本文详细介绍了socket编程中的宏定义，包括SO_DEBUG、SO_REUSEADDR等，以及相关数据结构如struct sockaddr、struct sockaddr_in等。这些定义和结构在设置套接字选项、地址操作等方面起着关键作用，对于理解和使用socket编程至关重要。
一 socket.h 宏定义
/*
* For setsockopt(2)
*
* This defines are ABI conformant as far as Linux supports these ...
*/
#define SOL_SOCKET 0xffff
#define SO_DEBUG 0x0001 /* Record debugging information. */
#define SO_REUSEADDR 0x0004 /* Allow reuse of local addresses. */
#define SO_KEEPALIVE 0x0008 /* Keep connections alive and send
SIGPIPE when they die. */
#define SO_DONTROUTE 0x0010 /* Don't do local routing. */
#define SO_BROADCAST 0x0020 /* Allow transmission of
broadcast messages. */
#define SO_LINGER 0x0080 /* Block on close of a reliable
socket to transmit pending data. */
#define SO_OOBINLINE 0x0100 /* Receive out-of-band data in-band. */
#if 0
To add: #define SO_REUSEPORT 0x0200 /* Allow local address and port reuse. */
#endif
#define SO_TYPE 0x1008 /* Compatible name for SO_STYLE. */
#define SO_STYLE SO_TYPE /* Synonym */
#define SO_ERROR 0x1007 /* get error status and clear */
#define SO_SNDBUF 0x1001 /* Send buffer size. */
#define SO_RCVBUF 0x1002 /* Receive buffer. */
#define SO_SNDLOWAT 0x1003 /* send low-water mark */
#define SO_RCVLOWAT 0x1004 /* receive low-water mark */
#define SO_SNDTIMEO 0x1005 /* send timeout */
#define SO_RCVTIMEO 0x1006 /* receive timeout */
#define SO_ACCEPTCONN 0x1009
#define SO_PROTOCOL 0x1028 /* protocol type */
#define SO_DOMAIN 0x1029 /* domain/socket family */
/* linux-specific, might as well be the same as on i386 */
#define SO_NO_CHECK 11
#define SO_PRIORITY 12
#define SO_BSDCOMPAT 14
#define SO_PASSCRED 17
#define SO_PEERCRED 18
/* Socket filtering */
#define SO_ATTACH_FILTER 26
#define SO_DETACH_FILTER 27
#define SO_PEERNAME 28
#define SO_TIMESTAMP 29
#define SCM_TIMESTAMP SO_TIMESTAMP
#define SO_PEERSEC 30
#define SO_SNDBUFFORCE 31
#define SO_RCVBUFFORCE 33
#define SO_PASSSEC 34
#define SO_TIMESTAMPNS 35
#define SCM_TIMESTAMPNS SO_TIMESTAMPNS
#define SO_MARK 36
#define SO_TIMESTAMPING 37
#define SCM_TIMESTAMPING SO_TIMESTAMPING
#define SO_RXQ_OVFL 40
/** sock_type - Socket types
*
* Please notice that for binary compat reasons MIPS has to
* override the enum sock_type in include/linux/net.h, so
* we define ARCH_HAS_SOCKET_TYPES here.
*
* @SOCK_DGRAM - datagram (conn.less) socket
* @SOCK_STREAM - stream (connection) socket
* @SOCK_RAW - raw socket
* @SOCK_RDM - reliably-delivered message
* @SOCK_SEQPACKET - sequential packet socket
* @SOCK_PACKET - linux specific way of getting packets at the dev level.
* For writing rarp and other similar things on the user level.
