====== تابع ()send ======

از این تابع برای نوشتن در یک سوکت از نوع stream استفاده می شود.

<code C>
#include <sys/types.h>
#include <sys/socket.h>

ssize_t send(int sockfd, const void *buf, size_t len, int flags);
</code>

مقدار بازگشتی این تابع تعداد بایتی است که توانسته ارسال کند. اگر این مقدار کمتر از len باشد ما موظیم مابقی buf را مجدد از طریق [[send]] ارسال کنیم.

مثال ارسال Hello world برروی بستر SOCK_STREAM توسط [[send]] :

<code C>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <arpa/inet.h>

#define PORT "3450"
#define BACKLOG 120

int main()
{
    char *msg = "Hello World!";
    void *addr;
    char *ipver;
    char ipstr[INET6_ADDRSTRLEN];

    int status, sockfd, clientfd, sockopt, len;
    struct addrinfo hints, *res, *rp;
    struct sockaddr_storage clientaddr;
    struct sockaddr *sa;
    socklen_t addrlen;

    memset(&hints, 0, sizeof(hints));
    hints.ai_flags = AI_PASSIVE;
    hints.ai_family = AF_INET6;
    hints.ai_socktype = SOCK_STREAM;
    hints.ai_protocol = 0;

    status = getaddrinfo(NULL, PORT, &hints, &res);
    if (status != 0) {
        fprintf(stderr, "getaddrinfo() error: %s\n", 
                gai_strerror(status));
        exit(EXIT_FAILURE);
    }

    for (rp = res; rp != NULL; rp = rp->ai_next) {
        sockfd = socket(rp->ai_family, rp->ai_socktype, 
                            rp->ai_protocol);
        if (sockfd == -1) {
            perror("socket() error");
            continue;
        }

        sockopt = 1;
        status = setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, 
                            &sockopt, sizeof(sockopt));
        if (status == -1) {
            perror("setsockopt() error");
            exit(EXIT_FAILURE);
        }

        sockopt = 0;
        status = setsockopt(sockfd, IPPROTO_IPV6, IPV6_V6ONLY,
                            &sockopt, sizeof(sockopt));
        if (status == -1) {
            perror("setsockopt() error");
            exit(EXIT_FAILURE);
        }

        status = bind(sockfd, rp->ai_addr, rp->ai_addrlen);
        if (status == -1) {
            perror("bind() error");
            continue;
        }

        break;
    }
    freeaddrinfo(res);

    if (rp == NULL) {
        fprintf(stderr, "Server: Failed to bind()\n");
        exit(EXIT_FAILURE);
    }

    status = listen(sockfd, BACKLOG);
    if (status == -1) {
        perror("listen() error");
        exit(EXIT_FAILURE);
    }

    fprintf(stdout, "Server: waiting for connections...\n");

    addrlen = sizeof(clientaddr);
    clientfd = accept(sockfd, (struct sockaddr*)&clientaddr, &addrlen);

    sa = (struct sockaddr*)&clientaddr;
    if (sa->sa_family == AF_INET) {
        ipver = "IPv4";
        addr = &(((struct sockaddr_in *)sa)->sin_addr);
    } else {
        ipver = "IPv6";
        addr = &(((struct sockaddr_in6 *)sa)->sin6_addr);
    }
    inet_ntop(sa->sa_family, addr, ipstr, sizeof(ipstr));
    fprintf(stdout, "Server: Got an %s connection from %s\n", ipver, ipstr);
    
    fprintf(stdout, "Server: Sending data ...\n");
    len = strlen(msg);
    status = send(clientfd, msg, len, 0);
    if (status == -1)
        perror("send() error ");
    else
        fprintf(stdout, "Server: byte sent = %d\n", status);

    close(clientfd);
    close(sockfd);
    return 0;
}
</code>

کلاینت

  $ telnet 127.0.0.1 3450
  Trying 127.0.0.1...
  Connected to 127.0.0.1.
  Escape character is '^]'.
  Hello World!Connection closed by foreign host.

خروجی سرور

  Server: waiting for connections...
  Server: Got an IPv6 connection from ::ffff:127.0.0.1
  Server: Sending data ...
  Server: byte sent = 12