Accept (Accept Socket Connection)
related functions
Socket, Bind, Listen, Connect
Header file
#include
Definition function
INT Accept (int S, Struct SockAddr * Addr, INT * Addrlen);
Function description
Accept () is used to accept the Socket connection of parameter s. The Socket of the parameter S is necessary to process the BIND (), the listen () function, and accept () will return a new socket processing code when there is a connection, and the subsequent data transfer and reading are processed via the new socket. And the original parameter S Socket can continue to use accept () to accept new connection requirements. When the connection is successful, the structure referred to by the parameter addr will be filled in the address data of the remote host, the parameter addrlen is the structural length of Scokdd. For the definition of structure SOCKADDR, please refer to Bind ().
return value
Success returns a new Socket processing code, failed to return -1, and the error is existed in Errno.
error code
EBADF parameter S non - legitimate Socket processing code. The Efault Parameters addR pointer points to the memory space that cannot be accessed. EnotSock parameter S is a file descriptor, non-socket. EopnotSupp Specifies Socket Not Sock_Stream. Eperm firewall rejects this connection. The buffering memory of the Enobufs system is insufficient. EnomeM core is insufficient.
example
Refer to Listen ().
Bind (targeting socket)
related functions
Socket, Accept, Connect, Listen
Header file
#include
Definition function
INT Bind (int Sockfd, struct sockaddr * my_addr, int addrlen);
Function description
Bind () is used to set a name for the Socket for the parameter sockfd. This name is directed by the parameter my_addr to a SockAddr structure, defines a universal data structure for different socket domain, which is the domain parameter when calling socket () for different socket Domain;}; sa_family AF_XXXX value. SA_DATA uses up to 14 characters long. This sockaddr structure due to the use of different socket domain and have different structure definitions, for example AF_INET domain, which socketaddr structure is defined so as struct socketaddr_in {unsigned short int sin_family; uint16_t sin_port; struct in_addr sin_addr; unsigned char sin_zero [8];} Struct in_addr {uint32_t s_addr;}; sin_family, the port number SIN_ADDR.S_ADDR SIN_ADDR.S_ADDR SIN_ADDR.S_ADDR for SA_FAMILYSIN_PORT is not used by IP addresses SIN_ZERO.
parameter
Addrlen is the structure length of SockAddr.
return value
Success returns 0, the failure returns -1, and the error is existed in Errno.
error code
EBADF parameter sockfd non-legitimate SOCKET processing code. EACCESS permissions The enotsock parameter sockfd is a file descriptor, non-socket.
example
Reference listen ()
Connect (create a Socket connection)
Related functions Socket, Bind, Listen
Header file
#include
Definition function
INT Connect (int sockfd, struct sockaddr * serv_addr, int addrlen);
Function description
Connect () is used to connect the parameter sockfd's socket to the network address specified by the parameter serv_addr. Structure SockAddr Please refer to Bind (). The parameter addrlen is the structure length of SockAddr.
return value
Success returns 0, the failure returns -1, and the error is existed in Errno.
error code
Ebadf parameter sockfd non-legitimate SOCKET Processing code EFault parameter serv_addr pointer points to the unacceptable memory space EnotSock parameter sockfd is a file descriptor, non-socket. The socket of the Eisconn parameter sockfd is the connection status of the ECONNREFUSED connection request to be rejected by the Server side. ETIMEDOUT attempts to connect operations than limited time still no response. ENETunReach cannot transmit packets to the specified host. The SA_FAMILY of the Eafnosupport SockAddr structure is incorrect. Ealready Socket has not been completed for unbrocessed and previous connection operations.
example
/ * Use the Socket TCP Client This program will connect TCP Server and transfer the keyboard input string to the Server. For the TCP Server example, please refer to Listen (). * / # include
carried out
$ ./connectwelcome to server! hi i amclient! / * Keyboard input * // *
EndProtoent (reading network protocol data)
related functions
GetProtoent, getProtobyname, getProtobynumber, setProtoent header file
#include
Definition function
Void endprotoent (void);
Function description
EndProtoent () is used to close files opened by getProtoent ().
return value
example
Reference getprotoent ()
EndServent (reading network service data)
related functions
GetServent, GetServByname, GetServbyport, SetServent
Header file
#include
Definition function
Void endServent (void);
Function description
EndServent () is used to close the files opened by GetServent ().
return value
example
Refer to GetServent ().
