/* tinyproxy - A fast light-weight HTTP proxy * Copyright (C) 2003 Steven Young * * 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 /* * 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 headers[] = "HTTP/1.0 %d %s\r\n" "Server: %s/%s\r\n" "Content-Type: text/html\r\n" "%s" "Connection: close\r\n" "\r\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 = code == 407 ? p_auth_str : (code == 401 ? w_auth_str : ""); return (write_message (connptr->client_fd, headers, code, message, PACKAGE, VERSION, add)); } /* * 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 = "\n" "\n" "\n" "%d %s\n" "\n" "

%s

\n" "

%s

\n" "
\n" "

Generated by %s version %s.

\n" "\n" "\n"; send_http_headers (connptr, connptr->error_number, connptr->error_string); error_file = get_html_file (connptr->error_number); if (!(infile = fopen (error_file, "r"))) { char *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)); }