*/
enum sock_type {
SOCK_DGRAM = 1,
SOCK_STREAM = 2,
SOCK_RAW = 3,
SOCK_RDM = 4,
SOCK_SEQPACKET = 5,
SOCK_DCCP = 6,
SOCK_PACKET = 10,
};
#define SOCK_MAX (SOCK_PACKET + 1)
/* Mask which covers at least up to SOCK_MASK-1. The
* * remaining bits are used as flags. */
#define SOCK_TYPE_MASK 0xf
/* Flags for socket, socketpair, paccept */
#define SOCK_CLOEXEC O_CLOEXEC
#define SOCK_NONBLOCK O_NONBLOCK
/* Address to accept any incoming messages. */
#define INADDR_ANY ((unsigned long int) 0x00000000)
/* Address to send to all hosts. */
#define INADDR_BROADCAST ((unsigned long int) 0xffffffff)
/* Address indicating an error return. */
#define INADDR_NONE ((unsigned long int) 0xffffffff)
/* Network number for local host loopback. */
#define IN_LOOPBACKNET 127
/* Address to loopback in software to local host. */
#define INADDR_LOOPBACK 0x7f000001 /* 127.0.0.1 */
#define IN_LOOPBACK(a) ((((long int) (a)) & 0xff000000) == 0x7f000000)
/* Defines for Multicast INADDR */
#define INADDR_UNSPEC_GROUP 0xe0000000U /* 224.0.0.0 */
#define INADDR_ALLHOSTS_GROUP 0xe0000001U /* 224.0.0.1 */
#define INADDR_ALLRTRS_GROUP 0xe0000002U /* 224.0.0.2 */
#define INADDR_MAX_LOCAL_GROUP 0xe00000ffU /* 224.0.0.255 */
二 types.h中类型宏
/* bsd */
typedef unsigned char u_char;
typedef unsigned short u_short;
typedef unsigned int u_int;
typedef unsigned long u_long;
/* sysv */
typedef unsigned char unchar;
typedef unsigned short ushort;
typedef unsigned int uint;
typedef unsigned long ulong;
#ifndef __BIT_TYPES_DEFINED__
#define __BIT_TYPES_DEFINED__
typedef __u8 u_int8_t;
typedef __s8 int8_t;
typedef __u16 u_int16_t;
typedef __s16 int16_t;
typedef __u32 u_int32_t;
typedef __s32 int32_t;
#endif /* !(__BIT_TYPES_DEFINED__) */
typedef __u8 uint8_t;
typedef __u16 uint16_t;
typedef __u32 uint32_t;
#if defined(__GNUC__)
typedef __u64 uint64_t;
typedef __u64 u_int64_t;
typedef __s64 int64_t;
#endif
/* this is a special 64bit data type that is 8-byte aligned */
#define aligned_u64 __u64 __attribute__((aligned(8)))
#define aligned_be64 __be64 __attribute__((aligned(8)))
#define aligned_le64 __le64 __attribute__((aligned(8)))
typedef struct {
int counter;
} atomic_t;
三 socket数据结构
typedef unsigned short sa_family_t;
/*
* 1003.1g requires sa_family_t and that sa_data is char.
*/
struct sockaddr {
sa_family_t sa_family; /* address family, AF_xxx */
char sa_data[14]; /* 14 bytes of protocol address */
};
struct in_addr {
__be32 s_addr;
};
/* Structure describing an Internet (IP) socket address. */
#define __SOCK_SIZE__ 16 /* sizeof(struct sockaddr) */
struct sockaddr_in {
sa_family_t sin_family; /* Address family */
__be16 sin_port; /* Port number */
struct in_addr sin_addr; /* Internet address */
/* Pad to size of `struct sockaddr'. */
unsigned char __pad[__SOCK_SIZE__ - sizeof(short int) - sizeof(unsigned short int) - sizeof(struct in_addr)];
};
struct net {
atomic_t count; /* To decided when the network
* namespace should be freed.
*/
#ifdef NETNS_REFCNT_DEBUG
atomic_t use_count; /* To track references we
* destroy on demand
*/
#endif
spinlock_t rules_mod_lock;
struct list_head list; /* list of network namespaces */
struct list_head cleanup_list; /* namespaces on death row */
struct list_head exit_list; /* Use only net_mutex */
struct proc_dir_entry *proc_net;
struct proc_dir_entry *proc_net_stat;
#ifdef CONFIG_SYSCTL
struct ctl_table_set sysctls;
#endif
struct sock *rtnl; /* rtnetlink socket */
struct sock *genl_sock;
struct list_head dev_base_head;
struct hlist_head *dev_name_head;
struct hlist_head *dev_index_head;
/* core fib_rules */
struct list_head rules_ops;
struct net_device *loopback_dev; /* The loopback */
struct netns_core core;
struct netns_mib mib;
struct netns_packet packet;
struct netns_unix unx;
struct netns_ipv4 ipv4;
#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
struct netns_ipv6 ipv6;
#endif
#if defined(CONFIG_IP_DCCP) || defined(CONFIG_IP_DCCP_MODULE)
struct netns_dccp dccp;
#endif
#ifdef CONFIG_NETFILTER
struct netns_xt xt;
#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
struct netns_ct ct;
#endif
struct sock *nfnl;
struct sock *nfnl_stash;
#endif
#ifdef CONFIG_WEXT_CORE
struct sk_buff_head wext_nlevents;
#endif
struct net_generic __rcu *gen;
/* Note : following structs are cache line aligned */
#ifdef CONFIG_XFRM
struct netns_xfrm xfrm;
#endif
};
/* Init's network namespace */
extern struct net init_net;
/* This is the per-socket lock. The spinlock provides a synchronization
* between user contexts and software interrupt processing, whereas the
* mini-semaphore synchronizes multiple users amongst themselves.
