443 lines
13 KiB
C
443 lines
13 KiB
C
/*
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* feuille.c
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* Main source file.
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*
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* Copyright (c) 2022
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* Tom MTT. <tom@heimdall.pm>
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*
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* This file is licensed under the 3-Clause BSD License.
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* You should have received a copy of the 3-Clause BSD License
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* along with this program. If not, see
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* <https://basedwa.re/tmtt/feuille/src/branch/main/LICENSE>.
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*/
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#define _DEFAULT_SOURCE
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#include "feuille.h"
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#include <errno.h> /* for errno, ERANGE, EAGAIN, EFBIG, ENOENT */
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#include <grp.h> /* for initgroups */
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#include <limits.h> /* for USHRT_MAX, ULONG_MAX, CHAR_MAX, PATH_MAX, UCHA... */
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#include <locale.h> /* for NULL, setlocale, LC_ALL */
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#include <pwd.h> /* for getpwnam, passwd */
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#include <signal.h> /* for signal, SIGPIPE, SIG_IGN */
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#include <stdio.h> /* for puts */
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#include <stdlib.h> /* for strtoll, free, realpath, srand */
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#include <string.h> /* for strerror, strlen */
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#include <sys/stat.h> /* for mkdir */
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#include <sys/wait.h> /* for wait */
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#include <syslog.h> /* for syslog, openlog, LOG_WARNING, LOG_NDELAY, LOG_... */
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#include <time.h> /* for time */
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#include <unistd.h> /* for getuid, access, chdir, chown, chroot, close */
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#include "arg.h" /* for EARGF, ARGBEGIN, ARGEND */
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#include "bin.h" /* for create_url, generate_id, write_paste */
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#include "server.h" /* for send_response, accept_connection, close_connec... */
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#include "util.h" /* for verbose, die, error */
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char *argv0;
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/* default settings */
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Settings settings = {
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.address = "0.0.0.0",
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.url = "http://localhost",
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.output = "/var/www/feuille",
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.user = "www",
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.id_length = 4,
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.worker_count = 4,
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.port = 9999,
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.timeout = 2,
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.max_size = 1048576, /* = 1MiB = 1024 * 1024 */
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.buffer_size = 131072, /* = 128KiB = 1024 * 128 */
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.verbose = 0,
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.foreground = 0
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};
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/* functions declarations */
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static void usage(int exit_code);
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static void version(void);
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static void accept_loop(int);
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/**
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* Display feuille's basic usage.
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* exit_code: the exit code to be used.
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*/
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void usage(int exit_code)
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{
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die(exit_code, "usage: %s [-abfhiopstuUvVw]\n"
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" see `man feuille'.\n", argv0);
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}
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/**
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* Display feuille's author(s) and version.
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*/
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void version(void)
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{
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die(0, "%s %s by Tom MTT. <tom@heimdall.pm>\n", argv0, VERSION);
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}
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/**
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* Feuille's accept loop.
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* server: the server socket.
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*/
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void accept_loop(int server)
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{
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/* get current process' pid */
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int pid = getpid();
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/* feed the random number god */
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srand(time(0) + pid);
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/* accept loop */
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int connection;
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while ((connection = accept_connection(server))) {
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verbose(1, "--- new incoming connection. connection ID: %d:%d ---", pid, time(0));
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unsigned long paste_size = 0;
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char *paste = NULL;
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char *id = NULL;
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char *url = NULL;
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/* read paste from connection */
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verbose(1, "reading paste from incoming connection...");
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if ((paste_size = read_paste(connection, &paste)) != 0) {
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/* generate random ID */
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verbose(1, "done.");
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verbose(2, "generating a random ID...");
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if ((id = generate_id(settings.id_length)) != NULL) {
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/* write paste to disk */
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verbose(2, "done.");
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verbose(1, "writing paste `%s' to disk...", id);
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if (write_paste(paste, paste_size, id) == 0) {
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/* create URL */
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verbose(1, "done.");
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verbose(2, "making the right URL...");
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if ((url = create_url(id)) != NULL) {
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/* send URL */
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verbose(2, "done.", url);
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verbose(1, "sending the link to the client...");
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send_response(connection, url);
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verbose(1, "All done.");
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free(url);
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} else {
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error("error while making a valid URL.");
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send_response(connection, "Could not create your paste URL.\nPlease try again later.\n");
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}
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} else {
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error("error while writing paste to disk.");
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send_response(connection, "Could not write your paste to disk.\nPlease try again later.\n");
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}
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free(id);
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} else {
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error("error while generating a random ID.");
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send_response(connection, "Could not generate your paste ID.\nPlease try again later.\n");
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}
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free(paste);
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} else {
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if (errno == EFBIG)
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send_response(connection, "Paste too big.\n");
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if (errno == ENOENT)
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send_response(connection, "Empty paste.\n");
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if (errno == EAGAIN)
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send_response(connection, "Timeout'd.\n");
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error("error %d while reading paste from incoming connection.", errno);
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}
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/* close connection */
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close_connection(connection);
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}
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}
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/**
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* Feuille's main function.
