Added ability to set and get cookie without escaping

TODO: add unit tests

Method resp:setcookie() implicitly escapes cookie values. Commit adds
ability to set cookie without any escaping with option 'raw':

resp:setcookie('name', 'value', {
    raw = true
})`

Method req:cookie() implicitly unescapes cookie values. Commit adds
ability to get cookie without unescaping:

req:cookie('name', {
    raw = true
})

Also added escaping of cookie path, and changed escaping algorithm
according to [1].

These changes were added as a part of http v2 support in commit 'Added
ability to set and get cookie without escaping'
(42e3002) and later reverted in scope
of ticket with discard v2.

1. https://tools.ietf.org/html/rfc6265

Follows up #126
Part of #134

README.md

@@ -226,7 +226,9 @@ end
 * `req:query_param(name)` - returns a single GET request parameter value.
   If `name` is `nil`, returns a Lua table with all arguments.
 * `req:param(name)` - any request parameter, either GET or POST.
-* `req:cookie(name)` - to get a cookie in the request.
+* `req:cookie(name, {raw = true})` | to get a cookie in the request. if `raw`
+  option was set then cookie will not be unescaped, otherwise cookie's value
+  will be unescaped.
 * `req:stash(name[, value])` - get or set a variable "stashed"
   when dispatching a route.
 * `req:url_for(name, args, query)` - returns the route's exact URL.
@@ -238,8 +240,9 @@ end
 * `resp.status` - HTTP response code.
 * `resp.headers` - a Lua table with normalized headers.
 * `resp.body` - response body (string|table|wrapped\_iterator).
-* `resp:setcookie({ name = 'name', value = 'value', path = '/', expires = '+1y', domain = 'example.com'))` -
-  adds `Set-Cookie` headers to `resp.headers`.
+* `resp:setcookie({ name = 'name', value = 'value', path = '/', expires = '+1y', domain = 'example.com'}, {raw = true})` -
+  adds `Set-Cookie` headers to `resp.headers`, if `raw` option was set then cookie will not be escaped,
+  otherwise cookie's value and path will be escaped
 
 ### Examples
 

http/server.lua

@@ -23,18 +23,58 @@ local function sprintf(fmt, ...)
     return string.format(fmt, ...)
 end
 
+local function valid_cookie_value_byte(byte)
+    -- https://tools.ietf.org/html/rfc6265#section-4.1.1
+    -- US-ASCII characters excluding CTLs, whitespace DQUOTE, comma, semicolon,
+    -- and backslash.
+    return 32 < byte and byte < 127 and byte ~= string.byte('"') and
+            byte ~= string.byte(",") and byte ~= string.byte(";") and byte ~= string.byte("\\")
+end
+
+local function valid_cookie_path_byte(byte)
+    -- https://tools.ietf.org/html/rfc6265#section-4.1.1
+    -- <any CHAR except CTLs or ";">
+    return 32 <= byte and byte < 127 and byte ~= string.byte(";")
+end
+
+local function escape_char(char)
+    return string.format('%%%02X', string.byte(char))
+end
+
+local function unescape_char(char)
+    return string.char(tonumber(char, 16))
+end
+
+
+local function escape_string(str, byte_filter)
+    local result = {}
+    for i = 1, str:len() do
+        local char = str:sub(i,i)
+        if byte_filter(string.byte(char)) then
+            result[i] = char
+        else
+            result[i] = escape_char(char)
+        end
+    end
+    return table.concat(result)
+end
+
+local function escape_value(cookie_value)
+    return escape_string(cookie_value, valid_cookie_value_byte)
+end
+
+local function escape_path(cookie_path)
+    return escape_string(cookie_path, valid_cookie_path_byte)
+end
+
 local function uri_escape(str)
     local res = {}
     if type(str) == 'table' then
         for _, v in pairs(str) do
             table.insert(res, uri_escape(v))
         end
     else
-        res = string.gsub(str, '[^a-zA-Z0-9_]',
-            function(c)
-                return string.format('%%%02X', string.byte(c))
-            end
-        )
+        res = string.gsub(str, '[^a-zA-Z0-9_]', escape_char)
     end
     return res
 end
@@ -50,11 +90,7 @@ local function uri_unescape(str, unescape_plus_sign)
             str = string.gsub(str, '+', ' ')
         end
 
-        res = string.gsub(str, '%%([0-9a-fA-F][0-9a-fA-F])',
-            function(c)
-                return string.char(tonumber(c, 16))
-            end
-        )
+        res = string.gsub(str, '%%([0-9a-fA-F][0-9a-fA-F])', unescape_char)
     end
     return res
 end
@@ -265,7 +301,8 @@ local function expires_str(str)
     return os.date(fmt, gmtnow + diff)
 end
 
-local function setcookie(resp, cookie)
+local function setcookie(resp, cookie, options)
+    options = options or {}
     local name = cookie.name
     local value = cookie.value
 
@@ -276,9 +313,16 @@ local function setcookie(resp, cookie)
         error('cookie.value is undefined')
     end
 