*/
typedef struct {
spinlock_t slock;
int owned;
wait_queue_head_t wq;
/*
* We express the mutex-alike socket_lock semantics
* to the lock validator by explicitly managing
* the slock as a lock variant (in addition to
* the slock itself):
*/
#ifdef CONFIG_DEBUG_LOCK_ALLOC
struct lockdep_map dep_map;
#endif
} socket_lock_t;
/**
* struct sock_common - minimal network layer representation of sockets
* @skc_node: main hash linkage for various protocol lookup tables
* @skc_nulls_node: main hash linkage for TCP/UDP/UDP-Lite protocol
* @skc_refcnt: reference count
* @skc_tx_queue_mapping: tx queue number for this connection
* @skc_hash: hash value used with various protocol lookup tables
* @skc_u16hashes: two u16 hash values used by UDP lookup tables
* @skc_family: network address family
* @skc_state: Connection state
* @skc_reuse: %SO_REUSEADDR setting
* @skc_bound_dev_if: bound device index if != 0
* @skc_bind_node: bind hash linkage for various protocol lookup tables
* @skc_portaddr_node: second hash linkage for UDP/UDP-Lite protocol
* @skc_prot: protocol handlers inside a network family
* @skc_net: reference to the network namespace of this socket
*
* This is the minimal network layer representation of sockets, the header
* for struct sock and struct inet_timewait_sock.
*/
struct sock_common {
/*
* first fields are not copied in sock_copy()
*/
union {
struct hlist_node skc_node;
struct hlist_nulls_node skc_nulls_node;
};
atomic_t skc_refcnt;
int skc_tx_queue_mapping;
union {
unsigned int skc_hash;
__u16 skc_u16hashes[2];
};
unsigned short skc_family;
volatile unsigned char skc_state;
unsigned char skc_reuse;
int skc_bound_dev_if;
union {
struct hlist_node skc_bind_node;
struct hlist_nulls_node skc_portaddr_node;
};
struct proto *skc_prot;
#ifdef CONFIG_NET_NS
struct net *skc_net;
#endif
};
/**
* struct sock - network layer representation of sockets
* @__sk_common: shared layout with inet_timewait_sock
* @sk_shutdown: mask of %SEND_SHUTDOWN and/or %RCV_SHUTDOWN
* @sk_userlocks: %SO_SNDBUF and %SO_RCVBUF settings
* @sk_lock: synchronizer
* @sk_rcvbuf: size of receive buffer in bytes
* @sk_wq: sock wait queue and async head
* @sk_dst_cache: destination cache
* @sk_dst_lock: destination cache lock
* @sk_policy: flow policy
* @sk_rmem_alloc: receive queue bytes committed
* @sk_receive_queue: incoming packets
* @sk_wmem_alloc: transmit queue bytes committed
* @sk_write_queue: Packet sending queue
* @sk_async_wait_queue: DMA copied packets
* @sk_omem_alloc: "o" is "option" or "other"
* @sk_wmem_queued: persistent queue size
* @sk_forward_alloc: space allocated forward
* @sk_allocation: allocation mode
* @sk_sndbuf: size of send buffer in bytes
* @sk_flags: %SO_LINGER (l_onoff), %SO_BROADCAST, %SO_KEEPALIVE,
* %SO_OOBINLINE settings, %SO_TIMESTAMPING settings
* @sk_no_check: %SO_NO_CHECK setting, wether or not checkup packets
* @sk_route_caps: route capabilities (e.g. %NETIF_F_TSO)
* @sk_route_nocaps: forbidden route capabilities (e.g NETIF_F_GSO_MASK)
* @sk_gso_type: GSO type (e.g. %SKB_GSO_TCPV4)
* @sk_gso_max_size: Maximum GSO segment size to build
* @sk_lingertime: %SO_LINGER l_linger setting
* @sk_backlog: always used with the per-socket spinlock held
* @sk_callback_lock: used with the callbacks in the end of this struct
* @sk_error_queue: rarely used
* @sk_prot_creator: sk_prot of original sock creator (see ipv6_setsockopt,
* IPV6_ADDRFORM for instance)
* @sk_err: last error
* @sk_err_soft: errors that don't cause failure but are the cause of a
* persistent failure not just 'timed out'
* @sk_drops: raw/udp drops counter
* @sk_ack_backlog: current listen backlog
* @sk_max_ack_backlog: listen backlog set in listen()
* @sk_priority: %SO_PRIORITY setting
* @sk_type: socket type (%SOCK_STREAM, etc)
* @sk_protocol: which protocol this socket belongs in this network family
* @sk_peer_pid: &struct pid for this socket's peer
* @sk_peer_cred: %SO_PEERCRED setting
* @sk_rcvlowat: %SO_RCVLOWAT setting
