此服务器的目标是以相对简单的方式传输小文件。我已经完成了代码并且所有编译都没有错误，当我尝试运行它时，服务器端没有问题，但是客户端在套接字绑定和分段错误中给出了错误。我想知道代码中是什么导致了这些问题。
服务器：
#include <stdio.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/fcntl.h>
#include <string.h>
#include <unistd.h>
#include <crypt.h>
#include <time.h>
#include <stdlib.h>
#include <sys/types.h>
#include <dirent.h>
#include <netinet/ip.h>
void timestamp_ss()
{
time_t current_time;
char* log_time;
log_time = ctime(¤t_time);
log_file_ss(log_time);
}
send_data(int sockfd, char info_to_send)
{
char eof_buffer[4] = "\EOF";
int sent_data, data_to_send;
data_to_send = strlen(&info_to_send);
while(data_to_send > 0)
{
sent_data = send(sockfd, &info_to_send, data_to_send, 0);
if(sent_data == -1)
perror("There was a problem in the sending of data!");
data_to_send -= sent_data;
info_to_send += sent_data;
}
send(sockfd, eof_buffer, 4, 0);
}
int recv_data(int sockfd, char *dest_buffer)
{
#define EoF "\EOF"
unsigned char *buffer;
int eof_match = 0, eof_size = 2;
buffer = dest_buffer;
while(recv(sockfd, buffer, 1, 0) == 1)
{
if(*buffer == EoF[eof_match])
{
eof_match++;
if(eof_match = eof_size)
{
*(buffer+1-eof_size) = '\0';
return strlen(dest_buffer);
}
else
{
eof_match = 0;
}
}
buffer++;
}
return 0;
}
int password_ss(char *password_attempt, char *password_actual)
{
char key[] = { "ZjQXStSi" };
char ivec[] = {"7eNP3U1b" };
char des_dec[] = { "DES_DECRYPT" };
char des_hw[] = { "DES_HW" };
int l, i;
l = strlen(password_attempt);
i = cbc_crypt(key, password_attempt, l, *des_dec | *des_hw, ivec);
if(i < 0)
error_escape("In decryption");
if(password_attempt == password_actual)
return 1;
else
return 0;
}
int log_file_ss(char *log_message)
{
char logfile[]= "/Server/log/C-File-Transfer-Server-Log";
int log_fd, len;
log_fd = open(logfile, O_WRONLY | O_APPEND | O_CREAT);
len = strlen(log_message);
write(log_fd, log_message, len);
}
void file_to_client_ss(int sockfd, struct sockaddr_in *client_addr_ptr)
{
char file_req_c[128];
char buffer[10000];
char files[256];
char pass_attempt[128];
char *error_403[20] = { "Error 403: Forbidden" };
char *error_404[25] = { "Error 404: File Not Found" };
char *pass_path[20] = { "/server/log/PASSWORD" };
char *pass_req[50] = { "This File Requires A Password, Please Enter It Now" };
char *no_pass[37] = { "This File Does Not Require A Password" };
char *username;
char *file_s;
char *string;
char *file1_path[26] = { "/server/received_files/r_w" };
char *file2_path[24] = { "/server/received_files/r" };
char *file3_path[24] = { "/server/received_files/n" };
char file_data;
FILE *cs, *ps;
int file1, file2, file3, file_test, pass;
cs = fopen(file_req_c, "r");
recv_data(sockfd, username);
chdir("/server/log/PASSWORD");
ps = fopen(username, "r");
fread(files, 1, file_size(ps), ps);
chdir("/server");
recv_data(sockfd, file_req_c);
file_test = file_exist(file1_path, file_req_c);
if(file_test = -1)
{
file_test = file_exist(file2_path, file_req_c);
if(file_test = -1)
{
file_test = file_exist(file3_path, file_req_c);
if(file_test = -1)
{
error_escape("Opening file request from client");
}
else
{
send_data(sockfd, **pass_req);
recv_data(sockfd, pass_attempt);
pass = password_ss(pass_attempt, files);
if(pass == 0)
{
send_data(sockfd, **error_403);
error_escape("Wrong Password");
