Patrick Welche <prlw1@cam.ac.uk>

[netbsd-mini2440.git] / external / ibm-public / postfix / dist / src / smtp / smtp.c

/*      $NetBSD$        */

/*++
/* NAME
/*      smtp 8
/* SUMMARY
/*      Postfix SMTP+LMTP client
/* SYNOPSIS
/*      \fBsmtp\fR [generic Postfix daemon options]
/* DESCRIPTION
/*      The Postfix SMTP+LMTP client implements the SMTP and LMTP mail
/*      delivery protocols. It processes message delivery requests from
/*      the queue manager. Each request specifies a queue file, a sender
/*      address, a domain or host to deliver to, and recipient information.
/*      This program expects to be run from the \fBmaster\fR(8) process
/*      manager.
/*
/*      The SMTP+LMTP client updates the queue file and marks recipients
/*      as finished, or it informs the queue manager that delivery should
/*      be tried again at a later time. Delivery status reports are sent
/*      to the \fBbounce\fR(8), \fBdefer\fR(8) or \fBtrace\fR(8) daemon as
/*      appropriate.
/*
/*      The SMTP+LMTP client looks up a list of mail exchanger addresses for
/*      the destination host, sorts the list by preference, and connects
/*      to each listed address until it finds a server that responds.
/*
/*      When a server is not reachable, or when mail delivery fails due
/*      to a recoverable error condition, the SMTP+LMTP client will try to
/*      deliver the mail to an alternate host.
/*
/*      After a successful mail transaction, a connection may be saved
/*      to the \fBscache\fR(8) connection cache server, so that it
/*      may be used by any SMTP+LMTP client for a subsequent transaction.
/*
/*      By default, connection caching is enabled temporarily for
/*      destinations that have a high volume of mail in the active
/*      queue. Connection caching can be enabled permanently for
/*      specific destinations.
/* SMTP DESTINATION SYNTAX
/* .ad
/* .fi
/*      SMTP destinations have the following form:
/* .IP \fIdomainname\fR
/* .IP \fIdomainname\fR:\fIport\fR
/*      Look up the mail exchangers for the specified domain, and
/*      connect to the specified port (default: \fBsmtp\fR).
/* .IP [\fIhostname\fR]
/* .IP [\fIhostname\fR]:\fIport\fR
/*      Look up the address(es) of the specified host, and connect to
/*      the specified port (default: \fBsmtp\fR).
/* .IP [\fIaddress\fR]
/* .IP [\fIaddress\fR]:\fIport\fR
/*      Connect to the host at the specified address, and connect
/*      to the specified port (default: \fBsmtp\fR). An IPv6 address
/*      must be formatted as [\fBipv6\fR:\fIaddress\fR].
/* LMTP DESTINATION SYNTAX
/* .ad
/* .fi
/*      LMTP destinations have the following form:
/* .IP \fBunix\fR:\fIpathname\fR
/*      Connect to the local UNIX-domain server that is bound to the specified
/*      \fIpathname\fR. If the process runs chrooted, an absolute pathname
/*      is interpreted relative to the Postfix queue directory.
/* .IP \fBinet\fR:\fIhostname\fR
/* .IP \fBinet\fB:\fIhostname\fR:\fIport\fR
/* .IP \fBinet\fR:[\fIaddress\fR]
/* .IP \fBinet\fR:[\fIaddress\fR]:\fIport\fR
/*      Connect to the specified TCP port on the specified local or
/*      remote host. If no port is specified, connect to the port defined as
/*      \fBlmtp\fR in \fBservices\fR(4).
/*      If no such service is found, the \fBlmtp_tcp_port\fR configuration
/*      parameter (default value of 24) will be used.
/*      An IPv6 address must be formatted as [\fBipv6\fR:\fIaddress\fR].
/* .PP
/* SECURITY
/* .ad
/* .fi
/*      The SMTP+LMTP client is moderately security-sensitive. It
/*      talks to SMTP or LMTP servers and to DNS servers on the
/*      network. The SMTP+LMTP client can be run chrooted at fixed
/*      low privilege.
/* STANDARDS
/*      RFC 821 (SMTP protocol)
/*      RFC 822 (ARPA Internet Text Messages)
/*      RFC 1651 (SMTP service extensions)
/*      RFC 1652 (8bit-MIME transport)
/*      RFC 1870 (Message Size Declaration)
/*      RFC 2033 (LMTP protocol)
/*      RFC 2034 (SMTP Enhanced Error Codes)
/*      RFC 2045 (MIME: Format of Internet Message Bodies)
/*      RFC 2046 (MIME: Media Types)
/*      RFC 2554 (AUTH command)
/*      RFC 2821 (SMTP protocol)
/*      RFC 2920 (SMTP Pipelining)
/*      RFC 3207 (STARTTLS command)
/*      RFC 3461 (SMTP DSN Extension)
/*      RFC 3463 (Enhanced Status Codes)
/*      RFC 4954 (AUTH command)
/* DIAGNOSTICS
/*      Problems and transactions are logged to \fBsyslogd\fR(8).
/*      Corrupted message files are marked so that the queue manager can
/*      move them to the \fBcorrupt\fR queue for further inspection.
/*
/*      Depending on the setting of the \fBnotify_classes\fR parameter,
/*      the postmaster is notified of bounces, protocol problems, and of
/*      other trouble.
/* BUGS
/*      SMTP and LMTP connection caching does not work with TLS. The necessary
/*      support for TLS object passivation and re-activation does not
/*      exist without closing the session, which defeats the purpose.
/*
/*      SMTP and LMTP connection caching assumes that SASL credentials
/*      are valid for all destinations that map onto the same IP
/*      address and TCP port.
/* CONFIGURATION PARAMETERS
/* .ad
/* .fi
/*      Before Postfix version 2.3, the LMTP client is a separate
/*      program that implements only a subset of the functionality
/*      available with SMTP: there is no support for TLS, and
/*      connections are cached in-process, making it ineffective
/*      when the client is used for multiple domains.
/*
/*      Most smtp_\fIxxx\fR configuration parameters have an
/*      lmtp_\fIxxx\fR "mirror" parameter for the equivalent LMTP
/*      feature. This document describes only those LMTP-related
/*      parameters that aren't simply "mirror" parameters.
/*
/*      Changes to \fBmain.cf\fR are picked up automatically, as \fBsmtp\fR(8)
/*      processes run for only a limited amount of time. Use the command
/*      "\fBpostfix reload\fR" to speed up a change.
/*
/*      The text below provides only a parameter summary. See
/*      \fBpostconf\fR(5) for more details including examples.
/* COMPATIBILITY CONTROLS
/* .ad
/* .fi
/* .IP "\fBignore_mx_lookup_error (no)\fR"
/*      Ignore DNS MX lookups that produce no response.
