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Diffstat (limited to '')
| -rw-r--r-- | src/smtp/smtp.c | 1688 |
1 files changed, 1688 insertions, 0 deletions
diff --git a/src/smtp/smtp.c b/src/smtp/smtp.c new file mode 100644 index 0000000..f7f2fc1 --- /dev/null +++ b/src/smtp/smtp.c @@ -0,0 +1,1688 @@ +/*++ +/* NAME +/* smtp 8 +/* SUMMARY +/* Postfix SMTP+LMTP client +/* SYNOPSIS +/* \fBsmtp\fR [generic Postfix daemon options] [flags=DORX] +/* 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 +/* The Postfix SMTP+LMTP client supports multiple destinations +/* separated by comma or whitespace (Postfix 3.5 and later). +/* 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 +/* The Postfix SMTP+LMTP client supports multiple destinations +/* separated by comma or whitespace (Postfix 3.5 and later). +/* 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\fR:\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]. +/* SINGLE-RECIPIENT DELIVERY +/* .ad +/* .fi +/* By default, the Postfix SMTP+LMTP client delivers mail to +/* multiple recipients per delivery request. This is undesirable +/* when prepending a \fBDelivered-to:\fR or \fBX-Original-To:\fR +/* message header. To prevent Postfix from sending multiple +/* recipients per delivery request, specify +/* .sp +/* .nf +/* \fItransport\fB_destination_recipient_limit = 1\fR +/* .fi +/* +/* in the Postfix \fBmain.cf\fR file, where \fItransport\fR +/* is the name in the first column of the Postfix \fBmaster.cf\fR +/* entry for this mail delivery service. +/* COMMAND ATTRIBUTE SYNTAX +/* .ad +/* .fi +/* .IP "\fBflags=DORX\fR (optional)" +/* Optional message processing flags. +/* .RS +/* .IP \fBD\fR +/* Prepend a "\fBDelivered-To: \fIrecipient\fR" message header +/* with the envelope recipient address. Note: for this to work, +/* the \fItransport\fB_destination_recipient_limit\fR must be +/* 1 (see SINGLE-RECIPIENT DELIVERY above for details). +/* .sp +/* The \fBD\fR flag also enforces loop detection: if a message +/* already contains a \fBDelivered-To:\fR header with the same +/* recipient address, then the message is returned as +/* undeliverable. The address comparison is case insensitive. +/* .sp +/* This feature is available as of Postfix 3.5. +/* .IP \fBO\fR +/* Prepend an "\fBX-Original-To: \fIrecipient\fR" message +/* header with the recipient address as given to Postfix. Note: +/* for this to work, the +/* \fItransport\fB_destination_recipient_limit\fR must be 1 +/* (see SINGLE-RECIPIENT DELIVERY above for details). +/* .sp +/* This feature is available as of Postfix 3.5. +/* .IP \fBR\fR +/* Prepend a "\fBReturn-Path: <\fIsender\fB>\fR" message header +/* with the envelope sender address. +/* .sp +/* This feature is available as of Postfix 3.5. +/* .IP \fBX\fR +/* Indicates that the delivery is final. This flag affects +/* the status reported in "success" DSN (delivery status +/* notification) messages, and changes it from "relayed" into +/* "delivered". +/* .sp +/* This feature is available as of Postfix 3.5. +/* .RE +/* SECURITY +/* 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 2782 (SRV resource records) +/* RFC 2920 (SMTP Pipelining) +/* RFC 3207 (STARTTLS command) +/* RFC 3461 (SMTP DSN Extension) +/* RFC 3463 (Enhanced Status Codes) +/* RFC 4954 (AUTH command) +/* RFC 5321 (SMTP protocol) +/* RFC 6531 (Internationalized SMTP) +/* RFC 6533 (Internationalized Delivery Status Notifications) +/* RFC 7672 (SMTP security via opportunistic DANE TLS) +/* DIAGNOSTICS +/* Problems and transactions are logged to \fBsyslogd\fR(8) +/* or \fBpostlogd\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 reuse for TLS (without closing the +/* SMTP or LMTP connection) is not supported before Postfix 3.4. +/* +/* SMTP and LMTP connection reuse 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 (998)\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 Postfix SMTP client MAIL FROM and RCPT TO commands +/* as required +/* by RFC 5321. +/* .IP "\fBsmtp_reply_filter (empty)\fR" +/* A mechanism to transform replies from remote SMTP servers one +/* line at a time. +/* .IP "\fBsmtp_skip_5xx_greeting (yes)\fR" +/* Skip remote SMTP servers that greet with a 5XX status code. +/* .