NAME

quvi-object - Overview of the libquvi quvi-object

DESCRIPTION

quvi-object is a collection of libquvi functions provided for the libquvi-scripts(7). These functions vary from HTTP functions to cryptographic functions. All of the quvi-object functions are implemented in C.

Note

The quvi-object should not be confused with the quvi-modules(7) which are a selection of importable modules implemented in Lua. These modules are intended to be loaded (require) from the libquvi-scripts(7).

OPTIONS

Each of the quvi-object functions may be passed a dictionary defining the additional option properties. The following options are supported by all of the functions:

qoo_croak_if_error=<boolean>

By default the library terminates the process if an error occurs. By setting this option to false, it will register the error and continues execution, leaving the error handling for the script to determine. See also "RETURN VALUES".

The qoo prefix is short for quvi object option. The functions will ignore any unknown options, e.g. the crypto functions would ignore the HTTP options.

Note

The options have been defined in the quvi/const of the quvi-modules(7)

Crypto

These options are specific to the quvi.crypto.* functions of the quvi-object.

qoo_crypto_algorithm=<value>

Specifies the algorithm that should be used. The value is expected to be a string, e.g. sha1 or aes256.

qoo_crypto_cipher_flags=<value>

Specifies the cipher flags (bit OR’d, see quvi-modules-3rdparty(7) for bit operations) to be used with the cipher. These values are identical to those defined by libgcrypt. See the quvi/const of the quvi-modules(7) for a complete list of the available cipher flags.

qoo_crypto_cipher_mode=<value>

Specifies the cipher mode to be used. These are identical to the values defined by libgcrypt. See the quvi/const of the quvi-modules(7) for a complete list of the available cipher modes.

qoo_crypto_cipher_key=<value>

Used to specify the cipher key. It should be noted that the key is expected to be passed in hexadecimal form. See quvi/hex of the quvi-modules(7) for the conversion functions.

NOTE: The key derivation is left for the script to do

NOTE: The key is not a pass{word,phrase}

See also: http://www.di-mgt.com.au/cryptokeys.html#passwordpassphraseandkey

HTTP

These options are specific to the quvi.http.* functions of the quvi-object.

qoo_fetch_from_charset=<charset>

Instructs the library to convert from this charset to UTF-8. Using this option may be required with the websites that use a specific (non-UTF8) encoding.

The purpose of this option is to make sure that the data is encoded to unicode (UTF-8) before any of it is parsed and returned to the application using libquvi.

By default, libquvi converts the data which is in the encoding used for the strings by the C runtime in the current locale into UTF-8. IF this fails, and the from charset option is set, the library will then try to convert to UTF-8 using the from charset value.

qoo_http_cookie_mode=<value>

Modify the cookie settings for the libcurl session handle. This feature wraps the cookie features provided by libcurl_easy_setopt(3). See the quvi/const of the quvi-modules(7) for a complete list of the available cookie modes.

See also libcurl-tutorial(3) which covers the use of cookies with the library in greater detail.

RETURN VALUES

Each quvi-object function will return a dictionary containing the following values:

error_message

The error message, or an empty value.

quvi_code

The code returned by the library. See also quvi/const of quvi-modules(7).

Refer to the function documentation for the information about the additional values returned in the dictionary.

FUNCTIONS

Base64

quvi.base64.encode(<plaintext>[,qoo])

Encode the plaintext to base64 format. The plaintext is expected to be passed in hexadecimal form. See quvi/hex of the quvi-modules(7) for the conversion functions.

The second argument (qoo) is expected to be a dictionary of additional quvi object options, if defined at all.

The function will return the base64 value in the dictionary.

quvi.base64.decode(<base64>)

Decode the base64 value to plaintext.

The function will return the plaintext value in the dictionary. The value is returned in hexadecimal form.

Crypto

The crypto facility of the quvi-object wraps the libgcrypt symmetric cryptography and the hash (message digest) functions.