Getsockopt (get a socket status)
related functions
Setsockopt
Header file
#include
Definition function
INT GetSockopt (int S, int Level, Int Optname, void * optval, socklen_t * optlen);
Function description
GetSockOpt () returns the Socket status specified by the parameter s. Parameters Optname represents what options to make, and parameter OPTVAL points to the memory address to save the result, and the parameter OPTLEN is the size of the space. Parameters Level, Optname Please refer to SetsockOpt ().
return value
Success, return 0, return -1 if there is an error, the error is existed in Errno
error code
Ebadf parameter S is not legal Socket processing code ENOTSOCK parameter S is a file descriptor, non-socketenoprotoopt parameter Optname specified option incorrect EFAULT parameter Optval pointer points to memory space that cannot be accessed
example
#include
carried out
Optval = 1 / * Sock_Stream definition is this value * /
HTONL (transitioning 32-bit host characters in order to network characters)
related functions
Htons, NTOHL, NTOHS
Header file
#include
Definition function
Unsigned long int htonl;
Function description
HTONL () is used to convert the 32-bit hostlong specified by the parameter into a network character order.
return value
Returns the corresponding network character sequence.
example
Refer to GetServByPort () or Connect ().
Htons (transitioning 16 host characters in the order of network characters)
related functions
HTONL, NTOHL, NTOHS
Header file
#include
Definition function
UNSIGNED SHORT INT HTONS (Unsigned Short Int Hostsh); function description
Htons () is used to convert the 16-bit hostshorts specified by the parameter into a network character order.
return value
Returns the corresponding network character sequence.
example
Refer to Connect ().
INET_ADDR (transfer network address to binary)
related functions
inet_aton, inet_ntoa
Header file
#include
Definition function
Unsigned long int inet_addr (const char * cp);
Function description
INET_ADDR () is used to convert the network address string referred to in the parameter CP into a binary number used by the network. The network address string is a string consisting of numbers and points, such as "163.13.132.68".
return value
Success returns to the corresponding network binary number, failed to return -1.
inet_aton (transfer network address to network binary)
related functions
INET_ADDR, INET_NTOA
Header file
#include
Definition function
INT INET_ATON (Const Char * CP, Struct In_Addr * INP);
Function description
inet_aton () is used to convert the network address string referred to in the parameter CP into a binary number used, and then exist in the IN_ADDR structure referred to in the parameter INP. Structure in_addr Defines the following struct in_addr {unsigned long int s_addr;};
return value
Success returns a non-0 value and returns 0.
INET_NTOA (converting network binary numbers into network addresses)
related functions
inet_addr, inet_aton
Header file
#include
Definition function
Char * inet_ntoa (struct in_addr in);
Function description
INET_NTOA () is used to convert the network binary numbers referred to in the parameter in to the network address, and then returns the pointer to this network address string.
return value
Success returns a string pointer and returns NULL.
Listen (wait connection)
related functions
Socket, Bind, Accept, Connect
Header file
#include
Definition function
INT Listen (int S, int backlog);
Function description
Listen () is used to wait for the Socket connection of the parameter S. Parameter backlog Specifies the maximum connection requirements at the same time. If the number of connections reaches the upper limit, the Client end will receive an ECONNREFUSED error. Listen () did not start receiving the connection, just set the socket as the Listen mode, and truly receiving the client connection is Accept (). Usually listen () will be called after socket (), bind (), then call Accept ().
return value
Success returns 0, failed to return -1, the error is existed in Errno
Additional information
Listen () is only applicable to the socket type of Sock_Stream or Sock_seqpacket. If the socket is AF_INET, the parameter backlog maximum can be set to 128.
