sys/socket.h
http://fxr.watson.org/fxr/source/sys/socket.h
这个是不是内核里头的啊？
1 /*- 2 * Copyright (c) 1982, 1985, 1986, 1988, 1993, 1994 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 4. Neither the name of the University nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 * @(#)socket.h 8.4 (Berkeley) 2/21/94 30 * $FreeBSD: head/sys/sys/socket.h 254925 2013-08-26 18:16:05Z jhb $ 31 */ 32 33 #ifndef _SYS_SOCKET_H_ 34 #define _SYS_SOCKET_H_ 35 36 #include37 #include 38 #include 39 #include 40 41 /* 42 * Definitions related to sockets: types, address families, options. 43 */ 44 45 /* 46 * Data types. 47 */ 48 #if __BSD_VISIBLE 49 #ifndef _GID_T_DECLARED 50 typedef __gid_t gid_t; 51 #define _GID_T_DECLARED 52 #endif 53 54 #ifndef _OFF_T_DECLARED 55 typedef __off_t off_t; 56 #define _OFF_T_DECLARED 57 #endif 58 59 #ifndef _PID_T_DECLARED 60 typedef __pid_t pid_t; 61 #define _PID_T_DECLARED 62 #endif 63 #endif 64 65 #ifndef _SA_FAMILY_T_DECLARED 66 typedef __sa_family_t sa_family_t; 67 #define _SA_FAMILY_T_DECLARED 68 #endif 69 70 #ifndef _SOCKLEN_T_DECLARED 71 typedef __socklen_t socklen_t; 72 #define _SOCKLEN_T_DECLARED 73 #endif 74 75 #ifndef _SSIZE_T_DECLARED 76 typedef __ssize_t ssize_t; 77 #define _SSIZE_T_DECLARED 78 #endif 79 80 #if __BSD_VISIBLE 81 #ifndef _UID_T_DECLARED 82 typedef __uid_t uid_t; 83 #define _UID_T_DECLARED 84 #endif 85 #endif 86 87 /* 88 * Types 89 */ 90 #define SOCK_STREAM 1 /* stream socket 流*/ 91 #define SOCK_DGRAM 2 /* datagram socket 数据报*/ 92 #define SOCK_RAW 3 /* raw-protocol interface 不懂*/ 93 #if __BSD_VISIBLE 94 #define SOCK_RDM 4 /* reliably-delivered message */ 95 #endif 96 #define SOCK_SEQPACKET 5 /* sequenced packet stream */ 97 98 #if __BSD_VISIBLE 99 /* 100 * Creation flags, OR'ed into socket() and socketpair() type argument. 101 */ 102 #define SOCK_CLOEXEC 0x10000000 103 #define SOCK_NONBLOCK 0x20000000 104 #endif 105 106 /* 107 * Option flags per-socket. 每个socket的选项标识 108 */ 109 #define SO_DEBUG 0x0001 /* turn on debugging info recording 打开调试信息*/ 110 #define SO_ACCEPTCONN 0x0002 /* socket has had listen() 监听？*/ 111 #define SO_REUSEADDR 0x0004 /* allow local address reuse 允许本地地址重用？*/ 112 #define SO_KEEPALIVE 0x0008 /* keep connections alive 保持连接在线*/ 113 #define SO_DONTROUTE 0x0010 /* just use interface addresses 仅仅使用接口地址？不使用路由？*/ 114 #define SO_BROADCAST 0x0020 /* permit sending of broadcast msgs 允许发送广播消息*/
115 #if __BSD_VISIBLE 116 #define SO_USELOOPBACK 0x0040 /* bypass hardware when possible */ 117 #endif 118 #define SO_LINGER 0x0080 /* linger on close if data present */ 119 #define SO_OOBINLINE 0x0100 /* leave received OOB data in line */ 120 #if __BSD_VISIBLE 121 #define SO_REUSEPORT 0x0200 /* allow local address & port reuse */ 122 #define SO_TIMESTAMP 0x0400 /* timestamp received dgram traffic */ 123 #define SO_NOSIGPIPE 0x0800 /* no SIGPIPE from EPIPE */ 124 #define SO_ACCEPTFILTER 0x1000 /* there is an accept filter */ 125 #define SO_BINTIME 0x2000 /* timestamp received dgram traffic */ 126 #endif 127 #define SO_NO_OFFLOAD 0x4000 /* socket cannot be offloaded */ 128 #define SO_NO_DDP 0x8000 /* disable direct data placement */ 129 130 /* 131 * Additional options, not kept in so_options. 啥意思？ 132 */ 133 #define SO_SNDBUF 0x1001 /* send buffer size 发送缓冲的大小*/ 134 #define SO_RCVBUF 0x1002 /* receive buffer size 接受缓冲的大小*/ 135 #define SO_SNDLOWAT 0x1003 /* send low-water mark 发送低水位的mark？？？？