HTTP/3: generate more H3_FRAME_UNEXPECTED. As per quic-http-34, these are the cases when this error should be generated: If an endpoint receives a second SETTINGS frame on the control stream, the endpoint MUST respond with a connection error of type H3_FRAME_UNEXPECTED SETTINGS frames MUST NOT be sent on any stream other than the control stream. If an endpoint receives a SETTINGS frame on a different stream, the endpoint MUST respond with a connection error of type H3_FRAME_UNEXPECTED. A client MUST NOT send a PUSH_PROMISE frame. A server MUST treat the receipt of a PUSH_PROMISE frame as a connection error of type H3_FRAME_UNEXPECTED; see Section 8. The MAX_PUSH_ID frame is always sent on the control stream. Receipt of a MAX_PUSH_ID frame on any other stream MUST be treated as a connection error of type H3_FRAME_UNEXPECTED. Receipt of an invalid sequence of frames MUST be treated as a connection error of type H3_FRAME_UNEXPECTED; see Section 8. In particular, a DATA frame before any HEADERS frame, or a HEADERS or DATA frame after the trailing HEADERS frame, is considered invalid. A CANCEL_PUSH frame is sent on the control stream. Receiving a CANCEL_PUSH frame on a stream other than the control stream MUST be treated as a connection error of type H3_FRAME_UNEXPECTED. The GOAWAY frame is always sent on the control stream.

/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 */


#include <ngx_config.h>
#include <ngx_core.h>


u_char  ngx_linux_kern_ostype[50];
u_char  ngx_linux_kern_osrelease[50];


static ngx_os_io_t ngx_linux_io = {
    ngx_unix_recv,
    ngx_readv_chain,
    ngx_udp_unix_recv,
    ngx_unix_send,
    ngx_udp_unix_send,
    ngx_udp_unix_sendmsg_chain,
#if (NGX_HAVE_SENDFILE)
    ngx_linux_sendfile_chain,
    NGX_IO_SENDFILE
#else
    ngx_writev_chain,
    0
#endif
};


ngx_int_t
ngx_os_specific_init(ngx_log_t *log)
{
    struct utsname  u;

    if (uname(&u) == -1) {
        ngx_log_error(NGX_LOG_ALERT, log, ngx_errno, "uname() failed");
        return NGX_ERROR;
    }

    (void) ngx_cpystrn(ngx_linux_kern_ostype, (u_char *) u.sysname,
                       sizeof(ngx_linux_kern_ostype));

    (void) ngx_cpystrn(ngx_linux_kern_osrelease, (u_char *) u.release,
                       sizeof(ngx_linux_kern_osrelease));

    ngx_os_io = ngx_linux_io;

    return NGX_OK;
}


void
ngx_os_specific_status(ngx_log_t *log)
{
    ngx_log_error(NGX_LOG_NOTICE, log, 0, "OS: %s %s",
                  ngx_linux_kern_ostype, ngx_linux_kern_osrelease);
}