-/*************************************************
-* Exim - an Internet mail transport agent *
-*************************************************/
-
-/* Copyright (c) University of Cambridge 1995 - 2016 */
-/* See the file NOTICE for conditions of use and distribution. */
-
-/* Transport shim for dkim signing */
-
-
-#include "exim.h"
-
-#ifndef DISABLE_DKIM /* rest of file */
-
-
-static BOOL
-dkt_sign_fail(struct ob_dkim * dkim, int * errp)
-{
-if (dkim->dkim_strict)
- {
- uschar * dkim_strict_result = expand_string(dkim->dkim_strict);
-
- if (dkim_strict_result)
- if ( (strcmpic(dkim->dkim_strict, US"1") == 0) ||
- (strcmpic(dkim->dkim_strict, US"true") == 0) )
- {
- /* Set errno to something halfway meaningful */
- *errp = EACCES;
- log_write(0, LOG_MAIN, "DKIM: message could not be signed,"
- " and dkim_strict is set. Deferring message delivery.");
- return FALSE;
- }
- }
-return TRUE;
-}
-
-/* Send the file at in_fd down the output fd */
-
-static BOOL
-dkt_send_file(int out_fd, int in_fd, off_t off, size_t size)
-{
-DEBUG(D_transport) debug_printf("send file fd=%d size=%u\n", out_fd, (unsigned)(size - off));
-
-/*XXX should implement timeout, like transport_write_block_fd() ? */
-
-#ifdef OS_SENDFILE
-/* We can use sendfile() to shove the file contents
- to the socket. However only if we don't use TLS,
- as then there's another layer of indirection
- before the data finally hits the socket. */
-if (tls_out.active != out_fd)
- {
- ssize_t copied = 0;
-
- while(copied >= 0 && off < size)
- copied = os_sendfile(out_fd, in_fd, &off, size - off);
- if (copied < 0)
- return FALSE;
- }
-else
-
-#endif
-
- {
- int sread, wwritten;
-
- /* Rewind file */
- if (lseek(in_fd, off, SEEK_SET) < 0) return FALSE;
-
- /* Send file down the original fd */
- while((sread = read(in_fd, deliver_out_buffer, DELIVER_OUT_BUFFER_SIZE)) > 0)
- {
- uschar * p = deliver_out_buffer;
- /* write the chunk */
-
- while (sread)
- {
-#ifdef SUPPORT_TLS
- wwritten = tls_out.active == out_fd
- ? tls_write(FALSE, p, sread, FALSE)
- : write(out_fd, CS p, sread);
-#else
- wwritten = write(out_fd, CS p, sread);
-#endif
- if (wwritten == -1)
- return FALSE;
- p += wwritten;
- sread -= wwritten;
- }
- }
-
- if (sread == -1)
- return FALSE;
- }
-
-return TRUE;
-}
-
-
-
-
-/* This function is a wrapper around transport_write_message().
- It is only called from the smtp transport if DKIM or Domainkeys support
- is active and no transport filter is to be used.
-
-Arguments:
- As for transport_write_message() in transort.c, with additional arguments
- for DKIM.
