fix($code): --20211120 fix a small bug in attack.c

category-network/DNS_Remote/Files/attack.c

@@ -7,72 +7,75 @@
 
 #define MAX_FILE_SIZE 1000000
 
-
 /* IP Header */
-struct ipheader {
-  unsigned char      iph_ihl:4, //IP header length
-                     iph_ver:4; //IP version
-  unsigned char      iph_tos; //Type of service
-  unsigned short int iph_len; //IP Packet length (data + header)
-  unsigned short int iph_ident; //Identification
-  unsigned short int iph_flag:3, //Fragmentation flags
-                     iph_offset:13; //Flags offset
-  unsigned char      iph_ttl; //Time to Live
-  unsigned char      iph_protocol; //Protocol type
-  unsigned short int iph_chksum; //IP datagram checksum
-  struct  in_addr    iph_sourceip; //Source IP address 
-  struct  in_addr    iph_destip;   //Destination IP address 
+struct ipheader
+{
+  unsigned char iph_ihl : 4,       //IP header length
+      iph_ver : 4;                 //IP version
+  unsigned char iph_tos;           //Type of service
+  unsigned short int iph_len;      //IP Packet length (data + header)
+  unsigned short int iph_ident;    //Identification
+  unsigned short int iph_flag : 3, //Fragmentation flags
+      iph_offset : 13;             //Flags offset
+  unsigned char iph_ttl;           //Time to Live
+  unsigned char iph_protocol;      //Protocol type
+  unsigned short int iph_chksum;   //IP datagram checksum
+  struct in_addr iph_sourceip;     //Source IP address
+  struct in_addr iph_destip;       //Destination IP address
 };
 
-void send_raw_packet(char * buffer, int pkt_size);
-void send_dns_request( );
-void send_dns_response( );
+void send_raw_packet(char *buffer, int pkt_size);
+void send_dns_request();
+void send_dns_response();
 
 int main()
 {
   srand(time(NULL));
 
   // Load the DNS request packet from file
-  FILE * f_req = fopen("ip_req.bin", "rb");
-  if (!f_req) {
-     perror("Can't open 'ip_req.bin'");
-     exit(1);
+  FILE *f_req = fopen("ip_req.bin", "rb");
+  if (!f_req)
+  {
+    perror("Can't open 'ip_req.bin'");
+    exit(1);
   }
   unsigned char ip_req[MAX_FILE_SIZE];
   int n_req = fread(ip_req, 1, MAX_FILE_SIZE, f_req);
 
   // Load the first DNS response packet from file
-  FILE * f_resp = fopen("ip_resp.bin", "rb");
-  if (!f_resp) {
-     perror("Can't open 'ip_resp.bin'");
-     exit(1);
+  FILE *f_resp = fopen("ip_resp.bin", "rb");
+  if (!f_resp)
+  {
+    perror("Can't open 'ip_resp.bin'");
+    exit(1);
   }
   unsigned char ip_resp[MAX_FILE_SIZE];
   int n_resp = fread(ip_resp, 1, MAX_FILE_SIZE, f_resp);
 
-  char a[26]="abcdefghijklmnopqrstuvwxyz";
-  while (1) {
+  char a[26] = "abcdefghijklmnopqrstuvwxyz";
+  while (1)
+  {
     // Generate a random name with length 5
-    char name[5];
-    for (int k=0; k<5; k++)  name[k] = a[rand() % 26];
+    char name[6];
+    name[5] = '\0';
+    for (int k = 0; k < 5; k++)
+      name[k] = a[rand() % 26];
 
     //##################################################################
     /* Step 1. Send a DNS request to the targeted local DNS server.
                This will trigger the DNS server to send out DNS queries */
 
     // ... Students should add code here.
 
-
     /* Step 2. Send many spoofed responses to the targeted local DNS server,
                each one with a different transaction ID. */
-    
+
     // ... Students should add code here.
-    
+
     //##################################################################
   }
 }
 
-
 /* Use for sending DNS request.
  * Add arguments to the function definition if needed.
  * */
@@ -81,7 +84,6 @@ void send_dns_request()
   // Students need to implement this function
 }
 
-
 /* Use for sending forged DNS response.
  * Add arguments to the function definition if needed.
  * */
@@ -90,12 +92,11 @@ void send_dns_response()
   // Students need to implement this function
 }
 
-
 /* Send the raw packet out 
  *    buffer: to contain the entire IP packet, with everything filled out.
  *    pkt_size: the size of the buffer.
  * */
-void send_raw_packet(char * buffer, int pkt_size)
+void send_raw_packet(char *buffer, int pkt_size)
 {
   struct sockaddr_in dest_info;
   int enable = 1;
@@ -105,15 +106,15 @@ void send_raw_packet(char * buffer, int pkt_size)
 
   // Step 2: Set socket option.
   setsockopt(sock, IPPROTO_IP, IP_HDRINCL,
-	     &enable, sizeof(enable));
+             &enable, sizeof(enable));
 
   // Step 3: Provide needed information about destination.
-  struct ipheader *ip = (struct ipheader *) buffer;
+  struct ipheader *ip = (struct ipheader *)buffer;
   dest_info.sin_family = AF_INET;
   dest_info.sin_addr = ip->iph_destip;
 
   // Step 4: Send the packet out.
   sendto(sock, buffer, pkt_size, 0,
-       (struct sockaddr *)&dest_info, sizeof(dest_info));
+         (struct sockaddr *)&dest_info, sizeof(dest_info));
   close(sock);
 }