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* argc: the argument count.
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* argv: the argument values.
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* -> an exit code.
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*/
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int main(int argc, char *argv[])
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{
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/* locale */
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setlocale(LC_ALL, "");
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/* syslog */
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openlog("feuille", LOG_NDELAY | LOG_PERROR, LOG_USER);
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/* ignore signals that could kill feuille */
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signal(SIGPIPE, SIG_IGN); /* when send(2) or write(2) fails */
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/* settings */
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long long tmp;
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/* set number of workers */
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if ((tmp = sysconf(_SC_NPROCESSORS_ONLN)) > settings.worker_count && tmp <= USHRT_MAX)
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settings.worker_count = tmp;
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ARGBEGIN {
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case 'a':
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/* set address */
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settings.address = EARGF(usage(1));
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break;
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case 'b':
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/* set buffer size */
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tmp = strtoll(EARGF(usage(1)), NULL, 10);
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if (tmp <= 0 || tmp > ULONG_MAX || errno == ERANGE)
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die(ERANGE, "invalid buffer size.\n"
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"see `man feuille'.\n");
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settings.buffer_size = tmp;
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break;
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case 'f':
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/* enable foreground execution */
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settings.foreground = 1;
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break;
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case 'h':
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/* get help */
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usage(0);
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break;
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case 'i':
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/* set id length */
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tmp = strtoll(EARGF(usage(1)), NULL, 10) + 1;
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if (tmp - 1 < 4 || tmp > UCHAR_MAX || errno == ERANGE)
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die(ERANGE, "invalid id length.\n"
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"see `man feuille'.\n");
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settings.id_length = tmp;
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break;
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case 'o':
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/* set output folder */
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settings.output = EARGF(usage(1));
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break;
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case 'p':
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/* set port */
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tmp = strtoll(EARGF(usage(1)), NULL, 10);
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if (tmp <= 0 || tmp > USHRT_MAX || errno == ERANGE)
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die(ERANGE, "invalid port.\n"
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"see `man feuille'.\n");
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settings.port = tmp;
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break;
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case 's':
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/* set max size */
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tmp = strtoll(EARGF(usage(1)), NULL, 10);
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if (tmp <= 0 || tmp > ULONG_MAX || errno == ERANGE)
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die(ERANGE, "invalid maximum size.\n"
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"see `man feuille'.\n");
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settings.max_size = tmp;
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break;
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case 't':
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/* set timeout */
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tmp = strtoll(EARGF(usage(1)), NULL, 10);
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if (tmp < 0 || tmp > UINT_MAX || errno == ERANGE)
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die(ERANGE, "invalid timeout.\n"
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"see `man feuille'.\n");
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settings.timeout = tmp;
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break;
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case 'u':
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/* set user */
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settings.user = EARGF(usage(1));
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break;
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case 'U':
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/* set url */
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settings.url = EARGF(usage(1));
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if (settings.url[strlen(settings.url) - 1] == '/')
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settings.url[strlen(settings.url) - 1] = 0;
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break;
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case 'v':
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/* enable verbose mode */
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if (settings.verbose == CHAR_MAX)
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die(ERANGE, "why? just why?\n"
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"please see `man feuille' and go touch grass.\n");
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settings.verbose++;
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break;
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case 'V':
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/* get version */
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version();
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break;
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case 'w':
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/* set worker count */
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tmp = strtoll(EARGF(usage(1)), NULL, 10);
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if (tmp <= 0 || tmp > USHRT_MAX || errno == ERANGE)
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die(ERANGE, "invalid worker count.\n"
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"see `man feuille'.\n");
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settings.worker_count = tmp;
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break;
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default:
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usage(1);
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} ARGEND;
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if (argc != 0)