/* .IP "\fBsmtp_always_send_ehlo (yes)\fR"
/*      Always send EHLO at the start of an SMTP session.
/* .IP "\fBsmtp_never_send_ehlo (no)\fR"
/*      Never send EHLO at the start of an SMTP session.
/* .IP "\fBsmtp_defer_if_no_mx_address_found (no)\fR"
/*      Defer mail delivery when no MX record resolves to an IP address.
/* .IP "\fBsmtp_line_length_limit (990)\fR"
/*      The maximal length of message header and body lines that Postfix
/*      will send via SMTP.
/* .IP "\fBsmtp_pix_workaround_delay_time (10s)\fR"
/*      How long the Postfix SMTP client pauses before sending
/*      ".<CR><LF>" in order to work around the PIX firewall
/*      "<CR><LF>.<CR><LF>" bug.
/* .IP "\fBsmtp_pix_workaround_threshold_time (500s)\fR"
/*      How long a message must be queued before the Postfix SMTP client
/*      turns on the PIX firewall "<CR><LF>.<CR><LF>"
/*      bug workaround for delivery through firewalls with "smtp fixup"
/*      mode turned on.
/* .IP "\fBsmtp_pix_workarounds (disable_esmtp, delay_dotcrlf)\fR"
/*      A list that specifies zero or more workarounds for CISCO PIX
/*      firewall bugs.
/* .IP "\fBsmtp_pix_workaround_maps (empty)\fR"
/*      Lookup tables, indexed by the remote SMTP server address, with
/*      per-destination workarounds for CISCO PIX firewall bugs.
/* .IP "\fBsmtp_quote_rfc821_envelope (yes)\fR"
/*      Quote addresses in SMTP MAIL FROM and RCPT TO commands as required
/*      by RFC 2821.
/* .IP "\fBsmtp_skip_5xx_greeting (yes)\fR"
/*      Skip SMTP servers that greet with a 5XX status code (go away, do
/*      not try again later).
/* .IP "\fBsmtp_skip_quit_response (yes)\fR"
/*      Do not wait for the response to the SMTP QUIT command.
/* .PP
/*      Available in Postfix version 2.0 and earlier:
/* .IP "\fBsmtp_skip_4xx_greeting (yes)\fR"
/*      Skip SMTP servers that greet with a 4XX status code (go away, try
/*      again later).
/* .PP
/*      Available in Postfix version 2.2 and later:
/* .IP "\fBsmtp_discard_ehlo_keyword_address_maps (empty)\fR"
/*      Lookup tables, indexed by the remote SMTP server address, with
/*      case insensitive lists of EHLO keywords (pipelining, starttls, auth,
/*      etc.) that the Postfix SMTP client will ignore in the EHLO response from a
/*      remote SMTP server.
/* .IP "\fBsmtp_discard_ehlo_keywords (empty)\fR"
/*      A case insensitive list of EHLO keywords (pipelining, starttls,
/*      auth, etc.) that the Postfix SMTP client will ignore in the EHLO
/*      response from a remote SMTP server.
/* .IP "\fBsmtp_generic_maps (empty)\fR"
/*      Optional lookup tables that perform address rewriting in the
/*      SMTP client, typically to transform a locally valid address into
/*      a globally valid address when sending mail across the Internet.
/* .PP
/*      Available in Postfix version 2.2.9 and later:
/* .IP "\fBsmtp_cname_overrides_servername (version dependent)\fR"
/*      Allow DNS CNAME records to override the servername that the
/*      Postfix SMTP client uses for logging, SASL password lookup, TLS
/*      policy decisions, or TLS certificate verification.
/* .PP
/*      Available in Postfix version 2.3 and later:
/* .IP "\fBlmtp_discard_lhlo_keyword_address_maps (empty)\fR"
/*      Lookup tables, indexed by the remote LMTP server address, with
/*      case insensitive lists of LHLO keywords (pipelining, starttls,
/*      auth, etc.) that the LMTP client will ignore in the LHLO response
/*      from a remote LMTP server.
/* .IP "\fBlmtp_discard_lhlo_keywords (empty)\fR"
/*      A case insensitive list of LHLO keywords (pipelining, starttls,
/*      auth, etc.) that the LMTP client will ignore in the LHLO response
/*      from a remote LMTP server.
/* .PP
/*      Available in Postfix version 2.4.4 and later:
/* .IP "\fBsend_cyrus_sasl_authzid (no)\fR"
/*      When authenticating to a remote SMTP or LMTP server with the
/*      default setting "no", send no SASL authoriZation ID (authzid); send
/*      only the SASL authentiCation ID (authcid) plus the authcid's password.
/* .PP
/*      Available in Postfix version 2.5 and later:
/* .IP "\fBsmtp_header_checks (empty)\fR"
/*      Restricted \fBheader_checks\fR(5) tables for the Postfix SMTP client.
/* .IP "\fBsmtp_mime_header_checks (empty)\fR"
/*      Restricted \fBmime_header_checks\fR(5) tables for the Postfix SMTP
/*      client.
/* .IP "\fBsmtp_nested_header_checks (empty)\fR"
/*      Restricted \fBnested_header_checks\fR(5) tables for the Postfix SMTP
/*      client.
/* .IP "\fBsmtp_body_checks (empty)\fR"
/*      Restricted \fBbody_checks\fR(5) tables for the Postfix SMTP client.
/* .PP
/*      Available in Postfix version 2.6 and later:
/* .IP "\fBtcp_windowsize (0)\fR"
/*      An optional workaround for routers that break TCP window scaling.
/* MIME PROCESSING CONTROLS
/* .ad
/* .fi
/*      Available in Postfix version 2.0 and later:
/* .IP "\fBdisable_mime_output_conversion (no)\fR"
/*      Disable the conversion of 8BITMIME format to 7BIT format.
/* .IP "\fBmime_boundary_length_limit (2048)\fR"
/*      The maximal length of MIME multipart boundary strings.
/* .IP "\fBmime_nesting_limit (100)\fR"
/*      The maximal recursion level that the MIME processor will handle.
/* EXTERNAL CONTENT INSPECTION CONTROLS
/* .ad
/* .fi
/*      Available in Postfix version 2.1 and later:
/* .IP "\fBsmtp_send_xforward_command (no)\fR"
/*      Send the non-standard XFORWARD command when the Postfix SMTP server
/*      EHLO response announces XFORWARD support.
/* SASL AUTHENTICATION CONTROLS
/* .ad
/* .fi
/* .IP "\fBsmtp_sasl_auth_enable (no)\fR"
/*      Enable SASL authentication in the Postfix SMTP client.
/* .IP "\fBsmtp_sasl_password_maps (empty)\fR"
/*      Optional SMTP client lookup tables with one username:password entry
/*      per remote hostname or domain, or sender address when sender-dependent
/*      authentication is enabled.
/* .IP "\fBsmtp_sasl_security_options (noplaintext, noanonymous)\fR"
/*      Postfix SMTP client SASL security options; as of Postfix 2.3
/*      the list of available
/*      features depends on the SASL client implementation that is selected
/*      with \fBsmtp_sasl_type\fR.
/* .PP
/*      Available in Postfix version 2.2 and later:
/* .IP "\fBsmtp_sasl_mechanism_filter (empty)\fR"
