Added chord.c and chord.h

server/chord.c

+#include<stdlib.h>
+#include<stdio.h>
+#include<stdbool.h>
+#include<string.h>
+#include <unistd.h> 
+#include <string.h> 
+#include <sys/types.h> 
+#include <sys/socket.h> 
+#include <arpa/inet.h> 
+#include <netinet/in.h> 
+
+#define MAXLOCATIONS 32
+
+int keyToId(char * key){
+    //To be filled
+}
+
+int nodeToId(char ip[], int port){
+    //To be filled
+    int id = 1;
+    return id;
+}
+
+typedef struct Node
+{
+    int nodeId;
+    char ip[16];
+}Node;
+
+typedef struct Finger
+{
+    int nextId;
+    int nextNodeId;
+    char ip[16];
+}Finger;
+
+typedef struct Chord
+{
+    int* finger;
+    int selfId;
+    char selfIp[16];
+    int selfPort;
+    int successor;
+    char successorIp[16];
+    int successorPort;
+    int predecessor;
+    char predecessorIp[16];
+    int predecessorPort;
+
+}Chord;
+
+Chord chord;
+
+void sendUDP(char * msg, char ip[], int port, bool recvResponse, char * buffer)
+{
+    int sockfd;
+    struct sockaddr_in     servaddr; 
+  
+    // Creating socket file descriptor 
+    if ( (sockfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0 ) { 
+        perror("socket creation failed"); 
+        exit(EXIT_FAILURE); 
+    } 
+  
+    memset(&servaddr, 0, sizeof(servaddr)); 
+      
+    // Filling server information 
+    servaddr.sin_family = AF_INET; 
+    servaddr.sin_port = htons(port); 
+    servaddr.sin_addr.s_addr = inet_addr(ip); 
+      
+    int n, len; 
+      
+    sendto(sockfd, (const char *)msg, strlen(msg), 
+        MSG_CONFIRM, (const struct sockaddr *) &servaddr,  
+            sizeof(servaddr)); 
+    
+    if (recvResponse)
+    {
+        n = recvfrom(sockfd, (char *)buffer, 1000,  
+                MSG_WAITALL, (struct sockaddr *) &servaddr, 
+                &len); 
+        buffer[n] = '\0'; 
+    }
+    
+    close(sockfd);
+}
+
+
+
+void initChordStructure(char * joinIp){
+    chord.finger = (Finger *) malloc(log(MAXLOCATIONS)*sizeof(Finger));
+    char ip[16] = getip();
+    int port =4;
+    strcpy(chord.selfIp ,ip);
+    chord.selfId = nodeToId(ip,port);
+    chord.predecessor =-1;
+    if (joinIp==NULL)
+    {
+        chord.successor = chord.selfId;
+    }
+    else
+    {
+        /* send find successor packet to the ip */
+        // Listen for reply 
+        // update successor
+    }
+    
+}
+
+void closestPreceedingNode(int id, char ip[]){
+    int m= log(MAXLOCATIONS);
+    Finger* f=chord.finger;
+    for (int i = m-1; i >=0; i--)
+    {        
+        int nextId = f[m].nextId;
+        if (nextId>chord.selfId && nextId<=id)
+        {
+            strcpy(ip,f[m].ip);
+            return;
+        }
+        
+    }
+    strcpy(ip,f[0].ip); //????
+}
+
+Node findSuccessor(int id, char ip[], int port, bool block){
+    Node n;
+    n.nodeId=-1;
+    if (id>=chord.selfId && id<=chord.successor)
+    {
+        n.nodeId=chord.selfId;
+        strcpy(n.ip,chord.selfIp);
+        if (block)
+        {
+            
+        }
+        else
+        {
+            return n;                    
+        }
+        
+    }
+    else
+    {
+        char preceedingIp[16];
+        closestPreceedingNode(id,preceedingIp);
+        char msg[1000],buffer[1000];
+        //make_packet and send
+        sendUDP(msg,ip,port,true,buffer);
+        return n;
+    }
+        
+}
+
+void sendPredecessor(char ip[], int port){
+    int sockfd; 
+    char msg[1000];
+    ToXML(msg,ip,port);//TO be changed
+    sendUDP(msg,ip,port,false,NULL);
+}
+
+void stabilize(){
+    char msg[1000],buffer[1000];
+    sendUDP(msg,chord.successorIp,chord.successorPort,true,buffer);
+}

server/chord.h

+void sendPredecessor();
\ No newline at end of file