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usage(1);
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/* output folder checks */
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char path[PATH_MAX];
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if (mkdir(settings.output, 0755) == 0)
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verbose(2, "creating folder `%s'...", settings.output);
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if (realpath(settings.output, path) == NULL)
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die(errno, "could not get real path of directory `%s': %s.\n", settings.output, strerror(errno));
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if (access(path, W_OK) != 0)
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die(errno, "cannot write to directory `%s': %s.\n", path, strerror(errno));
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chdir(path);
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/* user checks */
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int uid = 0, gid = 0;
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if (getuid() == 0) {
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if (strlen(settings.user) == 0)
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settings.user = "nobody";
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verbose(2, "getting uid and gid of user `%s'...", settings.user);
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struct passwd *user;
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if ((user = getpwnam(settings.user)) == NULL)
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die(1, "user `%s' doesn't exist.\n", settings.user);
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uid = user->pw_uid;
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gid = user->pw_gid;
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} else {
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puts("");
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syslog(LOG_WARNING, "running as non-root user.");
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syslog(LOG_WARNING, "`chroot' and user switching have been disabled.");
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puts("");
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}
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/* server socket creation (before dropping root permissions) */
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verbose(1, "initializing server socket...");
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int server;
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if ((server = initialize_server()) == -1)
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die(errno, "failed to initialize server socket: %f.\n", strerror(errno));
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/* make feuille run in the background */
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if (!settings.foreground) {
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verbose(1, "making feuille run in the background...");
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verbose(2, "closing input / output file descriptors...");
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daemon(1, 0);
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}
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/* chroot and drop root permissions */
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if (getuid() == 0) {
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verbose(2, "setting owner of `%s' to `%s'...", path, settings.user);
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chown(path, uid, gid);
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/* chroot */
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verbose(2, "chroot'ing into `%s'...", path);
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chroot(path);
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/* privileges drop */
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verbose(2, "dropping root privileges...");
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/* switching groups */
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if (setgid(gid) != 0 || getgid() != gid)
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die(1, "could not switch to group for user `%s'.\n", settings.user);
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if (initgroups(settings.user, gid) != 0)
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die(1, "could not initialize other groups for user `%s'.\n", settings.user);
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/* switching user */
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if (setuid(uid) != 0 || getuid() != uid)
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die(1, "could not switch to user `%s'.\n", settings.user);
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}
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#ifdef __OpenBSD__
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/* OpenBSD-only security measures */
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pledge("proc stdio rpath wpath cpath inet", "stdio rpath wpath cpath inet");
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#endif
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#ifdef DEBUG
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/* do not create a thread pool if in DEBUG mode */
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verbose(1, "running in DEBUG mode, won't create a worker pool.");
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accept_loop(server);
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#else
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/* create a thread pool for incoming connections */
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verbose(1, "initializing worker pool...");
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int pid;
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for (int i = 1; i <= settings.worker_count; i++) {
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if ((pid = fork()) == 0) {
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verbose(2, " worker n. %d...", i);
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accept_loop(server);
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} else if (pid < 0)
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die(errno, "could not initialize worker n. %d: %s.\n", i, strerror(errno));
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}
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sleep(1);
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verbose(1, "all workers have been initialized.");
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verbose(1, "beginning to accept incoming connections.");
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/* fork again if a child dies */
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int status;
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int child_pid;
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while ((child_pid = wait(&status)) > 0) {
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error("child %d unexpectedly died with exit code %d.", child_pid, WEXITSTATUS(status));
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/* do not fork if child was KILL'ed */
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if (WTERMSIG(status) == 9)
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continue;
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if ((pid = fork()) == 0) {
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accept_loop(server);
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} else if (pid < 0)
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error("could not fork killed child again: ", strerror(errno));
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}
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#endif
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close(server);
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return 0;
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}
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