feat: added PURL generation to ruby parser (#3939)

Signed-off-by: Meet Soni <[email protected]>

Author: inosmeet

cve_bin_tool/parsers/ruby.py

@@ -7,10 +7,54 @@
 
 
 class RubyParser(Parser):
+    """
+    Parser implementation for Ruby gem files (Gemfile.lock).
+
+    This parser is designed to parse Ruby gem files and generate Package URL (PURL) strings
+    based on the modules and their dependencies listed in the file.
+
+    Attributes:
+        cve_db (CVEDB): The CVE database instance used for vulnerability information.
+        logger (Logger): The logger instance for logging messages and debugging information.
+
+    Methods:
+        generate_purl(product, version, vendor):
+            Generates PURL after normalizing all components.
+        run_checker(filename):
+            Parse the Ruby gem file and yield valid PURLs for the modules listed in the file.
+
+    """
+
     def __init__(self, cve_db, logger):
         super().__init__(cve_db, logger)
+        self.purl_pkg_type = "gem"
+
+    def generate_purl(self, product, version, vendor, qualifier={}, subpath=None):
+        """Generates PURL after normalizing all components."""
+
+        product = re.sub(r"^[^a-z]|[^a-z0-9_-]", "", product)
+        version = re.sub(r"^[^0-9]|[^a-zA-Z0-9.+-]", "", version)
+        vendor = re.sub(r"^[^a-z]|[^a-z0-9_-]", "", vendor)
+
+        if not re.match(r"^[a-z]|[a-z0-9_-]", product):
+            return
+        if vendor == "":
+            vendor = "UNKNOWN"
+        if version == "":
+            version = "UNKNOWN"
+
+        purl = super().generate_purl(
+            product,
+            version,
+            vendor,
+            qualifier,
+            subpath,
+        )
+
+        return purl
 
     def run_checker(self, filename):
+        """Parse the file and yield valid PURLs."""
         self.filename = filename
         with open(filename) as fh:
             lines = fh.readlines()
@@ -29,7 +73,7 @@ def run_checker(self, filename):
                 ):
                     product = line.strip().split()[0]
                     version = line.strip().split("(")[1][:-1]
-                    vendor = self.find_vendor(product, version)
-                    if vendor is not None:
-                        yield from vendor
+                    vendors = self.find_vendor(product, version)
+                    if vendors is not None:
+                        yield from vendors
             self.logger.debug(f"Done scanning file: {self.filename}")