What causes "http req line fail:%s" in XX-net/XX-Net?

Inspect the logged req_line to see the raw bytes the client sent

http req line fail:%s

Error message

http req line fail:%s

What it means

The plain-HTTP request line did not contain 2 or 3 whitespace-separated tokens, so method/url extraction failed and the request is dropped.

Source

Thrown at code/default/smart_router/local/proxy_handler.py:344

        # xlog.debug("https %r connect to %s:%d", self.client_address, host, port)
        sock.send(b'HTTP/1.1 200 OK\r\n\r\n')

        handle_domain_proxy(sock, host, port, self.client_address)

    def http_handler(self):
        req_data = self.conn.recv(65537, socket.MSG_PEEK)
        rp = req_data.split(b"\r\n")
        req_line = rp[0]

        words = req_line.split()
        if len(words) == 3:
            method, url, http_version = words
        elif len(words) == 2:
            method, url = words
            http_version = b"HTTP/1.1"
        else:
            xlog.warn("http req line fail:%s", req_line)
            return

        if url.lower().startswith(b"http://"):
            o = urlparse(url)
            host, port = netloc_to_host_port(o.netloc)

            url_prex_len = url[7:].find(b"/")
            if url_prex_len >= 0:
                url_prex_len += 7
                path = url[url_prex_len:]
            else:
                url_prex_len = len(url)
                path = b"/"
        else:
            # not proxy request
            parsed_url = urlparse(utils.to_str(url))
            kv = parse_qs(parsed_url.query)
            if parsed_url.path == "/dns-query":

View on GitHub (pinned to cfa5bc17b6)

Solutions

Inspect the logged req_line to see the raw bytes the client sent
Verify the client actually speaks HTTP on this port (not TLS bytes)
Fix client request formatting / add proper CRLF line endings

Defensive patterns

Strategy: validation

Validate before calling

tokens = req_line.split(); assert 2 <= len(tokens) <= 3

Type guard

def is_http_request_line(l):
    t = l.split()
    return len(t) in (2,3) and t[0].isalpha()

Prevention

Never send TLS bytes to a plain HTTP port
Use real HTTP client libraries

When it happens

Trigger: Malformed first line such as 'GET' with no path, binary garbage, or a request missing HTTP version delimiters.

Common situations: Health probes or scanners sending non-HTTP bytes, broken clients, encoding corruption, or an HTTPS handshake reaching the HTTP handler.

Related errors

AI-assisted analysis of XX-net/XX-Net@cfa5bc17b6 (2026-08-27). Data as JSON: /api/errors/a6d045b50d52fcac. Report an issue: GitHub.