*/ 136 #define SO_RCVLOWAT 0x1004 /* receive low-water mark */ 137 #define SO_SNDTIMEO 0x1005 /* send timeout */ 138 #define SO_RCVTIMEO 0x1006 /* receive timeout */ 139 #define SO_ERROR 0x1007 /* get error status and clear */ 140 #define SO_TYPE 0x1008 /* get socket type */ 141 #if __BSD_VISIBLE 142 #define SO_LABEL 0x1009 /* socket's MAC label */ 143 #define SO_PEERLABEL 0x1010 /* socket's peer's MAC label */ 144 #define SO_LISTENQLIMIT 0x1011 /* socket's backlog limit */ 145 #define SO_LISTENQLEN 0x1012 /* socket's complete queue length */ 146 #define SO_LISTENINCQLEN 0x1013 /* socket's incomplete queue length */ 147 #define SO_SETFIB 0x1014 /* use this FIB to route */ 148 #define SO_USER_COOKIE 0x1015 /* user cookie (dummynet etc.) */ 149 #define SO_PROTOCOL 0x1016 /* get socket protocol (Linux name) */ 150 #define SO_PROTOTYPE SO_PROTOCOL /* alias for SO_PROTOCOL (SunOS name) */ 151 #endif 152 153 /* 154 * Space reserved for new socket options added by third-party vendors. 155 * This range applies to all socket option levels. New socket options 156 * in FreeBSD should always use an option value less than SO_VENDOR. 157 */ 158 #if __BSD_VISIBLE 159 #define SO_VENDOR 0x80000000 160 #endif 161 162 /* 163 * Structure used for manipulating linger option. 164 */ 165 struct linger { 166 int l_onoff; /* option on/off */ 167 int l_linger; /* linger time */ 168 }; 169 170 #if __BSD_VISIBLE 171 struct accept_filter_arg { 172 char af_name[16]; 173 char af_arg[256-16]; 174 }; 175 #endif 176 177 /* 178 * Level number for (get/set)sockopt() to apply to socket itself. 179 */ 180 #define SOL_SOCKET 0xffff /* options for socket level */ 181 182 /* 183 * Address families. 地址家族 184 */ 185 #define AF_UNSPEC 0 /* unspecified */ 186 #if __BSD_VISIBLE 187 #define AF_LOCAL AF_UNIX /* local to host (pipes, portals) */ 本地？如pipe ？ 188 #endif 189 #define AF_UNIX 1 /* standardized name for AF_LOCAL */ 190 #define AF_INET 2 /* internetwork: UDP, TCP, etc. */ internet？ 191 #if __BSD_VISIBLE 192 #define AF_IMPLINK 3 /* arpanet imp addresses */ 193 #define AF_PUP 4 /* pup protocols: e.g. BSP */ 194 #define AF_CHAOS 5 /* mit CHAOS protocols */ 195 #define AF_NETBIOS 6 /* SMB protocols */ 196 #define AF_ISO 7 /* ISO protocols */ 197 #define AF_OSI AF_ISO 198 #define AF_ECMA 8 /* European computer manufacturers */ 199 #define AF_DATAKIT 9 /* datakit protocols */ 200 #define AF_CCITT 10 /* CCITT protocols, X.25 etc */ 201 #define AF_SNA 11 /* IBM SNA */ 202 #define AF_DECnet 12 /* DECnet */ 203 #define AF_DLI 13 /* DEC Direct data link interface */ 204 #define AF_LAT 14 /* LAT */ 205 #define AF_HYLINK 15 /* NSC Hyperchannel */ 206 #define AF_APPLETALK 16 /* Apple Talk */ 207 #define AF_ROUTE 17 /* Internal Routing Protocol */ 208 #define AF_LINK 18 /* Link layer interface */ 209 #define pseudo_AF_XTP 19 /* eXpress Transfer Protocol (no AF) */ 210 #define AF_COIP 20 /* connection-oriented IP, aka ST II */ 211 #define AF_CNT 21 /* Computer Network Technology */ 212 #define pseudo_AF_RTIP 22 /* Help Identify RTIP packets */ 213 #define AF_IPX 23 /* Novell Internet Protocol */ 214 #define AF_SIP 24 /* Simple Internet Protocol */ 215 #define pseudo_AF_PIP 25 /* Help Identify PIP packets */ 216 #define AF_ISDN 26 /* Integrated Services Digital Network*/ 217 #define AF_E164 AF_ISDN /* CCITT E.164 recommendation */ 218 #define pseudo_AF_KEY 27 /* Internal key-management function */ 219 #endif 220 #define AF_INET6 28 /* IPv6 */ 221 #if __BSD_VISIBLE 222 #define AF_NATM 29 /* native ATM access */ 223 #define AF_ATM 30 /* ATM */ 224 #define pseudo_AF_HDRCMPLT 31 /* Used by BPF to not rewrite headers 225 * in interface output routine 226 */ 227 #define AF_NETGRAPH 32 /* Netgraph sockets */ 228 #define AF_SLOW 33 /* 802.3ad slow protocol */ 229 #define AF_SCLUSTER 34 /* Sitara cluster protocol */ 230 #define AF_ARP 35 231 #define AF_BLUETOOTH 36 /* Bluetooth sockets */ 232 #define AF_IEEE80211 37 /* IEEE 802.11 protocol */ 233 #define AF_INET_SDP 40 /* OFED Socket Direct Protocol ipv4 */ 234 #define AF_INET6_SDP 42 /* OFED Socket Direct Protocol ipv6 */ 235 #define AF_MAX 42 236 /* 237 * When allocating a new AF_ constant, please only allocate 238 * even numbered constants for FreeBSD until 134 as odd numbered AF_ 239 * constants 39-133 are now reserved for vendors. 