# Steve Young's code to implement file based HTML error messages,

  rather than the hard coded string.

2 files changed, 262 insertions, 0 deletions

diff --git a/src/htmlerror.c b/src/htmlerror.c
new file mode 100644
index 0000000..aee92f5
--- /dev/null
+++ b/src/htmlerror.c
@@ -0,0 +1,242 @@
+/* $Id: htmlerror.c,v 1.1 2003-03-13 21:25:06 rjkaes Exp $
+ * 
+ * This file contains source code for the handling and display of
+ * HTML error pages with variable substitution.
+ */
+#include "tinyproxy.h"
+
+#include "common.h"
+#include "buffer.h"
+#include "conns.h"
+#include "heap.h"
+#include "htmlerror.h"
+#include "network.h"
+#include "utils.h"
+
+/* Add an error number -> filename mapping to the errorpages list. */
+int add_new_errorpage(char *filepath, unsigned int errornum) {
+	static int errorpage_count = 1;
+
+	/* First, add space for another pointer to the errorpages array. */
+	config.errorpages = saferealloc(config.errorpages, sizeof(struct error_pages_s *) * (errorpage_count + 1));
+	if(!config.errorpages)
+		return(-1);
+
+	/* Allocate space for an actual structure */
+	config.errorpages[errorpage_count - 1] = safemalloc(sizeof(struct error_pages_s));
+	if(!config.errorpages[errorpage_count - 1])
+		return(-1);
+
+	/* Set values for errorpage structure. */
+	config.errorpages[errorpage_count - 1]->errorpage_path = safestrdup(filepath);
+	if(!config.errorpages[errorpage_count - 1]->errorpage_path)
+		return(-1);
+
+	config.errorpages[errorpage_count - 1]->errorpage_errnum = errornum;
+
+	/* Set NULL to denote end of array */
+	config.errorpages[errorpage_count] = NULL;
+
+	errorpage_count++;
+	return(0);
+}
+
+/* Get the file appropriate for a given error. */
+char *get_html_file(int errornum) {
+	int i;
+
+	if(!config.errorpages) return(config.errorpage_undef);
+
+	for(i = 0; config.errorpages[i]; i++) {
+		if(config.errorpages[i]->errorpage_errnum == errornum)
+			return(config.errorpages[i]->errorpage_path);
+	}
+
+	return(config.errorpage_undef);
+}
+
+/* Look up the value for a variable. */
+char *lookup_variable(struct conn_s *connptr, char *varname) {
+	int i;
+
+	for(i = 0; i<connptr->error_variable_count; i++) {
+		if(!strcasecmp(connptr->error_variables[i]->error_key, varname))
+			return(connptr->error_variables[i]->error_val);
+	}
+
+	return(NULL);
+}
+
+#define HTML_BUFSIZE 4096
+
+/* Send an already-opened file to the client with
+ * variable substitution. */
+int send_html_file(FILE *infile, struct conn_s *connptr) {
+	char inbuf[HTML_BUFSIZE], *varstart = NULL, *p;
+	char *varval;
+	int in_variable = 0, writeret;
+
+	while(fgets(inbuf, HTML_BUFSIZE, infile) != NULL) {
+		for(p = inbuf; *p; p++) {
+			switch(*p) {
+				case '}':
+					if(in_variable) {
+						*p = '\0';
+						if(!(varval = lookup_variable(connptr, varstart)))
+							varval = "(unknown)";
+						writeret = write_message(connptr->client_fd, "%s",
+												 varval);
+						if(writeret) return(writeret);
+						in_variable = 0;
+						break;
+					}
+					/* If we are not in a variable, then 
+					 * we fallthrough.  the code for { will
+					 * not do anything if in_variable is set to
+					 * 0.  it will end up in the default
+					 * handler which will send the }. 
+					 */
+				case '{':
+					/* a {{ will print a single {.  If we are NOT
+					 * already in a { variable, then proceed with
+					 * setup.  If we ARE already in a { variable,
+					 * this code will fallthrough to the code that
+					 * just dumps a character to the client fd.
+					 */
+					 if(!in_variable) {
+					 	varstart = p+1;
+						in_variable++;
+					}
+				default:
+					if(!in_variable) {
+						writeret = write_message(connptr->client_fd, "%c", 
+												 *p);
+						if(writeret) return(writeret);
+					}
+		
+			}
+		}
+		in_variable = 0;
+	}
+	return(0);
+}
+
+int send_http_headers(struct conn_s *connptr, int code, char *message) {
+	char *headers = \
+		"HTTP/1.0 %d %s\r\n" \
+		"Server: %s/%s\r\n" \
+		"Content-Type: text/html\r\n" \
+		"Connection: close\r\n" \
+		"\r\n";
+
+	return(write_message(connptr->client_fd, headers,
