1 files changed, 296 insertions, 0 deletions

diff --git a/src/tls/tls_bio_ops.c b/src/tls/tls_bio_ops.c
new file mode 100644
index 0000000..9b66195
--- /dev/null
+++ b/src/tls/tls_bio_ops.c
@@ -0,0 +1,296 @@
+/*++
+/* NAME
+/*	tls_bio_ops 3
+/* SUMMARY
+/*	TLS network basic I/O management
+/* SYNOPSIS
+/*	#define TLS_INTERNAL
+/*	#include <tls.h>
+/*
+/*	int tls_bio_connect(fd, timeout, context)
+/*	int	fd;
+/*	int	timeout;
+/*	TLS_SESS_STATE *context;
+/*
+/*	int tls_bio_accept(fd, timeout, context)
+/*	int	fd;
+/*	int	timeout;
+/*	TLS_SESS_STATE *context;
+/*
+/*	int tls_bio_shutdown(fd, timeout, context)
+/*	int	fd;
+/*	int	timeout;
+/*	TLS_SESS_STATE *context;
+/*
+/*	int tls_bio_read(fd, buf, len, timeout, context)
+/*	int	fd;
+/*	void	*buf;
+/*	int	len;
+/*	int	timeout;
+/*	TLS_SESS_STATE *context;
+/*
+/*	int tls_bio_write(fd, buf, len, timeout, context)
+/*	int	fd;
+/*	void	*buf;
+/*	int	len;
+/*	int	timeout;
+/*	TLS_SESS_STATE *context;
+/* DESCRIPTION
+/*	This module enforces VSTREAM-style timeouts on non-blocking
+/*	I/O while performing TLS handshake or input/output operations.
+/*
+/*	The Postfix VSTREAM read/write routines invoke the
+/*	tls_bio_read/write routines to send and receive plain-text
+/*	data.  In addition, this module provides tls_bio_connect/accept
+/*	routines that trigger the initial TLS handshake.  The
+/*	tls_bio_xxx routines invoke the corresponding SSL routines
+/*	that translate the requests into TLS protocol messages.
+/*
+/*	Whenever an SSL operation indicates that network input (or
+/*	output) needs to happen, the tls_bio_xxx routines wait for
+/*	the network to become readable (or writable) within the
+/*	timeout limit, then retry the SSL operation. This works
+/*	because the network socket is in non-blocking mode.
+/*
+/*	tls_bio_connect() performs the SSL_connect() operation.
+/*
+/*	tls_bio_accept() performs the SSL_accept() operation.
+/*
+/*	tls_bio_shutdown() performs the SSL_shutdown() operation.
+/*
+/*	tls_bio_read() performs the SSL_read() operation.
+/*
+/*	tls_bio_write() performs the SSL_write() operation.
+/*
+/*	Arguments:
+/* .IP fd
+/*	Network socket.
+/* .IP buf
+/*	Read/write buffer.
+/* .IP len
+/*	Read/write request size.
+/* .IP timeout
+/*	Read/write timeout.
+/* .IP TLScontext
+/*	TLS session state.
+/* DIAGNOSTICS
+/*	A result value > 0 means successful completion.
+/*
+/*	A result value < 0 means that the requested operation did
+/*	not complete due to TLS protocol failure, system call
+/*	failure, or for any reason described under "in addition"
+/*	below.
+/*
+/*	A result value of 0 from tls_bio_shutdown() means that the
+/*	operation is in progress. A result value of 0 from other
+/*	tls_bio_ops(3) operations means that the remote party either
+/*	closed the network connection or that it sent a TLS shutdown
+/*	request.
+/*
+/*	Upon return from the tls_bio_ops(3) routines the global
+/*	errno value is non-zero when the requested operation did not
+/*	complete due to system call failure.
+/*
+/*	In addition, the result value is set to -1, and the global
+/*	errno value is set to ETIMEDOUT, when some network read/write
+/*	operation did not complete within the time limit.
+/* LICENSE
+/* .ad
+/* .fi
+/*	This software is free. You can do with it whatever you want.
+/*	The original author kindly requests that you acknowledge
+/*	the use of his software.
+/* AUTHOR(S)
+/*	Originally written by:
+/*	Lutz Jaenicke
+/*	BTU Cottbus
+/*	Allgemeine Elektrotechnik
+/*	Universitaetsplatz 3-4
+/*	D-03044 Cottbus, Germany
+/*
+/*	Updated by:
+/*	Wietse Venema
+/*	IBM T.J. Watson Research
+/*	P.O. Box 704
+/*	Yorktown Heights, NY 10598, USA
+/*
+/*	Victor Duchovni
+/*	Morgan Stanley
+/*--*/
+
+/* System library. */
+
+#include <sys_defs.h>
+#include <sys/time.h>
+
+#ifndef timersub
+/* res = a - b */
+#define timersub(a, b, res) do { \
+	(res)->tv_sec = (a)->tv_sec - (b)->tv_sec; \
+	(res)->tv_usec = (a)->tv_usec - (b)->tv_usec; \
+	if ((res)->tv_usec < 0) { \
+		(res)->tv_sec--; \
+		(res)->tv_usec += 1000000; \
+	} \
+    } while (0)
+#endif
+
+#ifdef USE_TLS
+
+/* Utility library. */
+
+#include <msg.h>
+#include <iostuff.h>
+
+/* TLS library. */
+
+#define TLS_INTERNAL
+#include <tls.h>
+
+/* tls_bio - perform SSL input/output operation with extreme prejudice */
+
+int     tls_bio(int fd, int timeout, TLS_SESS_STATE *TLScontext,
+		        int (*hsfunc) (SSL *),
+		        int (*rfunc) (SSL *, void *, int),
+		        int (*wfunc) (SSL *, const void *, int),
+		        void *buf, int num)
+{
+    const char *myname = "tls_bio";
+    int     status;
+    int     err;
+    int     enable_deadline;
+    struct timeval time_left;		/* amount of time left */
+    struct timeval time_deadline;	/* time of deadline */
+    struct timeval time_now;		/* time after SSL_mumble() call */
+
+    /*
+     * Compensation for interface mis-match: With VSTREAMs, timeout <= 0
+     * means wait forever; with the read/write_wait() calls below, we need to
+     * specify timeout < 0 instead.
