一些服务器客户端的c例子

今天早上6点起床之后练习的一些c的网络编程的基础例子

client1

/*  Make the necessary includes and set up the variables.  */

#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <sys/un.h>
#include <unistd.h>
#include <stdlib.h>

int main()
{
    int sockfd;
    int len;
    struct sockaddr_un address;
    int result;
    char ch = 'A';

/*  Create a socket for the client.  */

    sockfd = socket(AF_UNIX, SOCK_STREAM, 0);

/*  Name the socket, as agreed with the server.  */

    address.sun_family = AF_UNIX;
    strcpy(address.sun_path, "server_socket");
    len = sizeof(address);

/*  Now connect our socket to the server's socket.  */

    result = connect(sockfd, (struct sockaddr *)&address, len);

    if(result == -1) {
        perror("oops: client1");
        exit(1);
    }

/*  We can now read/write via sockfd.  */

    write(sockfd, &ch, 1);
    read(sockfd, &ch, 1);
    printf("char from server = %c\n", ch);
    close(sockfd);
    exit(0);
}

　　server1.c

/*  Make the necessary includes and set up the variables.  */

#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <sys/un.h>
#include <unistd.h>
#include <stdlib.h>

int main()
{
    int server_sockfd, client_sockfd;
    int server_len, client_len;
    struct sockaddr_un server_address;
    struct sockaddr_un client_address;

/*  Remove any old socket and create an unnamed socket for the server.  */

    unlink("server_socket");
    server_sockfd = socket(AF_UNIX, SOCK_STREAM, 0);

/*  Name the socket.  */

    server_address.sun_family = AF_UNIX;
    strcpy(server_address.sun_path, "server_socket");
    server_len = sizeof(server_address);
    bind(server_sockfd, (struct sockaddr *)&server_address, server_len);

/*  Create a connection queue and wait for clients.  */

    listen(server_sockfd, 5);
    while(1) {
        char ch;

        printf("server waiting\n");

/*  Accept a connection.  */

        client_len = sizeof(client_address);
        client_sockfd = accept(server_sockfd, 
            (struct sockaddr *)&client_address, &client_len);

/*  We can now read/write to client on client_sockfd.  */

        read(client_sockfd, &ch, 1);
        ch++;
        write(client_sockfd, &ch, 1);
        close(client_sockfd);
    }
}

　　第二个服务器客户端的例子：

client

/*  Make the necessary includes and set up the variables.  */

#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <stdlib.h>

int main()
{
    int sockfd;
    int len;
    struct sockaddr_in address;
    int result;
    char ch = 'A';

/*  Create a socket for the client.  */

    sockfd = socket(AF_INET, SOCK_STREAM, 0);

/*  Name the socket, as agreed with the server.  */

    address.sin_family = AF_INET;
    address.sin_addr.s_addr = inet_addr("127.0.0.1");
    address.sin_port = htons(9734);
    len = sizeof(address);

/*  Now connect our socket to the server's socket.  */

    result = connect(sockfd, (struct sockaddr *)&address, len);

    if(result == -1) {
        perror("oops: client3");
        exit(1);
    }

/*  We can now read/write via sockfd.  */

    write(sockfd, &ch, 1);
    read(sockfd, &ch, 1);
    printf("char from server = %c\n", ch);
    close(sockfd);
    exit(0);
}

　　server

/*  Make the necessary includes and set up the variables.  */

#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <stdlib.h>

int main()
{
    int server_sockfd, client_sockfd;
    int server_len, client_len;
    struct sockaddr_in server_address;
    struct sockaddr_in client_address;

/*  Remove any old socket and create an unnamed socket for the server.  */

    server_sockfd = socket(AF_INET, SOCK_STREAM, 0);

/*  Name the socket.  */

    server_address.sin_family = AF_INET;
    server_address.sin_addr.s_addr = htonl(INADDR_ANY);
    server_address.sin_port = htons(9734);
    server_len = sizeof(server_address);
    bind(server_sockfd, (struct sockaddr *)&server_address, server_len);

/*  Create a connection queue and wait for clients.  */

    listen(server_sockfd, 5);
    while(1) {
        char ch;

        printf("server waiting\n");

/*  Accept a connection.  */

        client_len = sizeof(client_address);
        client_sockfd = accept(server_sockfd, 
            (struct sockaddr *)&client_address, &client_len);

/*  We can now read/write to client on client_sockfd.  */

        read(client_sockfd, &ch, 1);
        ch++;
        write(client_sockfd, &ch, 1);
        close(client_sockfd);
    }
}

　　