/*      If non-empty, a Postfix SMTP client filter for the remote SMTP
/*      server's list of offered SASL mechanisms.
/* .PP
/*      Available in Postfix version 2.3 and later:
/* .IP "\fBsmtp_sender_dependent_authentication (no)\fR"
/*      Enable sender-dependent authentication in the Postfix SMTP client; this is
/*      available only with SASL authentication, and disables SMTP connection
/*      caching to ensure that mail from different senders will use the
/*      appropriate credentials.
/* .IP "\fBsmtp_sasl_path (empty)\fR"
/*      Implementation-specific information that the Postfix SMTP client
/*      passes through to
/*      the SASL plug-in implementation that is selected with
/*      \fBsmtp_sasl_type\fR.
/* .IP "\fBsmtp_sasl_type (cyrus)\fR"
/*      The SASL plug-in type that the Postfix SMTP client should use
/*      for authentication.
/* .PP
/*      Available in Postfix version 2.5 and later:
/* .IP "\fBsmtp_sasl_auth_cache_name (empty)\fR"
/*      An optional table to prevent repeated SASL authentication
/*      failures with the same remote SMTP server hostname, username and
/*      password.
/* .IP "\fBsmtp_sasl_auth_cache_time (90d)\fR"
/*      The maximal age of an smtp_sasl_auth_cache_name entry before it
/*      is removed.
/* .IP "\fBsmtp_sasl_auth_soft_bounce (yes)\fR"
/*      When a remote SMTP server rejects a SASL authentication request
/*      with a 535 reply code, defer mail delivery instead of returning
/*      mail as undeliverable.
/* STARTTLS SUPPORT CONTROLS
/* .ad
/* .fi
/*      Detailed information about STARTTLS configuration may be found
/*      in the TLS_README document.
/* .IP "\fBsmtp_tls_security_level (empty)\fR"
/*      The default SMTP TLS security level for the Postfix SMTP client;
/*      when a non-empty value is specified, this overrides the obsolete
/*      parameters smtp_use_tls, smtp_enforce_tls, and smtp_tls_enforce_peername.
/* .IP "\fBsmtp_sasl_tls_security_options ($smtp_sasl_security_options)\fR"
/*      The SASL authentication security options that the Postfix SMTP
/*      client uses for TLS encrypted SMTP sessions.
/* .IP "\fBsmtp_starttls_timeout (300s)\fR"
/*      Time limit for Postfix SMTP client write and read operations
/*      during TLS startup and shutdown handshake procedures.
/* .IP "\fBsmtp_tls_CAfile (empty)\fR"
/*      A file containing CA certificates of root CAs trusted to sign
/*      either remote SMTP server certificates or intermediate CA certificates.
/* .IP "\fBsmtp_tls_CApath (empty)\fR"
/*      Directory with PEM format certificate authority certificates
/*      that the Postfix SMTP client uses to verify a remote SMTP server
/*      certificate.
/* .IP "\fBsmtp_tls_cert_file (empty)\fR"
/*      File with the Postfix SMTP client RSA certificate in PEM format.
/* .IP "\fBsmtp_tls_mandatory_ciphers (medium)\fR"
/*      The minimum TLS cipher grade that the Postfix SMTP client will
/*      use with
/*      mandatory TLS encryption.
/* .IP "\fBsmtp_tls_exclude_ciphers (empty)\fR"
/*      List of ciphers or cipher types to exclude from the Postfix
/*      SMTP client cipher
/*      list at all TLS security levels.
/* .IP "\fBsmtp_tls_mandatory_exclude_ciphers (empty)\fR"
/*      Additional list of ciphers or cipher types to exclude from the
/*      SMTP client cipher list at mandatory TLS security levels.
/* .IP "\fBsmtp_tls_dcert_file (empty)\fR"
/*      File with the Postfix SMTP client DSA certificate in PEM format.
/* .IP "\fBsmtp_tls_dkey_file ($smtp_tls_dcert_file)\fR"
/*      File with the Postfix SMTP client DSA private key in PEM format.
/* .IP "\fBsmtp_tls_key_file ($smtp_tls_cert_file)\fR"
/*      File with the Postfix SMTP client RSA private key in PEM format.
/* .IP "\fBsmtp_tls_loglevel (0)\fR"
/*      Enable additional Postfix SMTP client logging of TLS activity.
/* .IP "\fBsmtp_tls_note_starttls_offer (no)\fR"
/*      Log the hostname of a remote SMTP server that offers STARTTLS,
/*      when TLS is not already enabled for that server.
/* .IP "\fBsmtp_tls_policy_maps (empty)\fR"
/*      Optional lookup tables with the Postfix SMTP client TLS security
/*      policy by next-hop destination; when a non-empty value is specified,
/*      this overrides the obsolete smtp_tls_per_site parameter.
/* .IP "\fBsmtp_tls_mandatory_protocols (SSLv3, TLSv1)\fR"
/*      List of SSL/TLS protocols that the Postfix SMTP client will use with
/*      mandatory TLS encryption.
/* .IP "\fBsmtp_tls_scert_verifydepth (9)\fR"
/*      The verification depth for remote SMTP server certificates.
/* .IP "\fBsmtp_tls_secure_cert_match (nexthop, dot-nexthop)\fR"
/*      The server certificate peername verification method for the
/*      "secure" TLS security level.
/* .IP "\fBsmtp_tls_session_cache_database (empty)\fR"
/*      Name of the file containing the optional Postfix SMTP client
/*      TLS session cache.
/* .IP "\fBsmtp_tls_session_cache_timeout (3600s)\fR"
/*      The expiration time of Postfix SMTP client TLS session cache
/*      information.
/* .IP "\fBsmtp_tls_verify_cert_match (hostname)\fR"
/*      The server certificate peername verification method for the
/*      "verify" TLS security level.
/* .IP "\fBtls_daemon_random_bytes (32)\fR"
/*      The number of pseudo-random bytes that an \fBsmtp\fR(8) or \fBsmtpd\fR(8)
/*      process requests from the \fBtlsmgr\fR(8) server in order to seed its
/*      internal pseudo random number generator (PRNG).
/* .IP "\fBtls_high_cipherlist (ALL:!EXPORT:!LOW:!MEDIUM:+RC4:@STRENGTH)\fR"
/*      The OpenSSL cipherlist for "HIGH" grade ciphers.
/* .IP "\fBtls_medium_cipherlist (ALL:!EXPORT:!LOW:+RC4:@STRENGTH)\fR"
/*      The OpenSSL cipherlist for "MEDIUM" or higher grade ciphers.
/* .IP "\fBtls_low_cipherlist (ALL:!EXPORT:+RC4:@STRENGTH)\fR"
/*      The OpenSSL cipherlist for "LOW" or higher grade ciphers.
/* .IP "\fBtls_export_cipherlist (ALL:+RC4:@STRENGTH)\fR"
/*      The OpenSSL cipherlist for "EXPORT" or higher grade ciphers.
/* .IP "\fBtls_null_cipherlist (eNULL:!aNULL)\fR"
/*      The OpenSSL cipherlist for "NULL" grade ciphers that provide
/*      authentication without encryption.
/* .PP
/*      Available in Postfix version 2.4 and later:
