Introduce _fetch_writev(), which is the conn_t version of writev(2). In

the SSL case, it is no different from the old _fetch_write(), but in the
non-SSL case it uses writev(2) to send the entire vector as a single
packet (provided it can fit in one packet).  Implement _fetch_write()
and _fetch_putln() in terms of _fetch_writev().

This should improve performance in the non-SSL case (by reducing protocol
overhead) and solve the problem where too-smart-for-their-own-good
firewalls reject FTP packets that do not end in CRLF.

PR:		bin/44123
Submitted by:	fenner

2 files changed, 38 insertions, 7 deletions

diff --git a/lib/libfetch/common.c b/lib/libfetch/common.c
index 48ac5d3..ab3f4ca 100644
--- a/lib/libfetch/common.c
+++ b/lib/libfetch/common.c
@@ -454,6 +454,20 @@ _fetch_getln(conn_t *conn)
 ssize_t
 _fetch_write(conn_t *conn, const char *buf, size_t len)
 {
+	struct iovec iov;
+
+	iov.iov_base = (char *)buf;
+	iov.iov_len = len;
+	return _fetch_writev(conn, &iov, 1);
+}
+
+/*
+ * Write a vector to a connection w/ timeout
+ * Note: can modify the iovec.
+ */
+ssize_t
+_fetch_writev(conn_t *conn, struct iovec *iov, int iovcnt)
+{
 	struct timeval now, timeout, wait;
 	fd_set writefds;
 	ssize_t wlen, total;
@@ -466,7 +480,7 @@ _fetch_write(conn_t *conn, const char *buf, size_t len)
 	}
 
 	total = 0;
-	while (len > 0) {
+	while (iovcnt > 0) {
 		while (fetchTimeout && !FD_ISSET(conn->sd, &writefds)) {
 			FD_SET(conn->sd, &writefds);
 			gettimeofday(&now, NULL);
@@ -492,10 +506,11 @@ _fetch_write(conn_t *conn, const char *buf, size_t len)
 		errno = 0;
 #ifdef WITH_SSL
 		if (conn->ssl != NULL)
-			wlen = SSL_write(conn->ssl, buf, len);
+			wlen = SSL_write(conn->ssl,
+			    iov->iov_base, iov->iov_len);
 		else
 #endif
-			wlen = write(conn->sd, buf, len);
+			wlen = writev(conn->sd, iov, iovcnt);
 		if (wlen == 0) {
 			/* we consider a short write a failure */
 			errno = EPIPE;
@@ -507,9 +522,17 @@ _fetch_write(conn_t *conn, const char *buf, size_t len)
 				continue;
 			return (-1);
 		}
-		len -= wlen;
-		buf += wlen;
 		total += wlen;
+		while (iovcnt > 0 && wlen > iov->iov_len) {
+			wlen -= iov->iov_len;
+			iov++;
+			iovcnt--;
+		}
+		if (iovcnt > 0) {
+			iov->iov_len -= wlen;
+			iov->iov_base += wlen;
+			wlen = 0;
+		}
 	}
 	return (total);
 }
@@ -521,10 +544,14 @@ _fetch_write(conn_t *conn, const char *buf, size_t len)
 int
 _fetch_putln(conn_t *conn, const char *str, size_t len)
 {
+	struct iovec iov[2];
 
 	DEBUG(fprintf(stderr, ">>> %s\n", str));
-	if (_fetch_write(conn, str, len) == -1 ||
-	    _fetch_write(conn, ENDL, sizeof ENDL) == -1)
+	iov[0].iov_base = (char *)str;
+	iov[0].iov_len = len;
+	iov[1].iov_base = (char *)ENDL;
+	iov[1].iov_len = sizeof ENDL;
+	if (_fetch_writev(conn, iov, 2) == -1)
 		return (-1);
 	return (0);
 }
diff --git a/lib/libfetch/common.h b/lib/libfetch/common.h
index 42f68a8..4b42bf2 100644
--- a/lib/libfetch/common.h
+++ b/lib/libfetch/common.h
@@ -68,6 +68,9 @@ struct fetcherr {
 	const char	*string;
 };
 
+/* for _fetch_writev */
+struct iovec;
+
 void		 _fetch_seterr(struct fetcherr *, int);
 void		 _fetch_syserr(void);
 void		 _fetch_info(const char *, ...);
@@ -80,6 +83,7 @@ int		 _fetch_ssl(conn_t *, int);
 ssize_t		 _fetch_read(conn_t *, char *, size_t);
 int		 _fetch_getln(conn_t *);
 ssize_t		 _fetch_write(conn_t *, const char *, size_t);
+ssize_t		 _fetch_writev(conn_t *, struct iovec *, int);
 int		 _fetch_putln(conn_t *, const char *, size_t);
 int		 _fetch_close(conn_t *);
 int		 _fetch_add_entry(struct url_ent **, int *, int *,