Measuring speed of light

From all hetero known phenomena that travels, light is the fastest. Therefore it is not possible to measure speed of light using other methods. Only light can be used to measure it. What can be done is to mirror back a bean of light and measure the time taken to travel the known distance. This is the usual methods employed in all scientific measurement of speed of light. This is employed in the famous Michelson Morally experiment that predicts speed of light is constant everywhere irrespective of your moment at constant speeds.

But there is a contradiction in applying this. Say a light ray coming from sun, if it travels towards me at constant speed c, that ray before reaching me need to know me speed. Say I am traveling at speed v at the time the ray started to be emitted from sun, then the ray should be traveling at speed c irrespective me speed v. Suppose all is good so far, but if I change my speed to v', how does the ray know to travel towards me at speed c without knowing I have changed my speed. Forget reference frames and special relativity for a moment, my change of speed from v to v', should bring out some sort of change in the photon to keep it at the same speed c, before and after the change. The photon need to know the change I made to my speed, or else it is not to change it's speed. So a signal at infinite speed need to communicate the change to the photon.
It is important to point out that in all light measuring apparatus, an observer is involved at the time the photon is emitted and when the final measurement is made. That way the message of observer speed is indirectly passed on to the photon. So we may be able to assume that whenever an observer is involved in measuring speed of light, it has a constant speed c relative to the observer.

Then what can we say about a ray of light coming from the sun. What we can say is that it is un-measurable.