html.c: add html_url_arg

This function can be used to properly escape querystring parameter values.

Signed-off-by: Lars Hjemli <hjemli@gmail.com>

2 files changed, 17 insertions, 0 deletions

diff --git a/html.c b/html.c
index 36e9a2f..167127f 100644
--- a/html.c
+++ b/html.c
@@ -115,32 +115,48 @@ void html_attr(char *txt)
 		if (c=='<' || c=='>' || c=='\'') {
 			write(htmlfd, txt, t - txt);
 			if (c=='>')
 				html("&gt;");
 			else if (c=='<')
 				html("&lt;");
 			else if (c=='\'')
 				html("&quote;");
 			txt = t+1;
 		}
 		t++;
 	}
 	if (t!=txt)
 		html(txt);
 }
 
+void html_url_arg(char *txt)
+{
+	char *t = txt;
+	while(t && *t){
+		int c = *t;
+		if (c=='"' || c=='#' || c=='%' || c=='&' || c=='\'' || c=='+' || c=='?') {
+			write(htmlfd, txt, t - txt);
+			write(htmlfd, fmt("%%%2x", c), 3);
+			txt = t+1;
+		}
+		t++;
+	}
+	if (t!=txt)
+		html(txt);
+}
+
 void html_hidden(char *name, char *value)
 {
 	html("<input type='hidden' name='");
 	html_attr(name);
 	html("' value='");
 	html_attr(value);
 	html("'/>");
 }
 
 void html_option(char *value, char *text, char *selected_value)
 {
 	html("<option value='");
 	html_attr(value);
 	html("'");
 	if (selected_value && !strcmp(selected_value, value))
 		html(" selected='selected'");
diff --git a/html.h b/html.h
index 3c32935..038cf60 100644
--- a/html.h
+++ b/html.h
@@ -1,22 +1,23 @@
 #ifndef HTML_H
 #define HTML_H
 
 extern int htmlfd;
 
 extern void html_raw(const char *txt, size_t size);
 extern void html(const char *txt);
 extern void htmlf(const char *format,...);
 extern void html_status(int code, const char *msg, int more_headers);
 extern void html_txt(char *txt);
 extern void html_ntxt(int len, char *txt);
 extern void html_attr(char *txt);
+extern void html_url_arg(char *txt);
 extern void html_hidden(char *name, char *value);
 extern void html_option(char *value, char *text, char *selected_value);
 extern void html_link_open(char *url, char *title, char *class);
 extern void html_link_close(void);
 extern void html_fileperm(unsigned short mode);
 extern int html_include(const char *filename);
 
 extern int http_parse_querystring(char *txt, void (*fn)(const char *name, const char *value));
 
 #endif /* HTML_H */