Add basic code for server and client

Author: sambhav

login_file

@@ -0,0 +1,3 @@
+sam pass A
+manchu pass C
+maulik pass P

manchu

@@ -0,0 +1,8 @@
+abcd
+abce
+mm
+as
+as
+a
+s
+d

myclient.c

@@ -0,0 +1,97 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/socket.h>
+#include <string.h>
+#include <netinet/in.h>
+#include <unistd.h>
+#include <arpa/inet.h>
+
+
+#define RESPONSE_BYTES 512
+#define REQUEST_BYTES 512
+
+char* receiveMsgFromServer(int sock_fd) {
+    int numPacketsToReceive = 0;
+    int n = read(sock_fd, &numPacketsToReceive, sizeof(int));
+    if(n <= 0) {
+        shutdown(sock_fd, SHUT_WR);
+        return NULL;
+    }
+    char *str = (char*)malloc(numPacketsToReceive*RESPONSE_BYTES);
+    memset(str, 0, numPacketsToReceive*RESPONSE_BYTES);
+    char *str_p = str;
+    int i;
+    for(i = 0; i < numPacketsToReceive; ++i) {
+        int n = read(sock_fd, str, RESPONSE_BYTES);
+        str = str+RESPONSE_BYTES;
+    }
+    return str_p;
+}
+
+void sendMsgToServer(int sock_fd, char *str) {
+    int numPacketsToSend = (strlen(str)-1)/REQUEST_BYTES + 1;
+    int n = write(sock_fd, &numPacketsToSend, sizeof(int));
+    char *msgToSend = (char*)malloc(numPacketsToSend*REQUEST_BYTES);
+    strcpy(msgToSend, str);
+    int i;
+    for(i = 0; i < numPacketsToSend; ++i) {
+        int n = write(sock_fd, msgToSend, REQUEST_BYTES);
+        msgToSend += REQUEST_BYTES;
+    }
+}
+int main(int argc,char **argv)
+{
+	int sock_fd,port_no;
+	struct sockaddr_in serv_addr;
+	char *msgFromServer;
+    char msgToServer[256];
+
+
+	sock_fd=socket(AF_INET, SOCK_STREAM, 0);
+	port_no = atoi(argv[2]);
+
+	memset(&serv_addr, 0, sizeof(serv_addr));  //setting sockaddr_in serv_addr
+	serv_addr.sin_family = AF_INET;         //setting DOMAIN
+    serv_addr.sin_port = htons(port_no);     //setting port number
+    inet_aton(argv[1], &serv_addr.sin_addr);
+
+    connect(sock_fd, (struct sockaddr*)&serv_addr, sizeof(serv_addr));
+
+    printf("Connection Established.\n");
+    // printf("Asking server what to do(by receiving input from server).\n");
+
+    while(1) {
+        msgFromServer = receiveMsgFromServer(sock_fd);
+        if(msgFromServer == NULL)
+            break;
+        if(strncmp(msgFromServer, "unauth", 6) == 0) {
+            printf("Unautherized User.\n");
+            shutdown(sock_fd, SHUT_WR);
+            break;
+        }
+        printf("%s\n",msgFromServer);
+        free(msgFromServer);
+        
+        memset(msgToServer, 0, sizeof(msgToServer));
+        scanf("%s", msgToServer);
+        sendMsgToServer(sock_fd, msgToServer);
+        if(strncmp(msgToServer, "exit", 4) == 0) {
+            shutdown(sock_fd, SHUT_WR);
+            break;
+        }
+    }
+
+    while(1) {
+        msgFromServer = receiveMsgFromServer(sock_fd);
+        if(msgFromServer == NULL)
+            break;
+        printf("%s\n",msgFromServer);
+        free(msgFromServer);
+    }
+    printf("Write end closed by the server.\n");
+    shutdown(sock_fd, SHUT_RD);
+    printf("Connection closed gracefully.\n");
+    return 0;
+
+
+}