server client通过socket通讯

//server.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <unistd.h>

#define PORT 8888
#define BACKLOG 2

int main(int argc, char *argv[])
{
        int ss, sc;
        struct sockaddr_in server_addr;
        struct sockaddr_in client_addr;
        int err;
        pid_t pid;

        ss = socket(AF_INET, SOCK_STREAM, 0);

        if ( ss < 0 )
        {
                printf("socket error\n");
                return -1;
        }

        bzero(&server_addr, sizeof(server_addr));
        server_addr.sin_family = AF_INET;
        server_addr.sin_addr.s_addr=htonl(INADDR_ANY);
        server_addr.sin_port = htons(PORT);

        err = bind(ss, (struct sockaddr*)&server_addr, sizeof(server_addr));
        printf("bind err is %d \n", err);
        if ( err < 0 )
        {
                printf("bind error\n");
                return -1;
        }

        err=listen(ss, BACKLOG);
        printf("listen err is %d \n", err);
        if ( err < 0 )
        {
                printf("listen error\n");
                return -1;
        }
        printf("listen 8888\n");
        for(;;)
        {
                printf("in for loop 1\n");
                socklen_t addrlen = sizeof(struct sockaddr);
                sc = accept(ss, (struct sockaddr*)&client_addr, &addrlen);
                printf("in for loop 2\n");

                if(sc < 0 )
                {
                        printf("accept is %d ", sc);
                        continue;
                }
                pid =fork();
                if (pid ==0 )
                {
                        printf("have a client in 1\n");
                        close(ss);
                        process_conn_server(sc);
                }
                else
                {       printf("have a client in 1\n");
                        close(sc);
                }
        }
}

//client.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <unistd.h>

#define PORT 8888

int main(int argc, char *argv[])
{
        int s;
        struct sockaddr_in server_addr;

        s=socket(AF_INET, SOCK_STREAM, 0);
        printf("client socket fd:%d\n",s);
        if ( s < 0)
        {
                printf("socket error\n");
                return -1;
        }

        bzero(&server_addr, sizeof(server_addr));
        server_addr.sin_family = AF_INET;
        server_addr.sin_addr.s_addr=htonl(INADDR_ANY);
        server_addr.sin_port = htons(PORT);

        inet_pton(AF_INET, argv[1], &server_addr.sin_addr);
        printf("will connect \n");
        connect(s, (struct sockaddr*)&server_addr, sizeof(struct sockaddr));
        printf("connected \n");
        process_conn_client(s);
        close(s);
        printf("done  \n");
        return 0;

}

//process.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <unistd.h>

void process_conn_server(int s)
{
        ssize_t size=0;
        char buffer[1024];
        char cmd[1024]={0};
        for(;;)
        {
                memset(buffer, 0, sizeof(buffer));
                memset(cmd, 0, sizeof(cmd));
                size=read(s, buffer,1024);

                if(size == 0)
                        return ;
                printf("\n server get command from client:%s*size:%d**", buffer);
                strcpy(cmd, buffer);
                printf("cmd:%s*strlen:%d**\n", cmd, strlen(cmd));
                cmd[sizeof(strlen)]='\0';
                printf("handle cmd:%s***\n", cmd);
                if(strcmp(cmd, "a") == 0){
                        printf("will run command a\n");
                }
                else if (strcmp(cmd, "b") == 0){
                        printf("will run command b\n");
                }
                else 
                        printf("will run default command\n");
        }
}
void process_conn_client(int s)
{
        ssize_t size=0;
        char buffer[1024];

        for(;;)
        {
                //printf("client 1\n");
                size=read(0, buffer,1024);

                printf("client -> server command:%s* size:%d**\n", buffer, size);
                if(size > 0)
                {
                        write(s, buffer, size);
                }

        }
}

//Makefile
all:client server
client:process.o client.o
        gcc -o client process.o client.o
server:process.o server.o
        gcc -o server process.o server.o
process.o:
        gcc -c process.c -o process.o
clean:
        rm -f client server *.o

代码如上述所示，编译后：

root@tian:~/tech_learn/socket# ls

client client.c client.o Makefile process.c process.o server server.c server.o

在一个终端运行 server（./server）,列外一个终端运行client（./client 127.0.0.1）,运行结果如下：

server：

root@tian:~/tech_learn/socket# ./server 
bind err is 0 
listen err is 0 
listen 8888
in for loop 1
in for loop 2
have a client in 1
in for loop 1
have a client in 1

 server get command from client:a
*size:1024**cmd:a
*strlen:2**
handle cmd:a***
will run command a

 server get command from client:b
*size:1024**cmd:b
*strlen:2**
handle cmd:b***
will run command b

 server get command from client:c
*size:1024**cmd:c
*strlen:2**
handle cmd:c***
will run default command

client端运行结果如下：（client端传输命令给server，让server可以执行某个命令）

root@tian:~/tech_learn/socket# ./client 127.0.0.1
client socket fd:3
will connect 
connected 
a
client -> server command:a
ǽ�* size:2**
^C
root@tian:~/tech_learn/socket# ^C
root@tian:~/tech_learn/socket# ./client 127.0.0.1
client socket fd:3
will connect 
connected 
a
client -> server command:a
M��* size:2**
^C
root@tian:~/tech_learn/socket# ./client 127.0.0.1
client socket fd:3
will connect 
connected 
a
client -> server command:a
��* size:2**
b
client -> server command:b
��* size:2**
c
client -> server command:c
��* size:2**