[PATCH v3 07/18] tap, tcp: Move tap send path to tap.c

[David Gibson <david@gibson.dropbear.id.au>]

The functions which do the final steps of sending TCP packets on through
the tap interface - tcp_l2_buf_flush*() - no longer have anything that's
actually specific to TCP in them, other than comments and names.  Move them
all to tap.c.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 tap.c | 84 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 tap.h |  1 +
 tcp.c | 85 +++--------------------------------------------------------
 3 files changed, 89 insertions(+), 81 deletions(-)

diff --git a/tap.c b/tap.c
index 2e603ed..558a734 100644
--- a/tap.c
+++ b/tap.c
@@ -53,6 +53,7 @@
 #include "netlink.h"
 #include "pasta.h"
 #include "packet.h"
+#include "tap.h"
 #include "log.h"
 
 /* IPv4 (plus ARP) and IPv6 message batches from tap/guest to IP handlers */
@@ -302,6 +303,89 @@ void tap_icmp6_send(const struct ctx *c,
 		debug("tap: failed to send %lu bytes (IPv6)", len);
 }
 
+/**
+ * tap_send_frames_pasta() - Send multiple frames to the pasta tap
+ * @c:		Execution context
+ * @iov:	Array of buffers, each containing one frame
+ * @n:		Number of buffers/frames in @iov
+ *
+ * #syscalls:pasta write
+ */
+static void tap_send_frames_pasta(struct ctx *c,
+				  const struct iovec *iov, size_t n)
+{
+	size_t i;
+
+	for (i = 0; i < n; i++) {
+		if (write(c->fd_tap, (char *)iov->iov_base + 4,
+			  iov->iov_len - 4) < 0) {
+			debug("tap write: %s", strerror(errno));
+			if (errno != EAGAIN && errno != EWOULDBLOCK)
+				tap_handler(c, c->fd_tap, EPOLLERR, NULL);
+			i--;
+		}
+	}
+}
+
+/**
+ * tap_send_frames_passt() - Send multiple frames to the passt tap
+ * @c:		Execution context
+ * @iov:	Array of buffers, each containing one frame
+ * @n:		Number of buffers/frames in @iov
+ *
+ * #syscalls:passt sendmsg send
+ */
+static void tap_send_frames_passt(const struct ctx *c,
+				  const struct iovec *iov, size_t n)
+{
+	struct msghdr mh = {
+		.msg_iov = (void *)iov,
+		.msg_iovlen = n,
+	};
+	size_t end = 0, missing;
+	unsigned int i;
+	ssize_t sent;
+	char *p;
+
+	sent = sendmsg(c->fd_tap, &mh, MSG_NOSIGNAL | MSG_DONTWAIT);
+	if (sent < 0)
+		return;
+
+	/* Ensure a complete last message on partial sendmsg() */
+	for (i = 0; i < n; i++, iov++) {
+		end += iov->iov_len;
+		if (end >= (size_t)sent)
+			break;
+	}
+
+	missing = end - sent;
+	if (!missing)
+		return;
+
+	p = (char *)iov->iov_base + iov->iov_len - missing;
+	if (send(c->fd_tap, p, missing, MSG_NOSIGNAL))
+		debug("tap: failed to flush %lu missing bytes to tap", missing);
+}
+
+/**
+ * tap_send_frames() - Send out multiple prepared frames
+ * @c:		Execution context
+ * @iov:	Array of buffers, each containing one frame (with L2 headers)
+ * @n:		Number of buffers/frames in @iov
+ */
+void tap_send_frames(struct ctx *c, const struct iovec *iov, size_t n)
+{
+	if (!n)
+		return;
+
+	if (c->mode == MODE_PASST)
+		tap_send_frames_passt(c, iov, n);
+	else
+		tap_send_frames_pasta(c, iov, n);
+
+	pcap_multiple(iov, n, sizeof(uint32_t));
+}
+
 PACKET_POOL_DECL(pool_l4, UIO_MAXIOV, pkt_buf);
 
 /**
diff --git a/tap.h b/tap.h
index 674ab5c..ceac890 100644
--- a/tap.h
+++ b/tap.h
@@ -22,6 +22,7 @@ void tap_icmp6_send(const struct ctx *c,
 		    const struct in6_addr *src, const struct in6_addr *dst,
 		    void *in, size_t len);
 int tap_send(const struct ctx *c, const void *data, size_t len);
+void tap_send_frames(struct ctx *c, const struct iovec *iov, size_t n);
 void tap_handler(struct ctx *c, int fd, uint32_t events,
 		 const struct timespec *now);
 void tap_sock_init(struct ctx *c);
diff --git a/tcp.c b/tcp.c
index 9960a35..0c46a7e 100644
--- a/tcp.c
+++ b/tcp.c
@@ -1390,93 +1390,16 @@ static void tcp_rst_do(struct ctx *c, struct tcp_tap_conn *conn);
 		tcp_rst_do(c, conn);					\
 	} while (0)
 
