unix: add Connectx for darwin

connectx(2) can be used to initiate a connection with TCP Fast Open.

Change-Id: I113ee4dede7df1c01e16a0c07fec2b384b266cb0
GitHub-Last-Rev: 31665b9
GitHub-Pull-Request: #215
Reviewed-on: https://go-review.googlesource.com/c/sys/+/606155
Auto-Submit: Ian Lance Taylor <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Cherry Mui <[email protected]>
Reviewed-by: Ian Lance Taylor <[email protected]>

Author: database64128

unix/darwin_amd64_test.go

@@ -552,6 +552,7 @@ ccflags="$@"
 		$2 !~ /^RTC_VL_(ACCURACY|BACKUP|DATA)/ &&
 		$2 ~ /^(NETLINK|NLM|NLMSG|NLA|IFA|IFAN|RT|RTC|RTCF|RTN|RTPROT|RTNH|ARPHRD|ETH_P|NETNSA)_/ ||
 		$2 ~ /^SOCK_|SK_DIAG_|SKNLGRP_$/ ||
+		$2 ~ /^(CONNECT|SAE)_/ ||
 		$2 ~ /^FIORDCHK$/ ||
 		$2 ~ /^SIOC/ ||
 		$2 ~ /^TIOC/ ||

unix/darwin_arm64_test.go

@@ -566,6 +566,43 @@ func PthreadFchdir(fd int) (err error) {
 	return pthread_fchdir_np(fd)
 }
 
+// Connectx calls connectx(2) to initiate a connection on a socket.
+//
+// srcIf, srcAddr, and dstAddr are filled into a [SaEndpoints] struct and passed as the endpoints argument.
+//
+//   - srcIf is the optional source interface index. 0 means unspecified.
+//   - srcAddr is the optional source address. nil means unspecified.
+//   - dstAddr is the destination address.
+//
+// On success, Connectx returns the number of bytes enqueued for transmission.
+func Connectx(fd int, srcIf uint32, srcAddr, dstAddr Sockaddr, associd SaeAssocID, flags uint32, iov []Iovec, connid *SaeConnID) (n uintptr, err error) {
+	endpoints := SaEndpoints{
+		Srcif: srcIf,
+	}
+
+	if srcAddr != nil {
+		addrp, addrlen, err := srcAddr.sockaddr()
+		if err != nil {
+			return 0, err
+		}
+		endpoints.Srcaddr = (*RawSockaddr)(addrp)
+		endpoints.Srcaddrlen = uint32(addrlen)
+	}
+
+	if dstAddr != nil {
+		addrp, addrlen, err := dstAddr.sockaddr()
+		if err != nil {
+			return 0, err
+		}
+		endpoints.Dstaddr = (*RawSockaddr)(addrp)
+		endpoints.Dstaddrlen = uint32(addrlen)
+	}
+
+	err = connectx(fd, &endpoints, associd, flags, iov, &n, connid)
+	return
+}
+
+//sys	connectx(fd int, endpoints *SaEndpoints, associd SaeAssocID, flags uint32, iov []Iovec, n *uintptr, connid *SaeConnID) (err error)
 //sys	sendfile(infd int, outfd int, offset int64, len *int64, hdtr unsafe.Pointer, flags int) (err error)
 
 //sys	shmat(id int, addr uintptr, flag int) (ret uintptr, err error)

unix/mkerrors.sh

@@ -177,6 +177,12 @@ type XVSockPgen C.struct_xvsockpgen
 
 type _Socklen C.socklen_t
 
+type SaeAssocID C.sae_associd_t
+
+type SaeConnID C.sae_connid_t
+
+type SaEndpoints C.struct_sa_endpoints
+
 type Xucred C.struct_xucred
 
 type Linger C.struct_linger

unix/syscall_darwin.go

@@ -248,6 +248,11 @@ TEXT libc_pthread_fchdir_np_trampoline<>(SB),NOSPLIT,$0-0
 GLOBL	·libc_pthread_fchdir_np_trampoline_addr(SB), RODATA, $8
 DATA	·libc_pthread_fchdir_np_trampoline_addr(SB)/8, $libc_pthread_fchdir_np_trampoline<>(SB)
 
+TEXT libc_connectx_trampoline<>(SB),NOSPLIT,$0-0
+	JMP	libc_connectx(SB)
+GLOBL	·libc_connectx_trampoline_addr(SB), RODATA, $8
+DATA	·libc_connectx_trampoline_addr(SB)/8, $libc_connectx_trampoline<>(SB)
+
 TEXT libc_sendfile_trampoline<>(SB),NOSPLIT,$0-0
 	JMP	libc_sendfile(SB)
 GLOBL	·libc_sendfile_trampoline_addr(SB), RODATA, $8