为什么我得到分段错误时，从客户端发送数据到服务器

我制作了一个接受4个参数的客户端服务器程序。输入文件，输出文件，IP添加，端口号。但是当我试图发送结束字符时，我得到分割错误。

server.cpp

#include <unistd.h>
#include <iostream>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <errno.h>
#include <string.h>
#include <fstream>
#include <iomanip>
using namespace std;
int main (int argc, char **argv)
{
    int sock, cli, read_size, file_size;    //cli socket descriptor
    struct sockaddr_in server, client;
    char *send_buffer;
    char *fname;
    unsigned int sock_len;
    ofstream fout;
    cout << "Initializing a Socketn";
    if ((sock = socket(AF_INET, SOCK_STREAM, 0)) == -1)
    {
        perror("Socket: ");
        close(sock);
        exit(-1);
    }
    server.sin_family = AF_INET;
    server.sin_port = htons(7246);
    server.sin_addr.s_addr = INADDR_ANY;
    bzero(&server.sin_zero, 0);
    sock_len = sizeof(struct sockaddr);
    cout << "Binding a Socketn";
    if((bind(sock, (struct sockaddr *)&server, sock_len)) == -1)
    {
        perror("Bind: ");
        close(sock);
        exit(-1);
    }
    cout << "Listeningn";
    if((listen(sock, 5)) == -1)
    {
        perror("Listen: ");
    }
    //To accept connection and get data from server
    while(1)
    {
        cout << "Waiting...";
        if((cli = accept(sock, (struct sockaddr *)&client, &sock_len )) == -1)
        {
            perror("Accept: ");
            close(sock);
            exit(-1);
        }
        else
        {
            cout << "Server: Got connection from " << inet_ntoa(client.sin_addr) << endl;
            file_size = recv(cli, fname, 100, 0);
            cout << "nOpening filen";
            fout.open(fname, ios::out | ios::app | ios::binary);
            if(!fout)
            {
                cout << "Error opening the file " <<fname << endl;
                close(sock);
                exit(1);
            }
        }
        cout << "Start nown";
        //while((recv(cli, send_buffer, sizeof(send_buffer), 0)) != EOF)
        //while(*send_buffer != EOF)
        while(strcmp(send_buffer, "_EOF_") != 0)
        {
            recv(cli, send_buffer, 10, 0);
            cout << "Receiving Msg...";
            fout.write(send_buffer, sizeof(send_buffer));
            /*if(*send_buffer == EOF)   {
                cout << "Data Receivedn";
                close(sock);
                break;
            }*/
        }
        //fout.write(EOF, sizeof(EOF));
        /*if(read_size == 0)
        {
            cout << "Client Disconnected";
        }
        else if(read_size == -1)
        {
            perror("Receive Failed");
            close(sock);
        }*/
        //  fout.write(eof, sizeof(eof()));
        fout.close();

    }
    close(sock);
    return 0;
}

/*  
Authors: Manoj Parihar
Description: This program
*/
#include <unistd.h>
#include <iostream>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <errno.h>
#include <string.h>
#include <fstream>
#include <iomanip>
#include <netdb.h>
using namespace std;
int main (int argc, char *argv[])
{
    int sockfd, numbytes;
    char *buf_msg;
    struct sockaddr_in server_add;
    struct hostent *he;
    char *end = "_EOF_";
    ifstream fin;
    if(argc != 5)
    {
        perror("Credentials Incomplete... Try again");
        exit(1);
    }
    /*if ((he = gethostbyname(argv[1])) == NULL)    {
        cout << "Cannot get hostname" << endl;
        exit(1);
    }*/
    if((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1)
    {
        cout << "Socket Failure..." << endl;
        close(sockfd);
        exit(1);
    }
    memset(&server_add, 0, sizeof(server_add));
    server_add.sin_family = AF_INET;
    server_add.sin_port = htons(atoi(argv[4]));
    server_add.sin_addr.s_addr = inet_addr(argv[3]);
    bzero(&server_add.sin_zero, 0);
    cout << "Trying to connectn";
    if(connect(sockfd, (struct sockaddr *)&server_add, sizeof(struct sockaddr)) == -1)
    {
        perror("Connect Error");
        close(sockfd);
        exit(1);
    }
    else
        cout << "sending filename...n";
    send(sockfd, argv[2], strlen(argv[2]), 0);

    cout << "opening: " << argv[1] << strlen(argv[1]) << endl;
    fin.open (argv[1], ios::in | ios::app | ios::binary);
    if(!fin)
    {
        cout << "Client: Error opening file" << endl;
        close(sockfd);
        exit(1);
    }
    while(!(fin.eof()))
    {
        fin.read(buf_msg, 10);
        cout << buf_msg << sizeof(buf_msg) << endl;
        if(send(sockfd, buf_msg, sizeof(buf_msg), 0) == -1)
        {
            cout << "Failure Sending Msg";
            close(sockfd);
            exit(1);
        }
    }
    cout << "Sending end charactern";
    if(send(sockfd, "_EOF_", 5, 0) == -1)
    {
        cout << "Endpoint not sentn";
        close(sockfd);
        exit(1);
    }
    //send(sockfd, -1, sizeof(int), 0)
    cout << "Closing Client...";
    close(sockfd);
    return 0;
}