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fiche.c
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fiche.c
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/*
Fiche - Command line pastebin for sharing terminal output.
-------------------------------------------------------------------------------
License: MIT (http://www.opensource.org/licenses/mit-license.php)
Repository: https://github.com/solusipse/fiche/
Live example: http://termbin.com
-------------------------------------------------------------------------------
usage: fiche [-DepbsdolBuw].
[-D] [-e] [-d domain] [-p port] [-s slug size]
[-o output directory] [-B buffer size] [-u user name]
[-l log file] [-b banlist] [-w whitelist]
-D option is for daemonizing fiche
-e option is for using an extended character set for the URL
Compile with Makefile or manually with -O2 and -pthread flags.
To install use `make install` command.
Use netcat to push text - example:
$ cat fiche.c | nc localhost 9999
-------------------------------------------------------------------------------
*/
#include "fiche.h"
#include <stdio.h>
#include <stdarg.h>
#include <stdlib.h>
#include <string.h>
#include <pwd.h>
#include <time.h>
#include <unistd.h>
#include <pthread.h>
#include <fcntl.h>
#include <netdb.h>
#include <sys/time.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netinet/in.h>
/******************************************************************************
* Various declarations
*/
const char *Fiche_Symbols = "abcdefghijklmnopqrstuvwxyz0123456789";
/******************************************************************************
* Inner structs
*/
struct fiche_connection {
int socket;
struct sockaddr_in address;
Fiche_Settings *settings;
};
/******************************************************************************
* Static function declarations
*/
// Settings-related
/**
* @brief Sets domain name
* @warning settings.domain has to be freed after using this function!
*/
static int set_domain_name(Fiche_Settings *settings);
/**
* @brief Changes user running this program to requested one
* @warning Application has to be run as root to use this function
*/
static int perform_user_change(const Fiche_Settings *settings);
// Server-related
/**
* @brief Starts server with settings provided in Fiche_Settings struct
*/
static int start_server(Fiche_Settings *settings);
/**
* @brief Dispatches incoming connections by spawning threads
*/
static void dispatch_connection(int socket, Fiche_Settings *settings);
/**
* @brief Handles connections
* @remarks Is being run by dispatch_connection in separate threads
* @arg args Struct fiche_connection containing connection details
*/
static void *handle_connection(void *args);
// Server-related utils
/**
* @brief Generates a slug that will be used for paste creation
* @warning output has to be freed after using!
*
* @arg output pointer to output string containing full path to directory
* @arg length default or user-requested length of a slug
* @arg extra_length additional length that was added to speed-up the
* generation process
*
* This function is used in connection with create_directory function
* It generates strings that are used to create a directory for
* user-provided data. If directory already exists, we ask this function
* to generate another slug with increased size.
*/
static void generate_slug(char **output, uint8_t length, uint8_t extra_length);
/**
* @brief Creates a directory at requested path using requested slug
* @returns 0 if succeded, 1 if failed or dir already existed
*
* @arg output_dir root directory for all pastes
* @arg slug directory name for a particular paste
*/
static int create_directory(char *output_dir, char *slug);
/**
* @brief Saves data to file at requested path
*
* @arg data Buffer with data received from the user
* @arg path Path at which file containing data from the buffer will be created
*/
static int save_to_file(const Fiche_Settings *s, uint8_t *data, char *slug);
// Logging-related
/**
* @brief Displays error messages
*/
static void print_error(const char *format, ...);
/**
* @brief Displays status messages
*/
static void print_status(const char *format, ...);
/**
* @brief Displays horizontal line
*/
static void print_separator();
/**
* @brief Saves connection entry to the logfile
*/
static void log_entry(const Fiche_Settings *s, const char *ip,
const char *hostname, const char *slug);
/**
* @brief Returns string containing current date
* @warning Output has to be freed!