/* .IP "\fBsmtp_sasl_tls_verified_security_options ($smtp_sasl_tls_security_options)\fR"
/*      The SASL authentication security options that the Postfix SMTP
/*      client uses for TLS encrypted SMTP sessions with a verified server
/*      certificate.
/* .PP
/*      Available in Postfix version 2.5 and later:
/* .IP "\fBsmtp_tls_fingerprint_cert_match (empty)\fR"
/*      List of acceptable remote SMTP server certificate fingerprints
/*      for the "fingerprint" TLS security level (\fBsmtp_tls_security_level\fR =
/*      fingerprint).
/* .IP "\fBsmtp_tls_fingerprint_digest (md5)\fR"
/*      The message digest algorithm used to construct remote SMTP server
/*      certificate fingerprints.
/* .PP
/*      Available in Postfix version 2.6 and later:
/* .IP "\fBsmtp_tls_protocols (!SSLv2)\fR"
/*      List of TLS protocols that the Postfix SMTP client will exclude or
/*      include with opportunistic TLS encryption.
/* .IP "\fBsmtp_tls_ciphers (export)\fR"
/*      The minimum TLS cipher grade that the Postfix SMTP client
/*      will use with opportunistic TLS encryption.
/* .IP "\fBsmtp_tls_eccert_file (empty)\fR"
/*      File with the Postfix SMTP client ECDSA certificate in PEM format.
/* .IP "\fBsmtp_tls_eckey_file ($smtp_tls_eccert_file)\fR"
/*      File with the Postfix SMTP client ECDSA private key in PEM format.
/* OBSOLETE STARTTLS CONTROLS
/* .ad
/* .fi
/*      The following configuration parameters exist for compatibility
/*      with Postfix versions before 2.3. Support for these will
/*      be removed in a future release.
/* .IP "\fBsmtp_use_tls (no)\fR"
/*      Opportunistic mode: use TLS when a remote SMTP server announces
/*      STARTTLS support, otherwise send the mail in the clear.
/* .IP "\fBsmtp_enforce_tls (no)\fR"
/*      Enforcement mode: require that remote SMTP servers use TLS
/*      encryption, and never send mail in the clear.
/* .IP "\fBsmtp_tls_enforce_peername (yes)\fR"
/*      With mandatory TLS encryption, require that the remote SMTP
/*      server hostname matches the information in the remote SMTP server
/*      certificate.
/* .IP "\fBsmtp_tls_per_site (empty)\fR"
/*      Optional lookup tables with the Postfix SMTP client TLS usage
/*      policy by next-hop destination and by remote SMTP server hostname.
/* .IP "\fBsmtp_tls_cipherlist (empty)\fR"
/*      Obsolete Postfix < 2.3 control for the Postfix SMTP client TLS
/*      cipher list.
/* RESOURCE AND RATE CONTROLS
/* .ad
/* .fi
/* .IP "\fBsmtp_destination_concurrency_limit ($default_destination_concurrency_limit)\fR"
/*      The maximal number of parallel deliveries to the same destination
/*      via the smtp message delivery transport.
/* .IP "\fBsmtp_destination_recipient_limit ($default_destination_recipient_limit)\fR"
/*      The maximal number of recipients per message for the smtp
/*      message delivery transport.
/* .IP "\fBsmtp_connect_timeout (30s)\fR"
/*      The SMTP client time limit for completing a TCP connection, or
/*      zero (use the operating system built-in time limit).
/* .IP "\fBsmtp_helo_timeout (300s)\fR"
/*      The SMTP client time limit for sending the HELO or EHLO command,
/*      and for receiving the initial server response.
/* .IP "\fBlmtp_lhlo_timeout (300s)\fR"
/*      The LMTP client time limit for sending the LHLO command, and
/*      for receiving the initial server response.
/* .IP "\fBsmtp_xforward_timeout (300s)\fR"
/*      The SMTP client time limit for sending the XFORWARD command, and
/*      for receiving the server response.
/* .IP "\fBsmtp_mail_timeout (300s)\fR"
/*      The SMTP client time limit for sending the MAIL FROM command, and
/*      for receiving the server response.
/* .IP "\fBsmtp_rcpt_timeout (300s)\fR"
/*      The SMTP client time limit for sending the SMTP RCPT TO command, and
/*      for receiving the server response.
/* .IP "\fBsmtp_data_init_timeout (120s)\fR"
/*      The SMTP client time limit for sending the SMTP DATA command, and for
/*      receiving the server response.
/* .IP "\fBsmtp_data_xfer_timeout (180s)\fR"
/*      The SMTP client time limit for sending the SMTP message content.
/* .IP "\fBsmtp_data_done_timeout (600s)\fR"
/*      The SMTP client time limit for sending the SMTP ".", and for receiving
/*      the server response.
/* .IP "\fBsmtp_quit_timeout (300s)\fR"
/*      The SMTP client time limit for sending the QUIT command, and for
/*      receiving the server response.
/* .PP
/*      Available in Postfix version 2.1 and later:
/* .IP "\fBsmtp_mx_address_limit (5)\fR"
/*      The maximal number of MX (mail exchanger) IP addresses that can
/*      result from mail exchanger lookups, or zero (no limit).
/* .IP "\fBsmtp_mx_session_limit (2)\fR"
/*      The maximal number of SMTP sessions per delivery request before
/*      giving up or delivering to a fall-back relay host, or zero (no
/*      limit).
/* .IP "\fBsmtp_rset_timeout (20s)\fR"
/*      The SMTP client time limit for sending the RSET command, and
/*      for receiving the server response.
/* .PP
/*      Available in Postfix version 2.2 and earlier:
/* .IP "\fBlmtp_cache_connection (yes)\fR"
/*      Keep Postfix LMTP client connections open for up to $max_idle
/*      seconds.
/* .PP
/*      Available in Postfix version 2.2 and later:
/* .IP "\fBsmtp_connection_cache_destinations (empty)\fR"
/*      Permanently enable SMTP connection caching for the specified
/*      destinations.
/* .IP "\fBsmtp_connection_cache_on_demand (yes)\fR"
/*      Temporarily enable SMTP connection caching while a destination
/*      has a high volume of mail in the active queue.
/* .IP "\fBsmtp_connection_reuse_time_limit (300s)\fR"
/*      The amount of time during which Postfix will use an SMTP
/*      connection repeatedly.
/* .IP "\fBsmtp_connection_cache_time_limit (2s)\fR"
/*      When SMTP connection caching is enabled, the amount of time that
/*      an unused SMTP client socket is kept open before it is closed.
/* .PP
/*      Available in Postfix version 2.3 and later:
/* .IP "\fBconnection_cache_protocol_timeout (5s)\fR"
/*      Time limit for connection cache connect, send or receive
/*      operations.
/* TROUBLE SHOOTING CONTROLS
/* .ad
/* .fi
/* .IP "\fBdebug_peer_level (2)\fR"
/*      The increment in verbose logging level when a remote client or