error code
Ebadf Parameters SOCKFD Non Legal Socket Processing Code EACCESS Permissions The specified Socket is not supported in the Listen mode. example
#include carried out $ ./listenconnect from 127.0.0.1hi i amclientconnected closed. NTOHL (convert 32-bit network character sequence into host characters) related functions HTONL, HTONS, NTOHS Header file #include Definition function Unsigned long int NTOHL (Unsigned long int netlong); function description NTOHL () is used to convert the 32-bit NETLONG specified by the parameter into a host character sequence. return value Returns the corresponding host character sequence. example Refer to GetServent (). NTOHS (convert 16-bit network character sequence into host character sequence) related functions HTONL, HTONS, NTOHL Header file #include Definition function UNSIGNED SHORT INT NTOHS (UNSIGNED SHORT INT NETSHORT); Function description NTOHS () is used to convert the 16-bit Netshort specified by the parameter to the host character sequence. return value Returns the corresponding host order. example Refer to GetServent (). RECV (received data by Socket) related functions Recvfrom, Recvmsg, Send, Sendto, Socket Header file #include Definition function INT RECV (Int S, Void * BUF, INT LEN, UNSIGNED INT FLAGS); Function description RECV () is used to receive data from the specified Socket specified, and save the data to the memory space pointed to by the parameter BUF, and the parameter LEN is the maximum length of the received data. parameter Flags are generally 0. Other values are defined as follows: MSG_oob receives data sent in OUT-OF-BAND. The data returned by MSG_peek does not delete in the system, if the recall RECV () will return the same data content. MSG_WAITALL forced data to receive the Len size before returning, unless there is an error or signal generation. MSG_NOSignal This operation is not willing to be successfully returned by the SIGPIPE signal, returns the number of characters received, and the failure returns -1, and the error is stored in Errno. error code Ebadf Parameters S Non Legal Socket Processing Code EFault Parameters There is a pointer pointing to the unacceptable memory space EnotSock parameter S is a file descriptor, non-socket. EINTR is interrupted by the signal to block the process to block the process, but the Socket of the parameter S is insufficient to block the buffer memory that cannot block the Enobufs system. EnomeM core memory is incorrect with EINVAL pass to the system call. example Refer to Listen (). Recvfrom (received data received by Socket) related functions RECV, Recvmsg, Send, Sendto, Socket Header file #include Definition function INT Recvfrom (int LEN, Unsigned Int Flags, Struct SockAddr * from, int * fromlen); Function description Recv () is used to receive data from the specified Socket, and save the data to the memory space points to by the parameter BUF, the parameter LEN is the maximum length of the received data. Parameter Flags is typically set 0, please refer to RECV () for other numerical definitions. The parameter from the network address used to specify the network address to be transmitted, and the structure SockAddr refers to Bind (). Parameter from Fromlen is the structure length of SockAddr. return value Success returns the number of characters received, and the failure returns -1, and the error is existed in Errno. error code Ebadf parameter s non-legitimate Socket Processing code EFault parameters There is a pointer pointing to memory space that cannot be accessed. EnotSock parameter S is a file descriptor, non-socket. EINTR is interrupted by the signal. EAGAIN This action will block the process, but the Socket of the parameter S is not blockable. The Enobufs system's buffer memory is not enough ENOMEM core memory instead of EINVAL. example / * Using Socket's UDP Client This program will connect UDP Server and pass the keyboard input to the Server. For the UDP Server example, please refer to Sendto (). * / # include carried out (UDP Server and then execute UDP client) hello / * Enter string from the keyboard * / receive: Hello / * Server end comes back * / Recvmsg (received data by socket) related functions RECV, Recvfrom, Send, Sendto, Sendmsg, Socket Header file #include Definition function INT Recvmsg (int S, Struct Msghdr * MSG, Unsigned Int Flags); Function description Recvmsg () is used to receive data from the remote host to the specified Socket. The parameter S is a Socket that has been established, and if the UDP protocol is used, it does not need to be connected. Parameter MSG points to the data structure content of wiring, parameter FLAGS is generally 0, please refer to Send (), please refer to Send (). For the definition of structural MSGHDR, please refer to SendMSG (). return value Success returns the number of characters received, and the failure returns -1, and the error is existed in Errno. error code Ebadf parameter S non-legitimate Socket processing