-
-Returns: TRUE on success; FALSE (with errno) for any failure
-*/
-
-static BOOL
-dkt_direct(transport_ctx * tctx, struct ob_dkim * dkim,
- const uschar ** err)
-{
-int save_fd = tctx->u.fd;
-int save_options = tctx->options;
-BOOL save_wireformat = spool_file_wireformat;
-uschar * hdrs;
-gstring * dkim_signature;
-int hsize;
-const uschar * errstr;
-BOOL rc;
-
-DEBUG(D_transport) debug_printf("dkim signing direct-mode\n");
-
-/* Get headers in string for signing and transmission. Do CRLF
-and dotstuffing (but no body nor dot-termination) */
-
-tctx->u.msg = NULL;
-tctx->options = tctx->options & ~(topt_end_dot | topt_use_bdat)
- | topt_output_string | topt_no_body;
-
-rc = transport_write_message(tctx, 0);
-hdrs = string_from_gstring(tctx->u.msg);
-hsize = tctx->u.msg->ptr;
-
-tctx->u.fd = save_fd;
-tctx->options = save_options;
-if (!rc) return FALSE;
-
-/* Get signatures for headers plus spool data file */
-
-dkim->dot_stuffed = !!(save_options & topt_end_dot);
-
-if (!(dkim_signature = dkim_exim_sign(deliver_datafile, SPOOL_DATA_START_OFFSET,
- hdrs, dkim, &errstr)))
- if (!(rc = dkt_sign_fail(dkim, &errno)))
- {
- *err = errstr;
- return FALSE;
- }
-
-/* Write the signature and headers into the deliver-out-buffer. This should
-mean they go out in the same packet as the MAIL, RCPT and (first) BDAT commands
-(transport_write_message() sizes the BDAT for the buffered amount) - for short
-messages, the BDAT LAST command. We want no dotstuffing expansion here, it
-having already been done - but we have to say we want CRLF output format, and
-temporarily set the marker for possible already-CRLF input. */
-
-tctx->options &= ~topt_escape_headers;
-spool_file_wireformat = TRUE;
-transport_write_reset(0);
-if ( ( dkim_signature
- && dkim_signature->ptr > 0
- && !write_chunk(tctx, dkim_signature->s, dkim_signature->ptr)
- )
- || !write_chunk(tctx, hdrs, hsize)
- )
- return FALSE;
-
-spool_file_wireformat = save_wireformat;
-tctx->options = save_options | topt_no_headers | topt_continuation;
-
-if (!(transport_write_message(tctx, 0)))
- return FALSE;
-
-tctx->options = save_options;
-return TRUE;
-}
-
-
-/* This function is a wrapper around transport_write_message().
- It is only called from the smtp transport if DKIM or Domainkeys support
- is active and a transport filter is to be used. The function sets up a
- replacement fd into a -K file, then calls the normal function. This way, the
- exact bits that exim would have put "on the wire" will end up in the file
- (except for TLS encapsulation, which is the very very last thing). When we
- are done signing the file, send the signed message down the original fd (or
- TLS fd).
-
-Arguments:
- As for transport_write_message() in transort.c, with additional arguments
- for DKIM.
-
-Returns: TRUE on success; FALSE (with errno) for any failure
-*/
-
-static BOOL
-dkt_via_kfile(transport_ctx * tctx, struct ob_dkim * dkim, const uschar ** err)
-{
-int dkim_fd;
-int save_errno = 0;
-BOOL rc;
-uschar * dkim_spool_name;
-gstring * dkim_signature;
-int options, dlen;
-off_t k_file_size;
-const uschar * errstr;
-
-dkim_spool_name = spool_fname(US"input", message_subdir, message_id,
- string_sprintf("-%d-K", (int)getpid()));
-
-DEBUG(D_transport) debug_printf("dkim signing via file %s\n", dkim_spool_name);
-
-if ((dkim_fd = Uopen(dkim_spool_name, O_RDWR|O_CREAT|O_TRUNC, SPOOL_MODE)) < 0)
- {
- /* Can't create spool file. Ugh. */
- rc = FALSE;
- save_errno = errno;
- *err = string_sprintf("dkim spoolfile create: %s", strerror(errno));
- goto CLEANUP;
- }
-