/*      server matches a pattern in the debug_peer_list parameter.
/* .IP "\fBdebug_peer_list (empty)\fR"
/*      Optional list of remote client or server hostname or network
/*      address patterns that cause the verbose logging level to increase
/*      by the amount specified in $debug_peer_level.
/* .IP "\fBerror_notice_recipient (postmaster)\fR"
/*      The recipient of postmaster notifications about mail delivery
/*      problems that are caused by policy, resource, software or protocol
/*      errors.
/* .IP "\fBinternal_mail_filter_classes (empty)\fR"
/*      What categories of Postfix-generated mail are subject to
/*      before-queue content inspection by non_smtpd_milters, header_checks
/*      and body_checks.
/* .IP "\fBnotify_classes (resource, software)\fR"
/*      The list of error classes that are reported to the postmaster.
/* MISCELLANEOUS CONTROLS
/* .ad
/* .fi
/* .IP "\fBbest_mx_transport (empty)\fR"
/*      Where the Postfix SMTP client should deliver mail when it detects
/*      a "mail loops back to myself" error condition.
/* .IP "\fBconfig_directory (see 'postconf -d' output)\fR"
/*      The default location of the Postfix main.cf and master.cf
/*      configuration files.
/* .IP "\fBdaemon_timeout (18000s)\fR"
/*      How much time a Postfix daemon process may take to handle a
/*      request before it is terminated by a built-in watchdog timer.
/* .IP "\fBdelay_logging_resolution_limit (2)\fR"
/*      The maximal number of digits after the decimal point when logging
/*      sub-second delay values.
/* .IP "\fBdisable_dns_lookups (no)\fR"
/*      Disable DNS lookups in the Postfix SMTP and LMTP clients.
/* .IP "\fBinet_interfaces (all)\fR"
/*      The network interface addresses that this mail system receives
/*      mail on.
/* .IP "\fBinet_protocols (ipv4)\fR"
/*      The Internet protocols Postfix will attempt to use when making
/*      or accepting connections.
/* .IP "\fBipc_timeout (3600s)\fR"
/*      The time limit for sending or receiving information over an internal
/*      communication channel.
/* .IP "\fBlmtp_assume_final (no)\fR"
/*      When an LMTP server announces no DSN support, assume that the
/*      server performs final delivery, and send "delivered" delivery status
/*      notifications instead of "relayed".
/* .IP "\fBlmtp_tcp_port (24)\fR"
/*      The default TCP port that the Postfix LMTP client connects to.
/* .IP "\fBmax_idle (100s)\fR"
/*      The maximum amount of time that an idle Postfix daemon process waits
/*      for an incoming connection before terminating voluntarily.
/* .IP "\fBmax_use (100)\fR"
/*      The maximal number of incoming connections that a Postfix daemon
/*      process will service before terminating voluntarily.
/* .IP "\fBprocess_id (read-only)\fR"
/*      The process ID of a Postfix command or daemon process.
/* .IP "\fBprocess_name (read-only)\fR"
/*      The process name of a Postfix command or daemon process.
/* .IP "\fBproxy_interfaces (empty)\fR"
/*      The network interface addresses that this mail system receives mail
/*      on by way of a proxy or network address translation unit.
/* .IP "\fBsmtp_bind_address (empty)\fR"
/*      An optional numerical network address that the Postfix SMTP client
/*      should bind to when making an IPv4 connection.
/* .IP "\fBsmtp_bind_address6 (empty)\fR"
/*      An optional numerical network address that the Postfix SMTP client
/*      should bind to when making an IPv6 connection.
/* .IP "\fBsmtp_helo_name ($myhostname)\fR"
/*      The hostname to send in the SMTP EHLO or HELO command.
/* .IP "\fBlmtp_lhlo_name ($myhostname)\fR"
/*      The hostname to send in the LMTP LHLO command.
/* .IP "\fBsmtp_host_lookup (dns)\fR"
/*      What mechanisms when the Postfix SMTP client uses to look up a host's IP
/*      address.
/* .IP "\fBsmtp_randomize_addresses (yes)\fR"
/*      Randomize the order of equal-preference MX host addresses.
/* .IP "\fBsyslog_facility (mail)\fR"
/*      The syslog facility of Postfix logging.
/* .IP "\fBsyslog_name (see 'postconf -d' output)\fR"
/*      The mail system name that is prepended to the process name in syslog
/*      records, so that "smtpd" becomes, for example, "postfix/smtpd".
/* .PP
/*      Available with Postfix 2.2 and earlier:
/* .IP "\fBfallback_relay (empty)\fR"
/*      Optional list of relay hosts for SMTP destinations that can't be
/*      found or that are unreachable.
/* .PP
/*      Available with Postfix 2.3 and later:
/* .IP "\fBsmtp_fallback_relay ($fallback_relay)\fR"
/*      Optional list of relay hosts for SMTP destinations that can't be
/*      found or that are unreachable.
/* SEE ALSO
/*      generic(5), output address rewriting
/*      header_checks(5), message header content inspection
/*      body_checks(5), body parts content inspection
/*      qmgr(8), queue manager
/*      bounce(8), delivery status reports
/*      scache(8), connection cache server
/*      postconf(5), configuration parameters
/*      master(5), generic daemon options
/*      master(8), process manager
/*      tlsmgr(8), TLS session and PRNG management
/*      syslogd(8), system logging
/* README FILES
/* .ad
/* .fi
/*      Use "\fBpostconf readme_directory\fR" or
/*      "\fBpostconf html_directory\fR" to locate this information.
/* .na
/* .nf
/*      SASL_README, Postfix SASL howto
/*      TLS_README, Postfix STARTTLS howto
/* LICENSE
/* .ad
/* .fi
/*      The Secure Mailer license must be distributed with this software.
/* AUTHOR(S)
/*      Wietse Venema
/*      IBM T.J. Watson Research
/*      P.O. Box 704
/*      Yorktown Heights, NY 10598, USA
/*
/*      Command pipelining in cooperation with:
/*      Jon Ribbens
/*      Oaktree Internet Solutions Ltd.,
/*      Internet House,
/*      Canal Basin,
/*      Coventry,
/*      CV1 4LY, United Kingdom.
/*
/*      SASL support originally by:
/*      Till Franke
/*      SuSE Rhein/Main AG
/*      65760 Eschborn, Germany
/*
/*      TLS support originally by:
/*      Lutz Jaenicke
/*      BTU Cottbus
/*      Allgemeine Elektrotechnik
/*      Universitaetsplatz 3-4
/*      D-03044 Cottbus, Germany
/*
/*      Revised TLS and SMTP connection cache support by:
/*      Victor Duchovni
/*      Morgan Stanley
/*--*/