+		   				 code, message,
+		   				 PACKAGE, VERSION));
+}
+
+/*
+ * Display an error to the client.
+ */
+int
+send_http_error_message(struct conn_s *connptr)
+{
+	char *error_file;
+	FILE *infile;
+	int ret;
+	char *fallback_error = \
+		"<html><head><title>%s</title></head>" \
+		"<body><blockquote><i>%s %s</i><br>" \
+		"The page you requested was unavailable. The error code is listed " \
+		"below. In addition, the HTML file which has been configured as the " \
+		"page to be displayed when an error of this type was unavailable, " \
+		"with the error code %d (%s).  Please contact your administrator." \
+		"<center>%s</center>" \
+		"</body></html>" \
+        "\r\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"))) 
+		return(write_message(connptr->client_fd, fallback_error,
+							 connptr->error_string,
+							 PACKAGE, VERSION,
+							 errno, strerror(errno),
+							 connptr->error_string));
+
+	ret = send_html_file(infile, connptr);
+	fclose(infile);
+	return(ret);
+}
+
+/* 
+ * Add a key -> value mapping for HTML file substitution.
+ */
+int 
+add_error_variable(struct conn_s *connptr, char *key, char *val) 
+{
+	connptr->error_variable_count++;
+
+	/* Add space for a new pointer to the error_variables structure. */
+	connptr->error_variables = saferealloc(connptr->error_variables, sizeof(struct error_variable_s *) * connptr->error_variable_count);
+	if(!connptr->error_variables)
+		return(-1);
+	
+	/* Allocate a new variable mapping structure. */
+	connptr->error_variables[connptr->error_variable_count - 1] = safemalloc(sizeof(struct error_variable_s));
+	if(!connptr->error_variables[connptr->error_variable_count - 1])
+		return(-1);
+
+	/* Set values for variable mapping. */
+	connptr->error_variables[connptr->error_variable_count - 1]->error_key = safestrdup(key);
+	connptr->error_variables[connptr->error_variable_count - 1]->error_val = safestrdup(val);
+	if((!connptr->error_variables[connptr->error_variable_count - 1]->error_key)
+	|| (!connptr->error_variables[connptr->error_variable_count - 1]->error_val))
+	   	return(-1);
+
+	return(0);
+}
+
+#define ADD_VAR_RET(x, y) if(y) { if(add_error_variable(connptr, x, y) == -1) return(-1); }
+
+/* Set some standard variables used by all HTML pages */
+int add_standard_vars(struct conn_s *connptr) {
+	char timebuf[30];
+	time_t global_time = time(NULL);
+
+	strftime(timebuf, sizeof(timebuf), "%a, %d %b %Y %H:%M:%S GMT",
+			 gmtime(&global_time));
+
+	ADD_VAR_RET("request", connptr->request_line);
+	ADD_VAR_RET("cause", connptr->error_string);
+	ADD_VAR_RET("clientip", connptr->client_ip_addr);
+	ADD_VAR_RET("clienthost", connptr->client_string_addr);
+	ADD_VAR_RET("version", VERSION);
+	ADD_VAR_RET("package", PACKAGE);
+	ADD_VAR_RET("date", timebuf);
+	return(0);
+}
+
+/*
+ * Add the error information to the conn structure.
+ */
+int
+indicate_http_error(struct conn_s* connptr, int number, 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)
+			return(-1);
+	}
+
+	connptr->error_number = number;
+	connptr->error_string = safestrdup(message);
+
+	return(add_standard_vars(connptr));
+}
+
diff --git a/src/htmlerror.h b/src/htmlerror.h
new file mode 100644
index 0000000..705faaa
--- /dev/null
+++ b/src/htmlerror.h
@@ -0,0 +1,20 @@
+/* $Id: htmlerror.h,v 1.1 2003-03-13 21:25:04 rjkaes Exp $
+ *
+ * Contains header declarations for the HTML error functions in htmlerror.c
+ */
+
+#ifndef TINYPROXY_HTMLERROR_H
+#define TINYPROXY_HTMLERROR_H
+
+/* Forward declaration */
+struct conn_s;
+
+extern int add_new_errorpage(char *filepath, unsigned int errornum);
+extern int send_http_error_message(struct conn_s *connptr);
+extern int indicate_http_error(struct conn_s *connptr, int number, char *message, ...);
+extern int add_error_variable(struct conn_s *connptr, char *key, char *val);
+extern int send_html_file(FILE *infile, struct conn_s *connptr);
+extern int send_http_headers(struct conn_s *connptr, int code, char *message);
+extern int add_standard_vars(struct conn_s *connptr);
+
+#endif /* !TINYPROXY_HTMLERROR_H */