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
@@ -3,255 +3,271 @@
  * Copyright (C) 2006 Lars Hjemli
  *
  * Licensed under GNU General Public License v2
  *   (see COPYING for full license text)
  */
 
 #include <unistd.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <stdarg.h>
 #include <string.h>
 #include <errno.h>
 
 int htmlfd = STDOUT_FILENO;
 
 char *fmt(const char *format, ...)
 {
         static char buf[8][1024];
         static int bufidx;
         int len;
         va_list args;
 
         bufidx++;
         bufidx &= 7;
 
         va_start(args, format);
         len = vsnprintf(buf[bufidx], sizeof(buf[bufidx]), format, args);
         va_end(args);
         if (len>sizeof(buf[bufidx])) {
                 fprintf(stderr, "[html.c] string truncated: %s\n", format);
                 exit(1);
         }
         return buf[bufidx];
 }
 
 void html_raw(const char *data, size_t size)
 {
         write(htmlfd, data, size);
 }
 
 void html(const char *txt)
 {
         write(htmlfd, txt, strlen(txt));
 }
 
 void htmlf(const char *format, ...)
 {
         static char buf[65536];
         va_list args;
 
         va_start(args, format);
         vsnprintf(buf, sizeof(buf), format, args);
         va_end(args);
         html(buf);
 }
 
 void html_status(int code, const char *msg, int more_headers)
 {
         htmlf("Status: %d %s\n", code, msg);
         if (!more_headers)
                 html("\n");
 }
 
 void html_txt(char *txt)
 {
         char *t = txt;
         while(t && *t){
                 int c = *t;
                 if (c=='<' || c=='>' || c=='&') {
                         write(htmlfd, txt, t - txt);
                         if (c=='>')
                                 html("&gt;");
                         else if (c=='<')
                                 html("&lt;");
                         else if (c=='&')
                                 html("&amp;");
                         txt = t+1;
                 }
                 t++;
         }
         if (t!=txt)
                 html(txt);
 }
 
 void html_ntxt(int len, char *txt)
 {
         char *t = txt;
         while(t && *t && len--){
                 int c = *t;
                 if (c=='<' || c=='>' || c=='&') {
                         write(htmlfd, txt, t - txt);
                         if (c=='>')
                                 html("&gt;");
                         else if (c=='<')
                                 html("&lt;");
                         else if (c=='&')
                                 html("&amp;");
                         txt = t+1;
                 }
                 t++;
         }
         if (t!=txt)
                 write(htmlfd, txt, t - txt);
         if (len<0)
                 html("...");
 }
 
 void html_attr(char *txt)
 {
         char *t = txt;
         while(t && *t){
                 int c = *t;
                 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'");
         html(">");
         html_txt(text);
         html("</option>\n");
 }
 
 void html_link_open(char *url, char *title, char *class)
 {
         html("<a href='");
         html_attr(url);
         if (title) {
                 html("' title='");
                 html_attr(title);
         }
         if (class) {
                 html("' class='");
                 html_attr(class);
         }
         html("'>");
 }
 
 void html_link_close(void)
 {
         html("</a>");
 }
 
 void html_fileperm(unsigned short mode)
 {
         htmlf("%c%c%c", (mode & 4 ? 'r' : '-'),
               (mode & 2 ? 'w' : '-'), (mode & 1 ? 'x' : '-'));
 }
 
 int html_include(const char *filename)
 {
         FILE *f;
         char buf[4096];
         size_t len;
 
         if (!(f = fopen(filename, "r"))) {
                 fprintf(stderr, "[cgit] Failed to include file %s: %s (%d).\n",
                         filename, strerror(errno), errno);
                 return -1;
         }
         while((len = fread(buf, 1, 4096, f)) > 0)
                 write(htmlfd, buf, len);
         fclose(f);
         return 0;
 }
 
 int hextoint(char c)
 {
         if (c >= 'a' && c <= 'f')
                 return 10 + c - 'a';
         else if (c >= 'A' && c <= 'F')
                 return 10 + c - 'A';
         else if (c >= '0' && c <= '9')
                 return c - '0';
         else
                 return -1;
 }
 
 char *convert_query_hexchar(char *txt)
 {
         int d1, d2;
         if (strlen(txt) < 3) {
                 *txt = '\0';
                 return txt-1;
         }
         d1 = hextoint(*(txt+1));
         d2 = hextoint(*(txt+2));
         if (d1<0 || d2<0) {
                 strcpy(txt, txt+3);
                 return txt-1;
         } else {
                 *txt = d1 * 16 + d2;
                 strcpy(txt+1, txt+3);
                 return txt;
         }
 }
 
 int http_parse_querystring(char *txt, void (*fn)(const char *name, const char *value))
 {
         char *t, *value = NULL, c;
 
         if (!txt)
                 return 0;
 
         t = txt = strdup(txt);
         if (t == NULL) {
                 printf("Out of memory\n");
                 exit(1);
         }
         while((c=*t) != '\0') {
                 if (c=='=') {
                         *t = '\0';
                         value = t+1;
                 } else if (c=='+') {
                         *t = ' ';
                 } else if (c=='%') {
                         t = convert_query_hexchar(t);
                 } else if (c=='&') {
                         *t = '\0';
                         (*fn)(txt, value);
                         txt = t+1;
                         value = NULL;
                 }
                 t++;
         }
         if (t!=txt)
                 (*fn)(txt, value);
         return 0;
 }
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 */