(Read this before doing the discussion post)

Officer P, a university police officer, received information that a student living in a campus dormitory was selling drugs. This information was conveyed to Officer P by an anonymous caller to the officer's cell phone. Officer P knew the suspect in question and had similar suspicions. Officer P immediately went to the dormitory and stopped the student as he was leaving the building. Officer P arrested him, searched his pockets, and found drugs.

Were these actions valid? Justify your answer.