feat: added PURL generation to rust parser (#3859)

* Related: #3771

Signed-off-by: Meet Soni <meetsoni3017@gmail.com>

cve_bin_tool/parsers/rust.py

@@ -1,17 +1,61 @@
 # Copyright (C) 2022 Intel Corporation
 # SPDX-License-Identifier: GPL-3.0-or-later
 
+import re
+
 from cve_bin_tool.parsers import Parser
 
 
 class RustParser(Parser):
+    """
+    Parser implementation for Rust dependency files (Cargo.toml).
+
+    This parser is designed to parse Rust dependency files (Cargo.toml) and generate
+    Package URL (PURL) strings based on the packages and their versions 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 Rust dependency file and yield valid PURLs for the packages listed in the file.
+    """
+
     def __init__(self, cve_db, logger):
         super().__init__(cve_db, logger)
+        self.purl_pkg_type = "cargo"
+
+    def generate_purl(self, product, version, vendor, qualifier={}, subpath=None):
+        """Generates PURL after normalizing all components."""
+
+        product = re.sub(r"^[^a-zA-Z_]|[^a-zA-Z0-9_-]", "", product)
+        vendor = re.sub(r"^[^a-zA-Z_]|[^a-zA-Z0-9_-]", "", vendor)
+        version = re.sub(r"^[^0-9]|[^a-zA-Z0-9.+-]", "", version)
+
+        if not re.match(r"^[a-zA-Z_]|[a-zA-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:
-            # parse the multiline name and version format
             lines = fh.readlines()
             product = ""
             version = ""
@@ -23,9 +67,9 @@ def run_checker(self, filename):
                 else:
                     if product == "" and version == "":
                         continue
-                    vendor = self.find_vendor(product, version)
+                    vendors = self.find_vendor(product, version)
+                    if vendors is not None:
+                        yield from vendors
                     product = ""
                     version = ""
-                    if vendor is not None:
-                        yield from vendor
             self.logger.debug(f"Done scanning file: {self.filename}")