manually start merging core_net

core/net/common.odin

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+/*
+	Copyright 2022 Tetralux        <tetraluxonpc@gmail.com>
+	Copyright 2022 Colin Davidson  <colrdavidson@gmail.com>
+	Copyright 2022 Jeroen van Rijn <nom@duclavier.com>.
+	Made available under Odin's BSD-3 license.
+
+	List of contributors:
+		Tetralux:        Initial implementation
+		Colin Davidson:  Linux platform code, OSX platform code, Odin-native DNS resolver
+		Jeroen van Rijn: Cross platform unification, code style, documentation
+*/
+
+/*
+	Package net implements cross-platform Berkeley Sockets, DNS resolution and associated procedures.
+	For other protocols and their features, see subdirectories of this package.
+
+	This file collects structs, enums and settings applicable to the entire package in one handy place.
+	Platform-specific ones can be found in their respective `*_windows.odin` and similar files.
+*/
+package net
+
+import "core:runtime"
+
+/*
+	TUNEABLES
+*/
+
+/*
+	Determines the default value for whether dial_tcp() and accept_tcp() will set TCP_NODELAY on the new
+	socket, and the client socket, respectively.
+	This can also be set on a per-socket basis using the 'options' optional parameter to those procedures.
+
+	When TCP_NODELAY is set, data will be sent out to the peer as quickly as possible, rather than being
+	coalesced into fewer network packets.
+
+	This makes the networking layer more eagerly send data when you ask it to,
+	which can reduce latency by up to 200ms.
+
+	This does mean that a lot of small writes will negatively effect throughput however,
+	since the Nagle algorithm will be disabled, and each write becomes one
+	IP packet. This will increase traffic by a factor of 40, with IP and TCP
+	headers for each payload.
+
+	However, you can avoid this by buffering things up yourself if you wish to send a lot of
+	short data chunks, when TCP_NODELAY is enabled on that socket.
+*/
+ODIN_NET_TCP_NODELAY_DEFAULT :: #config(ODIN_NET_TCP_NODELAY_DEFAULT, true)
+
+/*
+	See also top of `dns.odin` for DNS configuration.
+*/
+
+/*
+	COMMON DEFINITIONS
+*/
+
+Maybe :: runtime.Maybe
+
+General_Error :: enum {
+	Unable_To_Enumerate_Network_Interfaces = 1,
+}
+
+/*
+	`Platform_Error` is used to wrap errors returned by the different platforms that defy translation into a common error.
+*/
+Platform_Error :: enum u32 {}
+
+/*
+	NOTE(tetra): Enums in Network_Error should not have a named zero value.
+	If you have a proc that returns an enum with an Ok=0 value, using or_return from the callsite, when the caller returns a union, works as expected.
+	However, if that proc returns the union directly, returning the Ok value will NOT work with the caller's or_return, as it will treat Error{.Ok} as != nil, and early-return with it.
+
+	The approach currently taken to avoid this is:
+	- Remove the named zero values for the enums
+	- Use the union everywhere
+*/
+Network_Error :: union {
+	General_Error,
+	Platform_Error,
+	Create_Socket_Error,
+	Dial_Error,
+	Listen_Error,
+	Accept_Error,
+	Bind_Error,
+	TCP_Send_Error,
+	UDP_Send_Error,
+	TCP_Recv_Error,
+	UDP_Recv_Error,
+	Shutdown_Error,
+	Socket_Option_Error,
+	Parse_Endpoint_Error,
+	Resolve_Error,
+	DNS_Error,
+}
+
+
+Resolve_Error :: enum {
+	Unable_To_Resolve = 1,
+}
+
+DNS_Error :: enum {
+	Invalid_Hostname_Error = 1,
+	Invalid_Hosts_Config_Error,
+	Invalid_Resolv_Config_Error,
+	Connection_Error,
+	Server_Error,
+	System_Error,
+}
+
+/*
+	SOCKET OPTIONS & DEFINITIONS
+*/
+
+TCP_Options :: struct {
+	no_delay: bool,
+}
+
+default_tcp_options := TCP_Options {
+	no_delay = ODIN_NET_TCP_NODELAY_DEFAULT,
+}
+
+/*
+	To allow freely using `Socket` in your own data structures in a cross-platform manner,
+	we treat it as a handle large enough to accomodate OS-specific notions of socket handles.
+
+	The platform code will perform the cast so you don't have to.