-/* Call transport utility function to write the -K file; does the CRLF expansion
-(but, in the CHUNKING case, neither dot-stuffing nor dot-termination). */
-
- {
- int save_fd = tctx->u.fd;
- tctx->u.fd = dkim_fd;
- options = tctx->options;
- tctx->options &= ~topt_use_bdat;
-
- rc = transport_write_message(tctx, 0);
-
- tctx->u.fd = save_fd;
- tctx->options = options;
- }
-
-/* Save error state. We must clean up before returning. */
-if (!rc)
- {
- save_errno = errno;
- goto CLEANUP;
- }
-
-/* Feed the file to the goats^W DKIM lib */
-
-dkim->dot_stuffed = !!(options & topt_end_dot);
-if (!(dkim_signature = dkim_exim_sign(dkim_fd, 0, NULL, dkim, &errstr)))
- {
- dlen = 0;
- if (!(rc = dkt_sign_fail(dkim, &save_errno)))
- {
- *err = errstr;
- goto CLEANUP;
- }
- }
-else
- dlen = dkim_signature->ptr;
-
-#ifndef OS_SENDFILE
-if (options & topt_use_bdat)
-#endif
- if ((k_file_size = lseek(dkim_fd, 0, SEEK_END)) < 0)
- {
- *err = string_sprintf("dkim spoolfile seek: %s", strerror(errno));
- goto CLEANUP;
- }
-
-if (options & topt_use_bdat)
- {
- /* On big messages output a precursor chunk to get any pipelined
- MAIL & RCPT commands flushed, then reap the responses so we can
- error out on RCPT rejects before sending megabytes. */
-
- if ( dlen + k_file_size > DELIVER_OUT_BUFFER_SIZE
- && dlen > 0)
- {
- if ( tctx->chunk_cb(tctx, dlen, 0) != OK
- || !transport_write_block(tctx,
- dkim_signature->s, dlen, FALSE)
- || tctx->chunk_cb(tctx, 0, tc_reap_prev) != OK
- )
- goto err;
- dlen = 0;
- }
-
- /* Send the BDAT command for the entire message, as a single LAST-marked
- chunk. */
-
- if (tctx->chunk_cb(tctx, dlen + k_file_size, tc_chunk_last) != OK)
- goto err;
- }
-
-if(dlen > 0 && !transport_write_block(tctx, dkim_signature->s, dlen, TRUE))
- goto err;
-
-if (!dkt_send_file(tctx->u.fd, dkim_fd, 0, k_file_size))
- {
- save_errno = errno;
- rc = FALSE;
- }
-
-CLEANUP:
- /* unlink -K file */
- if (dkim_fd >= 0) (void)close(dkim_fd);
- Uunlink(dkim_spool_name);
- errno = save_errno;
- return rc;
-
-err:
- save_errno = errno;
- rc = FALSE;
- goto CLEANUP;
-}
-
-
-
-/***************************************************************************************************
-* External interface to write the message, while signing it with DKIM and/or Domainkeys *
-***************************************************************************************************/
-
-/* This function is a wrapper around transport_write_message().
- It is only called from the smtp transport if DKIM or Domainkeys support
- is compiled in.
-
-Arguments:
- As for transport_write_message() in transort.c, with additional arguments
- for DKIM.
-
-Returns: TRUE on success; FALSE (with errno) for any failure
-*/
-
-BOOL
-dkim_transport_write_message(transport_ctx * tctx,
- struct ob_dkim * dkim, const uschar ** err)
-{
-/* If we can't sign, just call the original function. */
-
-if (!(dkim->dkim_private_key && dkim->dkim_domain && dkim->dkim_selector))
- return transport_write_message(tctx, 0);
-
-/* If there is no filter command set up, construct the message and calculate
-a dkim signature of it, send the signature and a reconstructed message. This
-avoids using a temprary file. */
-
-if ( !transport_filter_argv
- || !*transport_filter_argv
- || !**transport_filter_argv
- )
- return dkt_direct(tctx, dkim, err);
-
-/* Use the transport path to write a file, calculate a dkim signature,
-send the signature and then send the file. */
-
-return dkt_via_kfile(tctx, dkim, err);
-}
-
-#endif /* whole file */
-
-/* vi: aw ai sw=2
-*/
-/* End of dkim_transport.c */
git://git.exim.org / exim.git / blobdiff