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 +/* Postfix 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" +/* When the remote SMTP servername is a DNS CNAME, replace the +/* servername with the result from CNAME expansion for the purpose of +/* 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 Postfix 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 Postfix 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. +/* .PP +/* Available in Postfix version 2.8 and later: +/* .IP "\fBsmtp_dns_resolver_options (empty)\fR" +/* DNS Resolver options for the Postfix SMTP client. +/* .PP +/* Available in Postfix version 2.9 - 3.6: +/* .IP "\fBsmtp_per_record_deadline (no)\fR" +/* Change the behavior of the smtp_*_timeout time limits, from a +/* time limit per read or write system call, to a time limit to send +/* or receive a complete record (an SMTP command line, SMTP response +/* line, SMTP message content line, or TLS protocol message). +/* .PP +/* Available in Postfix version 2.9 and later: +/* .IP "\fBsmtp_send_dummy_mail_auth (no)\fR" +/* Whether or not to append the "AUTH=<>" option to the MAIL +/* FROM command in SASL-authenticated SMTP sessions. +/* .PP +/* Available in Postfix version 2.11 and later: +/* .IP "\fBsmtp_dns_support_level (empty)\fR" +/* Level of DNS support in the Postfix SMTP client. +/* .PP +/* Available in Postfix version 3.0 and later: +/* .IP "\fBsmtp_delivery_status_filter ($default_delivery_status_filter)\fR" +/* Optional filter for the \fBsmtp\fR(8) delivery agent to change the +/* delivery status code or explanatory text of successful or unsuccessful +/* deliveries. +/* .IP "\fBsmtp_dns_reply_filter (empty)\fR" +/* Optional filter for Postfix SMTP client DNS lookup results. +/* .PP +/* Available in Postfix version 3.3 and later: +/* .IP "\fBsmtp_balance_inet_protocols (yes)\fR" +/* When a remote destination resolves to a combination of IPv4 and +/* IPv6 addresses, ensure that the Postfix SMTP client can try both +/* address types before it runs into the smtp_mx_address_limit. +/* .PP +/* Available in Postfix 3.5 and later: +/* .IP "\fBinfo_log_address_format (external)\fR" +/* The email address form that will be used in non-debug logging +/* (info, warning, etc.). +/* .PP +/* Available in Postfix 3.6 and later: +/* .IP "\fBdnssec_probe (ns:.)\fR" +/* The DNS query type (default: "ns") and DNS query name (default: +/* ".") that Postfix may use to determine whether DNSSEC validation +/* is available. +/* .IP "\fBknown_tcp_ports (lmtp=24, smtp=25, smtps=submissions=465, submission=587)\fR" +/* Optional setting that avoids lookups in the \fBservices\fR(5) database. +/* .PP +/* Available in Postfix version 3.7 and later: +/* .IP "\fBsmtp_per_request_deadline (no)\fR" +/* Change the behavior of the smtp_*_timeout time limits, from a +/* time limit per plaintext or TLS read or write call, to a combined +/* time limit for sending a complete SMTP request and for receiving a +/* complete SMTP response. +/* .IP "\fBsmtp_min_data_rate (500)\fR" +/* The minimum plaintext data transfer rate in bytes/second for +/* DATA requests, when deadlines are enabled with smtp_per_request_deadline. +/* .IP "\fBheader_from_format (standard)\fR" +/* The format of the Postfix-generated \fBFrom:\fR header. +/* .PP +/* Available in Postfix version 3.8 and later: +/* .IP "\fBuse_srv_lookup (empty)\fR" +/* Enables discovery for the specified service(s) using DNS SRV +/* records. +/* .IP "\fBignore_srv_lookup_error (no)\fR" +/* When SRV record lookup fails, fall back to MX or IP address +/* lookup as if SRV record lookup was not enabled. +/* .IP "\fBallow_srv_lookup_fallback (no)\fR" +/* When SRV record lookup fails or no SRV record exists, fall back +/* to MX or IP address lookup as if SRV record lookup was not enabled. +/* 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 Postfix SMTP client lookup tables with one username:password +/* entry per sender, remote hostname or next-hop domain. +/* .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. +/* .PP +/* Available in Postfix version 2.9 and later: +/* .IP "\fBsmtp_send_dummy_mail_auth (no)\fR" +/* Whether or not to append the "AUTH=<>" option to the MAIL +/* FROM command in SASL-authenticated SMTP sessions. +/* 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. +/* .