+*/
+Socket     :: distinct i64
+
+TCP_Socket :: distinct Socket
+UDP_Socket :: distinct Socket
+
+Socket_Protocol :: enum {
+	TCP,
+	UDP,
+}
+
+Any_Socket :: union {
+	TCP_Socket,
+	UDP_Socket,
+}
+
+/*
+	ADDRESS DEFINITIONS
+*/
+
+IP4_Address :: distinct [4]u8
+IP6_Address :: distinct [8]u16be
+Address :: union {IP4_Address, IP6_Address}
+
+IP4_Loopback := IP4_Address{127, 0, 0, 1}
+IP6_Loopback := IP6_Address{0, 0, 0, 0, 0, 0, 0, 1}
+
+IP4_Any := IP4_Address{}
+IP6_Any := IP6_Address{}
+
+Endpoint :: struct {
+	address: Address,
+	port:    int,
+}
+
+Address_Family :: enum {
+	IP4,
+	IP6,
+}
+
+Netmask :: distinct Address
+
+/*
+	INTERFACE / LINK STATE
+*/
+Network_Interface :: struct {
+	adapter_name:     string, // On Windows this is a GUID that we could parse back into its u128 for more compact storage.
+	friendly_name:    string,
+	description:      string,
+	dns_suffix:       string,
+
+	physical_address: string, // MAC address, etc.
+	mtu:              u32,
+
+	unicast:          [dynamic]Lease,
+	multicast:        [dynamic]Address,
+	anycast:          [dynamic]Address,
+
+	gateways:         [dynamic]Address,
+	dhcp_v4:          Address,
+	dhcp_v6:          Address,
+
+	tunnel_type:      Tunnel_Type,
+
+	link: struct {
+		state:          Link_State,
+		transmit_speed: u64,
+		receive_speed:  u64,
+	},
+}
+
+/*
+	Empty bit set is unknown state.
+*/
+Link_States :: enum u32 {
+	Up               = 1,
+	Down             = 2,
+	Testing          = 3,
+	Dormant          = 4,
+	Not_Present      = 5,
+	Lower_Layer_Down = 6,
+	Loopback         = 7,
+}
+Link_State :: bit_set[Link_States; u32]
+
+Lease :: struct {
+	address:  Address,
+	netmask:  Netmask,
+	lifetime: struct {
+		valid:     u32,
+		preferred: u32,
+		lease:     u32,
+	},
+	origin: struct {
+		prefix: Prefix_Origin,
+		suffix: Suffix_Origin,
+	},
+	address_duplication: Address_Duplication,
+}
+
+Tunnel_Type :: enum i32 {
+	None         = 0,
+	Other        = 1,
+	Direct       = 2,
+	IPv4_To_IPv6 = 11,
+	ISA_TAP      = 13,
+	Teredo       = 14,
+	IP_HTTPS     = 15,
+}
+
+Prefix_Origin :: enum i32 {
+	Other                = 0,
+	Manual               = 1,
+	Well_Known           = 2,
+	DHCP                 = 3,
+	Router_Advertisement = 4,
+	Unchanged            = 16,
+}
+
+Suffix_Origin :: enum i32 {
+	Other                = 0,
+	Manual               = 1,
+	Well_Known           = 2,
+	DHCP                 = 3,
+	Link_Layer_Address   = 4,
+	Random               = 5,
+	Unchanged            = 16,
+}
+
+Address_Duplication :: enum i32 {
+	Invalid    = 0,
+	Tentative  = 1,
+	Duplicate  = 2,
+	Deprecated = 3,
+	Preferred  = 4,
+}
+
+/*
+	DNS DEFINITIONS
+*/
+
+DNS_Configuration :: struct {
+	/*
+		Configuration files.
+	*/
+	resolv_conf: string,
+	hosts_file:  string,
+
+	// TODO: Allow loading these up with `reload_configuration()` call or the like so we don't have to do it each call.
+	name_servers:       []Endpoint,
+	hosts_file_entries: []DNS_Record,
+}
+
+DNS_Record_Type :: enum u16 {
+	DNS_TYPE_A     = 0x1,  // IP4 address.
+	DNS_TYPE_NS    = 0x2,  // IP6 address.
+	DNS_TYPE_CNAME = 0x5,  // Another host name.
+	DNS_TYPE_MX    = 0xf,  // Arbitrary binary data or text.
+	DNS_TYPE_AAAA  = 0x1c, // Address of a name (DNS) server.
+	DNS_TYPE_TEXT  = 0x10, // Address and preference priority of a mail exchange server.
+	DNS_TYPE_SRV   = 0x21, // Address, port, priority, and weight of a host that provides a particular service.
