utils/generate-cyclonedx: fixup scp-style git sites

Commit e8c54ffb3d ("utils/generate-cyclonedx: generate vcs
externalReferences for source repos") added externalReferences to the source
code of packages.

This unfortunately causes issues with packages (in br2-external) fetching
from git using the scp-like syntax, E.G.:

 FOO_SITE_METHOD = git
 FOO_SITE = git@github.com:<project>/<repo>.git

Which ends up in the SBOM as:

[
  {
    "type": "vcs",
    "url": "git@github.com:<project>/<repo>.git",
    "comment": "git repository"
  }
]

This (correctly) causes Dependency track to reject the SBOM import with:

{
  "status": 400,
  "title": "The uploaded BOM is invalid",
  "detail": "Schema validation failed",
  "errors": [
    "$.components[2].externalReferences[0].url: does not match the iri-reference pattern must be a valid RFC 3987 IRI-reference",
    "$.components[2].externalReferences[0].url: does not match the iri-reference pattern must be a valid RFC 3987 IRI-reference",
    "$.components[2].externalReferences[0].url: does not match the regex pattern ^urn:cdx:[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}/[1-9][0-9]*$",
   ]
}

The CycloneDX spec indeed requires a URI:

The URI (URL or URN) to the external reference.  External references are
URIs and therefore can accept any URL scheme including https (RFC-7230),
mailto (RFC-2368), tel (RFC-3966), and dns (RFC-4501)

https://cyclonedx.org/docs/1.6/json/#metadata_tools_oneOf_i0_components_items_externalReferences_items_url

The user@host:project/repo.git is a git-specific shorthand for a git-over-ssh URL. From man git-clone:

 Git supports ssh, git, http, and https protocols (in addition, ftp and ftps
 can be used for fetching, but this is inefficient and deprecated; do not use
 them).

 The native transport (i.e.  git:// URL) does no authentication and should
 be used with caution on unsecured networks.

 The following syntaxes may be used with them:

 •   ssh://[user@]host.xz[:port]/path/to/repo.git/
 •   git://host.xz[:port]/path/to/repo.git/
 •   http[s]://host.xz[:port]/path/to/repo.git/
 •   ftp[s]://host.xz[:port]/path/to/repo.git/

 An alternative scp-like syntax may also be used with the ssh protocol:

 •   [user@]host.xz:path/to/repo.git/

So convert the scp-like syntax to ssh:// URLs in parse_uris() for spec
compliance.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
Acked-By: Thomas Perale <thomas.perale@mind.be>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

utils/generate-cyclonedx

@@ -280,6 +280,12 @@ def parse_uris(uris: list[str]) -> Iterator[tuple[list[str], str]]:
         scheme, _, stripped_uri = uri.partition("+")
         if stripped_uri:
             parsed = urllib.parse.urlparse(stripped_uri)
+
+            # convert scp-style host:path site to ssh:// uri
+            if scheme == "git" and not parsed.scheme:
+                host, _, path = stripped_uri.partition(":")
+                stripped_uri = "ssh://" + host + "/" + path
+
             if parsed.hostname != "sources.buildroot.net":
                 yield scheme.split("|"), stripped_uri