+     * 
+     * Safety: no time limit means no deadline.
+     */
+    if (timeout <= 0) {
+	timeout = -1;
+	enable_deadline = 0;
+    }
+
+    /*
+     * Deadline management is simpler than with VSTREAMs, because we don't
+     * need to decrement a per-stream time limit. We just work within the
+     * budget that is available for this tls_bio() call.
+     */
+    else {
+	enable_deadline =
+	    vstream_fstat(TLScontext->stream, VSTREAM_FLAG_DEADLINE);
+	if (enable_deadline) {
+	    GETTIMEOFDAY(&time_deadline);
+	    time_deadline.tv_sec += timeout;
+	}
+    }
+
+    /*
+     * If necessary, retry the SSL handshake or read/write operation after
+     * handling any pending network I/O.
+     */
+    for (;;) {
+
+	/*
+	 * Flush the per-thread SSL error queue. Otherwise, errors from other
+	 * code that also uses TLS may confuse SSL_get_error(3).
+	 */
+	ERR_clear_error();
+
+	if (hsfunc)
+	    status = hsfunc(TLScontext->con);
+	else if (rfunc)
+	    status = rfunc(TLScontext->con, buf, num);
+	else if (wfunc)
+	    status = wfunc(TLScontext->con, buf, num);
+	else
+	    msg_panic("%s: nothing to do here", myname);
+	err = SSL_get_error(TLScontext->con, status);
+
+	/*
+	 * Correspondence between SSL_ERROR_* error codes and tls_bio_(read,
+	 * write, accept, connect, shutdown) return values (for brevity:
+	 * retval).
+	 * 
+	 * SSL_ERROR_NONE corresponds with retval > 0. With SSL_(read, write)
+	 * this is the number of plaintext bytes sent or received. With
+	 * SSL_(accept, connect, shutdown) this means that the operation was
+	 * completed successfully.
+	 * 
+	 * SSL_ERROR_WANT_(WRITE, READ) start a new loop iteration, or force
+	 * (retval = -1, errno = ETIMEDOUT) when the time limit is exceeded.
+	 * 
+	 * All other SSL_ERROR_* cases correspond with retval <= 0. With
+	 * SSL_(read, write, accept, connect) retval == 0 means that the
+	 * remote party either closed the network connection or that it
+	 * requested TLS shutdown; with SSL_shutdown() retval == 0 means that
+	 * our own shutdown request is in progress. With all operations
+	 * retval < 0 means that there was an error. In the latter case,
+	 * SSL_ERROR_SYSCALL means that error details are returned via the
+	 * errno value.
+	 * 
+	 * Find out if we must retry the operation and/or if there is pending
+	 * network I/O.
+	 * 
+	 * XXX If we're the first to invoke SSL_shutdown(), then the operation
+	 * isn't really complete when the call returns. We could hide that
+	 * anomaly here and repeat the call.
+	 */
+	switch (err) {
+	case SSL_ERROR_WANT_WRITE:
+	case SSL_ERROR_WANT_READ:
+	    if (enable_deadline) {
+		GETTIMEOFDAY(&time_now);
+		timersub(&time_deadline, &time_now, &time_left);
+		timeout = time_left.tv_sec + (time_left.tv_usec > 0);
+		if (timeout <= 0) {
+		    errno = ETIMEDOUT;
+		    return (-1);
+		}
+	    }
+	    if (err == SSL_ERROR_WANT_WRITE) {
+		if (write_wait(fd, timeout) < 0)
+		    return (-1);		/* timeout error */
+	    } else {
+		if (read_wait(fd, timeout) < 0)
+		    return (-1);		/* timeout error */
+	    }
+	    break;
+
+	    /*
+	     * Unhandled cases: SSL_ERROR_WANT_(ACCEPT, CONNECT, X509_LOOKUP)
+	     * etc. Historically, Postfix silently treated these as ordinary
+	     * I/O errors so we don't really know how common they are. For
+	     * now, we just log a warning.
+	     */
+	default:
+	    msg_warn("%s: unexpected SSL_ERROR code %d", myname, err);
+	    /* FALLTHROUGH */
+
+	    /*
+	     * With tls_timed_read() and tls_timed_write() the caller is the
+	     * VSTREAM library module which is unaware of TLS, so we log the
+	     * TLS error stack here. In a better world, each VSTREAM I/O
+	     * object would provide an error reporting method in addition to
+	     * the timed_read and timed_write methods, so that we would not
+	     * need to have ad-hoc code like this.
+	     */
+	case SSL_ERROR_SSL:
+	    if (rfunc || wfunc)
+		tls_print_errors();
+	    /* FALLTHROUGH */
+	case SSL_ERROR_ZERO_RETURN:
+	case SSL_ERROR_NONE:
+	    errno = 0;				/* avoid bogus warnings */
+	    /* FALLTHROUGH */
+	case SSL_ERROR_SYSCALL:
+	    return (status);
+	}
+    }
+}
+
+#endif