}
else
{
if(file_exist(pass_path, username) == 0)
send_data(sockfd, *file_req_c);
else
errror_escape("Error in sending file");
}
}
}
else
{
chdir(*file2_path);
file_data = fread(buffer, 1, file_size(cs), cs);
send_data(sockfd, **no_pass);
send_data(sockfd, file_data);
}
}
else
{
chdir(*file1_path);
file_data = fread(buffer, 1, file_size(cs), cs);
send_data(sockfd, **no_pass);
send_data(sockfd, file_data);
}
}
int file_size(FILE *stream)
{
off_t file_len;
fseek(stream, 0, SEEK_END);
file_len = ftell(stream);
fclose(stream);
return file_len;
}
int file_exist(char *file_path, char *file_name)
{
DIR *dp;
FILE *fc;
struct dirent *ep;
dp = opendir(file_path);
if(dp == NULL)
perror("Opening path");
else
chdir(file_path);
closedir(dp);
fc = fopen(file_name, "r");
if(fc == NULL)
{
perror("Opening file");
return(-1);
}
else {
return(0);
}
}
error_escape(char *problem)
{
char error_message[256];
strcpy(error_message, "! There Has Been An Error !");
strncat(error_message, problem, 173);
perror("Error: ");
log_file_ss(error_message);
timestamp_ss();
exit(-1);
}
void file_accept_ss(int sockfd, struct sockaddr_in *client_addr_ptr)
{
char client_request[512], username[256], file_content[8192], buf[8192];
char *client_r_w[26] = { "/server/received_files/r_w" };
char *client_r[24] = { "/server/received_files/r" };
char *client_n[24] = { "/server/received_files/n" };
char *search_string_read[6] = { "O_READ" };
char *search_string_w[14] = { "O_READANDWRITE" };
char *password_path[20] = { "/server/log/PASSWORD" };
char *mkdir[37] = { "/server/log/PASSWORD" };
char *ret;
char file_data, recv_i;
char password[256];
int change_dir_test, recv_check;
FILE *fn, *Ps;
recv_data(sockfd, username);
recv_data(sockfd, password);
strcat(*mkdir, username);
strcat(*mkdir, password);
fn = fopen(*mkdir, "a");
chdir(*password_path);
Ps = fopen(*mkdir, "a");
chdir("/server");
recv_i = fread(buf, 1, file_size(fn), fn);
recv_check = recv_data(sockfd, &recv_i);
if(recv_check = -1)
error_escape("! There Was An Error In The Receiving Of The File From The Client !");
fread(file_content, 8, file_size(fn), fn);
ret = strstr(file_content, *search_string_read);
if(ret = NULL)
{
change_dir_test = chdir(*client_n);
if(change_dir_test = -1)
error_escape("! There Was An Error In The Changing Of Directories !");
else
{
file_data = fread(buf, 1, file_size(Ps), Ps);
recv_data(sockfd, &file_data);
chdir(*client_n);
strcat(*client_n, username);
rename(username, *client_n);
}
}
if(ret = *search_string_read)
{
change_dir_test = chdir(*client_r);
if(change_dir_test = -1)
error_escape("! There Was An Error In The Changing Of Directories !");
else
{
chdir(*client_r);
rename(username, *client_r);
}
}
if(ret = *search_string_w)
{
change_dir_test = chdir(*client_r_w);
if(change_dir_test = -1)
error_escape("! There Was An Error In The Changing Of Directories !");
else
{
chdir(*client_r_w);
rename(username, *client_r_w);
}
}
log_file_ss("Client:");
log_file_ss(username);
timestamp_ss();
}
int main(void)
{
struct sockaddr_in server, client;
int sockfd, bind_test, listen_test, client_sockfd, sin_size;
sockfd = socket(PF_INET, SOCK_STREAM, 0);
if(sockfd == -1)
error_escape("Making Socket");
server.sin_family = AF_INET;
