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/* Copyright (C) 2018, Project Pluto
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301, USA. */
#include <stdio.h>
#include <string.h>
#include "cgi_func.h"
/* Server-based versions of Find_Orb, sat_id, and astcheck (see
'fo_serve.cpp', 'sat_id2.cpp', cgicheck.cpp' respectively) all use
get_multipart_form_data( ) to parse CGI data. I use multipart for
these because those services require the option of file uploads.
The server-based code to list GNSS (navigation) satellites,
or satellite elements for a specific date, however, can (and do)
use enctype="application/x-www-form-urlencoded". This is a little
simpler and makes it easy for people to construct URLs to access
particular bits.
All of my server-based code uses avoid_runaway_process() to ensure that
if something went wrong and the code got hung up, it would abort after a
decent length of time and give an error message. (Which really should be
different for each program; at present, you get the Find_Orb message.)
*/
#if defined( __linux) || defined( __unix__) || defined( __APPLE__)
#include <sys/time.h> /* these allow resource limiting */
#include <sys/resource.h>
#include <unistd.h>
#include <stdlib.h>
#include <signal.h>
static const char *email_address_mangled_for_no_spam =
"p‮ôç.ötulpťcéjôřp@otúl‬m";
/* pluto at projectpluto address with diacritical marks and bidi */
/* text... should baffle all but the most devoted spammers. Put */
/* your mangled address here. */
static void sighandler( int signum, siginfo_t *info, void *unused_ucontext)
__attribute__ ((noreturn));
static void sighandler( int signum, siginfo_t *info, void *unused_ucontext)
{
if( signum == SIGXCPU)
{
printf( "\n\n<h1> Ran out of time </h1>\n");
printf( "<p> Find_Orb was unable to determine an orbit for these\n");
printf( "observations. That may just be because the problem exceeded\n");
printf( "the capabilities of this server; to avoid runaway processes,\n");
printf( "there's an intentional fifteen-second cap on getting a solution.\n");
printf( "<p> You should probably try again with a shorter\n");
printf( "arc, or else use the 'native' Windows or Linux or OS/X\n");
printf( "flavor of Find_Orb.\n");
}
else
{
printf( "\n\n<h1> Unknown signal </h1>\n");
printf( " <p> Got signal %d from process %ld.\n", signum,
(unsigned long)info->si_pid);
printf( "I'm still learning a bit about these signals. Please\n");
printf( "copy/paste this message and e-mail it to\n");
printf( "%s\n", email_address_mangled_for_no_spam);
}
exit( 0);
}
void avoid_runaway_process( const int max_time_to_run)
{
struct rlimit r;
struct sigaction act;
r.rlim_cur = max_time_to_run;
r.rlim_max = max_time_to_run + 5;
setrlimit( RLIMIT_CPU, &r);
memset(&act, 0, sizeof(act));
act.sa_sigaction = sighandler;
act.sa_flags = SA_SIGINFO;
sigaction(SIGXCPU, &act, NULL);
}
#else
/* In Win32, you can't do this sort of process limiting */
/* (I think), so we just have a dummy function. */
void avoid_runaway_process( const int max_time_to_run)
{
}
#endif /* _WIN32 */
static int get_urlencoded_piece( const char **idata,
char *buff, size_t max_buff, const char end_char)
{
int c;
const char *tptr = *idata;
max_buff--;
while( (c = *tptr++) > 13 && max_buff-- && c != end_char)
{
if( c == '+')
c = ' ';
else if( c == '%')
{
int i, c1;
c = 0;
for( i = 0; i < 2; i++)
{
c *= 16;
c1 = *tptr++;
if( c1 >= '0' && c1 <= '9')
c += c1 - '0';
else if( c1 >= 'A' && c1 <= 'F')
c += c1 - 'A' + 10;
else /* wasn't an hex digit: */
return( -1); /* not supposed to happen */
}
}
*buff++ = (char)c;
}
*buff = '\0';
*idata = tptr;
return( c);
}
int get_urlencoded_form_data( const char **idata,
char *field, const size_t max_field,
char *buff, const size_t max_buff)
{
int c;
if( get_urlencoded_piece( idata, field, max_field, '=') != '=')
return( -1);
c = get_urlencoded_piece( idata, buff, max_buff, '&');
return( c != '&' && c > 13);
}
int get_multipart_form_data( const char *boundary, char *field,
char *buff, char *filename, const size_t max_len)
{
char *tptr, *endptr;
size_t bytes_read = 0, blen = 0;
if( filename)
*filename = '\0';
while( boundary[blen] >= ' ')
blen++;
if( fgets( buff, (int)max_len, stdin)
&& (tptr = strstr( buff, "name=\"")) != NULL
&& (endptr = strchr( tptr + 6, '"')) != NULL)
{
char *filename_ptr = strstr( tptr, "filename=\"");
*endptr = '\0';
strcpy( field, tptr + 6);
if( filename && filename_ptr
&& (endptr = strchr( filename_ptr + 10, '"')) != NULL)
{
*endptr = '\0';
strcpy( filename, filename_ptr + 10);
}
if( fgets( buff, (int)max_len, stdin))
{
while( bytes_read < max_len - 1 &&
fgets( buff + bytes_read, (int)( max_len - bytes_read), stdin)
&& memcmp( buff + bytes_read, boundary, blen))
bytes_read += strlen( buff + bytes_read);
}
}
else
return( -1);
while( bytes_read && (buff[bytes_read - 1] == 10
|| buff[bytes_read - 1] == 13))
bytes_read--;
buff[bytes_read] = '\0';
return( (int)bytes_read);
}
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