http: Fix WebSockets with Firefox

[ac000]

    http: Fix WebSockets with Firefox
    
    Firefox (going back a couple of years at least) was unable to open a
    WebSocket connection to Unit due to it sending a Connection header of
    
      Connection: keep-alive, Upgrade
    
    However in Unit we were expecting only a single value in the header.
    
    Fix the 'Connection' parsing in nxt_h1p_connection() to address this.
    
    Closes: https://github.com/nginx/unit/issues/772
    Signed-off-by: Andrew Clayton <[email protected]>

[hongzhidao]

Hi @ac000,
It seems it only works for WS, then do we need to check if the header “Upgrader: websocket” exists?

[ac000]

True, as the code currently stands we are assuming that we only upgrade to websockets.

I guess strictly speaking we should check that's the case... but I would probably do that as a separate patch to this as this patch simply fixes the problem of determining if we are upgrading the connection.

[ac000]

@hongzhidao

Actually we do already check the Upgrade header for websocket in nxt_h1p_upgrade() where we set r->proto.h1->upgrade_websocket = 1 if it's found.

If we find upgrade in the Connection header we set r->proto.h1->connection_upgrade = 1

This combination is then checked for in nxt_h1p_header_process()

if (h1p->connection_upgrade && h1p->upgrade_websocket) {

So I think we're all good, right?

[hongzhidao]

Correct.
Btw, is there any other case like “upgrade, close”?
And I feel it's necessary to check the value strictly. I mean we need to check the value like Connection: xkeep-alive, xUpgrade.

[ac000]

Not sure it makes a lot of sense, but sure, we can do that...

[ac000]

• Check for 'close' the same way we do for the others...

$ git range-diff b844e40a...aede3ed6
1:  b844e40a ! 1:  aede3ed6 http: Fix WebSockets with Firefox
    @@ Metadata
      ## Commit message ##
         http: Fix WebSockets with Firefox
     
    -    Firefox (134 at least) was unable to open a WebSocket connection to Unit
    -    due to it sending a Connection header of
    +    Firefox (going back a couple of years at least) was unable to open a
    +    WebSocket connection to Unit due to it sending a Connection header of
     
           Connection: keep-alive, Upgrade
     
    @@ Commit message
     
         Fix the 'Connection' parsing in nxt_h1p_connection() to address this.
     
    -    We keep the check for 'close' basically the same as that really should
    -    be the only value.
    -
    -    Then we check for both of 'keep-alive' and 'upgrade'.
    -
         Closes: https://github.com/nginx/unit/issues/772
         Signed-off-by: Andrew Clayton <[email protected]>
     
    @@ src/nxt_h1proto.c: nxt_h1p_header_buffer_test(nxt_task_t *task, nxt_h1proto_t *h
          nxt_http_request_t  *r;
      
          r = ctx;
    -@@ src/nxt_h1proto.c: nxt_h1p_connection(void *ctx, nxt_http_field_t *field, uintptr_t data)
    -         && nxt_memcasecmp(field->value, "close", 5) == 0)
    -     {
    +     field->hopbyhop = 1;
    + 
    +-    if (field->value_length == 5
    +-        && nxt_memcasecmp(field->value, "close", 5) == 0)
    +-    {
    ++    end = field->value + field->value_length;
    ++
    ++    if (nxt_memcasestrn(field->value, end, "close", 5) != NULL) {
              r->proto.h1->keepalive = 0;
    -+        return NXT_OK;
     +    }
      
     -    } else if (field->value_length == 10
     -               && nxt_memcasecmp(field->value, "keep-alive", 10) == 0)
     -    {
    -+    end = field->value + field->value_length;
    -+
     +    if (nxt_memcasestrn(field->value, end, "keep-alive", 10) != NULL) {
              r->proto.h1->keepalive = 1;
     +    }