/*  As usual, make the appropriate includes and declare the variables.  */

#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>

int main(int argc, char *argv[])
{
    char *host, **names, **addrs;
    struct hostent *hostinfo;

/*  Set the host in question to the argument supplied with the getname call,
    or default to the user's machine.  */

    if(argc == 1) {
        char myname[256];
        gethostname(myname, 255);
        host = myname;
    }
    else
        host = argv[1];

/*  Make the call to gethostbyname and report an error if no information is found.  */

    hostinfo = gethostbyname(host);
    if(!hostinfo) {
        fprintf(stderr, "cannot get info for host: %s\n", host);
        exit(1);
    }

/*  Display the hostname and any aliases it may have.  */

    printf("results for host %s:\n", host);
    printf("Name: %s\n", hostinfo -> h_name);
    printf("Aliases:");
    names = hostinfo -> h_aliases;
    while(*names) {
        printf(" %s", *names);
        names++;
    }
    printf("\n");

/*  Warn and exit if the host in question isn't an IP host.  */

    if(hostinfo -> h_addrtype != AF_INET) {
        fprintf(stderr, "not an IP host!\n");
        exit(1);
    }

/*  Otherwise, display the IP address(es).  */

    addrs = hostinfo -> h_addr_list;
    while(*addrs) {
        printf(" %s", inet_ntoa(*(struct in_addr *)*addrs));
        addrs++;
    }
    printf("\n");
    exit(0);
}

　　

/*  Start with the usual includes and declarations.  */

#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>

int main(int argc, char *argv[])
{
    char *host;
    int sockfd;
    int len, result;
    struct sockaddr_in address;
    struct hostent *hostinfo;
    struct servent *servinfo;
    char buffer[128];

    if(argc == 1)
        host = "localhost";
    else
        host = argv[1];

/*  Find the host address and report an error if none is found.  */

    hostinfo = gethostbyname(host);
    if(!hostinfo) {
        fprintf(stderr, "no host: %s\n", host);
        exit(1);
    }

/*  Check that the daytime service exists on the host.  */

    servinfo = getservbyname("daytime", "tcp");
    if(!servinfo) {
        fprintf(stderr,"no daytime service\n");
        exit(1);
    }
    printf("daytime port is %d\n", ntohs(servinfo -> s_port));

/*  Create a socket.  */

    sockfd = socket(AF_INET, SOCK_STREAM, 0);

/*  Construct the address for use with connect...  */

    address.sin_family = AF_INET;
    address.sin_port = servinfo -> s_port;
    address.sin_addr = *(struct in_addr *)*hostinfo -> h_addr_list;
    len = sizeof(address);

/*  ...then connect and get the information.  */

    result = connect(sockfd, (struct sockaddr *)&address, len);
    if(result == -1) {
        perror("oops: getdate");
        exit(1);
    }

    result = read(sockfd, buffer, sizeof(buffer));
    buffer[result] = '\0';
    printf("read %d bytes: %s", result, buffer);

    close(sockfd);
    exit(0);
}

　　getdate-udp

/*  Start with the usual includes and declarations.  */

#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>

int main(int argc, char *argv[])
{
    char *host;
    int sockfd;
    int len, result;
    struct sockaddr_in address;
    struct hostent *hostinfo;
    struct servent *servinfo;
    char buffer[128];

    if(argc == 1)
        host = "localhost";
    else
        host = argv[1];

/*  Find the host address and report an error if none is found.  */

    hostinfo = gethostbyname(host);
    if(!hostinfo) {
        fprintf(stderr, "no host: %s\n", host);
        exit(1);
    }

/*  Check that the daytime service exists on the host.  */

    servinfo = getservbyname("daytime", "udp");
    if(!servinfo) {
        fprintf(stderr,"no daytime service\n");
        exit(1);
    }
    printf("daytime port is %d\n", ntohs(servinfo -> s_port));

/*  Create a UDP socket.  */

    sockfd = socket(AF_INET, SOCK_DGRAM, 0);

/*  Construct the address for use with sendto/recvfrom...  */

    address.sin_family = AF_INET;
    address.sin_port = servinfo -> s_port;
    address.sin_addr = *(struct in_addr *)*hostinfo -> h_addr_list;
    len = sizeof(address);

    result = sendto(sockfd, buffer, 1, 0, (struct sockaddr *)&address, len);
    result = recvfrom(sockfd, buffer, sizeof(buffer), 0, (struct sockaddr *)&address, &len);
    buffer[result] = '\0';
    printf("read %d bytes: %s", result, buffer);

    close(sockfd);
    exit(0);
}