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 Certification 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 +/* Postfix 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 (see 'postconf -d' output)\fR" +/* 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" +/* How the Postfix SMTP client verifies the server certificate +/* peername 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" +/* How the Postfix SMTP client verifies the server certificate +/* peername 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 (see 'postconf -d' output)\fR" +/* The OpenSSL cipherlist for "high" grade ciphers. +/* .IP "\fBtls_medium_cipherlist (see 'postconf -d' output)\fR" +/* The OpenSSL cipherlist for "medium" 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 in Postfix version 2.3..3.7: +/* .IP "\fBtls_low_cipherlist (see 'postconf -d' output)\fR" +/* The OpenSSL cipherlist for "low" or higher grade ciphers. +/* .IP "\fBtls_export_cipherlist (see 'postconf -d' output)\fR" +/* The OpenSSL cipherlist for "export" or higher grade ciphers. +/* .PP +/* Available in Postfix version 2.4 and later: +/* .IP "\fBsmtp_sasl_tls_verified_security_options ($smtp_sasl_tls_security_options)\fR" +/* The SASL authentication security options that the Postfix SMTP +/* client uses for TLS encrypted SMTP sessions with a verified server +/* certificate. +/* .PP +/* Available in Postfix version 2.5 and later: +/* .IP "\fBsmtp_tls_fingerprint_cert_match (empty)\fR" +/* List of acceptable remote SMTP server certificate fingerprints for +/* the "fingerprint" TLS security level (\fBsmtp_tls_security_level\fR = +/* fingerprint). +/* .IP "\fBsmtp_tls_fingerprint_digest (see 'postconf -d' output)\fR" +/* The message digest algorithm used to construct remote SMTP server +/* certificate fingerprints. +/* .PP +/* Available in Postfix version 2.6 and later: +/* .IP "\fBsmtp_tls_protocols (see postconf -d output)\fR" +/* TLS protocols that the Postfix SMTP client will use with +/* opportunistic TLS encryption. +/* .IP "\fBsmtp_tls_ciphers (medium)\fR" +/* The minimum TLS cipher grade that the Postfix SMTP client +/* will use with opportunistic TLS encryption. +/* .IP "\fBsmtp_tls_eccert_file (empty)\fR" +/* File with the Postfix SMTP client ECDSA certificate in PEM format. +/* .IP "\fBsmtp_tls_eckey_file ($smtp_tls_eccert_file)\fR" +/* File with the Postfix SMTP client ECDSA private key in PEM format. +/* .PP +/* Available in Postfix version 2.7 and later: +/* .IP "\fBsmtp_tls_block_early_mail_reply (no)\fR" +/* Try to detect a mail hijacking attack based on a TLS protocol +/* vulnerability (CVE-2009-3555), where an attacker prepends malicious +/* HELO, MAIL, RCPT, DATA commands to a Postfix SMTP client TLS session. +/* .PP +/* Available in Postfix version 2.8 and later: +/* .IP "\fBtls_disable_workarounds (see 'postconf -d' output)\fR" +/* List or bit-mask of OpenSSL bug work-arounds to disable. +/* .PP +/* Available in Postfix version 2.11-3.1: +/* .IP "\fBtls_dane_digest_agility (on)\fR" +/* Configure RFC7671 DANE TLSA digest algorithm agility. +/* .IP "\fBtls_dane_trust_anchor_digest_enable (yes)\fR" +/* Enable support for RFC 6698 (DANE TLSA) DNS records that contain +/* digests of trust-anchors with certificate usage "2". +/* .PP +/* Available in Postfix version 2.11 and later: +/* .IP "\fBsmtp_tls_trust_anchor_file (empty)\fR" +/* Zero or more PEM-format files with trust-anchor certificates +/* and/or public keys. +/* .IP "\fBsmtp_tls_force_insecure_host_tlsa_lookup (no)\fR" +/* Lookup the associated DANE TLSA RRset even when a hostname is +/* not an alias and its address records lie in an unsigned zone. +/* .IP "\fBtlsmgr_service_name (tlsmgr)\fR" +/* The name of the \fBtlsmgr\fR(8) service entry in master.cf. +/* .PP +/* Available in Postfix version 3.0 and later: +/* .IP "\fBsmtp_tls_wrappermode (no)\fR" +/* Request that the Postfix SMTP client connects using the +/* SUBMISSIONS/SMTPS protocol instead of using the STARTTLS command. +/* .PP +/* Available in Postfix version 3.1 and later: +/* .IP "\fBsmtp_tls_dane_insecure_mx_policy (see 'postconf -d' output)\fR" +/* The TLS policy for MX hosts with "secure" TLSA records when the +/* nexthop destination security level is \fBdane\fR, but the MX +/* record was found via an "insecure" MX lookup. +/* .PP +/* Available in Postfix version 3.2 and later: +/* .IP "\fBtls_eecdh_auto_curves (see 'postconf -d' output)\fR" +/* The prioritized list of elliptic curves supported by the Postfix +/* SMTP client and server. +/* .PP +/* Available in Postfix version 3.4 and later: +/* .IP "\fBsmtp_tls_connection_reuse (no)\fR" +/* Try to make multiple deliveries per