code. In the EFault parameter, you have a pointer to the unacceptable memory space EnotSock parameter S is a file descriptor, non-socket. EINTR is interrupted by the signal. EAGAIN This action will block the process, but the Socket of the parameter S cannot be blocked. The Enobufs system's buffer memory is not enough ENOMEM core memory instead of EINVAL. example Refer to RECVFROM (). Send (via Socket Transfer Data) related functions Sendto, Sendmsg, Recv, Recvfrom, Socket Header file #include Definition function INT Send (int LEN, Unsigned Int falgs); Function description Send () is used to pass the data by the specified Socket to the other party host. The parameter S is a Socket that has been established. The parameter MSG points to the data content that is wired, and the parameter LEN is the data length. Parameter Flags typically set 0, other values define the data transmitted by the MSG_oob as follows Out-of-Band. MSG_DONTROUTE Cancel Routing Table Query MSG_DONTWAIT Set to Unblable Operation MSG_NOSignal This action is not willing to be interrupted by the SIGPIPE signal. return value Success returns the number of characters that actually transmits, and the failure returns -1. Error reason exists in errno error code Ebadf parameter S non-legitimate Socket processing code. In the EFault parameter, you have a pointer to the unacceptable memory space EnotSock parameter S is a file descriptor, non-socket. EINTR is interrupted by the signal. EAGAIN This action will block the process, but the Socket of the parameter S cannot be blocked. The Enobufs system's buffer memory is not enough ENOMEM core memory instead of EINVAL. example Refer to Connect () Sendmsg (Socket Transfer Data) related functions Send, Sendto, Recv, Recvfrom, Recvmsg, Socket Header file #include Definition function INT Sendmsg (int S, Const strcut msghdr * msg, unsigned int flags); Function description Sendmsg () is used to pass the data by the specified Socket to the other party host. The parameter S is a Socket that has been established, and if the UDP protocol is used, it does not need to be connected. Parameter MSG points to the contents of the data structure to be wired, the parameter Flags is generally default to 0, and please refer to Send (). Structure msghdr defined as follows struct msghdr {void * msg_name; / * Address to send to / receive from * / socklen_t msg_namelen;. / * Length of addres data * / strcut iovec * msg_iov; / * Vector of data to send / receive into * / size_t msg_iovlen; / * Number of elements in the vector * / void * msg_control; / * Ancillary dat * / size_t msg_controllen; / * Ancillary data buffer length * / int msg_flags; / * Flags on received message * /}; return value Success, return the number of characters actually transmitted, and the failure returns -1, and the error is existed in Errno error code. Ebadf parameter S non-legitimate Socket processing code. In the EFault parameter, you have a pointer to the unacceptable memory space EnotSock parameter S is a file descriptor, non-socket. EINTR is interrupted by the signal. EAGAIN This action will block the process, but the Socket of the parameter S cannot be blocked. The Enobufs system's buffer memory is not enough ENOMEM core memory instead of EINVAL. example Refer to Sendto (). Sendto (Socket Transfer Data) related functions Send, Sendmsg, Recv, Recvfrom, Socket Header file #include Definition function Int Sendto (int LEN, Unsigned Int Flag, Int Len, Unsigned Int Flags, Const Struct SockAddr * To, INT TOLEN); Function description Sendto () is used to pass the data from the specified Socket to the other party. The parameter S is a Socket that has been built, and if the UDP protocol is used, it does not need to be operated. The parameter MSG points to the data content of the wiring, the parameter Flags is generally 0, and please refer to Send (). The parameter TO is used to specify the network address to be transferred, and the structure SOCKADDR is referred to BIND (). The parameter TOLEN is the result length of SockAddr. return value Success, return the number of characters actually transmitted, the failure returns -1, and the error is existed in Errno. error code Ebadf parameter s illegal Socket processing code. There is a pointer in the efault parameter to point to the memory that cannot be accessed. WNOTSOCK CANSHU S is a file description word, non-socket. EINTR is interrupted by the signal. EAGAIN This action will block the process, but the SOKET of the parameter S is blocking. The buffering memory of the Enobufs system is insufficient. The parameters passing to the system call to the system are incorrect. example #include Please refer to Recvfrom () SetProtoent (Open the data file of the network protocol) related functions GetProtobyname, GetProtobynumber, Endprotoent Header file #include Definition function Void setProtoent (int Stayopen); Function description SetProtoent () is used to open / etc / protocols, if the