URL CANONICALIZATION AND UTILITIES FUNCTIONS

This is a set a C functions to manipulate URL strings (in an RFC 3986 compliant
way) and achieve URL Canonicalization as described by Google in its Safe 
Browsing developer's guide. See :

https://developers.google.com/safe-browsing/developers_guide_v3#Canonicalization

It includes the following functions (see url.h for full documentation) :

- url_RemoveTabCRLF() : removes leading and trailing spaces, as well as tab
  (0x09), CR (0x0d), and LF (0x0a) characters from the URL.

- url_RemoveFragment() : removes the fragment part of an URL.

- url_RemoveQuery() : removes the query part of an URL.

- url_Unescape() : percent-decode an URL, calling itself until there is no 
  more percent-decoding to be done.

- url_Normalize() : applies URL normalization rules as described in Google Safe
  Browsing Developer's Guide.

- url_Escape() : Percent-encode an URL. Reserved characters (from RFC 3986
  that is one of "!*'();:@&=+$,/?#[]") are not encoded.

- url_EscapeIncludingReservedChars() : Percent-encode a string, including
  reserved characters.

- url_Encode() : encodes a string to be compliant with 
  application/x-www-form-urlencoded format. Same as 
  url_EscapeIncludingReservedChars() but also replaces spaces with '+'.

- url_Canonicalize() : canonicalizes an URL by successively calling 
  url_Normalize(), then url_Escape() to get a percent-encoded url.

- url_CanonicalizeWithFullEscape() : canonicalizes an URL (same as
  url_Canonicalize()) but returned string is fully percent-encoded, even the
  reserved characters.

- url_ParseNextKeyValuePair() : allows parsing of a "key=value&key=value&..."
  string.

- url_Split() : splits an URL into its schme, link and query parts, as defined
  by RFC3986.

- url_GetHostname() : returns the hostname part extracted from an URL.

- url_GetBase() : returns the base part of an URL.

- url_MakeAbsolute() : turn a relative URL into an absolute URL?


All these functions are supposed to be thread safe. Tests were made with
Valgrind to find and fix memory leaks.

test_url.c implements the tests provided by Google in its documentation to
help validate a canonicalization implementation. 

test_url.c also provides example of basic uses of the provided functions.

To compile : gcc -std=c99 test_url.c url.c -o test_url
Tu run tests : ./test_url