240 */ 241 #define AF_VENDOR00 39 242 #define AF_VENDOR01 41 243 #define AF_VENDOR02 43 244 #define AF_VENDOR03 45 245 #define AF_VENDOR04 47 246 #define AF_VENDOR05 49 247 #define AF_VENDOR06 51 248 #define AF_VENDOR07 53 249 #define AF_VENDOR08 55 250 #define AF_VENDOR09 57 251 #define AF_VENDOR10 59 252 #define AF_VENDOR11 61 253 #define AF_VENDOR12 63 254 #define AF_VENDOR13 65 255 #define AF_VENDOR14 67 256 #define AF_VENDOR15 69 257 #define AF_VENDOR16 71 258 #define AF_VENDOR17 73 259 #define AF_VENDOR18 75 260 #define AF_VENDOR19 77 261 #define AF_VENDOR20 79 262 #define AF_VENDOR21 81 263 #define AF_VENDOR22 83 264 #define AF_VENDOR23 85 265 #define AF_VENDOR24 87 266 #define AF_VENDOR25 89 267 #define AF_VENDOR26 91 268 #define AF_VENDOR27 93 269 #define AF_VENDOR28 95 270 #define AF_VENDOR29 97 271 #define AF_VENDOR30 99 272 #define AF_VENDOR31 101 273 #define AF_VENDOR32 103 274 #define AF_VENDOR33 105 275 #define AF_VENDOR34 107 276 #define AF_VENDOR35 109 277 #define AF_VENDOR36 111 278 #define AF_VENDOR37 113 279 #define AF_VENDOR38 115 280 #define AF_VENDOR39 117 281 #define AF_VENDOR40 119 282 #define AF_VENDOR41 121 283 #define AF_VENDOR42 123 284 #define AF_VENDOR43 125 285 #define AF_VENDOR44 127 286 #define AF_VENDOR45 129 287 #define AF_VENDOR46 131 288 #define AF_VENDOR47 133 289 #endif 290 291 /* 292 * Structure used by kernel to store most 这居然是内核用来存储大多数地址用的 293 * addresses. 294 */ 295 struct sockaddr { 296 unsigned char sa_len; /* total length */ “socket地址”的全部长度？ 297 sa_family_t sa_family; /* address family */ 地址家族 298 char sa_data[14]; /* actually longer; address value */ 实际的长度？地址值 299 }; 300 #if __BSD_VISIBLE 301 #define SOCK_MAXADDRLEN 255 /* longest possible addresses */ 302 303 /* 304 * Structure used by kernel to pass protocol 内科以raw socket 来传递协议信息的。 305 * information in raw sockets. 306 */ 307 struct sockproto { 308 unsigned short sp_family; /* address family */ 地址家族 309 unsigned short sp_protocol; /* protocol */ 协议 310 }; 311 #endif 312 313 #include314 315 #if __BSD_VISIBLE 316 /* 317 * Protocol families, same as address families for now. 318 */ 319 #define PF_UNSPEC AF_UNSPEC 320 #define PF_LOCAL AF_LOCAL 321 #define PF_UNIX PF_LOCAL /* backward compatibility */ 322 #define PF_INET AF_INET 323 #define PF_IMPLINK AF_IMPLINK 324 #define PF_PUP AF_PUP 325 #define PF_CHAOS AF_CHAOS 326 #define PF_NETBIOS AF_NETBIOS 327 #define PF_ISO AF_ISO 328 #define PF_OSI AF_ISO 329 #define PF_ECMA AF_ECMA 330 #define PF_DATAKIT AF_DATAKIT 331 #define PF_CCITT AF_CCITT 332 #define PF_SNA AF_SNA 333 #define PF_DECnet AF_DECnet 334 #define PF_DLI AF_DLI 335 #define PF_LAT AF_LAT 336 #define PF_HYLINK AF_HYLINK 337 #define PF_APPLETALK AF_APPLETALK 338 #define PF_ROUTE AF_ROUTE 339 #define PF_LINK AF_LINK 340 #define PF_XTP pseudo_AF_XTP /* really just proto family, no AF */ 341 #define PF_COIP AF_COIP 342 #define PF_CNT AF_CNT 343 #define PF_SIP AF_SIP 344 #define PF_IPX AF_IPX 345 #define PF_RTIP pseudo_AF_RTIP /* same format as AF_INET */ 346 #define PF_PIP pseudo_AF_PIP 347 #define PF_ISDN AF_ISDN 348 #define PF_KEY pseudo_AF_KEY 349 #define PF_INET6 AF_INET6 350 #define PF_NATM AF_NATM 351 #define PF_ATM AF_ATM 352 #define PF_NETGRAPH AF_NETGRAPH 353 #define PF_SLOW AF_SLOW 354 #define PF_SCLUSTER AF_SCLUSTER 355 #define PF_ARP AF_ARP 356 #define PF_BLUETOOTH AF_BLUETOOTH 357 #define PF_IEEE80211 AF_IEEE80211 358 #define PF_INET_SDP AF_INET_SDP 359 #define PF_INET6_SDP AF_INET6_SDP 360 361 #define PF_MAX AF_MAX 362 363 /* 364 * Definitions for network related sysctl, CTL_NET. 365 * 366 * Second level is protocol family. 