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tinyproxy/src/html-error.c

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/* tinyproxy - A fast light-weight HTTP proxy
* Copyright (C) 2003 Steven Young <sdyoung@miranda.org>
*
* 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.
*/
/* This file contains source code for the handling and display of
* HTML error pages with variable substitution.
*/
#include "common.h"
#include "main.h"
#include "buffer.h"
#include "conns.h"
#include "heap.h"
#include "html-error.h"
#include "network.h"
#include "utils.h"
#include "conf.h"
#include "log.h"
#include <regex.h>
/*
* Add an error number -> filename mapping to the errorpages list.
*/
#define ERRORNUM_BUFSIZE 8 /* this is more than required */
#define ERRPAGES_BUCKETCOUNT 16
int add_new_errorpage (struct config_s *conf, char *filepath,
unsigned int errornum)
{
char errornbuf[ERRORNUM_BUFSIZE], *k;
if (!conf->errorpages)
conf->errorpages = htab_create (ERRPAGES_BUCKETCOUNT);
if (!conf->errorpages)
return (-1);
snprintf (errornbuf, ERRORNUM_BUFSIZE, "%u", errornum);
k = safestrdup(errornbuf);
if (!k) return -1;
if (!htab_insert (conf->errorpages, k, HTV_P(filepath))) {
safefree(k);
return (-1);
}
return (0);
}
/*
* Get the file appropriate for a given error.
*/
static char *get_html_file (unsigned int errornum)
{
char errornbuf[ERRORNUM_BUFSIZE];
htab_value *hv;
assert (errornum >= 100 && errornum < 1000);
if (!config->errorpages)
return (config->errorpage_undef);
snprintf (errornbuf, ERRORNUM_BUFSIZE, "%u", errornum);
hv = htab_find (config->errorpages, errornbuf);
if (!hv) return (config->errorpage_undef);
return hv->p;
}
static char *lookup_variable (struct htab *map, const char *varname) {
htab_value *v;
v = htab_find(map, varname);
return v ? v->p : 0;
}
static void varsubst_sendline(struct conn_s *connptr, regex_t *re, char *p) {
int fd = connptr->client_fd;
while(*p) {
regmatch_t match;
char varname[32+1], *varval;
size_t l;
int st = regexec(re, p, 1, &match, 0);
if(st == 0) {
if(match.rm_so > 0) safe_write(fd, p, match.rm_so);
l = match.rm_eo - match.rm_so;
assert(l>2 && l-2 < sizeof(varname));
p += match.rm_so;
memcpy(varname, p+1, l-2);
varname[l-2] = 0;
varval = lookup_variable(connptr->error_variables, varname);
if(varval) write_message(fd, "%s", varval);
else if(varval && !*varval) write_message(fd, "(unknown)");
else safe_write(fd, p, l);
p += l;
} else {
write_message(fd, "%s", p);
break;
}
}
}
/*
* Send an already-opened file to the client with variable substitution.
*/
int
send_html_file (FILE *infile, struct conn_s *connptr)
{
regex_t re;
char *inbuf = safemalloc (4096);
(void) regcomp(&re, "{[a-z]\\{1,32\\}}", 0);
while (fgets (inbuf, 4096, infile)) {
varsubst_sendline(connptr, &re, inbuf);
}
regfree (&re);
safefree (inbuf);
return 1;
}
int send_http_headers (
struct conn_s *connptr, int code,
const char *message, const char *extra)
{
const char headers[] =
"HTTP/1.%u %d %s\r\n"
"Server: %s/%s\r\n"
"Content-Type: text/html\r\n"
"%s"
"Connection: close\r\n" "\r\n";
return (write_message (connptr->client_fd, headers,
connptr->protocol.major != 1 ? 0 : connptr->protocol.minor,
code, message, PACKAGE, VERSION,
extra));
}
/*
* Display an error to the client.