parameter stayopen value is 1, then the next getProtobyname () or getProtobynumber () will not automatically turn this file. SetServent (Open the data file of the host network service) related functions GetServent, GetServByname, GetServbyport, EndServent Header file #include Definition function Void setServent (int Stayopen); Function description SetServent () is used to open / etc / services, if the parameter StayOpen value is 1, then the next getServByName () or getServByport () will return to the automatic shutdown file. Setsockopt (Set up Socket Status) related functions GetSockopt Header file #include Definition function Int setsockopt (int S, int level, int iptname, const void * optval, socklen_toptlen); Function description Setsockopt () is used to set the Socket status specified by the parameter S. The parameter Level represents the network layer that wants to set, which is typically set to SOL_Socket to access the Socket layer. Parameter Optname Represents options to set, with the following values: SO_DEBUG Opening or closing the error mode SO_REUSEADDR Allows the local address to reuse the SOCKET form in the bind () process. SO_ERROR Returns the error reason for the resulting Error Reason for SO_DONTROUTE Do not use routing devices to transmit. SO_BROADCAST uses broadcast mode to transfer SO_SNDBUF Settings Send Temporal Size SO_RCVBUF Set whether the received temporary area SO_KEEPALIVE periodically determines whether the connection has been terminated. SO_OOBINLINE will immediately send it to the standard input device so_linger when it receives OOB data. Make sure data is safe and reliable. parameter OptVal represents the value set, the parameter OPTLEN is the length of OptVal. return value Success returns 0, if there is an error, return -1, the error is existed in Errno. Additional information EBADF parameter S is not legal Socket processing code ENOTSOCK parameter S is a file descriptor, non-socketenoprotoopt parameter OptName The option specified is incorrect. Efault Parameters Optval Pointer Pointer to Unrecognized memory space. example Refer to GetSockOpt (). Shutdown (Termination Socket Communication) related functions Socket, Connect Header file #include Definition function INT Shutdown (int S, int how); Function description Shutdown () is used to terminate the Socket connection specified by the parameter s. The parameter S is the Socket processing code in the connection. The parameter HOW has the following cases: how = 0 terminates the read operation. How = 1 Termination Transfer Operation How = 2 Terminate Read and Transfer Operation return value Success returns 0, failed to return -1, and the error is existed in Errno. error code EBADF parameter S is not a valid socket processing code ENOTSOCK parameter S is a file descriptor, the SocketConn parameter s specified Socket is not connected Socket (create a socket communication) related functions Accept, Bind, Connect, Listen Header file #include Definition function INT Socket (int Domain, int type, int protocol); Function description Socket () is used to create a new Socket, which is to register to the system, notify the system to establish a communication port. Parameter Domain Specifies what kind of address type, complete definition is within /usr/include/bits/socket.h, is a common protocol: PF_UNIX / PF_LOCAL / AF_UNIX / AF_LOCAL UNIX process communication protocol PF_INET? AF_INET IPv4 Network Protocol PF_INET6 / AF_INET6 Ipv6 network protocol PF_IPX / AF_IPX IPX-Novell protocol PF_NETLINK / AF_NETLINK core user interface device PF_X25 / AF_X25 ITU-T X.25 / ISO-8208 protocol PF_AX25 / AF_AX25 amateur radio AX.25 protocol PF_ATMPVC / AF_ATMPVC access the original ATM PVCsPF_APPLETALK / AF_APPLETALK AppleTalk (DDP) Protocol PF_PACKET / AF_PACKET Junior Packet Interface parameter Type has the following values: Sock_Stream provides two-way continuous and trusted data streams, namely TCP. Support OOB mechanisms, you must use Connect () to establish a connection status before all data transfer. SOCK_DGRAM Connection Sock_seqpacket provides continuously reliable packet connection SOCK_SEQPACKET to provide SOCK_RAW to provide raw network protocol Access SOCK_RDM to provide a trusted packet connection SOCK_PACKET Provider to communicate directly to the network driver. Protocol is used to specify the transfer protocol number used by the socket, usually this reference does not need to be used, set to 0. return value Success returns the socket processing code, failed to return -1. error code EPROTONOSUPPORT Parameter Domain Specifies the type of Type or Protocol, which is not supported, the core memory is insufficient, and unable to establish a new Socket structure Emfile process file table overflow, unable to establish a new SocketeAccess permission, unable to establish a Type or protocol specified protocol ENOBUFS / ENOMEM insufficient einval parameter Domain / Type / protocol is not legal example Refer to Connect ().