TLS-encrypted connection. +/* .IP "\fBsmtp_tls_chain_files (empty)\fR" +/* List of one or more PEM files, each holding one or more private keys +/* directly followed by a corresponding certificate chain. +/* .IP "\fBsmtp_tls_servername (empty)\fR" +/* Optional name to send to the remote SMTP server in the TLS Server +/* Name Indication (SNI) extension. +/* .PP +/* Available in Postfix 3.5, 3.4.6, 3.3.5, 3.2.10, 3.1.13 and later: +/* .IP "\fBtls_fast_shutdown_enable (yes)\fR" +/* A workaround for implementations that hang Postfix while shutting +/* down a TLS session, until Postfix times out. +/* .PP +/* Available in Postfix version 3.8 and later: +/* .IP "\fBtls_ffdhe_auto_groups (see 'postconf -d' output)\fR" +/* The prioritized list of finite-field Diffie-Hellman ephemeral +/* (FFDHE) key exchange groups supported by the Postfix SMTP client and +/* server. +/* .PP +/* Available in Postfix 3.9, 3.8.1, 3.7.6, 3.6.10, 3.5.20 and later: +/* .IP "\fBtls_config_file (default)\fR" +/* Optional configuration file with baseline OpenSSL settings. +/* .IP "\fBtls_config_name (empty)\fR" +/* The application name passed by Postfix to OpenSSL library +/* initialization functions. +/* 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_connect_timeout (30s)\fR" +/* The Postfix 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 Postfix SMTP client time limit for sending the HELO or EHLO command, +/* and for receiving the initial remote SMTP server response. +/* .IP "\fBlmtp_lhlo_timeout (300s)\fR" +/* The Postfix LMTP client time limit for sending the LHLO command, +/* and for receiving the initial remote LMTP server response. +/* .IP "\fBsmtp_xforward_timeout (300s)\fR" +/* The Postfix SMTP client time limit for sending the XFORWARD command, +/* and for receiving the remote SMTP server response. +/* .IP "\fBsmtp_mail_timeout (300s)\fR" +/* The Postfix SMTP client time limit for sending the MAIL FROM command, +/* and for receiving the remote SMTP server response. +/* .IP "\fBsmtp_rcpt_timeout (300s)\fR" +/* The Postfix SMTP client time limit for sending the SMTP RCPT TO +/* command, and for receiving the remote SMTP server response. +/* .IP "\fBsmtp_data_init_timeout (120s)\fR" +/* The Postfix SMTP client time limit for sending the SMTP DATA command, +/* and for receiving the remote SMTP server response. +/* .IP "\fBsmtp_data_xfer_timeout (180s)\fR" +/* The Postfix SMTP client time limit for sending the SMTP message content. +/* .IP "\fBsmtp_data_done_timeout (600s)\fR" +/* The Postfix SMTP client time limit for sending the SMTP ".", and +/* for receiving the remote SMTP server response. +/* .IP "\fBsmtp_quit_timeout (300s)\fR" +/* The Postfix SMTP client time limit for sending the QUIT command, +/* and for receiving the remote SMTP 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 Postfix SMTP client mail exchanger lookups, or zero (no +/* limit). +/* .IP "\fBsmtp_mx_session_limit (2)\fR" +/* The maximal number of SMTP sessions per delivery request before +/* the Postfix SMTP client +/* gives up or delivers to a fall-back relay host, or zero (no +/* limit). +/* .IP "\fBsmtp_rset_timeout (20s)\fR" +/* The Postfix SMTP client time limit for sending the RSET command, +/* and for receiving the remote SMTP 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. +/* .PP +/* Available in Postfix version 2.9 - 3.6: +/* .IP "\fBsmtp_per_record_deadline (no)\fR" +/* Change the behavior of the smtp_*_timeout time limits, from a +/* time limit per read or write system call, to a time limit to send +/* or receive a complete record (an SMTP command line, SMTP response +/* line, SMTP message content line, or TLS protocol message). +/* .PP +/* Available in Postfix version 2.11 and later: +/* .IP "\fBsmtp_connection_reuse_count_limit (0)\fR" +/* When SMTP connection caching is enabled, the number of times +/* that an SMTP session may be reused before it is closed, or zero (no +/* limit). +/* .PP +/* Available in Postfix version 3.4 and later: +/* .IP "\fBsmtp_tls_connection_reuse (no)\fR" +/* Try to make multiple deliveries per TLS-encrypted connection. +/* .PP +/* Available in Postfix version 3.7 and later: +/* .IP "\fBsmtp_per_request_deadline (no)\fR" +/* Change the behavior of the smtp_*_timeout time limits, from a +/* time limit per plaintext or TLS read or write call, to a combined +/* time limit for sending a complete SMTP request and for