*/
int send_http_error_message (struct conn_s *connptr)
{
char *error_file;
FILE *infile;
int ret;
const char *fallback_error =
"<?xml version=\"1.0\" encoding=\"UTF-8\" ?>\n"
"<!DOCTYPE html PUBLIC \"-//W3C//DTD XHTML 1.1//EN\" "
"\"http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd\">\n"
"<html>\n"
"<head><title>%d %s</title></head>\n"
"<body>\n"
"<h1>%s</h1>\n"
"<p>%s</p>\n"
"<hr />\n"
"<p><em>Generated by %s version %s.</em></p>\n" "</body>\n"
"</html>\n";
const char p_auth_str[] =
"Proxy-Authenticate: Basic realm=\""
PACKAGE_NAME "\"\r\n";
const char w_auth_str[] =
"WWW-Authenticate: Basic realm=\""
PACKAGE_NAME "\"\r\n";
/* according to rfc7235, the 407 error must be accompanied by
a Proxy-Authenticate header field. */
const char *add = connptr->error_number == 407 ? p_auth_str :
(connptr->error_number == 401 ? w_auth_str : "");
send_http_headers (connptr, connptr->error_number,
connptr->error_string, add);
error_file = get_html_file (connptr->error_number);
if (!error_file || !(infile = fopen (error_file, "r"))) {
char *detail;
if (error_file) log_message (LOG_ERR,
"Error opening error file '%s' (%s)",
error_file, strerror (errno));
detail = lookup_variable (connptr->error_variables, "detail");
return (write_message (connptr->client_fd, fallback_error,
connptr->error_number,
connptr->error_string,
connptr->error_string,
detail, PACKAGE, VERSION));
}
ret = send_html_file (infile, connptr);
fclose (infile);
return (ret);
}
/*
* Add a key -> value mapping for HTML file substitution.
*/
#define ERRVAR_BUCKETCOUNT 16
int
add_error_variable (struct conn_s *connptr, const char *key, const char *val)
{
char *k, *v;
if (!connptr->error_variables)
if (!
(connptr->error_variables =
htab_create (ERRVAR_BUCKETCOUNT)))
return (-1);
k = safestrdup(key);
v = safestrdup(val);
if (!v || !k) goto oom;
if(htab_insert (connptr->error_variables, k, HTV_P(v)))
return 1;
oom:;
safefree(k);
safefree(v);
return -1;
}
#define ADD_VAR_RET(x, y) \
do { \
if (y == NULL) \
break; \
if (add_error_variable(connptr, x, y) < 0) \
return -1; \
} while (0)
/*
* Set some standard variables used by all HTML pages
*/
int add_standard_vars (struct conn_s *connptr)
{
char errnobuf[16];
char timebuf[30];
time_t global_time;
struct tm tm_buf;
snprintf (errnobuf, sizeof errnobuf, "%d", connptr->error_number);
ADD_VAR_RET ("errno", errnobuf);
ADD_VAR_RET ("cause", connptr->error_string);
ADD_VAR_RET ("request", connptr->request_line);
ADD_VAR_RET ("clientip", connptr->client_ip_addr);
/* The following value parts are all non-NULL and will
* trigger warnings in ADD_VAR_RET(), so we use
* add_error_variable() directly.
*/
global_time = time (NULL);
strftime (timebuf, sizeof (timebuf), "%a, %d %b %Y %H:%M:%S GMT",
gmtime_r (&global_time, &tm_buf));
add_error_variable (connptr, "date", timebuf);
add_error_variable (connptr, "website",
"https://tinyproxy.github.io/");
add_error_variable (connptr, "version", VERSION);
add_error_variable (connptr, "package", PACKAGE);
return (0);
}
/*
* Add the error information to the conn structure.
*/
int
indicate_http_error (struct conn_s *connptr, int number,
const char *message, ...)
{
va_list ap;
char *key, *val;
va_start (ap, message);
while ((key = va_arg (ap, char *))) {
val = va_arg (ap, char *);
if (add_error_variable (connptr, key, val) == -1) {
va_end (ap);
return (-1);
}
}
connptr->error_number = number;
connptr->error_string = safestrdup (message);
va_end (ap);
return (add_standard_vars (connptr));
}
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