Note

The availability of the algorithms is determined by libgcrypt, and how it was built

quvi.crypto.encrypt(<plaintext>, <qoo>)

Encrypt the plaintext. The plaintext is expected to be passed in hexadecimal form. See quvi/hex of the quvi-modules(7) for the conversion functions.

The second argument (qoo) is expected to be a dictionary containing the cipher options.

The function will return the ciphertext value in the dictionary. The value is returned in hexadecimal form.

quvi.crypto.decrypt(<ciphertext>, <qoo>)

Decrypt the ciphertext. The ciphertext is expected to be passed in hexadecimal form. See quvi/hex of the quvi-modules(7) for the conversion functions.

The second argument (qoo) is expected to be a dictionary containing the cipher options.

The function will return the plaintext value in the dictionary. This value is returned in hexadecimal form.

quvi.crypto.hash(<value>, <qoo>)

Generate a hash from the value. The value is expected to be passed in hexadecimal format. See quvi/hex of the quvi-modules(7) for the conversion functions.

The second argument (qoo) is expected to be a dictionary containing the hash options, e.g. the algorithm that should be used.

The function will return the digest value in the dictionary. The value is returned in hexadecimal form.

HTTP

The HTTP functions will return response_code along the other "RETURN VALUES", and the values specific to the HTTP function.

quvi.http.cookie(<VALUE>,<qoo>)

Modify the libcurl session handle cookie settings that libquvi currently uses.

The second argument (qoo) is expected to be a dictionary containing the cookie options, e.g. the cookie mode that should be used.

The complete list of the available cookie modes can be found in the quvi/const module of the quvi-modules(7). The mode names are named after their equivalent CURLOPT_COOKIE{SESSION,FILE,LIST,JAR} variable names. For a description of each option, see libcurl_easy_setopt(3).

This function will not return any additional values in the dictionary.

Note

libquvi will ignore any calls to quvi.http.cookie unless QUVI_OPTION_ALLOW_COOKIES is QUVI_TRUE

Note

libcurl will parse the received cookies and use them in the subsequent HTTP requests only if libquvi QUVI_OPTION_ALLOW_COOKIES is QUVI_TRUE

quvi.http.fetch(<URL>[,qoo])

Fetch an URL over an HTTP connection.

The second argument (qoo) is expected to be a dictionary of additional quvi object options, if defined at all.

The function will return the data value among the values in the returned dictionary.

quvi.http.header(<VALUE>[,qoo])

Add, remove or replace internally used libcurl HTTP headers.

The second argument (qoo) is expected to be a dictionary of additional quvi object options, if defined at all.

This function essentially wraps CURLOPT_HTTPHEADER, and will not return any additional values in the dictionary. See curl_easy_setopt(3) for the full description of CURLOPT_HTTPHEADER.

Note

To clear the custom headers, pass "" as the VALUE; the custom headers are also cleared automatically when a support script function parse is called

quvi.http.metainfo(<URL>[,qoo])

Query the HTTP metainfo for the URL.

The second argument (qoo) is expected to be a dictionary of additional quvi object options, if defined at all.

The function will return the content_length and the content_type values among the values in the returned dictionary.

quvi.http.resolve(<URL>[,qoo])

Resolve an URL redirection.

The second argument (qoo) is expected to be a dictionary of additional quvi object options, if defined at all.

The function will return the resolved_url among the values in the returned dictionary. If the URL did not redirect to another location, the value of the resolved_url is left empty.

EXAMPLES

Base64

•Base64 encode a string:

local H = require 'quvi/hex'
local s = H.to_hex('foo') -- Pass in hexadecimal form
local r = quvi.base64.encode(s)
print(r.base64)

•Reverse the process:

local r = quvi.base64.decode(r.base64)
local s = H.to_str(r.plaintext)

Crypto

•Encrypt plaintext:

local plaintext = 'f34481ec3cc627bacd5dc3fb08f273e6'
local key = '00000000000000000000000000000000'
local C = require 'quvi/const'
local o = {
  [C.qoo_crypto_cipher_mode] = C.qoco_cipher_mode_cbc,
  [C.qoo_crypto_algorithm] = 'aes',
  [C.qoo_crypto_cipher_key = key
}
local r = quvi.crypto.encrypt(plaintext, o)
print(r.ciphertext)

