Re: [lwip-users] Download a file for firmware upgrade

[Giuseppe Modugno]

Il 21/05/2018 14:26, Sergio R. Caprile ha scritto:
> You can do whatever you want.
> The question is probably not what can you do but what do you have
> available to obtain what you need with lesser effort.
> There are FTP clients around, I've collaborated in one of them using the
> RAW API, search the list.
> FTP is sometimes tricky and can give you some headaches with firewalls
> (and/or admins).
> For HTTP you need a client. I wouldn't just GET and hope everything is
> fine unless I can manage both ends (that means: the server too) and
> guarantee there won't be other stuff than my file. 

I couldn't understand your concerns about a minimalistic HTTP client 
that opens that TCP connection, sends the GET request and wait for the 
response (as Ajay suggested).

> A HTTP client can be quite complicated, but you just need to get one
> resource at a specific URI

I know a full HTTP client is a very complex piece of code, but I only 
need to download a specific URI.


> You can even have a proprietary protocol running over TCP or UDP. If
> your device will be sold and installed on corporate networks, you might
> raise some concern among the net admins, asking to have open holes in
> the firewall does not seem to be a good way to make friends.

I know, but I'd prefer to avoid this approach.


> My bet is to go for the user to upload the file, leveraging your web
> server; 

This is a good suggestion.  However the original question arises again: 
how to upload a file to the Web server?  Should I use Javascript/jQuery 
to choose and send a local file to httpd through POST method (that I'm 
not actually using)?


> but if you must go out and get it, then perhaps FTP is the
> easiest full client and HTTP is the simplest firewall piercing. 

I think a minimalistic HTTP GET request should be enough.


> I don't
> know if there are running clients around. Particularly for your API,
> which you don't say. (I'm intentionally not considering TFTP for going
> out because of the possible firewall issue, but if it is your network,
> there is a client already available)

No, the firmware binary file will be on the public Internet and the 
device will be behind a NAT router... usually.