receiving a +/* complete SMTP response. +/* .IP "\fBsmtp_min_data_rate (500)\fR" +/* The minimum plaintext data transfer rate in bytes/second for +/* DATA requests, when deadlines are enabled with smtp_per_request_deadline. +/* .PP +/* Implemented in the qmgr(8) daemon: +/* .IP "\fBtransport_destination_concurrency_limit ($default_destination_concurrency_limit)\fR" +/* A transport-specific override for the +/* default_destination_concurrency_limit parameter value, where +/* \fItransport\fR is the master.cf name of the message delivery +/* transport. +/* .IP "\fBtransport_destination_recipient_limit ($default_destination_recipient_limit)\fR" +/* A transport-specific override for the +/* default_destination_recipient_limit parameter value, where +/* \fItransport\fR is the master.cf name of the message delivery +/* transport. +/* SMTPUTF8 CONTROLS +/* .ad +/* .fi +/* Preliminary SMTPUTF8 support is introduced with Postfix 3.0. +/* .IP "\fBsmtputf8_enable (yes)\fR" +/* Enable preliminary SMTPUTF8 support for the protocols described +/* in RFC 6531, RFC 6532, and RFC 6533. +/* .IP "\fBsmtputf8_autodetect_classes (sendmail, verify)\fR" +/* Detect that a message requires SMTPUTF8 support for the specified +/* mail origin classes. +/* .PP +/* Available in Postfix version 3.2 and later: +/* .IP "\fBenable_idna2003_compatibility (no)\fR" +/* Enable 'transitional' compatibility between IDNA2003 and IDNA2008, +/* when converting UTF-8 domain names to/from the ASCII form that is +/* used for DNS lookups. +/* TROUBLE SHOOTING CONTROLS +/* .ad +/* .fi +/* .IP "\fBdebug_peer_level (2)\fR" +/* The increment in verbose logging level when a nexthop destination, +/* remote client or server name or network address matches a pattern +/* given with the debug_peer_list parameter. +/* .IP "\fBdebug_peer_list (empty)\fR" +/* Optional list of nexthop destination, remote client or server +/* name or network address patterns that, if matched, 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 local network interface addresses that this mail system receives +/* mail on. +/* .IP "\fBinet_protocols (see 'postconf -d output')\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 a remote 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 remote network interface addresses that this mail system receives mail +/* on by way of a proxy or network address translation unit. +/* .IP "\fBsmtp_address_preference (any)\fR" +/* The address type ("ipv6", "ipv4" or "any") that the Postfix +/* SMTP client will try first, when a destination has IPv6 and IPv4 +/* addresses with equal MX preference. +/* .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 HELO or EHLO command. +/* .IP "\fBlmtp_lhlo_name ($myhostname)\fR" +/* The hostname to send in the LMTP LHLO command. +/* .IP "\fBsmtp_host_lookup (dns)\fR" +/* What mechanisms the Postfix SMTP client uses to look up a host's +/* IP address. +/* .IP "\fBsmtp_randomize_addresses (yes)\fR" +/* Randomize the order of equal-preference MX host addresses. +/* .IP "\fBsyslog_facility (mail)\fR" +/* The syslog facility of Postfix logging. +/* .IP "\fBsyslog_name (see 'postconf -d' output)\fR" +/* A prefix that is prepended to the process name in syslog +/* records, so that, for example, "smtpd" becomes "prefix/smtpd". +/* .PP +/* Available with Postfix 2.2 and earlier: +/* .IP "\fBfallback_relay (empty)\fR" +/* Optional list of relay hosts for SMTP destinations that can't be +/* found or that are unreachable. +/* .PP +/* Available with Postfix 2.3 and later: +/* .IP "\fBsmtp_fallback_relay ($fallback_relay)\fR" +/* Optional list of relay destinations that will be used when an +/* SMTP destination is not found, or when delivery fails due to a +/* non-permanent error. +/* .PP +/* Available with Postfix 3.0 and later: +/* .IP "\fBsmtp_address_verify_target (rcpt)\fR" +/* In the context of email address verification, the SMTP protocol +/* stage that determines whether an email address is deliverable. +/* .PP +/* Available with Postfix 3.1 and later: +/* .IP "\fBlmtp_fallback_relay (empty)\fR" +/* Optional list of relay hosts for LMTP destinations that can't be +/* found or that are unreachable. +/* .PP +/* Available with Postfix 3.2 and later: +/* .IP "\fBsmtp_tcp_port (smtp)\fR" +/* The default TCP port that the Postfix SMTP client connects to. +/* .PP +/* Available in Postfix 3.3 and later: +/* .IP "\fBservice_name (read-only)\fR" +/* The master.cf service name of a Postfix daemon process. +/* .PP +/* Available in Postfix 3.7 and later: +/* .IP "\fBsmtp_bind_address_enforce (no)\fR" +/* Defer delivery when the Postfix SMTP client cannot apply the +/* smtp_bind_address or smtp_bind_address6 setting. +/* 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 +/* postlogd(8), Postfix logging +/* 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 +/* +/* Wietse Venema +/* Google, Inc. +/* 111 8th Avenue +/* New York, NY 10011, 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> +#include <byte_mask.h> + +/* Global library. */ + +#include <deliver_request.h> +#include <delivered_hdr.h> +#include <mail_proto.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> +#include <hfrom_format.h> + +/* DNS library. */ + +#include <dns.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_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; +char *var_smtp_vrfy_tgt; +bool var_smtp_rand_addr; +int var_smtp_pix_thresh; +int var_queue_run_delay; +int var_min_backoff_time; +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; +int var_smtp_reuse_count; +char *var_smtp_cache_dest; +char *var_scache_service; /* You can now leave this here. */ +bool var_smtp_cache_demand; +char *var_smtp_ehlo_dis_words; +char *var_smtp_ehlo_dis_maps; +char *var_smtp_addr_pref; + +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; +bool var_smtp_tls_wrappermode; +bool var_smtp_tls_conn_reuse; +char *var_tlsproxy_service; + +#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_chain_files; +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; +char *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_tafile; +char *var_smtp_tls_proto; +char *var_smtp_tls_ciph; +char *var_smtp_tls_eccert_file; +char *var_smtp_tls_eckey_file; +char *var_smtp_tls_sni; +bool var_smtp_tls_blk_early_mail_reply; +bool var_smtp_tls_force_tlsa; +char *var_smtp_tls_insecure_mx_policy; + +#endif + +char *var_smtp_generic_maps; +char *var_prop_extension; +bool var_smtp_sender_auth; +char *var_smtp_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; +char *var_smtp_resp_filter; +bool var_lmtp_assume_final; +char *var_smtp_dns_res_opt; +char *var_smtp_dns_support; +bool var_smtp_dummy_mail_auth; +char *var_smtp_dsn_filter; +char *var_smtp_dns_re_filter; +bool var_smtp_balance_inet_proto; +bool var_smtp_req_deadline; +int var_smtp_min_data_rate; +char *var_use_srv_lookup; +bool var_ign_srv_lookup_err; +bool var_allow_srv_fallback; + + /* 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; + +char *var_hfrom_format; +bool var_smtp_bind_addr_enforce; + + /* + * Global variables. + */ +int smtp_mode; +int smtp_host_lookup_mask; +int smtp_dns_support; +STRING_LIST *smtp_cache_dest; +SCACHE *smtp_scache; +MAPS *smtp_ehlo_dis_maps; +MAPS *smtp_generic_maps; +int smtp_ext_prop_mask; +unsigned smtp_dns_res_opt; +MAPS *smtp_pix_bug_maps; +HBC_CHECKS *smtp_header_checks; /* limited header checks */ +HBC_CHECKS *smtp_body_checks; /* limited body checks */ +SMTP_CLI_ATTR smtp_cli_attr; /* parsed command-line */ +int smtp_hfrom_format; /* postmaster notifications */ +STRING_LIST *smtp_use_srv_lookup; + +#ifdef USE_TLS + + /* + * OpenSSL client state (opaque handle) + */ +TLS_APPL_STATE *smtp_tls_ctx; +int smtp_tls_insecure_mx_policy; + +#endif + + /* + * IPv6 preference. + */ +static int smtp_addr_pref; + +/* get_cli_attr - get command-line attributes */ + +static void get_cli_attr(SMTP_CLI_ATTR *attr, char **argv) +{ + const char myname[] = "get_cli_attr"; + const char *last_flags = "flags="; /* i.e. empty */ + static const BYTE_MASK flags_map[] = { + 'D', SMTP_CLI_FLAG_DELIVERED_TO, + 'O', SMTP_CLI_FLAG_ORIG_RCPT, + 'R', SMTP_CLI_FLAG_RETURN_PATH, + 'X', SMTP_CLI_FLAG_FINAL_DELIVERY, + 0, + }; + + /* + * Initialize. + */ + attr->flags = 0; + + /* + * Iterate over the command-line attribute list. Errors are fatal. + */ + for ( /* void */ ; *argv != 0; argv++) { + + /* + * flags=stuff. Errors are fatal. + */ + if (strncasecmp("flags=", *argv, sizeof("flags=") - 1) == 0) { + last_flags = *argv; + if (msg_verbose) + msg_info("%s: %s", myname, last_flags); + attr->flags = byte_mask(*argv, flags_map, + *argv + sizeof("flags=") - 1); + } + + /* + * Bad. + */ + else + msg_fatal("unknown attribute name: %s", *argv); + } + + /* + * Backwards compatibility, redundancy, and obsolescence. + */ + if (!smtp_mode && var_lmtp_assume_final + && (attr->flags & SMTP_CLI_FLAG_FINAL_DELIVERY) == 0) { + attr->flags |= SMTP_CLI_FLAG_FINAL_DELIVERY; + msg_warn("%s is obsolete; instead, specify \"%sX\" in %s", + VAR_LMTP_ASSUME_FINAL, last_flags, MASTER_CONF_FILE); + } +} + +/* 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); + + /* + * D flag checks. + */ + if (smtp_cli_attr.flags & SMTP_CLI_FLAG_DELIVERED_TO) { + + /* + * The D flag cannot be specified for multi-recipient deliveries. + */ + if (request->rcpt_list.len > 1) { + msg_warn("flag `D' requires %s_destination_recipient_limit = 1", + service); + return (reject_deliver_request(service, request, "4.3.5", + "mail system configuration error")); + } + + /* + * The recipient cannot appear in a Delivered-To: header. + */ + else { + DELIVERED_HDR_INFO *delivered_info = delivered_hdr_init( + request->fp, request->data_offset, FOLD_ADDR_ALL); + VSTRING *generic_rcpt = vstring_alloc(100); + int have_delivered_loop; + + smtp_rewrite_generic_internal(generic_rcpt, + request->rcpt_list.info->address); + have_delivered_loop = delivered_hdr_find( + delivered_info, STR(generic_rcpt)); + vstring_free(generic_rcpt); + delivered_hdr_free(delivered_info); + if (have_delivered_loop) { + return (reject_deliver_request(service, request, "5.4.6", + "mail forwarding loop for %s", + request->rcpt_list.info->address)); + } + } + } + + /* + * The O flag cannot be specified for multi-recipient deliveries. + */ + if ((smtp_cli_attr.flags & SMTP_CLI_FLAG_ORIG_RCPT) + && request->rcpt_list.len > 1) { + msg_warn("flag `O' requires %s_destination_recipient_limit = 1", + service); + return (reject_deliver_request(service, request, "4.3.5", + "mail system configuration error")); + } + + /* + * 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; + state->misc_flags |= smtp_addr_pref; + state->debug_peer_per_nexthop = + debug_peer_check(request->nexthop, "noaddr"); + 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 **unused_argv) +{ + DELIVER_REQUEST *request; + int status; + + /* + * 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 **argv) +{ + static const NAME_MASK lookup_masks[] = { + SMTP_HOST_LOOKUP_DNS, SMTP_HOST_FLAG_DNS, + SMTP_HOST_LOOKUP_NATIVE, SMTP_HOST_FLAG_NATIVE, + 0, + }; + static const NAME_MASK dns_res_opt_masks[] = { + SMTP_DNS_RES_OPT_DEFNAMES, RES_DEFNAMES, + SMTP_DNS_RES_OPT_DNSRCH, RES_DNSRCH, + 0, + }; + static const NAME_CODE dns_support[] = { + SMTP_DNS_SUPPORT_DISABLED, SMTP_DNS_DISABLED, + SMTP_DNS_SUPPORT_ENABLED, SMTP_DNS_ENABLED, +#if (RES_USE_DNSSEC != 0) && (RES_USE_EDNS0 != 0) + SMTP_DNS_SUPPORT_DNSSEC, SMTP_DNS_DNSSEC, +#endif + 0, SMTP_DNS_INVALID, + }; + + if (*var_smtp_dns_support == 0) { + /* Backwards compatible empty setting */ + smtp_dns_support = + var_disable_dns ? SMTP_DNS_DISABLED : SMTP_DNS_ENABLED; + } else { + smtp_dns_support = + name_code(dns_support, NAME_CODE_FLAG_NONE, var_smtp_dns_support); + if (smtp_dns_support == SMTP_DNS_INVALID) + msg_fatal("invalid %s: \"%s\"", VAR_LMTP_SMTP(DNS_SUPPORT), + var_smtp_dns_support); + var_disable_dns = (smtp_dns_support == SMTP_DNS_DISABLED); + } + +#ifdef USE_TLS + if (smtp_mode) { + smtp_tls_insecure_mx_policy = + tls_level_lookup(var_smtp_tls_insecure_mx_policy); + switch (smtp_tls_insecure_mx_policy) { + case TLS_LEV_MAY: + case TLS_LEV_ENCRYPT: + case TLS_LEV_DANE: + break; + default: + msg_fatal("invalid %s: \"%s\"", VAR_SMTP_TLS_INSECURE_MX_POLICY, + var_smtp_tls_insecure_mx_policy); + } + } +#endif + + /* + * Select hostname lookup mechanisms. + */ + if (smtp_dns_support == SMTP_DNS_DISABLED) + smtp_host_lookup_mask = SMTP_HOST_FLAG_NATIVE; + else + smtp_host_lookup_mask = + name_mask(VAR_LMTP_SMTP(HOST_LOOKUP), lookup_masks, + var_smtp_host_lookup); + if (msg_verbose) + msg_info("host name lookup methods: %s", + str_name_mask(VAR_LMTP_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 + + /* + * Select DNS query flags. + */ + smtp_dns_res_opt = name_mask(VAR_LMTP_SMTP(DNS_RES_OPT), dns_res_opt_masks, + var_smtp_dns_res_opt); + + /* + * Address verification. + */ + smtp_vrfy_init(); + + /* + * Look up service command-line attributes; these do not change during + * the process lifetime. + */ + get_cli_attr(&smtp_cli_attr, argv); + + /* + * header_from format, for postmaster notifications. + */ + smtp_hfrom_format = hfrom_format_parse(VAR_HFROM_FORMAT, var_hfrom_format); + + /* + * Service discovery with