From 48e338130e87e1e2a8fb0ae7d08cf11f84e57eb2 Mon Sep 17 00:00:00 2001
From: Josh Bleecher Snyder <josh@tailscale.com>
Date: Tue, 1 Jun 2021 16:06:59 -0700
Subject: [PATCH] mve sockaddr_in to Go

---
 net/uring/io_uring.c        | 19 +++++--------------
 net/uring/io_uring_linux.go |  4 +++-
 2 files changed, 8 insertions(+), 15 deletions(-)

diff --git a/net/uring/io_uring.c b/net/uring/io_uring.c
index 6e13a58d4..b90d20628 100644
--- a/net/uring/io_uring.c
+++ b/net/uring/io_uring.c
@@ -17,6 +17,7 @@
 typedef struct io_uring go_uring;
 typedef struct msghdr go_msghdr;
 typedef struct iovec go_iovec;
+typedef struct sockaddr_in go_sockaddr_in;
 
 // Wait for a completion to be available, fetch the data
 static int receive_into(int sock, struct io_uring *ring, char *ip, uint16_t *port) {
@@ -44,13 +45,9 @@ again:;
     }
     int n = cqe->res;
 
-    struct sockaddr_in sa;
-    memcpy(&sa, mhdr->msg_name, mhdr->msg_namelen);
-
-    memcpy(ip, &sa.sin_addr, 4);
-    *port = ntohs(sa.sin_port);
-
-    free(mhdr->msg_name);
+    struct sockaddr_in *sa = (void *)mhdr->msg_name;
+    memcpy(ip, &sa->sin_addr, 4);
+    *port = ntohs(sa->sin_port);
 
     io_uring_cqe_seen(ring, cqe);
     return n;
@@ -58,19 +55,13 @@ again:;
 
 // submit a recvmsg request via liburing
 // TODO: What recvfrom support arrives, maybe use that instead?
-static int submit_recvmsg_request(int sock, struct io_uring *ring, struct msghdr *mhdr, struct iovec *iov, char *buf, int buflen) {
-    char *sender = malloc(sizeof(struct sockaddr_in));
-    if (!sender) {
-        perror("malloc(sender)");
-        return 1;
-    }
+static int submit_recvmsg_request(int sock, struct io_uring *ring, struct msghdr *mhdr, struct iovec *iov, struct sockaddr_in *sender, char *buf, int buflen) {
     iov->iov_base = buf;
     iov->iov_len = buflen;
 
     mhdr->msg_iov = iov;
     mhdr->msg_iovlen = 1;
 
-    memset(sender, 0, sizeof(struct sockaddr_in));
     mhdr->msg_name = sender;
     mhdr->msg_namelen = sizeof(struct sockaddr_in);
 
diff --git a/net/uring/io_uring_linux.go b/net/uring/io_uring_linux.go
index fd0bca3ed..d7c8cc38b 100644
--- a/net/uring/io_uring_linux.go
+++ b/net/uring/io_uring_linux.go
@@ -72,8 +72,9 @@ func (u *UDPConn) ReadFromNetaddr(buf []byte) (int, netaddr.IPPort, error) {
 	}
 	mhdr := new(C.go_msghdr)
 	iov := new(C.go_iovec)
+	sa := new(C.go_sockaddr_in)
 	// TODO: eventually separate submitting the request and waiting for the response.
-	errno := C.submit_recvmsg_request(u.fd, u.ptr, mhdr, iov, (*C.char)(unsafe.Pointer(&buf[0])), C.int(len(buf)))
+	errno := C.submit_recvmsg_request(u.fd, u.ptr, mhdr, iov, sa, (*C.char)(unsafe.Pointer(&buf[0])), C.int(len(buf)))
 	if errno < 0 {
 		return 0, netaddr.IPPort{}, fmt.Errorf("uring.UDPConn recv failed: %v", errno) // TODO: Improve errno
 	}
@@ -87,6 +88,7 @@ func (u *UDPConn) ReadFromNetaddr(buf []byte) (int, netaddr.IPPort, error) {
 	ipp := netaddr.IPPortFrom(netaddr.IPFrom4(*a), uint16(port))
 	runtime.KeepAlive(mhdr)
 	runtime.KeepAlive(iov)
+	runtime.KeepAlive(sa)
 	return int(n), ipp, nil
 }