--- /dev/null
+/*
+ * sink.c -- forwarding/delivery support for fetchmail
+ *
+ * The interface of this module (open_sink(), stuff_line(), close_sink(),
+ * release_sink()) seals off the delivery logic from the protocol machine,
+ * so the latter won't have to care whether it's shipping to an SMTP
+ * listener daemon or an MDA pipe.
+ *
+ * Copyright 1998 by Eric S. Raymond
+ * For license terms, see the file COPYING in this directory.
+ */
+
+#include "config.h"
+#include <stdio.h>
+#include <errno.h>
+#include <string.h>
+#include <signal.h>
+#ifdef HAVE_MEMORY_H
+#include <memory.h>
+#endif /* HAVE_MEMORY_H */
+#if defined(STDC_HEADERS)
+#include <stdlib.h>
+#endif
+#if defined(HAVE_UNISTD_H)
+#include <unistd.h>
+#endif
+#if defined(HAVE_ALLOCA_H)
+#include <alloca.h>
+#else
+#ifdef _AIX
+ #pragma alloca
+#endif
+#endif
+
+#include "fetchmail.h"
+#include "socket.h"
+#include "smtp.h"
+
+/* BSD portability hack...I know, this is an ugly place to put it */
+#if !defined(SIGCHLD) && defined(SIGCLD)
+#define SIGCHLD SIGCLD
+#endif
+
+#if INET6
+#define SMTP_PORT "smtp" /* standard SMTP service port */
+#else /* INET6 */
+#define SMTP_PORT 25 /* standard SMTP service port */
+#endif /* INET6 */
+
+static int smtp_open(struct query *ctl)
+/* try to open a socket to the appropriate SMTP server for this query */
+{
+ /* maybe it's time to close the socket in order to force delivery */
+ if (NUM_NONZERO(ctl->batchlimit) && (ctl->smtp_socket != -1) && batchcount++ == ctl->batchlimit)
+ {
+ close(ctl->smtp_socket);
+ ctl->smtp_socket = -1;
+ batchcount = 0;
+ }
+
+ /* if no socket to any SMTP host is already set up, try to open one */
+ if (ctl->smtp_socket == -1)
+ {
+ /*
+ * RFC 1123 requires that the domain name in HELO address is a
+ * "valid principal domain name" for the client host. If we're
+ * running in invisible mode, violate this with malice
+ * aforethought in order to make the Received headers and
+ * logging look right.
+ *
+ * In fact this code relies on the RFC1123 requirement that the
+ * SMTP listener must accept messages even if verification of the
+ * HELO name fails (RFC1123 section 5.2.5, paragraph 2).
+ *
+ * How we compute the true mailhost name to pass to the
+ * listener doesn't affect behavior on RFC1123- violating
+ * listeners that check for name match; we're going to lose
+ * on those anyway because we can never give them a name
+ * that matches the local machine fetchmail is running on.
+ * What it will affect is the listener's logging.
+ */
+ struct idlist *idp;
+ char *id_me = run.invisible ? ctl->server.truename : fetchmailhost;
+ int oldphase = phase;
+
+ errno = 0;
+
+ /*
+ * Run down the SMTP hunt list looking for a server that's up.
+ * Use both explicit hunt entries (value TRUE) and implicit
+ * (default) ones (value FALSE).
+ */
+ oldphase = phase;
+ phase = LISTENER_WAIT;
+
+ set_timeout(ctl->server.timeout);
+ for (idp = ctl->smtphunt; idp; idp = idp->next)
+ {
+ char *cp, *parsed_host = alloca(strlen(idp->id) + 1);
+#ifdef INET6
+ char *portnum = SMTP_PORT;
+#else
+ int portnum = SMTP_PORT;
+#endif /* INET6 */
+
+ ctl->smtphost = idp->id; /* remember last host tried. */
+
+ strcpy(parsed_host, idp->id);
+ if ((cp = strrchr(parsed_host, '/')))
+ {
+ *cp++ = 0;
+#ifdef INET6
+ portnum = cp;
+#else
+ portnum = atoi(cp);
+#endif /* INET6 */
+ }
+
+ if ((ctl->smtp_socket = SockOpen(parsed_host,portnum,NULL)) == -1)
+ continue;
+
+ /* first, probe for ESMTP */
+ if (SMTP_ok(ctl->smtp_socket) == SM_OK &&
+ SMTP_ehlo(ctl->smtp_socket, id_me,
+ &ctl->server.esmtp_options) == SM_OK)
+ break; /* success */
+
+ /*
+ * RFC 1869 warns that some listeners hang up on a failed EHLO,
+ * so it's safest not to assume the socket will still be good.