SRV record lookup. + */ + if (*var_use_srv_lookup) + smtp_use_srv_lookup = string_list_init(VAR_USE_SRV_LOOKUP, + MATCH_FLAG_RETURN, + var_use_srv_lookup); +} + +/* pre_init - pre-jail initialization */ + +static void pre_init(char *unused_name, char **unused_argv) +{ + int use_tls; + static const NAME_CODE addr_pref_map[] = { + INET_PROTO_NAME_IPV6, SMTP_MISC_FLAG_PREF_IPV6, + INET_PROTO_NAME_IPV4, SMTP_MISC_FLAG_PREF_IPV4, + INET_PROTO_NAME_ANY, 0, + 0, -1, + }; + + /* + * 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_LMTP_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_DANE_ONLY: + case TLS_LEV_FPRINT: + case TLS_LEV_ENCRYPT: + var_smtp_use_tls = var_smtp_enforce_tls = 1; + break; + case TLS_LEV_DANE: + 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; + + tls_pre_jail_init(TLS_ROLE_CLIENT); + + /* + * 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. + * + * With tlsproxy(8) turned on, this is still needed for DANE-related + * initializations. + */ + smtp_tls_ctx = + TLS_CLIENT_INIT(&props, + log_param = VAR_LMTP_SMTP(TLS_LOGLEVEL), + log_level = var_smtp_tls_loglevel, + verifydepth = var_smtp_tls_scert_vd, + cache_type = LMTP_SMTP_SUFFIX(TLS_MGR_SCACHE), + chain_files = var_smtp_tls_chain_files, + 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, + mdalg = var_smtp_tls_fpt_dgst); + smtp_tls_list_init(); + tls_dane_loglevel(VAR_LMTP_SMTP(TLS_LOGLEVEL), var_smtp_tls_loglevel); +#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(VAR_SMTP_CACHE_DEST, + MATCH_FLAG_RETURN, + var_smtp_cache_dest); + + /* + * EHLO keyword filter. + */ + if (*var_smtp_ehlo_dis_maps) + smtp_ehlo_dis_maps = maps_create(VAR_LMTP_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_LMTP_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_LMTP_SMTP(GENERIC_MAPS), var_smtp_generic_maps, + DICT_FLAG_LOCK | DICT_FLAG_FOLD_FIX + | DICT_FLAG_UTF8_REQUEST); + + /* + * Header/body checks. + */ + smtp_header_checks = hbc_header_checks_create( + VAR_LMTP_SMTP(HEAD_CHKS), var_smtp_head_chks, + VAR_LMTP_SMTP(MIME_CHKS), var_smtp_mime_chks, + VAR_LMTP_SMTP(NEST_CHKS), var_smtp_nest_chks, + smtp_hbc_callbacks); + smtp_body_checks = hbc_body_checks_create( + VAR_LMTP_SMTP(BODY_CHKS), var_smtp_body_chks, + smtp_hbc_callbacks); + + /* + * Server reply filter. + */ + if (*var_smtp_resp_filter) + smtp_chat_resp_filter = + dict_open(var_smtp_resp_filter, O_RDONLY, + DICT_FLAG_LOCK | DICT_FLAG_FOLD_FIX); + + /* + * Address family preference. + */ + if (*var_smtp_addr_pref) { + smtp_addr_pref = name_code(addr_pref_map, NAME_CODE_FLAG_NONE, + var_smtp_addr_pref); + if (smtp_addr_pref < 0) + msg_fatal("bad %s value: %s", VAR_LMTP_SMTP(ADDR_PREF), + var_smtp_addr_pref); + } + + /* + * DNS reply filter. + */ + if (*var_smtp_dns_re_filter) + dns_rr_filter_compile(VAR_LMTP_SMTP(DNS_RE_FILTER), + var_smtp_dns_re_filter); +} + +/* 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) +{ + char *sane_procname; + +#include "smtp_params.c" +#include "lmtp_params.c" + + /* + * Fingerprint executables and core dumps. + */ + MAIL_VERSION_STAMP_ALLOCATE; + + /* + * XXX At this point, var_procname etc. are not initialized. + * + * The process name, "smtp" or "lmtp", determines the protocol, the DSN + * server reply type, SASL service information lookup, and more. Prepare + * for the possibility there may be another personality. + */ + sane_procname = sane_basename((VSTRING *) 0, argv[0]); + if (strcmp(sane_procname, "smtp") == 0) + smtp_mode = 1; + else if (strcmp(sane_procname, "lmtp") == 0) + smtp_mode = 0; + else + /* TODO: logging is not initialized. */ + msg_fatal("unexpected process name \"%s\" - " + "specify \"smtp\" or \"lmtp\"", var_procname); + + /* + * Initialize with the LMTP or SMTP parameter name space. + */ + single_server_main(argc, argv, smtp_service, + CA_MAIL_SERVER_TIME_TABLE(smtp_mode ? + smtp_time_table : lmtp_time_table), + CA_MAIL_SERVER_INT_TABLE(smtp_mode ? + smtp_int_table : lmtp_int_table), + CA_MAIL_SERVER_STR_TABLE(smtp_mode ? + smtp_str_table : lmtp_str_table), + CA_MAIL_SERVER_BOOL_TABLE(smtp_mode ? + smtp_bool_table : lmtp_bool_table), + CA_MAIL_SERVER_NBOOL_TABLE(smtp_mode ? + smtp_nbool_table : lmtp_nbool_table), + CA_MAIL_SERVER_PRE_INIT(pre_init), + CA_MAIL_SERVER_POST_INIT(post_init), + CA_MAIL_SERVER_PRE_ACCEPT(pre_accept), + CA_MAIL_SERVER_BOUNCE_INIT(VAR_SMTP_DSN_FILTER, + &var_smtp_dsn_filter), + 0); +} |