uploading dh.c before 12

dh.c

+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+#include <string.h>
+#include <strings.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <netdb.h>
+#include <unistd.h>
+#include <ctype.h>
+#define G 15
+#define P 97
+
+
+
+//used this instead of the power, but not sure why
+int calculate(int g, int m, int p)
+{
+	int r;
+	int y = 1;
+	while (m > 0){
+		r = m % 2;
+		// fast exponention
+		if (r == 1)
+			y = (y*g) % p;
+		g = g*g % p;
+		m = m / 2;
+	}
+	return y;
+}
+
+//to calculate the hex value
+int toInt(char a){
+	if(isalpha(a)){
+		a = a - 87;
+	}else{
+		a = a - 48;
+	}
+	return (int) a;
+}
+
+int main(int argc, char ** argv)
+{
+	char buffer[256];
+	//get the sha256 file
+    FILE* file = popen("openssl sha256 dh.c", "r");
+    if(!file){
+        printf("something wrong with your command or file\n");
+        exit(0);
+    }
+
+    while(fgets(buffer, 256, file)){
+		
+    }
+	
+    pclose(file);
+	//copy the file
+    //printf("buffer = %s\n", buffer);
+
+    char hashed[256];
+	strcpy(hashed, buffer);
+	
+	//convert to integer
+	int hex1 = toInt(hashed[14]);
+	int hex2 = toInt(hashed[15]);
+	//printf("%d\n", hex1);
+	//printf("%d\n", hex2);
+	//this b is for the one to calculate
+	int b = hex1 * 16 + hex2;
+	//printf("b = %d\n", b);
+	//calculate the one to send
+	int B = calculate(G, b, P);
+	printf("B = %d\n", B);
+	
+	
+	
+	//time to establish connection
+	int sockfd, portno, n;
+    struct sockaddr_in serv_addr;
+    struct hostent * server;
+
+    portno = 7800;
+
+
+    /* Translate host name into peer's IP address ;
+     * This is name translation service by the operating system
+     */
+    server = gethostbyname("172.26.37.44");
+
+    if (server == NULL)
+    {
+        fprintf(stderr, "ERROR, no such host\n");
+        exit(0);
+    }
+
+    /* Building data structures for socket */
+
+    bzero((char *)&serv_addr, sizeof(serv_addr));
+
+    serv_addr.sin_family = AF_INET;
+
+    bcopy(server->h_addr_list[0], (char *)&serv_addr.sin_addr.s_addr, server->h_length);
+
+    serv_addr.sin_port = htons(portno);
+
+    /* Create TCP socket -- active open
+    * Preliminary steps: Setup: creation of active open socket
+    */
+
+    sockfd = socket(AF_INET, SOCK_STREAM, 0);
+
+    if (sockfd < 0)
+    {
+        perror("ERROR opening socket");
+        exit(0);
+    }
+
+    if (connect(sockfd, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0)
+    {
+        perror("ERROR connecting");
+        exit(0);
+    }
+	printf("successfully creat socket\n");
+	
+    bzero(buffer, 256);
+	
+	//send name
+	strcpy(buffer, "qifant\n");
+	n = write(sockfd, buffer, strlen(buffer));
+	printf("successfully sent name\n");
+	
+	//send the value of B
+	bzero(buffer, 256);
+	//put integer B into into buffer
+	sprintf(buffer, "%d\n", B);
+	n = write(sockfd,buffer, strlen(buffer));
+	printf("successfully sent B\n");
+	
+	bzero(buffer, 256);
+	//wait for the response
+	n = read(sockfd, buffer, 255);
+	
+	if (n < 0){
+        perror("ERROR reading from socket");
+        exit(0);
+    }
+	
+	//should receive a int
+	int receive = atoi(buffer);
+	//printf("receive = %d\n",receive);
+	printf("successfully received");
+	
+	int key = calculate(receive, b, P);
+	//printf("key = %d\n", key);
+	
+	bzero(buffer, 256);
+	
+	//confirm the key
+	sprintf(buffer, "%d\n", key);
+	n = write(sockfd, buffer, strlen(buffer));
+	bzero(buffer, 256);
+	
+	//receive the result
+	n = read(sockfd, buffer, 255);
+	if (n < 0){
+        perror("ERROR reading from socket");
+        exit(0);
+    }
+	
+	printf("result: %s\n", buffer);
+	
+	
+}
+