+ */
+ SockClose(ctl->smtp_socket);
+ ctl->smtp_socket = -1;
+
+ /* if opening for ESMTP failed, try SMTP */
+ if ((ctl->smtp_socket = SockOpen(parsed_host,portnum,NULL)) == -1)
+ continue;
+
+ if (SMTP_ok(ctl->smtp_socket) == SM_OK &&
+ SMTP_helo(ctl->smtp_socket, id_me) == SM_OK)
+ break; /* success */
+
+ SockClose(ctl->smtp_socket);
+ ctl->smtp_socket = -1;
+ }
+ set_timeout(0);
+ phase = oldphase;
+ }
+
+ /*
+ * RFC 1123 requires that the domain name part of the
+ * RCPT TO address be "canonicalized", that is a FQDN
+ * or MX but not a CNAME. Some listeners (like exim)
+ * enforce this. Now that we have the actual hostname,
+ * compute what we should canonicalize with.
+ */
+ ctl->destaddr = ctl->smtpaddress ? ctl->smtpaddress : ( ctl->smtphost ? ctl->smtphost : "localhost");
+
+ if (outlevel >= O_VERBOSE && ctl->smtp_socket != -1)
+ error(0, 0, "forwarding to %s", ctl->smtphost);
+
+ return(ctl->smtp_socket);
+}
+
+/* these are shared by open_sink and stuffline */
+static FILE *sinkfp;
+static RETSIGTYPE (*sigchld)();
+
+int stuffline(struct query *ctl, char *buf)
+/* ship a line to the given control block's output sink (SMTP server or MDA) */
+{
+ int n, oldphase;
+ char *last;
+
+ /* The line may contain NUL characters. Find the last char to use
+ * -- the real line termination is the sequence "\n\0".
+ */
+ last = buf;
+ while ((last += strlen(last)) && (last[-1] != '\n'))
+ last++;
+
+ /* fix message lines that have only \n termination (for qmail) */
+ if (ctl->forcecr)
+ {
+ if (last - 1 == buf || last[-2] != '\r')
+ {
+ last[-1] = '\r';
+ *last++ = '\n';
+ *last = '\0';
+ }
+ }
+
+ oldphase = phase;
+ phase = FORWARDING_WAIT;
+
+ /*
+ * SMTP byte-stuffing. We only do this if the protocol does *not*
+ * use .<CR><LF> as EOM. If it does, the server will already have
+ * decorated any . lines it sends back up.
+ */
+ if (*buf == '.')
+ if (ctl->server.base_protocol->delimited) /* server has already byte-stuffed */
+ {
+ if (ctl->mda)
+ ++buf;
+ else
+ /* writing to SMTP, leave the byte-stuffing in place */;
+ }
+ else /* if (!protocol->delimited) -- not byte-stuffed already */
+ {
+ if (!ctl->mda)
+ SockWrite(ctl->smtp_socket, buf, 1); /* byte-stuff it */
+ else
+ /* leave it alone */;
+ }
+
+ /* we may need to strip carriage returns */
+ if (ctl->stripcr)
+ {
+ char *sp, *tp;
+
+ for (sp = tp = buf; sp < last; sp++)
+ if (*sp != '\r')
+ *tp++ = *sp;
+ *tp = '\0';
+ last = tp;
+ }
+
+ n = 0;
+ if (ctl->mda)
+ n = fwrite(buf, 1, last - buf, sinkfp);
+ else if (ctl->smtp_socket != -1)
+ n = SockWrite(ctl->smtp_socket, buf, last - buf);
+
+ phase = oldphase;
+
+ return(n);
+}
+
+static void sanitize(char *s)
+/* replace unsafe shellchars by an _ */
+{
+ static char *ok_chars = " 1234567890!@%-_=+:,./abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
+ char *cp;
+
+ for (cp = s; *(cp += strspn(cp, ok_chars)); /* NO INCREMENT */)
+ *cp = '_';
+}
+
+int open_sink(struct query *ctl,
+ char *return_path,
+ struct idlist *xmit_names,
+ long reallen,
+ int *good_addresses, int *bad_addresses)
+/* set up sinkfp to be an input sink we can ship a message to */
+{
+ struct idlist *idp;
+
+ *bad_addresses = *good_addresses = 0;
+
+ if (ctl->mda) /* we have a declared MDA */
+ {
+ int length = 0, fromlen = 0, nameslen = 0;
+ char *names = NULL, *before, *after, *from = NULL;
+
+ ctl->destaddr = "localhost";
+
+ for (idp = xmit_names; idp; idp = idp->next)
+ if (idp->val.status.mark == XMIT_ACCEPT)
+ (*good_addresses)++;
+
+ length = strlen(ctl->mda);
+ before = xstrdup(ctl->mda);
+
+ /* get user addresses for %T (or %s for backward compatibility) */
+ if (strstr(before, "%s") || strstr(before, "%T"))
+ {
+ /*
+ * We go through this in order to be able to handle very
+ * long lists of users and (re)implement %s.