367 * Third level is protocol number. 368 * 369 * Further levels are defined by the individual families below. 370 */ 371 #define NET_MAXID AF_MAX 372 373 /* 374 * PF_ROUTE - Routing table 路由表 375 * 376 * Three additional levels are defined: 377 * Fourth: address family, 0 is wildcard 378 * Fifth: type of info, defined below 379 * Sixth: flag(s) to mask with for NET_RT_FLAGS 380 */ 381 #define NET_RT_DUMP 1 /* dump; may limit to a.f. */ 382 #define NET_RT_FLAGS 2 /* by flags, e.g. RESOLVING */ 383 #define NET_RT_IFLIST 3 /* survey interface list */ 384 #define NET_RT_IFMALIST 4 /* return multicast address list */ 385 #define NET_RT_IFLISTL 5 /* Survey interface list, using 'l'en 386 * versions of msghdr structs. */ 387 #define NET_RT_MAXID 6 388 389 #endif /* __BSD_VISIBLE */ 390 391 /* 392 * Maximum queue length specifiable by listen. 监听的最大的队列的长度 393 */ 394 #define SOMAXCONN 128 395 396 /* 397 * Message header for recvmsg and sendmsg calls. recvmsg和sendmsg调用的消息头 398 * Used value-result for recvmsg, value only for sendmsg. 399 */ 400 struct msghdr { 401 void *msg_name; /* optional address */ 402 socklen_t msg_namelen; /* size of address */ 403 struct iovec *msg_iov; /* scatter/gather array */ 404 int msg_iovlen; /* # elements in msg_iov */ 405 void *msg_control; /* ancillary data, see below */ 406 socklen_t msg_controllen; /* ancillary data buffer len */ 407 int msg_flags; /* flags on received message */ 408 }; 409 410 #define MSG_OOB 0x1 /* process out-of-band data */ 411 #define MSG_PEEK 0x2 /* peek at incoming message */ 412 #define MSG_DONTROUTE 0x4 /* send without using routing tables */ 413 #define MSG_EOR 0x8 /* data completes record */ 414 #define MSG_TRUNC 0x10 /* data discarded before delivery */ 415 #define MSG_CTRUNC 0x20 /* control data lost before delivery */ 416 #define MSG_WAITALL 0x40 /* wait for full request or error */ 417 #if __POSIX_VISIBLE >= 200809 418 #define MSG_NOSIGNAL 0x20000 /* do not generate SIGPIPE on EOF */ 419 #endif 420 #if __BSD_VISIBLE 421 #define MSG_DONTWAIT 0x80 /* this message should be nonblocking */ 422 #define MSG_EOF 0x100 /* data completes connection */ 423 #define MSG_NOTIFICATION 0x2000 /* SCTP notification */ 424 #define MSG_NBIO 0x4000 /* FIONBIO mode, used by fifofs */ 425 #define MSG_COMPAT 0x8000 /* used in sendit() */ 426 #define MSG_CMSG_CLOEXEC 0x40000 /* make received fds close-on-exec */ 427 #endif 428 #ifdef _KERNEL 429 #define MSG_SOCALLBCK 0x10000 /* for use by socket callbacks - soreceive (TCP) */ 430 #endif 431 432 /* 433 * Header for ancillary data objects in msg_control buffer. 434 * Used for additional information with/about a datagram 435 * not expressible by flags. The format is a sequence 436 * of message elements headed by cmsghdr structures. 437 */ 438 struct cmsghdr { 439 socklen_t cmsg_len; /* data byte count, including hdr */ 440 int cmsg_level; /* originating protocol */ 441 int cmsg_type; /* protocol-specific type */ 442 /* followed by u_char cmsg_data[]; */ 443 }; 444 445 #if __BSD_VISIBLE 446 /* 447 * While we may have more groups than this, the cmsgcred struct must 448 * be able to fit in an mbuf and we have historically supported a 449 * maximum of 16 groups. 