srcIp, uint8_t * icmp, uint32_t len, uint8_t * mac) 202 { 203 uint8_t * block; 204 205 block = (uint8_t *)g_ipSndBuffer; 206 207 // Áô³ö 14(MAC)+20(IP)¸ö×Ö½Ú 208 block+=(14+20); 209 210 // ----------- ICMP ²ã 211 memcpy(block, icmp, len); 212 213 block[0] = ICMP_ECHO_REPLY; 214 block[1] = 0; // code 215 216 *(uint16_t *)&block[2] = 0; // УÑéºÍÏÈÌîÉÏ0 217 218 *(uint16_t *)&block[2] = calcChecksum((uint16_t *)block, len); 219 220 ipSnd(srcIp, (void *)block, len, PROT_ICMP, mac); 221 } 222 void udpsend(uint32_t srcIp, uint8_t * udp, uint32_t len, uint8_t * mac) 223 { 224 uint8_t * block; 225 int i; 226 char sendData[10]={'R','e','c','e','i','v','e','.','.','.'}; 227 block = (uint8_t *)g_ipSndBuffer; 228 // Áô³ö 14(MAC)+20(IP)¸ö×Ö½Ú 229 block+=(14+20); 230 memcpy(block,udp,len); 231 232 memcpy(block,udp+2,2); 233 memcpy(block+2,udp,2); 234 235 for(i=0;i<10;i++) 236 { 237 block[8+i]=sendData[i]; 238 } 239 240 *(uint16_t *)&block[4] = htons(len); 241 242 *(uint16_t *)&block[6] = 0;// УÑéºÍÏÈÌîÉÏ0 243 244 *(uint16_t *)&UDPChecksum[10]=htons(len); 245 memcpy(UDPChecksum+11,block,len); 246 *(uint16_t *)&block[6] = calcChecksum((uint16_t *)UDPChecksum, len+12); 247 uartPrint("Checksum:0x%04x\r\n",ntohs(*(uint16_t *)&block[6])); 248 ipSnd(srcIp, (void *)block, len, PROT_UDP, mac); 249 } 250 //udp½ÓÊÕ 251 void udpRcv(uint32_t srcIp,uint8_t * udp, uint32_t len, uint8_t * mac) 252 { 253 int i; 254 uartPrint("Recevie UDP message:\r\n"); 255 uartPrint("UDP Head:\r\n"); 256 uartPrint("Source Port:%d\r\n",ntohs(*(uint16_t *)(udp))); 257 uartPrint("Destination Port:%d\r\n",ntohs(*(uint16_t *)(udp+2))); 258 uartPrint("Total Length:%d bytes\r\n",ntohs(*(uint16_t *)(udp+4))); 259 uartPrint("Checksum:0x%04x\r\n",ntohs(*(uint16_t *)(udp+6))); 260 uartPrint("UDP Data:\r\n"); 261 for(i=0;i<len-8;i++) 262 { 263 uartPrint("%c",udp[8+i]); 264 } 265 uartPrint("\r\nsending UDP Data...\r\n"); 266 udpsend(srcIp, udp, len, mac); 267 uartPrint("sent UDP Data.\r\n\r\n"); 268 } 269 // ½ÓÊÕµ½IP°üµÄ´¦Àí 270 void ipRcv(uint8_t * frame, uint32_t frameLen, uint8_t * mac) 271 { 272 uint16_t ipLength, flag; 273 uint32_t srcIp, dstIp; 274 275 if (frameLen < 20) 276 { 277 return; 278 } 279 280 if (calcChecksum((uint16_t *)frame, 20)) 281 { 282 // УÑéºÍ²»ÕýÈ· 283 return; 284 } 285 286 if (frame[0] != 0x45) 287 { 288 // IP VERSION ӦΪ4£¬³¤¶ÈӦΪ20£¨5¸öbit32£©×Ö½Ú¡£ 289 return; 290 } 291 292 // ignore Type Of Service 293 294 ipLength = ntohs(*(uint16_t *)&frame[2]); 295 296 // ignore identification 297 298 flag = ntohs(*(uint16_t *)&frame[6]); 299 300 if (!