/* System library. */

#include <sys_defs.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <dict.h>
#include <stringops.h>

/* Utility library. */

#include <msg.h>
#include <mymalloc.h>
#include <name_mask.h>
#include <name_code.h>

/* Global library. */

#include <deliver_request.h>
#include <mail_params.h>
#include <mail_version.h>
#include <mail_conf.h>
#include <debug_peer.h>
#include <flush_clnt.h>
#include <scache.h>
#include <string_list.h>
#include <maps.h>
#include <ext_prop.h>

/* Single server skeleton. */

#include <mail_server.h>

/* Application-specific. */

#include "smtp.h"
#include "smtp_sasl.h"

 /*
  * Tunable parameters. These have compiled-in defaults that can be overruled
  * by settings in the global Postfix configuration file.
  */
int     var_smtp_conn_tmout;
int     var_smtp_helo_tmout;
int     var_smtp_xfwd_tmout;
int     var_smtp_mail_tmout;
int     var_smtp_rcpt_tmout;
int     var_smtp_data0_tmout;
int     var_smtp_data1_tmout;
int     var_smtp_data2_tmout;
int     var_smtp_rset_tmout;
int     var_smtp_quit_tmout;
char   *var_inet_interfaces;
char   *var_notify_classes;
int     var_smtp_skip_5xx_greeting;
int     var_ign_mx_lookup_err;
int     var_skip_quit_resp;
char   *var_fallback_relay;
char   *var_bestmx_transp;
char   *var_error_rcpt;
int     var_smtp_always_ehlo;
int     var_smtp_never_ehlo;
char   *var_smtp_sasl_opts;
char   *var_smtp_sasl_path;
char   *var_smtp_sasl_passwd;
bool    var_smtp_sasl_enable;
char   *var_smtp_sasl_mechs;
char   *var_smtp_sasl_type;
char   *var_smtp_bind_addr;
char   *var_smtp_bind_addr6;
bool    var_smtp_rand_addr;
int     var_smtp_pix_thresh;
int     var_smtp_pix_delay;
int     var_smtp_line_limit;
char   *var_smtp_helo_name;
char   *var_smtp_host_lookup;
bool    var_smtp_quote_821_env;
bool    var_smtp_defer_mxaddr;
bool    var_smtp_send_xforward;
int     var_smtp_mxaddr_limit;
int     var_smtp_mxsess_limit;
int     var_smtp_cache_conn;
int     var_smtp_reuse_time;
char   *var_smtp_cache_dest;
char   *var_scache_service;
bool    var_smtp_cache_demand;
char   *var_smtp_ehlo_dis_words;
char   *var_smtp_ehlo_dis_maps;

char   *var_smtp_tls_level;
bool    var_smtp_use_tls;
bool    var_smtp_enforce_tls;
char   *var_smtp_tls_per_site;
char   *var_smtp_tls_policy;