* @sk_rcvtimeo: %SO_RCVTIMEO setting
* @sk_sndtimeo: %SO_SNDTIMEO setting
* @sk_rxhash: flow hash received from netif layer
* @sk_filter: socket filtering instructions
* @sk_protinfo: private area, net family specific, when not using slab
* @sk_timer: sock cleanup timer
* @sk_stamp: time stamp of last packet received
* @sk_socket: Identd and reporting IO signals
* @sk_user_data: RPC layer private data
* @sk_sndmsg_page: cached page for sendmsg
* @sk_sndmsg_off: cached offset for sendmsg
* @sk_send_head: front of stuff to transmit
* @sk_security: used by security modules
* @sk_mark: generic packet mark
* @sk_classid: this socket's cgroup classid
* @sk_write_pending: a write to stream socket waits to start
* @sk_state_change: callback to indicate change in the state of the sock
* @sk_data_ready: callback to indicate there is data to be processed
* @sk_write_space: callback to indicate there is bf sending space available
* @sk_error_report: callback to indicate errors (e.g. %MSG_ERRQUEUE)
* @sk_backlog_rcv: callback to process the backlog
* @sk_destruct: called at sock freeing time, i.e. when all refcnt == 0
*/
struct sock {
/*
* Now struct inet_timewait_sock also uses sock_common, so please just
* don't add nothing before this first member (__sk_common) --acme
*/
struct sock_common __sk_common;
#define sk_node __sk_common.skc_node
#define sk_nulls_node __sk_common.skc_nulls_node
#define sk_refcnt __sk_common.skc_refcnt
#define sk_tx_queue_mapping __sk_common.skc_tx_queue_mapping
#define sk_copy_start __sk_common.skc_hash
#define sk_hash __sk_common.skc_hash
#define sk_family __sk_common.skc_family
#define sk_state __sk_common.skc_state
#define sk_reuse __sk_common.skc_reuse
#define sk_bound_dev_if __sk_common.skc_bound_dev_if
#define sk_bind_node __sk_common.skc_bind_node
#define sk_prot __sk_common.skc_prot
#define sk_net __sk_common.skc_net
kmemcheck_bitfield_begin(flags);
unsigned int sk_shutdown : 2,
sk_no_check : 2,
sk_userlocks : 4,
sk_protocol : 8,
sk_type : 16;
kmemcheck_bitfield_end(flags);
int sk_rcvbuf;
socket_lock_t sk_lock;
/*
* The backlog queue is special, it is always used with
* the per-socket spinlock held and requires low latency
* access. Therefore we special case it's implementation.
*/
struct {
struct sk_buff *head;
struct sk_buff *tail;
int len;
} sk_backlog;
struct socket_wq *sk_wq;
struct dst_entry *sk_dst_cache;
#ifdef CONFIG_XFRM
struct xfrm_policy *sk_policy[2];
#endif
spinlock_t sk_dst_lock;
atomic_t sk_rmem_alloc;
atomic_t sk_wmem_alloc;
atomic_t sk_omem_alloc;
int sk_sndbuf;
struct sk_buff_head sk_receive_queue;
struct sk_buff_head sk_write_queue;
#ifdef CONFIG_NET_DMA
struct sk_buff_head sk_async_wait_queue;
#endif
int sk_wmem_queued;
int sk_forward_alloc;
gfp_t sk_allocation;
int sk_route_caps;
int sk_route_nocaps;
int sk_gso_type;
unsigned int sk_gso_max_size;
int sk_rcvlowat;
#ifdef CONFIG_RPS
__u32 sk_rxhash;
#endif
unsigned long sk_flags;
unsigned long sk_lingertime;
struct sk_buff_head sk_error_queue;
struct proto *sk_prot_creator;
rwlock_t sk_callback_lock;
int sk_err,
sk_err_soft;
atomic_t sk_drops;
unsigned short sk_ack_backlog;
unsigned short sk_max_ack_backlog;
__u32 sk_priority;
struct pid *sk_peer_pid;
const struct cred *sk_peer_cred;
long sk_rcvtimeo;
long sk_sndtimeo;
struct sk_filter __rcu *sk_filter;
void *sk_protinfo;
struct timer_list sk_timer;
ktime_t sk_stamp;
struct socket *sk_socket;
void *sk_user_data;
struct page *sk_sndmsg_page;
struct sk_buff *sk_send_head;
__u32 sk_sndmsg_off;
int sk_write_pending;
#ifdef CONFIG_SECURITY
void *sk_security;
#endif
__u32 sk_mark;
u32 sk_classid;
void (*sk_state_change)(struct sock *sk);
void (*sk_data_ready)(struct sock *sk, int bytes);
void (*sk_write_space)(struct sock *sk);
void (*sk_error_report)(struct sock *sk);
int (*sk_backlog_rcv)(struct sock *sk,
struct sk_buff *skb);
void (*sk_destruct)(struct sock *sk);
};
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