fix: split function accounting for quotes (#158)

* fix #157: split function accounting for quotes

Added Util.splitCSVLine() function that splits a CSV-formatted string into an array of tokens, accounting for quotes (single and double) and escape characters.

* fix CI warning

Warning: "src/util/Util.lua:263:24: (W311) value assigned to variable sep is unused"

* update split function

- renamed from splitCSVLine to splitEnhanced, since it's not compliant to RFC 4180 and it could be  deceiving;
- added optional parameters;
- now throws error if quotes are not closed;

* update Util.splitEnhanced()

- fixed its behaviour to comply with Casbin documentation (see the note at https://casbin.org/docs/policy-storage#loading-policy-from-a-csv-file and issue 886 at casbin/casbin):
  "If your file contains commas and double quotes, you should enclose the field in double quotes and double any embedded double quotes."

Therefore I removed the extra behaviour related to single quotes ' and escape character \ and refactored the function.

* added example with double quotes

* Unit test for Util.splitEnhanced()

* fixed basic with regex example

* Update basic_policy_with_regex.csv

typo

* Unit test for regexMatch with {N,M} quantifier

* more unit tests for Util.splitEnhanced

- check if the last field is a quoted field
- throwing error when there are extra characters after the double quote that closes the quoted field.

* Update Util.lua

- support for quotes in last field;
- throws an exception if there are other characters after the double quote that closes the quoted field.

* changed "sep" parameter name to "delim"

(uniform to Util.split() )

* changed "line" parameter name to "str"

(uniform to Util.split() )

examples/basic_model_with_regex.conf

@@ -0,0 +1,11 @@
+[request_definition]
+r = sub, obj, act
+
+[policy_definition]
+p = sub, obj, act
+
+[policy_effect]
+e = some(where (p.eft == allow))
+
+[matchers]
+m = regexMatch(r.sub, p.sub) && regexMatch(r.obj, p.obj) && regexMatch(r.act, p.act)

examples/basic_policy_with_regex.csv

@@ -0,0 +1,3 @@
+p, ^admin$, .*, .*
+p, ^user.*, "^/users/[a-zA-Z0-9]{4,10}$", PUT|POST|PATCH|GET|OPTIONS
+p, ^guest$, ^/guest/.*, GET|OPTIONS

src/persist/Adapter.lua

@@ -28,7 +28,7 @@ function Adapter.loadPolicyLine(line, model)
         return
     end
 
-    local tokens = Util.split(line, ",")
+    local tokens = Util.splitEnhanced(line, ',', true)
     local key = tokens[1]
     local sec = key:sub(1, 1)
 

src/util/Util.lua

@@ -252,4 +252,85 @@ function Util.printTable(t)
     return s
 end
 
+function Util.isOnlyWhitespaces(str)
+    return str:match("^%s*$") ~= nil
+end
+
+function Util.splitEnhanced(str, delim, trimFields)
+    local result = {}
+    local i = 1
+    local quotedField
+    local escaping = false
+    local field = ""
+
+    if delim == nil then delim = ',' end
+    if trimFields == nil then trimFields = true end
+
+    -- Loop over the characters of the string
+    while i <= #str do
+        local char = str:sub(i, i)
+
+        -- Check if it's the first character and it's a double quote.
+        if Util.isOnlyWhitespaces(field) and char == '"' then
+            -- Then this field is a quoted field
+            quotedField = true
+        else
+            if quotedField then
+                if escaping then
+                    -- ", End of quoted field
+                    if char == delim then
+                        if trimFields then
+                            field = Util.trim(field)
+                        end
+
+                        table.insert(result, field)
+                        field = ""
+                        quotedField = false
+                    -- "" Escapes the double quote character
+                    elseif char == '"' then
+                        field = field .. char
+                        escaping = false
+                    -- " followed by some other character (not allowed)
+                    else
+                        error("Quoted fields cannot have extra characters outside double quotes.")
+                    end
+                else -- Not escaping
+                    if char == '"' then
+                        escaping = true
+                    else
+                        field = field .. char
+                    end
+                end
+
+            else -- Not quotedField
+                if char == delim then
+                    if trimFields then
+                        field = Util.trim(field)
+                    end
+
+                    table.insert(result, field)
+                    field = ""
+                else
+                    field = field .. char
+                end
+            end
+        end
+
+        i = i + 1
+    end
+
+    -- Throw error if there are quotes left open
+    if quotedField and not escaping then
+        error("Unmatched quotes.")
+    end
+
+    -- Add the last field (since it won't have the delimiter after it)
+    if trimFields then
+        field = Util.trim(field)
+    end
+    table.insert(result, field)
+
+    return result
+end
+
 return Util