450 */ 451 #define CMGROUP_MAX 16 452 453 /* 454 * Credentials structure, used to verify the identity of a peer 455 * process that has sent us a message. This is allocated by the 456 * peer process but filled in by the kernel. This prevents the 457 * peer from lying about its identity. (Note that cmcred_groups[0] 458 * is the effective GID.) 459 */ 460 struct cmsgcred { 461 pid_t cmcred_pid; /* PID of sending process */ 462 uid_t cmcred_uid; /* real UID of sending process */ 463 uid_t cmcred_euid; /* effective UID of sending process */ 464 gid_t cmcred_gid; /* real GID of sending process */ 465 short cmcred_ngroups; /* number or groups */ 466 gid_t cmcred_groups[CMGROUP_MAX]; /* groups */ 467 }; 468 469 /* 470 * Socket credentials证书. 471 */ 472 struct sockcred { 473 uid_t sc_uid; /* real user id */ 474 uid_t sc_euid; /* effective user id */ 475 gid_t sc_gid; /* real group id */ 476 gid_t sc_egid; /* effective group id */ 477 int sc_ngroups; /* number of supplemental groups */ 478 gid_t sc_groups[1]; /* variable length */ 479 }; 480 481 /* 482 * Compute size of a sockcred structure with groups. 483 */ 484 #define SOCKCREDSIZE(ngrps) \ 485 (sizeof(struct sockcred) + (sizeof(gid_t) * ((ngrps) - 1))) 486 487 #endif /* __BSD_VISIBLE */ 488 489 /* given pointer to struct cmsghdr, return pointer to data */ 490 #define CMSG_DATA(cmsg) ((unsigned char *)(cmsg) + \ 491 _ALIGN(sizeof(struct cmsghdr))) 492 493 /* given pointer to struct cmsghdr, return pointer to next cmsghdr */ 494 #define CMSG_NXTHDR(mhdr, cmsg) \ 495 ((char *)(cmsg) == NULL ? CMSG_FIRSTHDR(mhdr) : \ 496 ((char *)(cmsg) + _ALIGN(((struct cmsghdr *)(cmsg))->cmsg_len) + \ 497 _ALIGN(sizeof(struct cmsghdr)) > \ 498 (char *)(mhdr)->msg_control + (mhdr)->msg_controllen) ? \ 499 (struct cmsghdr *)0 : \ 500 (struct cmsghdr *)(void *)((char *)(cmsg) + \ 501 _ALIGN(((struct cmsghdr *)(cmsg))->cmsg_len))) 502 503 /* 504 * RFC 2292 requires to check msg_controllen, in case that the kernel returns 505 * an empty list for some reasons. 506 */ 507 #define CMSG_FIRSTHDR(mhdr) \ 508 ((mhdr)->msg_controllen >= sizeof(struct cmsghdr) ? \ 509 (struct cmsghdr *)(mhdr)->msg_control : \ 510 (struct cmsghdr *)NULL) 511 512 #if __BSD_VISIBLE 513 /* RFC 2292 additions */ 514 #define CMSG_SPACE(l) (_ALIGN(sizeof(struct cmsghdr)) + _ALIGN(l)) 515 #define CMSG_LEN(l) (_ALIGN(sizeof(struct cmsghdr)) + (l)) 516 #endif 517 518 #ifdef _KERNEL 519 #define CMSG_ALIGN(n) _ALIGN(n) 520 #endif 521 522 /* "Socket"-level control message types: */ 523 #define SCM_RIGHTS 0x01 /* access rights (array of int) */ 524 #if __BSD_VISIBLE 525 #define SCM_TIMESTAMP 0x02 /* timestamp (struct timeval) */ 526 #define SCM_CREDS 0x03 /* process creds (struct cmsgcred) */ 527 #define SCM_BINTIME 0x04 /* timestamp (struct bintime) */ 528 #endif 529 530 #if __BSD_VISIBLE 531 /* 532 * 4.3 compat sockaddr, move to compat file later 533 */ 534 struct osockaddr { 535 unsigned short sa_family; /* address family */ 536 char sa_data[14]; /* up to 14 bytes of direct address */ 537 }; 538 539 /* 540 * 4.3-compat message header (move to compat file later). 541 */ 542 struct omsghdr { 543 char *msg_name; /* optional address */ 544 int msg_namelen; /* size of address */ 545 struct iovec *msg_iov; /* scatter/gather array */ 546 int msg_iovlen; /* # elements in msg_iov */ 547 char *msg_accrights; /* access rights sent/received */ 548 int msg_accrightslen; 549 }; 550 #endif 551 552 /* 553 * howto arguments for shutdown(2), specified by Posix.1g. 554 */ 555 #define SHUT_RD 0 /* shut down the reading side */ 556 #define SHUT_WR 1 /* shut down the writing side */ 557 #define SHUT_RDWR 2 /* shut down both sides */ 558 559 #if __BSD_VISIBLE 560 /* for SCTP */ 561 /* we cheat and use the SHUT_XX defines for these */ 562 #define PRU_FLUSH_RD SHUT_RD 563 #define PRU_FLUSH_WR SHUT_WR 564 #define PRU_FLUSH_RDWR SHUT_RDWR 565 #endif 566 567 568 #if __BSD_VISIBLE 569 /* 570 * sendfile(2) header/trailer struct 571 */ 572 struct sf_hdtr { 573 struct iovec *headers; /* pointer to an array of header struct iovec's */ 574 int hdr_cnt; /* number of header iovec's */ 575 struct iovec *trailers; /* pointer to an array of trailer struct iovec's */ 576 int trl_cnt; /* number of trailer iovec's */ 577 }; 578 579 /* 580 * Sendfile-specific flag(s) 581 */ 582 #define SF_NODISKIO 0x00000001 583 #define SF_MNOWAIT 0x00000002 584 #define SF_SYNC 0x00000004 585 586 #ifdef _KERNEL 587 #define SFK_COMPAT 0x00000001 588 #endif /* _KERNEL */ 589 #endif /* __BSD_VISIBLE */ 590 591 #ifndef _KERNEL 592 593 #include 594 595 __BEGIN_DECLS 596 int accept(int, struct sockaddr * __restrict, socklen_t * __restrict); 597 int bind(int, const struct sockaddr *, socklen_t); 598 int connect(int, const struct sockaddr *, socklen_t); 599 #if __BSD_VISIBLE 600 int accept4(int, struct sockaddr * __restrict, socklen_t * __restrict, int); 601 int bindat(int, int, const struct sockaddr *, socklen_t); 602 int connectat(int, int, const struct sockaddr *, socklen_t); 603 #endif 604 int getpeername(int, struct sockaddr * __restrict, socklen_t * __restrict); 605 int getsockname(int, struct sockaddr * __restrict, socklen_t * __restrict); 606 int getsockopt(int, int, int, void * __restrict, socklen_t * __restrict); 607 int listen(int, int); 608 ssize_t recv(int, void *, size_t, int); 609 ssize_t recvfrom(int, void *, size_t, int, struct sockaddr * __restrict, socklen_t * __restrict); 610 ssize_t recvmsg(int, struct msghdr *, int); 611 ssize_t send(int, const void *, size_t, int); 612 ssize_t sendto(int, const void *, 613 size_t, int, const struct sockaddr *, socklen_t); 614 ssize_t sendmsg(int, const struct msghdr *, int); 615 #if __BSD_VISIBLE 616 int sendfile(int, int, off_t, size_t, struct sf_hdtr *, off_t *, int); 617 int setfib(int); 618 #endif 619 int setsockopt(int, int, int, const void *, socklen_t); 620 int shutdown(int, int); 621 int sockatmark(int); 622 int socket(int, int, int); 623 int socketpair(int, int, int, int *); 624 __END_DECLS 625 626 #endif /* !_KERNEL */ 627 628 #ifdef _KERNEL 629 struct socket; 630 631 struct tcpcb *so_sototcpcb(struct socket *so); 632 struct inpcb *so_sotoinpcb(struct socket *so); 633 struct sockbuf *so_sockbuf_snd(struct socket *); 634 struct sockbuf *so_sockbuf_rcv(struct socket *); 635 636 int so_state_get(const struct socket *); 637 void so_state_set(struct socket *, int); 638 639 int so_options_get(const struct socket *); 640 void so_options_set(struct socket *, int); 641 642 int so_error_get(const struct socket *); 643 void so_error_set(struct socket *, int); 644 645 int so_linger_get(const struct socket *); 646 void so_linger_set(struct socket *, int); 647 648 struct protosw *so_protosw_get(const struct socket *); 649 void so_protosw_set(struct socket *, struct protosw *); 650 651 void so_sorwakeup_locked(struct socket *so); 652 void so_sowwakeup_locked(struct socket *so); 653 654 void so_sorwakeup(struct socket *so); 655 void so_sowwakeup(struct socket *so); 656 657 void so_lock(struct socket *so); 658 void so_unlock(struct socket *so); 659 660 void so_listeners_apply_all(struct socket *so, void (*func)(struct socket *, void *), void *arg); 661 662 #endif 663 664 665 #endif /* !_SYS_SOCKET_H_ */
http://man7.org/linux/man-pages/man2/socket.2.html
SOCKET(2) Linux Programmer's Manual SOCKET(2)
NAME top
socket - create an endpoint for communication
SYNOPSIS top
#include/* See NOTES */ #include int socket(int domain, int type, int protocol);
DESCRIPTION top