#ifdef USE_TLS
char   *var_smtp_sasl_tls_opts;
char   *var_smtp_sasl_tlsv_opts;
int     var_smtp_starttls_tmout;
char   *var_smtp_tls_CAfile;
char   *var_smtp_tls_CApath;
char   *var_smtp_tls_cert_file;
char   *var_smtp_tls_mand_ciph;
char   *var_smtp_tls_excl_ciph;
char   *var_smtp_tls_mand_excl;
char   *var_smtp_tls_dcert_file;
char   *var_smtp_tls_dkey_file;
bool    var_smtp_tls_enforce_peername;
char   *var_smtp_tls_key_file;
int     var_smtp_tls_loglevel;
bool    var_smtp_tls_note_starttls_offer;
char   *var_smtp_tls_mand_proto;
char   *var_smtp_tls_sec_cmatch;
int     var_smtp_tls_scert_vd;
char   *var_smtp_tls_vfy_cmatch;
char   *var_smtp_tls_fpt_cmatch;
char   *var_smtp_tls_fpt_dgst;
char   *var_smtp_tls_proto;
char   *var_smtp_tls_ciph;
char   *var_smtp_tls_eccert_file;
char   *var_smtp_tls_eckey_file;

#endif

char   *var_smtp_generic_maps;
char   *var_prop_extension;
bool    var_smtp_sender_auth;
char   *var_lmtp_tcp_port;
int     var_scache_proto_tmout;
bool    var_smtp_cname_overr;
char   *var_smtp_pix_bug_words;
char   *var_smtp_pix_bug_maps;
char   *var_cyrus_conf_path;
char   *var_smtp_head_chks;
char   *var_smtp_mime_chks;
char   *var_smtp_nest_chks;
char   *var_smtp_body_chks;
bool    var_lmtp_assume_final;

 /* Special handling of 535 AUTH errors. */
char   *var_smtp_sasl_auth_cache_name;
int     var_smtp_sasl_auth_cache_time;
bool    var_smtp_sasl_auth_soft_bounce;

 /*
  * Global variables.
  */
int     smtp_host_lookup_mask;
STRING_LIST *smtp_cache_dest;
SCACHE *smtp_scache;
MAPS   *smtp_ehlo_dis_maps;
MAPS   *smtp_generic_maps;
int     smtp_ext_prop_mask;
MAPS   *smtp_pix_bug_maps;
HBC_CHECKS *smtp_header_checks;         /* limited header checks */
HBC_CHECKS *smtp_body_checks;           /* limited body checks */

#ifdef USE_TLS

 /*
  * OpenSSL client state (opaque handle)
  */
TLS_APPL_STATE *smtp_tls_ctx;

#endif

/* deliver_message - deliver message with extreme prejudice */

static int deliver_message(const char *service, DELIVER_REQUEST *request)
{
    SMTP_STATE *state;
    int     result;

    if (msg_verbose)
        msg_info("deliver_message: from %s", request->sender);

    /*
     * Sanity checks. The smtp server is unprivileged and chrooted, so we can
     * afford to distribute the data censoring code, instead of having it all
     * in one place.
     */
    if (request->nexthop[0] == 0)
        msg_fatal("empty nexthop hostname");
    if (request->rcpt_list.len <= 0)
        msg_fatal("recipient count: %d", request->rcpt_list.len);

    /*
     * Initialize. Bundle all information about the delivery request, so that
     * we can produce understandable diagnostics when something goes wrong
     * many levels below. The alternative would be to make everything global.
     */
    state = smtp_state_alloc();
    state->request = request;
    state->src = request->fp;
    state->service = service;
    SMTP_RCPT_INIT(state);

    /*
     * Establish an SMTP session and deliver this message to all requested
     * recipients. At the end, notify the postmaster of any protocol errors.
     * Optionally deliver mail locally when this machine is the best mail
     * exchanger.
     */
    result = smtp_connect(state);

    /*
     * Clean up.
     */
    smtp_state_free(state);

    return (result);
}

/* smtp_service - perform service for client */

static void smtp_service(VSTREAM *client_stream, char *service, char **argv)
{
    DELIVER_REQUEST *request;
    int     status;

    /*
     * Sanity check. This service takes no command-line arguments.
     */
    if (argv[0])
        msg_fatal("unexpected command-line argument: %s", argv[0]);

    /*
     * This routine runs whenever a client connects to the UNIX-domain socket
     * dedicated to remote SMTP delivery service. What we see below is a
     * little protocol to (1) tell the queue manager that we are ready, (2)
     * read a request from the queue manager, and (3) report the completion
     * status of that request. All connection-management stuff is handled by
     * the common code in single_server.c.
     */
    if ((request = deliver_request_read(client_stream)) != 0) {
        status = deliver_message(service, request);
        deliver_request_done(client_stream, request, status);
    }
}

/* post_init - post-jail initialization */

static void post_init(char *unused_name, char **unused_argv)
{
    static const NAME_MASK lookup_masks[] = {
        SMTP_HOST_LOOKUP_DNS, SMTP_HOST_FLAG_DNS,
        SMTP_HOST_LOOKUP_NATIVE, SMTP_HOST_FLAG_NATIVE,
        0,
    };

    /*
     * Select hostname lookup mechanisms.
     */
    if (var_disable_dns)
        smtp_host_lookup_mask = SMTP_HOST_FLAG_NATIVE;
    else
        smtp_host_lookup_mask = name_mask(VAR_SMTP_HOST_LOOKUP, lookup_masks,
                                          var_smtp_host_lookup);
    if (msg_verbose)
        msg_info("host name lookup methods: %s",
                 str_name_mask(VAR_SMTP_HOST_LOOKUP, lookup_masks,
                               smtp_host_lookup_mask));

    /*
     * Session cache instance.
     */
    if (*var_smtp_cache_dest || var_smtp_cache_demand)
#if 0
        smtp_scache = scache_multi_create();
#else
        smtp_scache = scache_clnt_create(var_scache_service,
                                         var_scache_proto_tmout,
                                         var_ipc_idle_limit,
                                         var_ipc_ttl_limit);
#endif
}

/* pre_init - pre-jail initialization */

static void pre_init(char *unused_name, char **unused_argv)
{
    int     use_tls;

    /*
     * Turn on per-peer debugging.
     */
    debug_peer_init();