+ */
+ nameslen = 0;
+ for (idp = xmit_names; idp; idp = idp->next)
+ if (idp->val.status.mark == XMIT_ACCEPT)
+ nameslen += (strlen(idp->id) + 1); /* string + ' ' */
+ if (*good_addresses = 0)
+ nameslen = strlen(run.postmaster);
+
+ names = (char *)xmalloc(nameslen + 1); /* account for '\0' */
+ if (*good_addresses == 0)
+ strcpy(names, run.postmaster);
+ else
+ {
+ names[0] = '\0';
+ for (idp = xmit_names; idp; idp = idp->next)
+ if (idp->val.status.mark == XMIT_ACCEPT)
+ {
+ strcat(names, idp->id);
+ strcat(names, " ");
+ }
+ names[--nameslen] = '\0'; /* chop trailing space */
+ }
+
+ /* sanitize names in order to contain only harmless shell chars */
+ sanitize(names);
+ }
+
+ /* get From address for %F */
+ if (strstr(before, "%F"))
+ {
+ from = xstrdup(return_path);
+
+ /* sanitize from in order to contain *only* harmless shell chars */
+ sanitize(from);
+
+ fromlen = strlen(from);
+ }
+
+ /* do we have to build an mda string? */
+ if (names || from)
+ {
+ char *sp, *dp;
+
+ /* find length of resulting mda string */
+ sp = before;
+ while (sp = strstr(sp, "%s")) {
+ length += nameslen - 2; /* subtract %s */
+ sp += 2;
+ }
+ sp = before;
+ while (sp = strstr(sp, "%T")) {
+ length += nameslen - 2; /* subtract %T */
+ sp += 2;
+ }
+ sp = before;
+ while (sp = strstr(sp, "%F")) {
+ length += fromlen - 2; /* subtract %F */
+ sp += 2;
+ }
+
+ after = xmalloc(length + 1);
+
+ /* copy mda source string to after, while expanding %[sTF] */
+ for (dp = after, sp = before; *dp = *sp; dp++, sp++) {
+ if (sp[0] != '%') continue;
+
+ /* need to expand? BTW, no here overflow, because in
+ ** the worst case (end of string) sp[1] == '\0' */
+ if (sp[1] == 's' || sp[1] == 'T') {
+ strcpy(dp, names);
+ dp += nameslen;
+ sp++; /* position sp over [sT] */
+ dp--; /* adjust dp */
+ } else if (sp[1] == 'F') {
+ strcpy(dp, from);
+ dp += fromlen;
+ sp++; /* position sp over F */
+ dp--; /* adjust dp */
+ }
+ }
+
+ if (names) {
+ free(names);
+ names = NULL;
+ }
+ if (from) {
+ free(from);
+ from = NULL;
+ }
+
+ free(before);
+
+ before = after;
+ }
+
+
+ if (outlevel == O_VERBOSE)
+ error(0, 0, "about to deliver with: %s", before);
+
+#ifdef HAVE_SETEUID
+ /*
+ * Arrange to run with user's permissions if we're root.
