upd5

socket_addr.c.v

@@ -2,6 +2,8 @@ module netio
 
 import encoding.binary
 
+struct C.sockaddr_storage {}
+
 // max_unix_path_size value is used to pad the sockaddr_un struct.
 const max_unix_path_size = $if linux {
 	108
@@ -11,6 +13,13 @@ const max_unix_path_size = $if linux {
 	104
 }
 
+pub struct SocketAddr {
+mut:
+	data &u8 = unsafe { nil }
+	len  int
+	pos  int
+}
+
 // SocketAddr.ipv4 creates new AF_INET socket address.
 // addr must be set in network (big-endian) byte order.
 pub fn SocketAddr.ipv4(addr [4]u8, port u16) SocketAddr {
@@ -54,14 +63,14 @@ pub fn SocketAddr.unix(path string) !SocketAddr {
 // the address itself, you need to do that manually. The benefit is that you can create the
 // any kind of socket address.
 //
-// SocketAddr is a "constructor" for
+// SocketAddr is a builder for
 // [sockaddr(3type)](https://www.man7.org/linux/man-pages/man3/sockaddr.3type.html) objects.
-// Use this function only if you understand what you do. You must manually write the data
-// for the desired socket address, ensuring the correct sizes of all types, the order of
-// the fields in the struct, the byte order, and the total size of the struct. The sizes
-// and byte order may vary by platform, so you'll need to keep an eye on that as well.
-// A mistake while creating an address will crash your application. So this function is
-// marked as `unsafe`.
+// Use this function only if you understand what you do. Using the `push()` method you must
+// write the data for the desired socket address, ensuring the correct sizes of all types,
+// the order of the fields in the struct, the byte order, and the total size of the struct.
+// The sizes and byte order may vary by platform, so you'll need to keep an eye on that as
+// well. A mistake while creating an address will crash your application. So this function
+// is marked as `unsafe`.
 //
 // The example below creates a sockaddr_in struct describing the loopback IPv4-address
 // 127.0.0.1 with port number 1080. Note the comment in the example. This is a fragment
@@ -118,6 +127,9 @@ pub fn SocketAddr.new(af AddrFamily, size isize) SocketAddr {
 // SocketAddr.from_ptr creates new socket address by copying data from specified pointer.
 @[unsafe]
 pub fn SocketAddr.from_ptr(ptr voidptr, size isize) !SocketAddr {
+	if isnil(ptr) {
+		return error('${@METHOD}: cannot accept nil ptr')
+	}
 	data := unsafe { vcalloc(usize(size)) }
 	unsafe {
 		vmemcpy(data, ptr, size)
@@ -128,25 +140,37 @@ pub fn SocketAddr.from_ptr(ptr voidptr, size isize) !SocketAddr {
 	}
 }
 
-pub struct SocketAddr {
-mut:
-	data &u8 = unsafe { nil }
-	len  int
-	pos  int
-}
-
 // family returns the socket address family.
+// Note: It returns 0 if socket address is nil, see also `is_empty()`.
 pub fn (a SocketAddr) family() AddrFamily {
-	mut f := AddrFamily(0)
+	if isnil(a.data) {
+		return 0
+	}
+	mut f := 0
 	unsafe { vmemcpy(&f, a.data, isize(2)) }
 	return f
 }
 
+// is_empty returns true if socket address is unspecified — the data pointer is nil or
+// data contains only zeros. Empty address cannot be used in `bind` and `connect` calls.
+pub fn (a SocketAddr) is_empty() bool {
+	if isnil(a.data) {
+		return true
+	}
+	if a.u8_array().all(|e| e == 0) {
+		return true
+	}
+	return false
+}
+
 // push appends the `inp` bytes into internal data buffer.
 @[unsafe]
 pub fn (mut a SocketAddr) push(inp []u8) ! {
+	if isnil(a.data) {
+		return error('${@METHOD}: SocketAddr is nil')
+	}
 	if a.pos + inp.len > a.len {
-		return error('push: data overflow')
+		return error('${@METHOD}: data overflow')
 	}
 	mut i := 0
 	for a.pos + 1 < a.len {
@@ -180,9 +204,9 @@ pub fn (a SocketAddr) u8_array() []u8 {
 
 // str returns the string representation of socket address.
 // Supported address families are AF_INET, AF_INET6, and AF_UNIX.
-// For others a string like 'SocketAddr(0x00000000)' will be returned.
-// Examples: '172.16.16.132:1080', '[fdf1:72d1:0033:0000:0000:0000:0000:0247]:25535,
-// '/run/app.sock'. See also `translate_name()`.
+// Examples: '172.16.16.132:1080', '[fdf1:72d1:0033:0000:0000:0000:0000:0247]:25535',
+// '/run/app.sock'. For others a string like 'SocketAddr(0x00000000)' will be returned.
+// See also `translate_name()`.
 pub fn (a SocketAddr) str() string {
 	match a.family() {
 		af_inet {