Added support for alternate firmware download URL

New command line option `--fw-url` accepts an alternate URL to use for
downloading firmware images.
Note this feature is moderately opinionated when it comes to directory
structure. The intent is to be compatible with GitHub releases, so the
latest version info is expected to be found at
"{fw-url}latest/download/release.json" and firmware images at
"{fw-url}download/{version}/{firmware_file.zip}".

RNS/Utilities/rnodeconf.py

@@ -53,6 +53,7 @@ rnode_baudrate = 115200
 known_keys = [["unsigned.io", "30819f300d06092a864886f70d010101050003818d0030818902818100bf831ebd99f43b477caf1a094bec829389da40653e8f1f83fc14bf1b98a3e1cc70e759c213a43f71e5a47eb56a9ca487f241335b3e6ff7cdde0ee0a1c75c698574aeba0485726b6a9dfc046b4188e3520271ee8555a8f405cf21f81f2575771d0b0887adea5dd53c1f594f72c66b5f14904ffc2e72206a6698a490d51ba1105b0203010001"], ["unsigned.io", "30819f300d06092a864886f70d010101050003818d0030818902818100e5d46084e445595376bf7efd9c6ccf19d39abbc59afdb763207e4ff68b8d00ebffb63847aa2fe6dd10783d3ea63b55ac66f71ad885c20e223709f0d51ed5c6c0d0b093be9e1d165bb8a483a548b67a3f7a1e4580f50e75b306593fa6067ae259d3e297717bd7ff8c8f5b07f2bed89929a9a0321026cf3699524db98e2d18fb2d020300ff39"]]
 firmware_update_url = "https://github.com/markqvist/RNode_Firmware/releases/download/"
 fw_filename = None
+fw_url = None
 mapped_model = None
 
 class KISS():
@@ -1002,8 +1003,33 @@ def ensure_firmware_file(fw_filename):
                 if not upd_nocheck:
                     try:
                         try:
+                            # if custom firmware url, download latest release
+                            if fw_url != None:
+                                try:
+                                    RNS.log("Retrieving latest version from custom url "+fw_url+"latest/download/release.json")
+                                    urlretrieve(fw_url+"latest/download/release.json", UPD_DIR+"/fallback_release_info.json")
+                                    import json
+                                    with open(UPD_DIR+"/fallback_release_info.json", "rb") as rif:
+                                        rdat = json.loads(rif.read())
+                                        variant = rdat[fw_filename]
+                                        with open(UPD_DIR+"/"+fw_filename+".version.latest", "wb") as verf:
+                                            inf_str = str(variant["version"])+" "+str(variant["hash"])
+                                            verf.write(inf_str.encode("utf-8"))
+
+                                except Exception as e:
+                                    RNS.log("Error while trying custom URL: "+str(e))
+                                    raise e
+                            else:
                                 urlretrieve(firmware_version_url+fw_filename, UPD_DIR+"/"+fw_filename+".version.latest")
                         except Exception as e:
+                            # if custom firmware url, don't fallback
+                            if fw_url != None:
+                                RNS.log("Failed to retrive latest version information for your board from the specified url.")
+                                RNS.log("Check your internet connection and try again.")
+                                RNS.log("If you don't have Internet access currently, use the --fw-version option to manually specify a version.")
+                                RNS.log("You can also use --extract to copy the firmware from a known-good RNode of the same model.")
+                                exit()
+
                             RNS.log("")
                             RNS.log("WARNING!")
                             RNS.log("Failed to retrieve latest version information for your board from the default server")
@@ -1051,6 +1077,11 @@ def ensure_firmware_file(fw_filename):
                     RNS.log("use the --fw-version option to manually specify a version.")
                     exit(98)
 
+            # if custom firmware url, use it
+            if fw_url != None:
+                update_target_url = fw_url+"download/"+selected_version+"/"+fw_filename
+                RNS.log("Retrieving firmware from custom url "+update_target_url)
+            else:
                 update_target_url = firmware_update_url+selected_version+"/"+fw_filename
 
             try:
@@ -1128,7 +1159,7 @@ device_signer = None
 force_update = False
 upd_nocheck = False
 def main():
-    global mapped_product, mapped_model, fw_filename, selected_version, force_update, upd_nocheck, device_signer
+    global mapped_product, mapped_model, fw_filename, fw_url, selected_version, force_update, upd_nocheck, device_signer
 
     try:
         if not util.find_spec("serial"):
@@ -1160,6 +1191,7 @@ def main():
         parser.add_argument("-u", "--update", action="store_true", help="Update firmware to the latest version")
         parser.add_argument("-U", "--force-update", action="store_true", help="Update to specified firmware even if version matches or is older than installed version")
         parser.add_argument("--fw-version", action="store", metavar="version", default=None, help="Use a specific firmware version for update or autoinstall")
+        parser.add_argument("--fw-url", action="store", metavar="url", default=None, help="Use an alternate firmware download URL")
         parser.add_argument("--nocheck", action="store_true", help="Don't check for firmware updates online")
         parser.add_argument("-e", "--extract", action="store_true", help="Extract firmware from connected RNode for later use")
         parser.add_argument("-E", "--use-extracted", action="store_true", help="Use the extracted firmware for autoinstallation or update")
@@ -1232,6 +1264,9 @@ def main():
                 RNS.log("Selected version \""+selected_version+"\" does not appear to be a number.")
                 exit()
 
+        if args.fw_url != None:
+            fw_url = args.fw_url
+
         if args.force_update:
             force_update = True