-    local str = sprintf('%s=%s', name, uri_escape(value))
+    if not options.raw then
+        value = escape_value(value)
+    end
+    local str = sprintf('%s=%s', name, value)
     if cookie.path ~= nil then
-        str = sprintf('%s;path=%s', str, cookie.path)
+        local cookie_path = cookie.path
+        if not options.raw then
+            cookie_path = escape_path(cookie.path)
+        end
+        str = sprintf('%s;path=%s', str, cookie_path)
     end
     if cookie.domain ~= nil then
         str = sprintf('%s;domain=%s', str, cookie.domain)
@@ -304,14 +348,18 @@ local function setcookie(resp, cookie)
     return resp
 end
 
-local function cookie(tx, cookie)
+local function cookie(tx, cookie, options)
+    options = options or {}
     if tx.headers.cookie == nil then
         return nil
     end
     for k, v in string.gmatch(
                 tx.headers.cookie, "([^=,; \t]+)=([^,; \t]+)") do
         if k == cookie then
-            return uri_unescape(v)
+            if not options.raw then
+                v = uri_unescape(v)
+            end
+            return v
         end
     end
     return nil

test/integration/http_server_requests_test.lua

@@ -211,49 +211,101 @@ pgroup.test_chunked_encoding = function(g)
     t.assert_equals(r.body, 'chunkedencodingt\r\nest', 'chunked body')
 end
 
--- Get cookie.
-pgroup.test_get_cookie = function(g)
+-- Get raw cookie value (Günter -> Günter).
+pgroup.test_get_raw_cookie = function(g)
+    local cookie = 'Günter'
     local httpd = g.httpd
     httpd:route({
         path = '/receive_cookie'
     }, function(req)
-        local foo = req:cookie('foo')
-        local baz = req:cookie('baz')
+        local name = req:cookie('name', {
+            raw = true
+        })
         return req:render({
-            text = ('foo=%s; baz=%s'):format(foo, baz)
+            text = ('name=%s'):format(name)
         })
     end)
+
     local r = http_client.get(helpers.base_uri .. '/receive_cookie', {
         headers = {
-            cookie = 'foo=bar; baz=feez',
+            cookie = 'name=' .. cookie,
         }
     })
-    t.assert_equals(r.status, 200, 'status')
-    t.assert_equals(r.body, 'foo=bar; baz=feez', 'body')
+
+    t.assert_equals(r.status, 200, 'response status')
+    t.assert_equals(r.body, 'name=' .. cookie, 'body with raw cookie')
+end
+
+-- Get escaped cookie (G%C3%BCnter -> Günter).
+pgroup.test_get_escaped_cookie = function(g)
+    local str_escaped = 'G%C3%BCnter'
+    local str_non_escaped = 'Günter'
+    local httpd = g.httpd
+    httpd:route({
+        path = '/receive_cookie'
+    }, function(req)
+        local name = req:cookie('name')
+        return req:render({
+            text = ('name=%s'):format(name)
+        })
+    end)
+
+    local r = http_client.get(helpers.base_uri .. '/receive_cookie', {
+        headers = {
+            cookie = 'name=' .. str_escaped,
+        }
+    })
+
+    t.assert_equals(r.status, 200, 'response status')
+    t.assert_equals(r.body, 'name=' .. str_non_escaped, 'body with escaped cookie')
 end
 
--- Cookie.
-pgroup.test_set_cookie = function(g)
+-- Set escaped cookie (Günter -> G%C3%BCnter).
+pgroup.test_set_escaped_cookie = function(g)
+    local str_escaped = 'G%C3%BCnter'
+    local str_non_escaped = 'Günter'
+
     local httpd = g.httpd
     httpd:route({
         path = '/cookie'
     }, function(req)
-        local resp = req:render({text = ''})
+        local resp = req:render({
+            text = ''
+        })
         resp:setcookie({
-            name = 'test',
-            value = 'tost',
-            expires = '+1y',
-            path = '/abc'
+            name = 'name',
+            value = str_non_escaped
+        })
+        return resp
+    end)
+
+    local r = http_client.get(helpers.base_uri .. '/cookie')
+    t.assert_equals(r.status, 200, 'response status')
+    t.assert_equals(r.headers['set-cookie'], 'name=' .. str_escaped, 'header with escaped cookie')
+end
+
+-- Set raw cookie (Günter -> Günter).
+pgroup.test_set_raw_cookie = function(g)
+    local cookie = 'Günter'
+    local httpd = g.httpd
+    httpd:route({
+        path = '/cookie'
+    }, function(req)
+        local resp = req:render({
+            text = ''
         })
         resp:setcookie({
-            name = 'xxx',
-            value = 'yyy'
+            name = 'name',
+            value = cookie
+        }, {
+            raw = true
         })
         return resp
     end)
+
     local r = http_client.get(helpers.base_uri .. '/cookie')
-    t.assert_equals(r.status, 200, 'status')
-    t.assert(r.headers['set-cookie'] ~= nil, 'header')
+    t.assert_equals(r.status, 200, 'response status')
+    t.assert_equals(r.headers['set-cookie'], 'name=' .. cookie, 'header with raw cookie')
 end
 
 -- Request object methods.