*/
static void get_date(char *buf);
/**
* @brief Time seed
*/
unsigned int seed;
/******************************************************************************
* Public fiche functions
*/
void fiche_init(Fiche_Settings *settings) {
// Initialize everything to default values
// or to NULL in case of pointers
struct Fiche_Settings def = {
// domain
"example.com",
// output dir
"code",
// listen_addr
"0.0.0.0",
// port
9999,
// slug length
4,
// https
false,
// buffer length
32768,
// user name
NULL,
// path to log file
NULL,
// path to banlist
NULL,
// path to whitelist
NULL
};
// Copy default settings to provided instance
*settings = def;
}
int fiche_run(Fiche_Settings settings) {
seed = time(NULL);
// Display welcome message
{
char date[64];
get_date(date);
print_status("Starting fiche on %s...", date);
}
// Try to set requested user
if ( perform_user_change(&settings) != 0) {
print_error("Was not able to change the user!");
return -1;
}
// Check if output directory is writable
// - First we try to create it
{
mkdir(
settings.output_dir_path,
S_IRWXU | S_IRGRP | S_IROTH | S_IXOTH | S_IXGRP
);
// - Then we check if we can write there
if ( access(settings.output_dir_path, W_OK) != 0 ) {
print_error("Output directory not writable!");
return -1;
}
}
// Check if log file is writable (if set)
if ( settings.log_file_path ) {
// Create log file if it doesn't exist
FILE *f = fopen(settings.log_file_path, "a+");
fclose(f);
// Then check if it's accessible
if ( access(settings.log_file_path, W_OK) != 0 ) {
print_error("Log file not writable!");
return -1;
}
}
// Try to set domain name
if ( set_domain_name(&settings) != 0 ) {
print_error("Was not able to set domain name!");
return -1;
}
// Main loop in this method
start_server(&settings);
// Perform final cleanup
// This is allways allocated on the heap
free(settings.domain);
return 0;
}
/******************************************************************************
* Static functions below
*/
static void print_error(const char *format, ...) {
va_list args;
va_start(args, format);
printf("[Fiche][ERROR] ");
vprintf(format, args);
printf("\n");
va_end(args);
}
static void print_status(const char *format, ...) {
va_list args;
va_start(args, format);
printf("[Fiche][STATUS] ");
vprintf(format, args);
printf("\n");
va_end(args);
}
static void print_separator() {
printf("============================================================\n");
}
static void log_entry(const Fiche_Settings *s, const char *ip,
const char *hostname, const char *slug)
{
// Logging to file not enabled, finish here
if (!s->log_file_path) {
return;
}
FILE *f = fopen(s->log_file_path, "a");
if (!f) {
print_status("Was not able to save entry to the log!");
return;
}
char date[64];
get_date(date);
// Write entry to file
fprintf(f, "%s -- %s -- %s (%s)\n", slug, date, ip, hostname);
fclose(f);
}
static void get_date(char *buf) {
struct tm curtime;
time_t ltime;
ltime=time(<ime);
localtime_r(<ime, &curtime);
// Save data to provided buffer
if (asctime_r(&curtime, buf) == 0) {
// Couldn't get date, setting first byte of the
// buffer to zero so it won't be displayed
buf[0] = 0;
return;
}
// Remove newline char
buf[strlen(buf)-1] = 0;
}
static int set_domain_name(Fiche_Settings *settings) {
char *prefix = "";
if (settings->https) {
prefix = "https://";
} else {
prefix = "http://";
}
const int len = strlen(settings->domain) + strlen(prefix) + 1;
char *b = malloc(len);
if (!b) {
return -1;
}
strcpy(b, prefix);
strcat(b, settings->domain);
settings->domain = b;
print_status("Domain set to: %s.", settings->domain);
return 0;
}
static int perform_user_change(const Fiche_Settings *settings) {
// User change wasn't requested, finish here
if (settings->user_name == NULL) {
return 0;
}
// Check if root, if not - finish here
if (getuid() != 0) {
print_error("Run as root if you want to change the user!");
return -1;
}
// Get user details
