Socket
The socket is also called a socket, and the application sends a request to the network or responds to the network through sockets
Network communication is actually the communication between sockets
Data transfers data between two sockets via IO
The socket is a pure C language and is a cross-platform
The HTTP protocol is socket-based, and the HTTP protocol is used at the bottom of the socket
The communication process of the socket
Create socket
Connect to Server
Sending data to the server
Receiving data from the server
Close connection
Creation of sockets
Import Header File
#import <sys/socket.h>
#import <netinet/in.h>
#import <arpa/inet.h>
Create socket
int socket (int domain, int type, int protocol);
Parameter 1 Domain protocol domains Af_inet--ipv4
Parameter 2 type SOCKET sock_stream (TCP)/socket_dgram (UDP)
Parameter 3 protocol IPPROTO_TCP/IPPROTO_UDP if incoming 0 selects the appropriate value according to the second parameter
Return value >0 descriptor for creating a successful socket
Example: int clientsocket = socket (af_inet, sock_stream, ipproto_tcp);
Connecting to a server
Open Netcat, Simulate server
Open Terminal
Nc-lk 12345
Tools for debugging and checking the network under the Nc-->netcat terminal
Connecting to a server
int connect (int sockfd,struct sockaddr * serv_addr,int addrlen);
Parameter 1 SOCKFD Client socket
Parameter 2 serv_addr server address struct-body pointer
Parameter 3 addrlen structure data length
Return value succeeds returns 0, failure returns non 0
Example:
Return value succeeds returns 0, failure returns non 0
struct sockaddr_in serveraddr;
IPV4
serveraddr.sin_family = af_inet;
Port
Serveraddr.sin_port = htons (12345);
IP Address
SERVERADDR.SIN_ADDR.S_ADDR = inet_addr ("127.0.0.1");
int connresult = connect (clientsocket, (const struct sockaddr *) &serveraddr, sizeof (SERVERADDR));
if (Connresult = = 0) {
NSLog (@ "connected successfully");
}else{
NSLog (@ "Connection failed");
}
Socket to send and receive data
Sending data to the server
const char *sendmessage = "Hello World";
ssize_t Sendlen = Send (Clientsocket, SendMessage, strlen (SendMessage), 0);
NSLog (@ "number of bytes Sent:%ld", Sendlen);
Data returned by the receiving server
uint8_t buffer[1024];
ssize_t Recvlen = recv (clientsocket, buffer, sizeof (buffer), 0);
if (Recvlen > 0) {
NSLog (@ "received%ld bytes", Recvlen);
Reading data from a buffer
NSData *data = [NSData datawithbytes:buffer Length:recvlen];
NSString *msg = [[NSString alloc] Initwithdata:data encoding:nsutf8stringencoding];
NSLog (@ "%@", msg);
}
Close the connection close (Clientsocket);
ios-Network Socket operation