-/**
- * tcp_l2_buf_flush_pasta() - Send frames on the pasta tap interface
- * @c:		Execution context
- * @iov:	Pointer to array of buffers, one per frame
- * @n:		Number of buffers/frames to flush
- */
-static void tcp_l2_buf_flush_pasta(struct ctx *c,
-				  const struct iovec *iov, size_t n)
-{
-	size_t i;
-
-	for (i = 0; i < n; i++) {
-		if (write(c->fd_tap, (char *)iov->iov_base + 4,
-			  iov->iov_len - 4) < 0) {
-			debug("tap write: %s", strerror(errno));
-			if (errno != EAGAIN && errno != EWOULDBLOCK)
-				tap_handler(c, c->fd_tap, EPOLLERR, NULL);
-			i--;
-		}
-	}
-}
-
-/**
- * tcp_l2_buf_flush_passt() - Send a message on the passt tap interface
- * @c:		Execution context
- * @iov:	Pointer to array of buffers, one per frame
- * @n:		Number of buffers/frames to flush
- */
-static void tcp_l2_buf_flush_passt(const struct ctx *c,
-				   const struct iovec *iov, size_t n)
-{
-	struct msghdr mh = {
-		.msg_iov = (void *)iov,
-		.msg_iovlen = n,
-	};
-	size_t end = 0, missing;
-	unsigned int i;
-	ssize_t sent;
-	char *p;
-
-	sent = sendmsg(c->fd_tap, &mh, MSG_NOSIGNAL | MSG_DONTWAIT);
-	if (sent < 0)
-		return;
-
-	/* Ensure a complete last message on partial sendmsg() */
-	for (i = 0; i < n; i++, iov++) {
-		end += iov->iov_len;
-		if (end >= (size_t)sent)
-			break;
-	}
-
-	missing = end - sent;
-	if (!missing)
-		return;
-
-	p = (char *)iov->iov_base + iov->iov_len - missing;
-	if (send(c->fd_tap, p, missing, MSG_NOSIGNAL))
-		debug("TCP: failed to flush %lu missing bytes to tap", missing);
-}
-
-/**
- * tcp_l2_flags_buf_flush() - Send out buffers for segments with or without data
- * @c:		Execution context
- */
-static void tcp_l2_buf_flush(struct ctx *c, const struct iovec *iov, size_t n)
-{
-	if (!n)
-		return;
-
-	if (c->mode == MODE_PASST)
-		tcp_l2_buf_flush_passt(c, iov, n);
-	else
-		tcp_l2_buf_flush_pasta(c, iov, n);
-
-	pcap_multiple(iov, n, sizeof(uint32_t));
-}
-
 /**
  * tcp_l2_flags_buf_flush() - Send out buffers for segments with no data (flags)
  * @c:		Execution context
  */
 static void tcp_l2_flags_buf_flush(struct ctx *c)
 {
-	tcp_l2_buf_flush(c, tcp6_l2_flags_iov, tcp6_l2_flags_buf_used);
+	tap_send_frames(c, tcp6_l2_flags_iov, tcp6_l2_flags_buf_used);
 	tcp6_l2_flags_buf_used = 0;
 
-	tcp_l2_buf_flush(c, tcp4_l2_flags_iov, tcp4_l2_flags_buf_used);
+	tap_send_frames(c, tcp4_l2_flags_iov, tcp4_l2_flags_buf_used);
 	tcp4_l2_flags_buf_used = 0;
 }
 
@@ -1486,10 +1409,10 @@ static void tcp_l2_flags_buf_flush(struct ctx *c)
  */
 static void tcp_l2_data_buf_flush(struct ctx *c)
 {
-	tcp_l2_buf_flush(c, tcp6_l2_iov, tcp6_l2_buf_used);
+	tap_send_frames(c, tcp6_l2_iov, tcp6_l2_buf_used);
 	tcp6_l2_buf_used = 0;
 
-	tcp_l2_buf_flush(c, tcp4_l2_iov, tcp4_l2_buf_used);
+	tap_send_frames(c, tcp4_l2_iov, tcp4_l2_buf_used);
 	tcp4_l2_buf_used = 0;
 }
 