+
+	IP4            = DNS_TYPE_A,
+	IP6            = DNS_TYPE_AAAA,
+	CNAME          = DNS_TYPE_CNAME,
+	TXT            = DNS_TYPE_TEXT,
+	NS             = DNS_TYPE_NS,
+	MX             = DNS_TYPE_MX,
+	SRV            = DNS_TYPE_SRV,
+}
+
+/*
+	Base DNS Record. All DNS responses will carry a hostname and TTL (time to live) field.
+*/
+DNS_Record_Base :: struct {
+	record_name: string,
+	ttl_seconds: u32,    	// The time in seconds that this service will take to update, after the record is updated.
+}
+
+/*
+	An IP4 address that the domain name maps to. There can be any number of these.
+*/
+DNS_Record_IP4 :: struct {
+	using base: DNS_Record_Base,
+	address:    IP4_Address,
+}
+
+/*
+	An IPv6 address that the domain name maps to. There can be any number of these.
+*/
+DNS_Record_IP6 :: struct {
+	using base: DNS_Record_Base,
+	address:    IP6_Address,
+}
+
+/*
+	Another domain name that the domain name maps to.
+	Domains can be pointed to another domain instead of directly to an IP address.
+	`get_dns_records` will recursively follow these if you request this type of record.
+*/
+DNS_Record_CNAME :: struct {
+	using base: DNS_Record_Base,
+	host_name:  string,
+}
+
+/*
+	Arbitrary string data that is associated with the domain name.
+	Commonly of the form `key=value` to be parsed, though there is no specific format for them.
+	These can be used for any purpose.
+*/
+DNS_Record_TXT :: struct {
+	using base: DNS_Record_Base,
+	value:      string,
+}
+
+/*
+	Domain names of other DNS servers that are associated with the domain name.
+	TODO(tetra): Expand on what these records are used for, and when you should use pay attention to these.
+*/
+DNS_Record_NS :: struct {
+	using base: DNS_Record_Base,
+	host_name:  string,
+}
+
+// Domain names for email servers that are associated with the domain name.
+// These records also have values which ranks them in the order they should be preferred. Lower is more-preferred.
+DNS_Record_MX :: struct {
+	using base: DNS_Record_Base,
+	host_name:  string,
+	preference: int,
+}
+
+// An endpoint for a service that is available through the domain name.
+// This is the way to discover the services that a domain name provides.
+//
+// Clients MUST attempt to contact the host with the lowest priority that they can reach.
+// If two hosts have the same priority, they should be contacted in the order according to their weight.
+// Hosts with larger weights should have a proportionally higher chance of being contacted by clients.
+// A weight of zero indicates a very low weight, or, when there is no choice (to reduce visual noise).
+//
+// The host may be "." to indicate that it is "decidedly not available" on this domain.
+DNS_Record_SRV :: struct {
+	// base contains the full name of this record.
+	// e.g: _sip._tls.example.com
+	using base: DNS_Record_Base,
+
+	// The hostname or address where this service can be found.
+	target:        string,
+	// The port on which this service can be found.
+	port:          int,
+
+	service_name:  string, // NOTE(tetra): These are substrings of 'record_name'
+	protocol_name: string, // NOTE(tetra): These are substrings of 'record_name'
+
+	// Lower is higher priority
+	priority:      int,
+	// Relative weight of this host compared to other of same priority; the chance of using this host should be proporitional to this weight.
+	// The number of seconds that it will take to update the record.
+	weight:        int,
+}
+
+DNS_Record :: union {
+	DNS_Record_IP4,
+	DNS_Record_IP6,
+	DNS_Record_CNAME,
+	DNS_Record_TXT,
+	DNS_Record_NS,
+	DNS_Record_MX,
+	DNS_Record_SRV,
+}
+
+DNS_Response_Code :: enum u16be {
+	No_Error,
+	Format_Error,
+	Server_Failure,
+	Name_Error,
+	Not_Implemented,
+	Refused,
+}
+
+DNS_Query :: enum u16be {
+	Host_Address              = 1,
+	Authoritative_Name_Server = 2,
+	Mail_Destination          = 3,
+	Mail_Forwarder            = 4,
+	CNAME                     = 5,
+	All                       = 255,
+}
+
+DNS_Header :: struct {
+	id:                     u16be,
+	is_response:            bool,
+	opcode:                 u16be,
+	is_authoritative:       bool,
+	is_truncated:           bool,
+	is_recursion_desired:   bool,
+	is_recursion_available: bool,
+	response_code:          DNS_Response_Code,
+}
+
+DNS_Record_Header :: struct #packed {
+	type:   u16be,
+	class:  u16be,
+	ttl:    u32be,
+	length: u16be,
+}
+
+DNS_Host_Entry :: struct {
+	name: string,
+	addr: Address,
+}