acmecert: Handle application/problem responses better.

diff --git a/acmecert b/acmecert
index a4fb4a4..12e1847 100755 (executable)
--- a/acmecert
+++ b/acmecert
@@ -14,7 +14,7 @@ def directory():
     global _directory
     if _directory is None:
         with req(service) as resp:
-            _directory = json.loads(resp.read().decode("utf-8"))
+            _directory = json.load(resp)
     return _directory
 
 def base64url(dat):
@@ -41,6 +41,48 @@ def req(url, data=None, ctype=None, headers={}, method=None, **kws):
         req.add_header("Content-Type", ctype)
     return urllib.request.urlopen(req)
 
+class problem(msgerror):
+    def __init__(self, code, data, *args, url=None, **kw):
+        super().__init__(*args, **kw)
+        self.code = code
+        self.data = data
+        self.url = url
+        if not isinstance(data, dict):
+            raise ValueError("unexpected problem object type: %r" % (data,))
+
+    @property
+    def type(self):
+        return self.data.get("type", "about:blank")
+    @property
+    def title(self):
+        return self.data.get("title")
+    @property
+    def detail(self):
+        return self.data.get("detail")
+
+    def report(self, out):
+        extra = None
+        if self.title is None:
+            msg = self.detail
+            if "\n" in msg:
+                extra, msg = msg, None
+        else:
+            msg = self.title
+            extra = self.detail
+        if msg is None:
+            msg = self.data.get("type")
+        if msg is not None:
+            out.write("acemcert: %s: %s\n" % (
+                ("remote service error" if self.url is None else self.url),
+                ("unspecified error" if msg is None else msg)))
+        if extra is not None:
+            out.write("%s\n" % (extra,))
+
+    @classmethod
+    def read(cls, err, **kw):
+        self = cls(err.code, json.load(err), **kw)
+        return self
+
 def jreq(url, data, auth):
     authdata = {"alg": "RS256", "url": url, "nonce": getnonce()}
     authdata.update(auth.authdata())
@@ -51,8 +93,13 @@ def jreq(url, data, auth):
         data = base64url(json.dumps(data).encode("us-ascii"))
     seal = base64url(auth.sign(("%s.%s" % (authdata, data)).encode("us-ascii")))
     enc = {"protected": authdata, "payload": data, "signature": seal}
-    with req(url, data=enc) as resp:
-        return json.loads(resp.read().decode("utf-8")), resp.headers
+    try:
+        with req(url, data=enc) as resp:
+            return json.load(resp), resp.headers
+    except urllib.error.HTTPError as exc:
+        if exc.headers["Content-Type"] == "application/problem+json":
+            raise problem.read(exc, url=url)
+        raise
 
 class certificate(object):
     @property