From ac0b714dca311d163a937d0b4ca2b5e11c0b67c8 Mon Sep 17 00:00:00 2001
From: Fabian Keil <fk@fabiankeil.de>
Date: Sun, 6 Nov 2011 11:44:56 +0000
Subject: [PATCH] Add percent_encode_url()

Percent-encodes characters in URLs RFC 3986 doesn't permit.
---
 encode.c | 79 +++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 encode.h |  3 ++-
 2 files changed, 80 insertions(+), 2 deletions(-)

diff --git a/encode.c b/encode.c
index 5203a98c..7b5d3e8d 100644
--- a/encode.c
+++ b/encode.c
@@ -1,4 +1,4 @@
-const char encode_rcs[] = "$Id: encode.c,v 1.21 2011/11/06 11:42:14 fabiankeil Exp $";
+const char encode_rcs[] = "$Id: encode.c,v 1.22 2011/11/06 11:44:32 fabiankeil Exp $";
 /*********************************************************************
  *
  * File        :  $Source: /cvsroot/ijbswa/current/encode.c,v $
@@ -380,6 +380,83 @@ char *url_decode(const char * s)
 }
 
 
+/*********************************************************************
+ *
+ * Function    :  percent_encode_url
+ *
+ * Description :  Percent-encodes a string so it no longer contains
+ *                any characters that aren't valid in an URL according
+ *                to RFC 3986.
+ *
+ *                XXX: Do not confuse with encode_url()
+ *
+ * Parameters  :
+ *          1  :  s = String to encode.  Null-terminated.
+ *
+ * Returns     :  Encoded string, newly allocated on the heap.
+ *                Caller is responsible for freeing it with free().
+ *                If s is NULL, or on out-of memory, returns NULL.
+ *
+ *********************************************************************/
+char *percent_encode_url(const char *s)
+{
+   static const char allowed_characters[128] = {
+      '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0',
+      '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0',
+      '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0', '\0',
+      '\0', '\0', '\0', '!',  '\0', '#',  '$',  '%',  '&',  '\'',
+      '(',  ')',  '*',  '+',  ',',  '-',  '.',  '/',  '0',  '1',
+      '2',  '3',  '4',  '5',  '6',  '7',  '8',  '9',  ':',  ';',
+      '\0', '=',  '\0', '?',  '@',  'A',  'B',  'C',  'D',  'E',
+      'F',  'G',  'H',  'I',  'J',  'K',  'L',  'M',  'N',  'O',
+      'P',  'Q',  'R',  'S',  'T',  'U',  'V',  'W',  'X',  'Y',
+      'Z',  '[',  '\0', ']',  '\0', '_',  '\0', 'a',  'b',  'c',
+      'd',  'e',  'f',  'g',  'h',  'i',  'j',  'k',  'l',  'm',
+      'n',  'o',  'p',  'q',  'r',  's',  't',  'u',  'v',  'w',
+      'x',  'y',  'z',  '\0', '\0', '\0', '~',  '\0'
+   };
+   char *buf;
+   size_t buf_size;
+
+   assert(s != NULL);
+
+   /* Each input char can expand to at most 3 chars. */
+   buf_size = (strlen(s) * 3) + 1;
+   buf = (char *)malloc(buf_size);
+
+   if (buf != NULL)
+   {
+      char c;
+      char *p = buf;
+      while((c = *s++) != '\0')
+      {
+         const unsigned int i = (unsigned char)c;
+         if (i >= sizeof(allowed_characters) || '\0' == allowed_characters[i])
+         {
+            const char *replace_with = url_code_map[i];
+            assert(replace_with != NULL);
+            if (replace_with != NULL)
+            {
+               const size_t bytes_written = (size_t)(p - buf);
+               assert(bytes_written < buf_size);
+               p += strlcpy(p, replace_with, buf_size - bytes_written);
+            }
+         }
+         else
+         {
+            *p++ = c;
+         }
+      }
+      *p = '\0';
+   }
+
+   assert(strlen(buf) < buf_size);
+
+   return(buf);
+
+}
+
+
 /*
   Local Variables:
   tab-width: 3
diff --git a/encode.h b/encode.h
index e8acf549..c6d93940 100644
--- a/encode.h
+++ b/encode.h
@@ -1,6 +1,6 @@
 #ifndef ENCODE_H_INCLUDED
 #define ENCODE_H_INCLUDED
-#define ENCODE_H_VERSION "$Id: encode.h,v 1.10 2009/05/16 13:27:20 fabiankeil Exp $"
+#define ENCODE_H_VERSION "$Id: encode.h,v 1.11 2011/09/04 11:10:56 fabiankeil Exp $"
 /*********************************************************************
  *
  * File        :  $Source: /cvsroot/ijbswa/current/encode.h,v $
@@ -45,6 +45,7 @@ extern char * url_encode(const char *s);
 extern char * url_decode(const char *str);
 extern int    xtoi(const char *s);
 extern char * html_encode_and_free_original(char *s);
+extern char * percent_encode_url(const char *s);
 
 /* Revision control strings from this header and associated .c file */
 extern const char encode_rcs[];
-- 
2.39.2