const struct passwd *userdata = getpwnam(settings->user_name);
const int uid = userdata->pw_uid;
const int gid = userdata->pw_gid;
if (uid == -1 || gid == -1) {
print_error("Could find requested user: %s!", settings->user_name);
return -1;
}
if (setgid(gid) != 0) {
print_error("Couldn't switch to requested user: %s!", settings->user_name);
}
if (setuid(uid) != 0) {
print_error("Couldn't switch to requested user: %s!", settings->user_name);
}
print_status("User changed to: %s.", settings->user_name);
return 0;
}
static int start_server(Fiche_Settings *settings) {
// Perform socket creation
int s = socket(AF_INET, SOCK_STREAM, 0);
if (s < 0) {
print_error("Couldn't create a socket!");
return -1;
}
// Set socket settings
if ( setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &(int){ 1 } , sizeof(int)) != 0 ) {
print_error("Couldn't prepare the socket!");
return -1;
}
// Prepare address and port handler
struct sockaddr_in address;
address.sin_family = AF_INET;
address.sin_addr.s_addr = inet_addr(settings->listen_addr);
address.sin_port = htons(settings->port);
// Bind to port
if ( bind(s, (struct sockaddr *) &address, sizeof(address)) != 0) {
print_error("Couldn't bind to the port: %d!", settings->port);
return -1;
}
// Start listening
if ( listen(s, 128) != 0 ) {
print_error("Couldn't start listening on the socket!");
return -1;
}
print_status("Server started listening on: %s:%d.",
settings->listen_addr, settings->port);
print_separator();
// Run dispatching loop
while (1) {
dispatch_connection(s, settings);
}
// Give some time for all threads to finish
// NOTE: this code is reached only in testing environment
// There is currently no way to kill the main thread from any thread
// Something like this can be done for testing purpouses:
// int i = 0;
// while (i < 3) {
// dispatch_connection(s, settings);
// i++;
// }
sleep(5);
return 0;
}
static void dispatch_connection(int socket, Fiche_Settings *settings) {
// Create address structs for this socket
struct sockaddr_in address;
socklen_t addlen = sizeof(address);
// Accept a connection and get a new socket id
const int s = accept(socket, (struct sockaddr *) &address, &addlen);
if (s < 0 ) {
print_error("Error on accepting connection!");
return;
}
// Set timeout for accepted socket
const struct timeval timeout = { 5, 0 };
if ( setsockopt(s, SOL_SOCKET, SO_RCVTIMEO, &timeout, sizeof(timeout)) != 0 ) {
print_error("Couldn't set a timeout!");
}
if ( setsockopt(s, SOL_SOCKET, SO_SNDTIMEO, &timeout, sizeof(timeout)) != 0 ) {
print_error("Couldn't set a timeout!");
}
// Create an argument for the thread function
struct fiche_connection *c = malloc(sizeof(*c));
if (!c) {
print_error("Couldn't allocate memory!");
return;
}
c->socket = s;
c->address = address;
c->settings = settings;
// Spawn a new thread to handle this connection
pthread_t id;
if ( pthread_create(&id, NULL, &handle_connection, c) != 0 ) {
print_error("Couldn't spawn a thread!");
return;
}
// Detach thread if created succesfully
// TODO: consider using pthread_tryjoin_np
pthread_detach(id);
}
static void *handle_connection(void *args) {
// Cast args to it's previous type
struct fiche_connection *c = (struct fiche_connection *) args;
// Get client's IP
const char *ip = inet_ntoa(c->address.sin_addr);
// Get client's hostname
char hostname[1024];
if (getnameinfo((struct sockaddr *)&c->address, sizeof(c->address),
hostname, sizeof(hostname), NULL, 0, 0) != 0 ) {
// Couldn't resolve a hostname
strcpy(hostname, "n/a");
}
// Print status on this connection
{
char date[64];
get_date(date);
print_status("%s", date);
print_status("Incoming connection from: %s (%s).", ip, hostname);
}
// Create a buffer
uint8_t buffer[c->settings->buffer_len];
memset(buffer, 0, c->settings->buffer_len);
const int r = recv(c->socket, buffer, sizeof(buffer), MSG_WAITALL);
if (r <= 0) {
print_error("No data received from the client!");
print_separator();
// Close the socket
close(c->socket);
// Cleanup