server.sin_port = htons(80);
server.sin_addr.s_addr = INADDR_ANY;
bind_test = bind(sockfd, (struct sockaddr *)&server, sizeof(server));
if(bind_test < 0)
error_escape("Binding Socket");
listen_test = listen(sockfd, 20);
if(listen_test < 0)
error_escape("Listening");
while(1)
{
sin_size = sizeof(struct sockaddr_in);
client_sockfd = accept(sockfd, (struct sockaddr *)&client, &sin_size);
file_accept_ss(client_sockfd, &client);
file_to_client_ss(client_sockfd, &client);
}
shutdown(client_sockfd, SHUT_RDWR);
return 0;
}
客户：
#include <stdio.h>
#include <string.h>
#include <dirent.h>
#include <sys/types.h>
#include <unistd.h>
#include <crypt.h>
#include <sys/socket.h>
#include <netinet/ip.h>
send_data(int sockfd, char info_to_send)
{
char eof_buffer[4] = "\EOF";
int sent_data, data_to_send;
data_to_send = strlen(&info_to_send);
while(data_to_send > 0)
{
sent_data = send(sockfd, &info_to_send, data_to_send, 0);
if(sent_data == -1)
perror("There was a problem in the sending of data!");
data_to_send -= sent_data;
info_to_send += sent_data;
}
send(sockfd, eof_buffer, 4, 0);
}
send_file_cs(int sockfd)
{
char file_buffer[4096], file_name[256];
char name, username, password;
char *search_st, file_data, *file_location;
int perm_choice, password_max = 20, ch;
off_t size_of_file;
FILE *fp;
printf("%s\n", "Please enter the path to file you would like to move to server:");
scanf("%s", &file_location);
ch = chdir(file_location);
if(ch == -1)
perror("! There Has Been An Error In The Directory Path !");
else
chdir(file_location);
printf("%s\n", "Now Enter The Name Of The File You Would Like To Transfer:");
printf("%s\n", "! Warning, The File May Not Exceed 4 kilobytes !");
scanf("%s", &name);
printf("%s", "What would you like the username for this file to be?");
name = *file_name;
size_of_file = file_size(fp);
if(size_of_file > 4096)
printf("! The File Is Greater Than 4 Kilobytes !");
fp = fopen(file_name, "r+");
printf("%s\n", "What Permissions Would You Like The File To Have?\n (1) For Other Clients To See The File\n (2) For Other CLients To See But Not Be Able To Access\n (3) Other Clients Cannot See Or Access The File");
scanf("%d", &perm_choice);
if(perm_choice > 3 || perm_choice < 1)
perror("! Incorrect Permissions !");
if(perm_choice = 1)
{
search_st = "O_READ";
fopen(file_name, "a");
fwrite(search_st, 1, strlen(search_st), fp);
}
if(perm_choice = 2)
{
search_st = "O_READANDWRITE";
fopen(file_name, "a");
fwrite(search_st, 1, strlen(search_st), fp);
}
if(perm_choice = 3)
{
search_st = "O_NOACCESS";
fopen(file_name, "a");
fwrite(search_st, 1, strlen(search_st), fp);
printf("%s", "Please enter a password");
scanf("%s", &password);
send_data(sockfd, password);
}
file_data = fread(file_buffer, 1, 4096, fp);
send_data(sockfd, file_data);
}
int recv_data(int sockfd, char *dest_buffer)
{
#define EoF "\EOF"
unsigned char *buffer;
int eof_match = 0, eof_size = 2;
buffer = dest_buffer;
while(recv(sockfd, buffer, 1, 0) == 1)
{
if(*buffer == EoF[eof_match])
{
eof_match++;
if(eof_match = eof_size)
{
*(buffer+1-eof_size) = '\0';
return strlen(dest_buffer);
}
else
{
eof_match = 0;
}
}
buffer++;
}
return 0;
}
int password_cs(int max_length, int sockfd)
{
char salt[] = { "ZjQXStSi" };
char ivec[] = { "7eNP3U1b" };
