sys/socket.h

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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 #include <sys/cdefs.h>   37 #include <sys/_types.h>   38 #include <sys/_iovec.h>   39 #include <machine/_align.h>   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 #include <sys/_sockaddr_storage.h>  314   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 <sys/cdefs.h>  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 <sys/types.h>          /* See NOTES */       #include <sys/socket.h>       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 <sys/socket.h>. 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 <sys/socket.h>. 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 <sys/types.h>, 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).

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)