Getting garbage values when transfering file from server to client in c?

this is my c code of the server and the client. /* TCP server */

#include <sys/socket.h>
#include <netinet/in.h>
#include <stdio.h>

    #include <string.h>
    #include <errno.h>

        #include <stdlib.h>

            FILE *fp;

        int main(int argc, char**argv){


            int listenfd,connfd,n;


            struct sockaddr_in servaddr,cliaddr;
            socklen_t clilen;

            char * banner = "1077"; // size of the file
            char buffer[1000];


            /* one socket is dedicated to listening */

            listenfd=socket(AF_INET,SOCK_STREAM,0);

            /* initialize a sockaddr_in struct with our own address information for
            binding the socket */

            servaddr.sin_family = AF_INET;
            servaddr.sin_addr.s_addr=htonl(INADDR_ANY);
            servaddr.sin_port=htons(32000);

            /* binding */
            bind(listenfd,(struct sockaddr *)&servaddr,sizeof(servaddr));
            listen(listenfd,0); //listen( --,--);
            clilen=sizeof(cliaddr);

            /* accept the client with a different socket. */
            connfd = accept(listenfd,(struct sockaddr *)&cliaddr,&clilen); // the uninitialized cliaddr variable is filled in with the
            n = recvfrom(connfd,buffer,1000,0,(struct sockaddr *)&cliaddr,&clilen);//information of the client by recvfrom function
                buffer[n] = 0;
            sendto(connfd,banner,strlen(banner),0,(struct sockaddr *)&cliaddr,sizeof(cliaddr));
            printf("Received:%s\n",buffer);


             char file_name[] ="severtext.txt";




                 fp = fopen(file_name,"r"); // read mode

                           if( fp == NULL )
                           {
                              perror("Error while opening the file.\n");
                              exit(EXIT_FAILURE);
                           }

                printf("The contents of %s file are :\n", file_name);
            char sendData[1000];
        /*open servertext.txt and coppy it to a char array */
                fread(sendData, 1000, 1, fp);

                printf("The contents of sending\n");

                         sendto(connfd,sendData,sizeof(sendData),0,(struct sockaddr *)&cliaddr,sizeof(cliaddr));

        /*information of the client by recvfrom function */
                         n = recvfrom(connfd,buffer,1000,0,(struct sockaddr *)&cliaddr,&clilen);
                         buffer[n] = 0;
                         printf("Received:%s\n",buffer);









                 printf("End of connection \n");


            return 0;
        }

...client code /* Sample TCP client */

 #include <sys/socket.h>
    #include <netinet/in.h>
    #include <arpa/inet.h>
    #include <stdio.h>
    #include <string.h>
    #include <errno.h>



    int main(int argc, char**argv){



            int sockfd,n;
            FILE *fp;
            fp = fopen("file.txt", "w+");
        struct sockaddr_in servaddr;
        char banner[] = "request serverfile.txt";

           char revbuf1[1000];

        char buffer[4];

        if (argc != 2){
            printf("usage: ./%s <IP address>\n",argv[0]);
            return -1;
        }
        /* socket to connect */
        sockfd=socket(AF_INET,SOCK_STREAM,0);
        /* IP address information of the server to connect to */
        servaddr.sin_family = AF_INET;
        servaddr.sin_addr.s_addr=inet_addr(argv[1]);
        servaddr.sin_port=htons(32000);
        connect(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr));

        sendto(sockfd,banner,strlen(banner),0, (struct sockaddr *)&servaddr,sizeof(servaddr));

        n=recvfrom(sockfd,buffer,10,0,NULL,NULL);
        buffer[n]=0;

        printf("Received: %s\n",buffer);


            printf("[Client] Receiveing file from Server and saving it as final.txt...");
            char * banner1="ok";


            printf("\ndata1 set\n"); 

            n=recvfrom(sockfd,revbuf1,1000,0,NULL,NULL);
        revbuf1[n]=0;
            sendto(sockfd,banner1,strlen(banner1),0, (struct sockaddr *)&servaddr,sizeof(servaddr));
        printf("Received: %s\n",revbuf1);
            //open file.txt and over write it with the recieved data in the client side.
            fwrite(revbuf1, 1000, 1, fp);
            fclose(fp);


             close (sockfd);
             printf("[Client] Connection lost.\n");
        return 0;


    }

When i run these two programs i get garbage values in the file.txt with the servertext.txt content, Can someone help to fix this problem?