(flag & DONT_FRAGMENT)) 301 { 302 // IP¿ÉÒÔ±»·Ö°ü£¬µ«ÎÒÃÇÖ»´¦Àí²»·Ö°üµÄÇé¿ö¡£ 303 304 if (flag & MORE_FRAGMENT) 305 { 306 // ·Ç×îºóµÄÒ»°ü£¬¶ªÆú¡£ 307 return; 308 } 309 310 // ÊÇ×îºóÒ»°ü¡£ 311 312 if (flag & FRAGMENT_OFFSET) 313 { 314 // ÊÇ×îºóÒ»°ü£¬ÇÒÆ«ÒÆÁ¿²»Îª0£¬Ò²¶ªÆú¡£ 315 return; 316 } 317 318 // ×îºóÒ»°ü£¬ÇÒÆ«ÒÆÁ¿Îª0£¬ÊÇÕû°ü£¬´¦Àí£¡ 319 } 320 321 if (frameLen < ipLength) 322 { 323 return; 324 } 325 326 // ignore fragment offset 327 328 //ttl = (uint32_t)frame[8]; 329 330 //srcIp = (frame[12] | (frame[13]<< 8) | (frame[14] << 16) | (frame[15] << 24)); 331 //dstIp = (frame[16] | (frame[17]<< 8) | (frame[18] << 16) | (frame[19] << 24)); 332 333 srcIp = *(uint16_t *)(frame + 12) | ((uint32_t)*(uint16_t *)(frame + 14) << 16); 334 dstIp = *(uint16_t *)(frame + 16) | ((uint32_t)*(uint16_t *)(frame + 18) << 16); 335 336 if ((dstIp != g_ethIpAddr) && (dstIp != 0x0100007F) && (dstIp != 0xffffffff)) 337 { 338 return; 339 } 340 341 // if (frame[9] != PROT_ICMP) 342 // { 343 // // ·ÇICMP°ü£¬Ôݲ»´¦Àí 344 // return; 345 // } 346 if(frame[9] == PROT_UDP) 347 { 348 //αͷ²¿ 349 UDPChecksum=(uint8_t *)g_ipSndBuffer; 350 memcpy(UDPChecksum,frame+12,4); 351 memcpy(UDPChecksum+4,frame+16,4); 352 UDPChecksum[8]=0; 353 UDPChecksum[9]=frame[9]; 354 udpRcv(srcIp,frame + 20, ipLength - 20,mac); 355 } 356 357 if (frame[20] == ICMP_ECHO_REQUEST) 358 { 359 icmpRcvRequest(srcIp, frame + 20, ipLength - 20, mac); 360 } 361 } 362 363 364 // IP²ã½ÓÊÕMAC²ãÊý¾ÝÖ¡µÄº¯Êý 365 uint32_t ipRcvMacFrame(uint8_t * block, uint32_t frameLen) 366 { 367 //0xFFFF ¹ã²¥·½Ê½ 368 if ( ((*(uint16_t *)block == 0xFFFF) && (*(uint16_t *)(block + 2) == 0xFFFF) && (*(uint16_t *)(block + 4) == 0xFFFF)) 369 ||(memcmp(block, g_ethMacAddr, 6) == 0)) 370 { 371 // ÊÇ·¢¸ø±¾»úµÄ¡£ 372 switch (ntohs(*(uint16_t *)(block+12))) 373 { 374 case MAC_TYPE_ARP: 375 arpRcv(block + 14, frameLen -14); 376 break; 377 case MAC_TYPE_IP: 378 ipRcv(block + 14, frameLen - 14, block+6); 379 break; 380 default: 381 break; 382 } 383 } 384 return 1; 385 } 386 387 void ipInit(uint8_t * mac, uint32_t ip) 388 { 389 memcpy(g_ethMacAddr, mac, 6); 390 g_ethIpAddr = ip; 391 }
通过上面代码，实现UDP报文接收与发送，实现UDP数据通讯。