-- 
@@ -1390,93 +1390,16 @@ static void tcp_rst_do(struct ctx *c, struct tcp_tap_conn *conn);
 		tcp_rst_do(c, conn);					\
 	} while (0)
 
-/**
- * tcp_l2_buf_flush_pasta() - Send frames on the pasta tap interface
- * @c:		Execution context
- * @iov:	Pointer to array of buffers, one per frame
- * @n:		Number of buffers/frames to flush
- */
-static void tcp_l2_buf_flush_pasta(struct ctx *c,
-				  const struct iovec *iov, size_t n)
-{
-	size_t i;
-
-	for (i = 0; i < n; i++) {
-		if (write(c->fd_tap, (char *)iov->iov_base + 4,
-			  iov->iov_len - 4) < 0) {
-			debug("tap write: %s", strerror(errno));
-			if (errno != EAGAIN && errno != EWOULDBLOCK)
-				tap_handler(c, c->fd_tap, EPOLLERR, NULL);
-			i--;
-		}
-	}
-}
-
-/**
- * tcp_l2_buf_flush_passt() - Send a message on the passt tap interface
- * @c:		Execution context
- * @iov:	Pointer to array of buffers, one per frame
- * @n:		Number of buffers/frames to flush
- */
-static void tcp_l2_buf_flush_passt(const struct ctx *c,
-				   const struct iovec *iov, size_t n)
-{
-	struct msghdr mh = {
-		.msg_iov = (void *)iov,
-		.msg_iovlen = n,
-	};
-	size_t end = 0, missing;
-	unsigned int i;
-	ssize_t sent;
-	char *p;
-
-	sent = sendmsg(c->fd_tap, &mh, MSG_NOSIGNAL | MSG_DONTWAIT);
-	if (sent < 0)
-		return;
-
-	/* Ensure a complete last message on partial sendmsg() */
-	for (i = 0; i < n; i++, iov++) {
-		end += iov->iov_len;
-		if (end >= (size_t)sent)
-			break;
-	}
-
-	missing = end - sent;
-	if (!missing)
-		return;
-
-	p = (char *)iov->iov_base + iov->iov_len - missing;
-	if (send(c->fd_tap, p, missing, MSG_NOSIGNAL))
-		debug("TCP: failed to flush %lu missing bytes to tap", missing);
-}
-
-/**
- * tcp_l2_flags_buf_flush() - Send out buffers for segments with or without data
- * @c:		Execution context
- */
-static void tcp_l2_buf_flush(struct ctx *c, const struct iovec *iov, size_t n)
-{
-	if (!n)
-		return;
-
-	if (c->mode == MODE_PASST)
-		tcp_l2_buf_flush_passt(c, iov, n);
-	else
-		tcp_l2_buf_flush_pasta(c, iov, n);
-
-	pcap_multiple(iov, n, sizeof(uint32_t));
-}
-
 /**
  * tcp_l2_flags_buf_flush() - Send out buffers for segments with no data (flags)
  * @c:		Execution context
  */
 static void tcp_l2_flags_buf_flush(struct ctx *c)
 {
-	tcp_l2_buf_flush(c, tcp6_l2_flags_iov, tcp6_l2_flags_buf_used);
+	tap_send_frames(c, tcp6_l2_flags_iov, tcp6_l2_flags_buf_used);
 	tcp6_l2_flags_buf_used = 0;
 
-	tcp_l2_buf_flush(c, tcp4_l2_flags_iov, tcp4_l2_flags_buf_used);
+	tap_send_frames(c, tcp4_l2_flags_iov, tcp4_l2_flags_buf_used);
 	tcp4_l2_flags_buf_used = 0;
 }
 
@@ -1486,10 +1409,10 @@ static void tcp_l2_flags_buf_flush(struct ctx *c)
  */
 static void tcp_l2_data_buf_flush(struct ctx *c)
 {
-	tcp_l2_buf_flush(c, tcp6_l2_iov, tcp6_l2_buf_used);
+	tap_send_frames(c, tcp6_l2_iov, tcp6_l2_buf_used);
 	tcp6_l2_buf_used = 0;
 
-	tcp_l2_buf_flush(c, tcp4_l2_iov, tcp4_l2_buf_used);
+	tap_send_frames(c, tcp4_l2_iov, tcp4_l2_buf_used);
 	tcp4_l2_buf_used = 0;
 }
 
-- 
2.39.0