+ * This will initialize the ownership of any files the
+ * MDA creates properly. (The seteuid call is available
+ * under all BSDs and Linux)
+ */
+ seteuid(ctl->uid);
+#endif /* HAVE_SETEUID */
+
+ sinkfp = popen(before, "w");
+ free(before);
+ before = NULL;
+
+#ifdef HAVE_SETEUID
+ /* this will fail quietly if we didn't start as root */
+ seteuid(0);
+#endif /* HAVE_SETEUID */
+
+ if (!sinkfp)
+ {
+ error(0, 0, "MDA open failed");
+ return(PS_IOERR);
+ }
+
+ sigchld = signal(SIGCHLD, SIG_DFL);
+ }
+ else
+ {
+ char *ap, options[MSGBUFSIZE], addr[128];
+
+ /* build a connection to the SMTP listener */
+ if ((smtp_open(ctl) == -1))
+ {
+ error(0, errno, "SMTP connect to %s failed",
+ ctl->smtphost ? ctl->smtphost : "localhost");
+ return(PS_SMTP);
+ }
+
+ /*
+ * Compute ESMTP options.
+ */
+ options[0] = '\0';
+ if (ctl->server.esmtp_options & ESMTP_8BITMIME) {
+ if (ctl->pass8bits || (ctl->mimemsg & MSG_IS_8BIT))
+ strcpy(options, " BODY=8BITMIME");
+ else if (ctl->mimemsg & MSG_IS_7BIT)
+ strcpy(options, " BODY=7BIT");
+ }
+
+ if ((ctl->server.esmtp_options & ESMTP_SIZE) && reallen > 0)
+ sprintf(options + strlen(options), " SIZE=%ld", reallen);
+
+ /*
+ * Try to get the SMTP listener to take the Return-Path
+ * address as MAIL FROM . If it won't, fall back on the
+ * calling-user ID. This won't affect replies, which use the
+ * header From address anyway.
+ *
+ * RFC 1123 requires that the domain name part of the
+ * MAIL FROM address be "canonicalized", that is a
+ * FQDN or MX but not a CNAME. We'll assume the From
+ * header is already in this form here (it certainly
+ * is if rewrite is on). RFC 1123 is silent on whether
+ * a nonexistent hostname part is considered canonical.
+ *
+ * This is a potential problem if the MTAs further upstream
+ * didn't pass canonicalized From/Return-Path lines, *and* the
+ * local SMTP listener insists on them.
+ *
+ * None of these error conditions generates bouncemail. Comments
+ * below explain for each case why this is so.
+ */
+ ap = (return_path[0]) ? return_path : user;
+ if (SMTP_from(ctl->smtp_socket, ap, options) != SM_OK)
+ {
+ int smtperr = atoi(smtp_response);
+
+ if (str_find(&ctl->antispam, smtperr))
+ {
+ /*
+ * SMTP listener explicitly refuses to deliver mail
+ * coming from this address, probably due to an
+ * anti-spam domain exclusion. Respect this. Don't
+ * try to ship the message, and don't prevent it from
+ * being deleted. Typical values:
+ *
+ * 501 = exim's old antispam response
+ * 550 = exim's new antispam response (temporary)
+ * 553 = sendmail 8.8.7's generic REJECT
+ * 571 = sendmail's "unsolicited email refused"
+ *
+ * We don't send bouncemail on antispam failures because
+ * we don't want the scumbags to know the address is even
+ * valid.
+ */
+ SMTP_rset(ctl->smtp_socket); /* required by RFC1870 */
+ return(PS_REFUSED);
+ }
+
+ /*
+ * Suppress error message only if the response specifically
+ * meant `excluded for policy reasons'. We *should* see
+ * an error when the return code is less specific.
+ */
+ if (smtperr >= 400)
+ error(0, -1, "SMTP error: %s", smtp_response);
+
+ switch (smtperr)
+ {
+ case 452: /* insufficient system storage */
+ /*
+ * Temporary out-of-queue-space condition on the
+ * ESMTP server. Don't try to ship the message,
+ * and suppress deletion so it can be retried on
+ * a future retrieval cycle.
