http¶

Name¶

http — Central server for RPC and the message database

Synopsis¶

http [-c config]

Description¶

http(8gx) is a trivial HTTP server. It understands the special HTTP methods as used by RPC-over-HTTP protocol as used by Outlook, it can serve files verbatim, or forward requests to a FastCGI server such as php-fpm(8).

Options¶

-c config: Read configuration directives from the given file. If this option is not specified, /etc/gromox/http.cfg will be read if it exists.
-?: Display option summary.

URI processing order¶

Requests are passed to the mod_rewrite(4gx) module (built-in) to have their URI potentially rewritten.
If a HTTP request is using the methods RPC_IN_DATA or RPC_OUT_DATA, the data stream is handed off to the exchange_emsmdb(4gx) plugin.
Otherwise, HTTP processing modules (HPM) are invoked. Processing ends when one module signals that the request was handled. The order depends on the HPM list (which is fixed): mh_emsmdb, mh_nsp.
Otherwise, the mod_fastcgi(4gx) module (built-in) is invoked. Processing ends if the module handled the request.
Otherwise, the mod_cache(4gx) module (built-in) is invoked. Processing ends if the module handled the request.
Otherwise, the request is rejected.

RPC-over-HTTP¶

RPC-over-HTTP utilizes two special HTTP methods, RPC_IN_DATA and RPC_OUT_DATA. These requests can, similarly to HTTP CONNECT, be very long-lived. The RPC data stream is handled by the included exchange_emsmdb(4gx) plugin.

Configuration directives¶

The usual config file location is /etc/gromox/http.cfg.

block_interval_auths: The amount of time a user is blocked from connecting to the service after too many failed logins.

Default: 1 minute
config_file_path: Colon-separated list of directories which will be scanned when locating further configuration files, especially those used by plugin instances.

Default: /etc/gromox/http:/etc/gromox
context_average_mem: Default: 256K
context_num: Default: 400
data_file_path: Colon-separated list of directories which will be scanned when locating data files.

Default: /usr/share/gromox/http
fastcgi_cache_size: If the HTTP request to a CGI endpoint uses Chunked Transfer Encoding and the Content-Length field contains a larger value than this limit, the data is buffered in a file.

Default: 256K
fastcgi_exec_timeout: Maximum execution time for CGI scripts.

Default: 10 minutes
fastcgi_max_size: If the Content-Length of a HTTP request to a CGI endpoint is larger than this value, the request is rejected.

Default: 4M
host_id: A unique identifier for this system. It is used for the Server HTTP responses header, for service plugins like exmdb_provider(4gx), which makes use of it for SMTP HELO lines, for DSN report texts, for MIDB database/EML cache. The identifier should only use characters allowed for hostnames.

Default: (system hostname)
hpm_cache_size: If the HTTP request to a HPM endpoint uses Chunked Transfer Encoding or the Content-Length field contains a larger value than this limit, the data is buffered in a file /tmp/http-%d (%d replaced by internal context id).

Default: 512K
hpm_max_size: If the Content-Length of a HTTP request to a HPM endpoint is larger than this value, the request is rejected.

Default: 4M
http_auth_times: The number of login tries a user is allowed before the account is blocked.

Default: 10
http_certificate_passwd: The password to unlock TLS certificates.

Default: (unset)
http_certificate_path: Filesystem path to a certificate file for use with encrypted connections. The complete certificate chain should be present (as there is no other config directive to pull CA certs in).

Default: (unset)
http_conn_timeout: If a HTTP connection stalls for the given period, the connection is terminated.

Default: 3 minutes
http_debug: If set to 1, prints all incoming and outgoing HTTP traffic to stderr.

Default: 0
http_listen_addr: AF_INET6 socket address to bind the HTTP service to.

Default: ::
http_listen_port: The TCP port to expose the HTTP protocol service on.

Default: 80
http_listen_tls_port: The TCP port to expose implicit-TLS HTTP protocol service (HTTPS) on.

Default: (unset)
http_log_file: Target for log messages here. Special values: "-" (stderr/syslog depending on parent PID) or "syslog" are recognized.

Default: - (auto)
http_log_level: Maximum verbosity of logging. 1=crit, 2=error, 3=warn, 4=notice, 5=info, 6=debug.

Default: 4 (notice)
http_private_key_path: Filesystem path to the key file needed to unlock the TLS certificate.

Default: (unset)
http_support_tls: This flag controls whether (or not) the server offers TLS at all. The default is false because you need a certificate for this first.

Default: false
http_thread_charge_num: The maximum number of connections that each thread is allowed to process.

Default: 20
http_thread_init_num: The minimum number of client processing threads to keep around.

Default: 5
msrpc_debug: Log every completed RPC call and the return code of the operation in a minimal fashion to stderr. Level 1 emits RPCs with a failure return code, level 2 emits all RPCs. Note the daemon log level needs to be "debug" (6), too.

Default: 0
request_max_mem: The maximum hint size for fragmented RPC PDU requests that will be allowed (C706 §12.6.3.7, MS-RPCE v33 §2.2.2.6).
tls_min_proto: The lowest TLS version to offer. Possible values are: tls1.0, tls1.1, tls1.2, and, if supported by the system, tls1.3.

Default: tls1.2
running_identity: An unprivileged user account to switch the process to after startup. To inhibit the switch, assign the empty value.

Default: gromox
state_path: Directory for runtime variadic data.

Default: /var/lib/gromox
tcp_mss_size: Sets the TCP_MAXSEG socket option with the given MSS value for the listening socket(s), cf. tcp(7).

Default: 0 (do not limit the MSS)
user_default_lang: Default: en

Files¶

/usr/lib/gromox/libgxh_*.so: HTTP processing plugins
/usr/lib/gromox/libgxp_*.so: PDU processing plugins
/usr/lib/gromox/libgxs_*.so: service plugins

Normative references¶

MS-RPCE: Remote Procedure Call Protocol Extensions
DCERPC / C706: Technical Standard DCE 1.1: Remote Procedure Call by The Open Group, 1997