We're dealing with country borders, that is the set of multiple disjoint domains that is made of polygons.
To extract the different point on the map by a given country we've been said to implement the ray casting algorithm which is absolutely fine, but the country is hardly to be the simply-connected domain. For example, the Italy consists of many disjoint domains (islands).
In this case the crossing number algorithm or the even-odd rule algorithm is still a valid approach to validate if the point in question is within the country borders or not?
After days of research finally found one discussion: MySQL implementation of ray-casting Algorithm? which gives the exhausting number of links, answers and code snippets to implement the algorithm in code (Pseudo-code: http://rosettacode.org/wiki/Ray-casting_algorithm).