•Reverse the process:

local r = quvi.crypto.decrypt(r.ciphertext, o)
print(r.plaintext)

•Generate a hash (message digest):

local H = require 'quvi/hex'
local s = H.to_hex('foo') -- Pass in hexadecimal form
local C = require 'quvi/const'
local o = { [C.qoo_crypto_algorithm] = 'sha1' }
local r = quvi.crypto.hash(s, o)
print(r.digest)

•Same as above, but use the shorthand function:

local A = require 'quvi/hash'
local r = A.sha1sum('foo')
print(r)

HTTP

•Dump the cookies in the memory to stdout:

local C = require 'quvi/const'
local o = { [C.qoo_http_cookie_mode] = C.qohco_mode_jar }
local r = quvi.http.cookie('-', o)

•Identical to the above but use the wrapper module:

local K = require 'quvi/http/cookie'
local r = K.jar('-')

•Fetch an URL:

local r = quvi.http.fetch('http://example.com')

r.data would now hold the contents. If an error occurred, e.g. connection failed, the library would exit the process with an error.

•Same as above, but handle the error in the script:

local C = require 'quvi/const'
local o = { [C.qoo_croak_if_error] = false }
local r = quvi.http.fetch('http://example.com', o)
if r.quvi_code ~= C.qerr_ok then
  local s =
    string.format('quvi.http.fetch: %s (libquvi=%d, http/%d)',
                  r.error_message, r.quvi_code, r.response_code)
  error(s)
end

By setting qoo_croak_if_error to false, we tell the library to only register that an error occurred and return the control to the script. Handling of the error is then left for the script to do.

Note
Typically, the scripts would not need to handle the error

•Force conversion from ISO-8859-1 to UTF-8:

local C = require 'quvi/const'
local o = { [C.qoo_fetch_from_charset] = 'ISO-8859-1' }
local r = quvi.http.fetch('http://example.com', o)

•Override user-agent header in the HTTP request:

local r = quvi.http.header('User-Agent: foo/1.0')
r = quvi.http.fetch(...)

•Disable an internal header in the HTTP request:

local r = quvi.http.header('Accept:')
r = quvi.http.fetch(...)

•Send a cookie in the HTTP request:

local r = quvi.http.header('Cookie: foo=1')
r = quvi.http.fetch(...)

•Query metainfo for an URL:

local r = quvi.http.metainfo('http://is.gd/SKyg8m')
print(r.content_length, r.content_type)

•Resolve URL redirection:

local r = quvi.http.resolve('http://is.gd/SKyg8m')
if #r.resolved_url >0 then
  print('new location:', r.resolved_url)
end

FURTHER RESOURCES

Home

http://quvi.sourceforge.net/

Development code

git://repo.or.cz/libquvi.git

gitweb

http://repo.or.cz/w/libquvi.git

C API reference

The latest C API reference documentation may be viewed online at http://quvi.sourceforge.net/r/api/0.9/.

GLib

http://developer.gnome.org/glib/stable/glib-Base64-Encoding.html

libcurl

http://curl.haxx.se/libcurl/c/curl_easy_setopt.html#CURLOPTUSERAGENT http://curl.haxx.se/libcurl/c/curl_easy_setopt.html#CURLOPTCOOKIE

libgcrypt reference manual

http://www.gnupg.org/documentation/manuals/gcrypt/

AUTHORS

Toni Gundogdu <legatvs@gmail.com>

Author.

REPORTING BUGS

Report bugs to the quvi-devel mailing list <quvi-devel@lists.sourceforge.net> where the development and the maintenance is primarily done. You do not have to be subscribed to the list to send a message there.

LICENSE

libquvi is Free Software licensed under the GNU Affero GPLv3+

LIBQUVI

Part of the libquvi(3) suite