+ *
+ * Bouncemail *might* be appropriate here as a delay
+ * notification. But it's not really necessary because
+ * this is not an actual failure, we're very likely to be
+ * able to recover on the next cycle.
+ */
+ SMTP_rset(ctl->smtp_socket); /* required by RFC1870 */
+ return(PS_TRANSIENT);
+
+ case 552: /* message exceeds fixed maximum message size */
+ case 553: /* invalid sending domain */
+ /*
+ * Permanent no-go condition on the
+ * ESMTP server. Don't try to ship the message,
+ * and allow it to be deleted.
+ *
+ * Bouncemail would be appropriate for 552, but in these
+ * latter days 553 usually means a spammer is trying to
+ * cover his tracks. We'd rather deny the scumbags any
+ * feedback that the address is valid.
+ */
+ SMTP_rset(ctl->smtp_socket); /* required by RFC1870 */
+ return(PS_REFUSED);
+
+ default: /* retry with postmaster's address */
+ if (SMTP_from(ctl->smtp_socket,run.postmaster,options)!=SM_OK)
+ {
+ error(0, -1, "SMTP error: %s", smtp_response);
+ return(PS_SMTP); /* should never happen */
+ }
+ }
+ }
+
+ /*
+ * Now list the recipient addressees
+ */
+ for (idp = xmit_names; idp; idp = idp->next)
+ if (idp->val.status.mark == XMIT_ACCEPT)
+ {
+ if (strchr(idp->id, '@'))
+ strcpy(addr, idp->id);
+ else
+#ifdef HAVE_SNPRINTF
+ snprintf(addr, sizeof(addr)-1, "%s@%s", idp->id, ctl->destaddr);
+#else
+ sprintf(addr, "%s@%s", idp->id, ctl->destaddr);
+#endif /* HAVE_SNPRINTF */
+
+ if (SMTP_rcpt(ctl->smtp_socket, addr) == SM_OK)
+ (*good_addresses)++;
+ else
+ {
+ (*bad_addresses)++;
+ idp->val.status.mark = XMIT_ANTISPAM;
+ error(0, 0,
+ "SMTP listener doesn't like recipient address `%s'",
+ addr);
+ }
+ }
+ if (!(*good_addresses))
+ {
+#ifdef HAVE_SNPRINTF
+ snprintf(addr, sizeof(addr)-1, "%s@%s", run.postmaster, ctl->destaddr);
+#else
+ sprintf(addr, "%s@%s", run.postmaster, ctl->destaddr);
+#endif /* HAVE_SNPRINTF */
+
+ if (SMTP_rcpt(ctl->smtp_socket, addr) != SM_OK)
+ {
+ error(0, 0, "can't even send to %s!", run.postmaster);
+ return(PS_SMTP);
+ }
+ }
+
+ /* tell it we're ready to send data */
+ SMTP_data(ctl->smtp_socket);
+ }
+
+ return(PS_SUCCESS);
+}
+
+void release_sink(struct query *ctl)
+/* release the per-message output sink, whether it's a pipe or SMTP socket */
+{
+ if (ctl->mda)
+ {
+ if (sinkfp)
+ {
+ pclose(sinkfp);
+ sinkfp = (FILE *)NULL;
+ }
+ signal(SIGCHLD, sigchld);
+ }
+}
+
+int close_sink(struct query *ctl, flag forward)
+/* perform end-of-message actions on the current output sink */
+{
+ if (ctl->mda)
+ {
+ int rc;
+
+ /* close the delivery pipe, we'll reopen before next message */
+ if (sinkfp)
+ {
+ rc = pclose(sinkfp);
+ sinkfp = (FILE *)NULL;
+ }
+ else
+ rc = 0;
+ signal(SIGCHLD, sigchld);
+ if (rc)
+ {
+ error(0, -1, "MDA exited abnormally or returned nonzero status");
+ return(FALSE);
+ }
+ }
+ else if (forward)
+ {
+ /* write message terminator */
+ if (SMTP_eom(ctl->smtp_socket) != SM_OK)
+ {
+ error(0, -1, "SMTP listener refused delivery");
+ return(FALSE);
+ }
+ }
+
+ return(TRUE);
+}
+
+/* sink.c ends here */
projects / ~andy / fetchmail / commitdiff