    /*
     * SASL initialization.
     */
    if (var_smtp_sasl_enable)
#ifdef USE_SASL_AUTH
        smtp_sasl_initialize();
#else
        msg_warn("%s is true, but SASL support is not compiled in",
                 VAR_SMTP_SASL_ENABLE);
#endif

    if (*var_smtp_tls_level != 0)
        switch (tls_level_lookup(var_smtp_tls_level)) {
        case TLS_LEV_SECURE:
        case TLS_LEV_VERIFY:
        case TLS_LEV_FPRINT:
        case TLS_LEV_ENCRYPT:
            var_smtp_use_tls = var_smtp_enforce_tls = 1;
            break;
        case TLS_LEV_MAY:
            var_smtp_use_tls = 1;
            var_smtp_enforce_tls = 0;
            break;
        case TLS_LEV_NONE:
            var_smtp_use_tls = var_smtp_enforce_tls = 0;
            break;
        default:
            /* tls_level_lookup() logs no warning. */
            /* session_tls_init() assumes that var_smtp_tls_level is sane. */
            msg_fatal("Invalid TLS level \"%s\"", var_smtp_tls_level);
        }
    use_tls = (var_smtp_use_tls || var_smtp_enforce_tls);

    /*
     * Initialize the TLS data before entering the chroot jail
     */
    if (use_tls || var_smtp_tls_per_site[0] || var_smtp_tls_policy[0]) {
#ifdef USE_TLS
        TLS_CLIENT_INIT_PROPS props;

        /*
         * We get stronger type safety and a cleaner interface by combining
         * the various parameters into a single tls_client_props structure.
         * 
         * Large parameter lists are error-prone, so we emulate a language
         * feature that C does not have natively: named parameter lists.
         */
        smtp_tls_ctx =
            TLS_CLIENT_INIT(&props,
                            log_level = var_smtp_tls_loglevel,
                            verifydepth = var_smtp_tls_scert_vd,
                            cache_type = strcmp(var_procname, "smtp") == 0 ?
                            TLS_MGR_SCACHE_SMTP : TLS_MGR_SCACHE_LMTP,
                            cert_file = var_smtp_tls_cert_file,
                            key_file = var_smtp_tls_key_file,
                            dcert_file = var_smtp_tls_dcert_file,
                            dkey_file = var_smtp_tls_dkey_file,
                            eccert_file = var_smtp_tls_eccert_file,
                            eckey_file = var_smtp_tls_eckey_file,
                            CAfile = var_smtp_tls_CAfile,
                            CApath = var_smtp_tls_CApath,
                            fpt_dgst = var_smtp_tls_fpt_dgst);
        smtp_tls_list_init();
#else
        msg_warn("TLS has been selected, but TLS support is not compiled in");
#endif
    }

    /*
     * Flush client.
     */
    flush_init();

    /*
     * Session cache domain list.
     */
    if (*var_smtp_cache_dest)
        smtp_cache_dest = string_list_init(MATCH_FLAG_NONE, var_smtp_cache_dest);

    /*
     * EHLO keyword filter.
     */
    if (*var_smtp_ehlo_dis_maps)
        smtp_ehlo_dis_maps = maps_create(VAR_SMTP_EHLO_DIS_MAPS,
                                         var_smtp_ehlo_dis_maps,
                                         DICT_FLAG_LOCK);

    /*
     * PIX bug workarounds.
     */
    if (*var_smtp_pix_bug_maps)
        smtp_pix_bug_maps = maps_create(VAR_SMTP_PIX_BUG_MAPS,
                                        var_smtp_pix_bug_maps,
                                        DICT_FLAG_LOCK);

    /*
     * Generic maps.
     */
    if (*var_prop_extension)
        smtp_ext_prop_mask =
            ext_prop_mask(VAR_PROP_EXTENSION, var_prop_extension);
    if (*var_smtp_generic_maps)
        smtp_generic_maps =
            maps_create(VAR_SMTP_GENERIC_MAPS, var_smtp_generic_maps,
                        DICT_FLAG_LOCK | DICT_FLAG_FOLD_FIX);

    /*
     * Header/body checks.
     */
    smtp_header_checks = hbc_header_checks_create(
                                     VAR_SMTP_HEAD_CHKS, var_smtp_head_chks,
                                     VAR_SMTP_MIME_CHKS, var_smtp_mime_chks,
                                     VAR_SMTP_NEST_CHKS, var_smtp_nest_chks,
                                                  smtp_hbc_callbacks);
    smtp_body_checks = hbc_body_checks_create(
                                     VAR_SMTP_BODY_CHKS, var_smtp_body_chks,
                                              smtp_hbc_callbacks);
}

/* pre_accept - see if tables have changed */

static void pre_accept(char *unused_name, char **unused_argv)
{
    const char *table;

    if ((table = dict_changed_name()) != 0) {
        msg_info("table %s has changed -- restarting", table);
        exit(0);
    }
}

MAIL_VERSION_STAMP_DECLARE;

/* main - pass control to the single-threaded skeleton */

int     main(int argc, char **argv)
{
#include "smtp_params.c"
#include "lmtp_params.c"
    int     smtp_mode;

    /*
     * Fingerprint executables and core dumps.
     */
    MAIL_VERSION_STAMP_ALLOCATE;

    /*
     * XXX At this point, var_procname etc. are not initialized.
     */
    smtp_mode = (strcmp(sane_basename((VSTRING *) 0, argv[0]), "smtp") == 0);

    /*
     * Initialize with the LMTP or SMTP parameter name space.
     */
    single_server_main(argc, argv, smtp_service,
                       MAIL_SERVER_TIME_TABLE, smtp_mode ?
                       smtp_time_table : lmtp_time_table,
                       MAIL_SERVER_INT_TABLE, smtp_mode ?
                       smtp_int_table : lmtp_int_table,
                       MAIL_SERVER_STR_TABLE, smtp_mode ?
                       smtp_str_table : lmtp_str_table,
                       MAIL_SERVER_BOOL_TABLE, smtp_mode ?
                       smtp_bool_table : lmtp_bool_table,
                       MAIL_SERVER_PRE_INIT, pre_init,
                       MAIL_SERVER_POST_INIT, post_init,
                       MAIL_SERVER_PRE_ACCEPT, pre_accept,
                       0);
}