tests/main/enforcer_spec.lua

@@ -515,4 +515,28 @@ describe("Enforcer tests", function ()
         assert.is.True(e:enforce("bob", "data2", "write"))
         assert.is.False(e:enforce("bogus", "data2", "write")) -- Non-existent subject
     end)
+
+
+    it("regexMatch test", function ()
+
+        local model  = path .. "/examples/basic_model_with_regex.conf"
+        local policy  = path .. "/examples/basic_policy_with_regex.csv"
+        local e = Enforcer:new(model, policy)
+
+        assert.is.True(e:enforce("admin", "/", "PUT"))
+        assert.is.True(e:enforce("admin", "/admin", "GET"))
+        assert.is.True(e:enforce("admin", "/admin/anything", "POST"))
+        assert.is.False(e:enforce("admin123", "/admin", "PUT"))
+
+        assert.is.True(e:enforce("user", "/users/alice", "GET"))
+        assert.is.True(e:enforce("user", "/users/alice", "PUT"))
+        assert.is.True(e:enforce("user123", "/users/alice", "PUT"))
+        assert.is.False(e:enforce("user", "/users/", "PUT"))
+        assert.is.False(e:enforce("user", "/users/123", "PUT"))
+        assert.is.False(e:enforce("user", "/users/alice123456789", "PUT"))
+        assert.is.False(e:enforce("user", "/admin", "PUT"))
+
+        assert.is.True(e:enforce("guest", "/guest/test", "GET"))
+        assert.is.False(e:enforce("guest", "/guest/test", "PUT"))
+    end)
 end)

tests/util/util_spec.lua

@@ -84,6 +84,35 @@ describe("util tests", function()
         assert.are.same({"a", "b", "c"}, Util.split("  a,     b   ,c     ", ","))
     end)
 
+    it("test isOnlyWhitespaces", function()
+        assert.is.True(Util.isOnlyWhitespaces("     "))
+        assert.is.True(Util.isOnlyWhitespaces(""))
+        assert.is.True(Util.isOnlyWhitespaces("\t\t"))
+        assert.is.False(Util.isOnlyWhitespaces("  abc"))
+        assert.is.False(Util.isOnlyWhitespaces("abc\t"))
+        assert.is.False(Util.isOnlyWhitespaces("\""))
+    end)
+
+    it("test splitEnhanced", function()
+        assert.are.same({"a", "b", "c"}, Util.splitEnhanced("a ,b ,c", ",", true))
+        assert.are.same({"a", "b", "c"}, Util.splitEnhanced("a,b,c", ",", true))
+        assert.are.same({"a", "b", "c"}, Util.splitEnhanced("a, b, c", ",", true))
+        assert.are.same({"a", "b", "c"}, Util.splitEnhanced("  a,     b   ,c     ", ",", true))
+
+        assert.are.same({"a", " b", " c"}, Util.splitEnhanced('a, b, c', ",", false))
+        assert.are.same({"a", "b", "c"}, Util.splitEnhanced('a,b,c', ",", false))
+        assert.are.same({"    a", "b", "c"}, Util.splitEnhanced('    a,b,c', ",", false))
+        assert.are.same({"a, b", "c"}, Util.splitEnhanced('"a, b", c', ",", true))
+        assert.are.same({"a,   b", "c"}, Util.splitEnhanced('"   a,   b", c', ",", true))
+        assert.are.same({"a == \"b\"", "c"}, Util.splitEnhanced('a == "b", c', ",", true))
+        assert.are.same({"a == \"b\"", "c"}, Util.splitEnhanced('"a == ""b"" ", c', ",", true))
+        assert.are.same({"a", "b, c"}, Util.splitEnhanced('a, "b, c"', ",", true))
+
+        assert.has_error(function () Util.splitEnhanced('a, "b, c"   ', ",", true) end, "Quoted fields cannot have extra characters outside double quotes.")
+        assert.has_error(function () Util.splitEnhanced('"a, b" hello, c', ",", true) end, "Quoted fields cannot have extra characters outside double quotes.")
+        assert.has_error(function () Util.splitEnhanced('a, b, "c  ') end, "Unmatched quotes.")
+    end)
+
     it("test isInstance", function()
         local parent = {}
         parent.__index = parent