socket() creates an endpoint for communication and returns a descriptor. The domain argument specifies a communication domain; this selects the protocol family which will be used for communication. These families are defined in. The currently understood formats include: Name Purpose Man page AF_UNIX, AF_LOCAL Local communication unix(7) AF_INET IPv4 Internet protocols ip(7) AF_INET6 IPv6 Internet protocols ipv6(7) AF_IPX IPX - Novell protocols AF_NETLINK Kernel user interface device netlink(7) AF_X25 ITU-T X.25 / ISO-8208 protocol x25(7) AF_AX25 Amateur radio AX.25 protocol AF_ATMPVC Access to raw ATM PVCs AF_APPLETALK Appletalk ddp(7) AF_PACKET Low level packet interface packet(7) The socket has the indicated type, which specifies the communication semantics语义的. Currently defined types are: SOCK_STREAM Provides sequenced, reliable, two-way, connection- based byte streams. An out-of-band data transmission mechanism may be supported. SOCK_DGRAM Supports datagrams (connectionless, unreliable messages of a fixed maximum length). SOCK_SEQPACKET Provides a sequenced, reliable, two-way connection- based data transmission path for datagrams of fixed maximum length; a consumer is required to read an entire packet with each input system call. SOCK_RAW Provides raw network protocol access. SOCK_RDM Provides a reliable datagram layer that does not guarantee ordering. SOCK_PACKET Obsolete and should not be used in new programs; see packet(7). Some socket types may not be implemented by all protocol families; for example, SOCK_SEQPACKET is not implemented for AF_INET. Since Linux 2.6.27, the type argument serves a second purpose: in addition to specifying a socket type, it may include the bitwise OR of any of the following values, to modify the behavior of socket(): SOCK_NONBLOCK Set the O_NONBLOCK file status flag on the new open file description. Using this flag saves extra calls to fcntl(2) to achieve the same result. SOCK_CLOEXEC Set the close-on-exec (FD_CLOEXEC) flag on the new file descriptor. See the description of the O_CLOEXEC flag in open(2) for reasons why this may be useful. The protocol specifies a particular protocol to be used with the socket. Normally only a single protocol exists to support a particular socket type within a given protocol family, in which case protocol can be specified as 0. However, it is possible that many protocols may exist, in which case a particular protocol must be specified in this manner. The protocol number to use is specific to the "communication domain" in which communication is to take place; see protocols(5). See getprotoent(3) on how to map protocol name strings to protocol numbers. Sockets of type SOCK_STREAM are full-duplex byte streams, similar to pipes. They do not preserve record boundaries. A stream socket must be in a connected state before any data may be sent or received on it. A connection to another socket is created with a connect(2) call. Once connected, data may be transferred using read(2) and write(2) calls or some variant of the send(2) and recv(2) calls. When a session has been completed a close(2) may be performed. Out- of-band data may also be transmitted as described in send(2) and received as described in recv(2). The communications protocols which implement a SOCK_STREAM ensure that data is not lost or duplicated. If a piece of data for which the peer protocol has buffer space cannot be successfully transmitted within a reasonable length of time, then the connection is considered to be dead. When SO_KEEPALIVE is enabled on the socket the protocol checks in a protocol-specific manner if the other end is still alive. A SIGPIPE signal is raised if a process sends or receives on a broken stream; this causes naive processes, which do not handle the signal, to exit. SOCK_SEQPACKET sockets employ the same system calls as SOCK_STREAM sockets. The only difference is that read(2) calls will return only the amount of data requested, and any data remaining in the arriving packet will be