free(c);
pthread_exit(NULL);
return 0;
}
// - Check if request was performed with a known protocol
// TODO
// - Check if on whitelist
// TODO
// - Check if on banlist
// TODO
// Generate slug and use it to create an url
char *slug;
uint8_t extra = 0;
do {
// Generate slugs until it's possible to create a directory
// with generated slug on disk
generate_slug(&slug, c->settings->slug_len, extra);
// Something went wrong in slug generation, break here
if (!slug) {
break;
}
// Increment counter for additional letters needed
++extra;
// If i was incremented more than 128 times, something
// for sure went wrong. We are closing connection and
// killing this thread in such case
if (extra > 128) {
print_error("Couldn't generate a valid slug!");
print_separator();
// Cleanup
free(c);
free(slug);
close(c->socket);
pthread_exit(NULL);
return NULL;
}
}
while(create_directory(c->settings->output_dir_path, slug) != 0);
// Slug generation failed, we have to finish here
if (!slug) {
print_error("Couldn't generate a slug!");
print_separator();
close(c->socket);
// Cleanup
free(c);
pthread_exit(NULL);
return NULL;
}
// Save to file failed, we have to finish here
if ( save_to_file(c->settings, buffer, slug) != 0 ) {
print_error("Couldn't save a file!");
print_separator();
close(c->socket);
// Cleanup
free(c);
free(slug);
pthread_exit(NULL);
return NULL;
}
// Write a response to the user
{
// Create an url (additional byte for slash and one for new line)
const size_t len = strlen(c->settings->domain) + strlen(slug) + 3;
char url[len];
snprintf(url, len, "%s%s%s%s", c->settings->domain, "/", slug, "\n");
// Send the response
write(c->socket, url, len);
}
print_status("Received %d bytes, saved to: %s.", r, slug);
print_separator();
// Log connection
// TODO: log unsuccessful and rejected connections
log_entry(c->settings, ip, hostname, slug);
// Close the connection
close(c->socket);
// Perform cleanup of values used in this thread
free(slug);
free(c);
pthread_exit(NULL);
return NULL;
}
static void generate_slug(char **output, uint8_t length, uint8_t extra_length) {
// Realloc buffer for slug when we want it to be bigger
// This happens in case when directory with this name already
// exists. To save time, we don't generate new slugs until
// we spot an available one. We add another letter instead.
if (extra_length > 0) {
free(*output);
}
// Create a buffer for slug with extra_length if any
*output = calloc(length + 1 + extra_length, sizeof(char));
if (*output == NULL) {
return;
}
// Take n-th symbol from symbol table and use it for slug generation
for (int i = 0; i < length + extra_length; i++) {
int n = rand_r(&seed) % strlen(Fiche_Symbols);
*(output[0] + sizeof(char) * i) = Fiche_Symbols[n];
}
}
static int create_directory(char *output_dir, char *slug) {
if (!slug) {
return -1;
}
// Additional byte is for the slash
size_t len = strlen(output_dir) + strlen(slug) + 2;
// Generate a path
char *path = malloc(len);
if (!path) {
return -1;
}
snprintf(path, len, "%s%s%s", output_dir, "/", slug);
// Create output directory, just in case
mkdir(output_dir, S_IRWXU | S_IRGRP | S_IROTH | S_IXOTH | S_IXGRP);
// Create slug directory
const int r = mkdir(
path,
S_IRWXU | S_IRGRP | S_IROTH | S_IXOTH | S_IXGRP
);
free(path);
return r;
}
static int save_to_file(const Fiche_Settings *s, uint8_t *data, char *slug) {
char *file_name = "index.txt";
// Additional 2 bytes are for 2 slashes
size_t len = strlen(s->output_dir_path) + strlen(slug) + strlen(file_name) + 3;
// Generate a path
char *path = malloc(len);
if (!path) {
return -1;
}
snprintf(path, len, "%s%s%s%s%s", s->output_dir_path, "/", slug, "/", file_name);
// Attempt file saving
FILE *f = fopen(path, "w");
if (!f) {
free(path);
return -1;
}
// Null-terminate buffer if not null terminated already
data[s->buffer_len - 1] = 0;
if ( fprintf(f, "%s", data) < 0 ) {
fclose(f);
free(path);
return -1;
}
fclose(f);
free(path);
return 0;
}