ip转发二叉树查找方法c实现

1 //路由表元素节点
2 typedef struct node {
3     struct node *pLeftChild;
4     struct node *pRightChild;
5     int iPort;
6 }NODE;

  1 #include <stdio.h>
  2 #include <stdlib.h>
  3 #include <string.h>
  4 
  5 #define BUFFER_SIZE 9000
  6 #define DBG_PRINT if(1 == g_ulDbgPrint) printf
  7 int g_ulDbgPrint = 0;
  8 //路由表元素节点
  9 typedef struct node {
 10     struct node *pLeftChild;
 11     struct node *pRightChild;
 12     int iPort;
 13 }NODE;
 14 
 15 //路由表root
 16 NODE *g_pRouteTree = NULL;
 17 
 18 //创建节点函数
 19 NODE *createNode() {
 20     NODE *pNode = malloc(sizeof(NODE));
 21     pNode->pLeftChild = NULL;
 22     pNode->pRightChild = NULL;
 23     pNode->iPort = -1;
 24     return pNode;
 25 }
 26 
 27 //创建路由表函数
 28 void createRouteTree(int iRoute, int iMask, int iPort) {
 29     int i = 0;
 30     // 0 -- left, 1 -- right
 31     int iLeftOrRight = 0;
 32     static int iInitFlag = 0;
 33     
 34     if (0 == iInitFlag) {
 35         g_pRouteTree = createNode();
 36         iInitFlag = 1;
 37     }
 38     
 39     DBG_PRINT("input rounte: %8x, mask: %d, port: %d\n", iRoute, iMask, iPort);
 40 
 41     NODE *pCurrNode = g_pRouteTree;
 42     for (i = 0; i < iMask; i++) {
 43         iLeftOrRight = (iRoute >> (31 - i)) & 0x1;
 44         
 45         if(0 == iLeftOrRight) {
 46             if (NULL == pCurrNode->pLeftChild) {
 47                 pCurrNode->pLeftChild = createNode();
 48             }
 49             pCurrNode = pCurrNode->pLeftChild;
 50             DBG_PRINT("0 left\n");
 51         }
 52         else {
 53             if (NULL == pCurrNode->pRightChild) {
 54                 pCurrNode->pRightChild = createNode();
 55             }
 56             pCurrNode = pCurrNode->pRightChild;
 57             DBG_PRINT("1 right\n");
 58         }
 59         
 60     }
 61 
 62     pCurrNode->iPort = iPort;
 63     DBG_PRINT("%d port\n", iPort);
 64     return;
 65 }
 66 
 67 //ip转发查找路由表函数
 68 int getIpFwdPort(int iIp) {
 69     int i = 0, iLeftOrRight = 0, iPort = -1;
 70     NODE *pCurrNode = g_pRouteTree;
 71     iPort = (-1 == pCurrNode->iPort)?iPort:pCurrNode->iPort;
 72     
 73     DBG_PRINT("input ip: %8x\n", iIp);
 74 
 75     for (i = 0; i < 32; i++) {
 76         iLeftOrRight = (iIp >> (31-i)) & 0x1;
 77         
 78         if (0 == iLeftOrRight) {
 79             if (NULL != pCurrNode->pLeftChild) {
 80                 pCurrNode = pCurrNode->pLeftChild;
 81                 iPort = (-1 == pCurrNode->iPort)?iPort:pCurrNode->iPort;
 82                 DBG_PRINT("0 go left, %d port\n", iPort);
 83             }
 84             else {
 85                 break;
 86             }
 87         }
 88         else {
 89             if (NULL != pCurrNode->pRightChild) {
 90                 pCurrNode = pCurrNode->pRightChild;
 91                 iPort = (-1 == pCurrNode->iPort)?iPort:pCurrNode->iPort;
 92                 DBG_PRINT("1 go right, %d port\n", iPort);
 93             }
 94             else {
 95                 break;
 96             }
 97         }
 98     }
 99     return iPort;
100 }
101 
102 
103 int main() {
104     int a[4] = {0}, iMask = 0, iPort = -1;
105     unsigned char aucTag[10] = {‘\0‘};
106     unsigned char aucBuf[BUFFER_SIZE] = {‘\0‘};
107     int iLen = 0;
108     unsigned char ucTmp = ‘\0‘;
109     unsigned int uiPayload = 0, uiVersion = 0;
110     int i = 0;
111     int iRoute = 0, iIp = 0;
112 
113     //读取路由表
114     while(0 != scanf("fib %d.%d.%d.%d/%d e%d\n", &a[0], &a[1], &a[2], &a[3], &iMask, &iPort)) {
115         DBG_PRINT("fib %d.%d.%d.%d/%d e%d\n", a[0], a[1], a[2], a[3], iMask, iPort);
116         iRoute = (a[0] << 24) | (a[1] << 16) | (a[2] << 8) | (a[3] << 0);
117         createRouteTree(iRoute, iMask, iPort);
118     }
119     
120     //读取ip报文input标示
121     scanf("%s", aucTag);
122     if (0 == strncmp("input", aucTag, 5)) {
123         //读取ip报文16进制内容，注意格式%2hhx，一次读取一个字节
124         while((BUFFER_SIZE > iLen) && (1 == scanf("%2hhx", &ucTmp))) {
125             aucBuf[iLen] = ucTmp;
126             iLen++;
127         }
128         
129         //获取协议类型和ip版本号
130         uiPayload |= (unsigned int)aucBuf[13];
131         uiPayload |= (((unsigned int)aucBuf[12]) << 8);
132         uiVersion = aucBuf[14] >> 4;
133 
134         //判断是否是ipv4报文
135         if(0x0800 != uiPayload) { 
136             printf("Error: Not IPv4 payload\n");
137             return 0;
138         }
139         else if (0x4 != uiVersion) {
140             printf("Error: Wrong IP version\n");
141             return 0;
142         }
143 
144         //判断长度是否合法
145         if(33 < iLen) {
146             DBG_PRINT("%d.%d.%d.%d\n", aucBuf[30],aucBuf[31],aucBuf[32],aucBuf[33]);
147             iIp = (aucBuf[30] << 24) | (aucBuf[31] << 16) | (aucBuf[32] << 8) | (aucBuf[33] << 0);
148             printf("e%d\n", getIpFwdPort(iIp));
149         }
150         else {
151             printf("Error: Packet too short\n");
152         }
153 
154     }
155     return 0;
156 }