discarded. Also all message boundaries in incoming datagrams are preserved. SOCK_DGRAM and SOCK_RAW sockets allow sending of datagrams to correspondents named in sendto(2) calls. Datagrams are generally received with recvfrom(2), which returns the next datagram along with the address of its sender. SOCK_PACKET is an obsolete socket type to receive raw packets directly from the device driver. Use packet(7) instead. An fcntl(2) F_SETOWN operation can be used to specify a process or process group to receive a SIGURG signal when the out-of-band data arrives or SIGPIPE signal when a SOCK_STREAM connection breaks unexpectedly. This operation may also be used to set the process or process group that receives the I/O and asynchronous notification of I/O events via SIGIO. Using F_SETOWN is equivalent to an ioctl(2) call with the FIOSETOWN or SIOCSPGRP argument. When the network signals an error condition to the protocol module (e.g., using a ICMP message for IP) the pending error flag is set for the socket. The next operation on this socket will return the error code of the pending error. For some protocols it is possible to enable a per-socket error queue to retrieve detailed information about the error; see IP_RECVERR in ip(7). The operation of sockets is controlled by socket level options. These options are defined in . The functions setsockopt(2) and getsockopt(2) are used to set and get options, respectively.
RETURN VALUE top
On success, a file descriptor for the new socket is returned. On
error, -1 is returned, and errno is set appropriately.
ERRORS top
EACCES Permission to create a socket of the specified type and/or protocol is denied. EAFNOSUPPORT The implementation does not support the specified address family. EINVAL Unknown protocol, or protocol family not available. EINVAL Invalid flags in type. EMFILE Process file table overflow. ENFILE The system limit on the total number of open files has been reached. ENOBUFS or ENOMEM Insufficient memory is available. The socket cannot be created until sufficient resources are freed. EPROTONOSUPPORT The protocol type or the specified protocol is not supported within this domain. Other errors may be generated by the underlying protocol modules.
CONFORMING TO top
4.4BSD, POSIX.1-2001.
The SOCK_NONBLOCK and SOCK_CLOEXEC flags are Linux-specific.
socket() appeared in 4.2BSD. It is generally portable to/from non-
BSD systems supporting clones of the BSD socket layer (including
System V variants).
NOTES top
POSIX.1-2001 does not require the inclusion of, and this header file is not required on Linux. However, some historical (BSD) implementations required this header file, and portable applications are probably wise to include it. The manifest constants used under 4.x BSD for protocol families are PF_UNIX, PF_INET, and so on, while AF_UNIX, AF_INET, and so on are used for address families. However, already the BSD man page promises: "The protocol family generally is the same as the address family", and subsequent standards use AF_* everywhere.
EXAMPLE top
An example of the use of socket() is shown in getaddrinfo(3).
SEE ALSO top
accept(2), bind(2), connect(2), fcntl(2), getpeername(2),
getsockname(2), getsockopt(2), ioctl(2), listen(2), read(2), recv(2),
select(2), send(2), shutdown(2), socketpair(2), write(2),
getprotoent(3), ip(7), socket(7), tcp(7), udp(7), unix(7)
"An Introductory 4.3BSD Interprocess Communication Tutorial" and "BSD
Interprocess Communication Tutorial", reprinted in UNIX Programmer's
Supplementary Documents Volume 1.
COLOPHON top
This page is part of release 3.54 of the Linux man-pages project. A
description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.
Linux 2009-01-19 SOCKET(2)