char des_enc[] = { "DES_ENCRYPT" };
char des_hw[] = { "DES_HW" };
char password;
char *ret, *ret2;
int l, i;
printf("%s", "Please set your password:");
scanf("%s", &password);
l = strlen(&password);
if(l > max_length)
printf("%s : %d", "Password must be less than", max_length);
i = cbc_crypt(salt, password, l, *des_enc | *des_hw, ivec);
if(i < 0)
perror("In erncryption");
send_data(sockfd, password);
return 0;
}
int file_size(FILE *stream)
{
off_t file_len;
fseek(stream, 0, SEEK_END);
file_len = ftell(stream);
fclose(stream);
return file_len;
}
int file_exist(char *file_path, char *file_name)
{
DIR *dp;
FILE *fc;
struct dirent *ep;
dp = opendir(file_path);
if(dp == NULL)
perror("Opening path");
else
chdir(file_path);
closedir(dp);
fc = fopen(file_name, "r");
if(fc == NULL)
{
perror("Opening file");
return(-1);
}
else {
return(0);
}
}
void client_request_file_cs(int sockfd)
{
char password_buf[128], file[4096], recv_file[256];
char *requires[16] = { "Requires" };
char *str, *restr, *file_contents, *name2, *path, *rebuf;
char file_req, password, name, username;
int test;
FILE *re;
printf("%s\n", "What file would you like from the server?");
scanf("%s", &file_req);
printf("%s", "What is the user name associated with the file?");
scanf("%s", &username);
send_data(sockfd, username);
printf("%s\n", "Where Would You Like The File To Be Put, Please Enter The Path:");
scanf("%s", &path);
test = chdir(path);
if(test == -1)
printf("%s\n", "Invalid Path");
printf("%s\n", "What Would You Like To Call The File?");
scanf("%s", &name);
name2 = &name;
re = fopen(name2, "w");
fread(file_contents, 1, file_size(re), re);
send_data(sockfd, file_req);
recv_data(sockfd, password_buf);
printf("%s\n", password_buf);
str = strstr(password_buf, *requires);
if(str == NULL)
recv_data(sockfd, file);
else
{
scanf("%s", &password);
send_data(sockfd, password);
}
recv_data(sockfd, rebuf);
fwrite(rebuf, 1, sizeof(rebuf), re);
fclose(re);
restr = strstr(file_contents, "error_");
if(restr != NULL)
printf("%s\n", re);
}
int main(void)
{
struct sockaddr_in client, server_addr;
int sockfd, connected;
server_addr.sin_family = AF_INET;
server_addr.sin_port = htons(80);
sockfd = socket(AF_INET, SOCK_STREAM, 0);
if(sockfd == -1)
printf("%s", "Error opening socket");
connected = connect(sockfd, (struct sockaddr *)&server_addr, sizeof(struct sockaddr));
if(connected == -1)
printf("%s", "Error binding socket");
send_file_cs(sockfd);
client_request_file_cs(sockfd);
shutdown(sockfd, SHUT_RDWR);
return 0;
}
提前感谢您的帮助。
答案 0 :(得分：0)
在评论中的其他有效问题/点中，代码中的内存分配可能会导致您的分段错误......
正在使用 char *file_location（和其他人），就像分配了内存一样。
在分配内存之前在scanf("%s", &file_location);中使用变量会调用未定义的行为，并且很可能（至少部分地）对运行时错误负责。
在 scanf语句之前添加内存。以下是如何执行此操作的两个示例：
1）创建堆内存（使用[m] [c] alloc）：
char *file_location;
file_location = malloc(MAX_FILENAME_LEN);//or your systems value for max directory length
if(file_location)
{
scanf("%s", &file_location);
...
2）使用堆栈内存:(将指针指向带内存的地方）
char file_name[256];
char *file_location = file_name;
file_location = file_name;
scanf("%s", &file_location);
但最简单的方法（如果没有任何限制你使用指针的话）就是在堆栈上创建变量并在scanf(...)中使用它：
char file_location[256];
scanf("%s", &file_location);
示例代码中还有其他变量（除了file_location），在使用前需要内存。完成使用后，请记得使用 on the heap 创建的内存释放任何变量。