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--- socket-programming:recv [2024/06/18 00:29] – ایجاد شد pejman
+++ socket-programming:recv [2024/06/18 01:01] (فعلی) – حذف شد pejman
@@ خط 1: / خط 1: @@
-====== تابع ()recv  ======
-از این تابع برای خواندن از یک سوکت از نوع stream استفاده می شود.
-<code C>
-#include <sys/types.h>
-#include <sys/socket.h>
-ssize_t recv(int sockfd, void *buf, size_t len, int flags);
-</code>
-مقدار بازگشتی این تابع برابر است با تعداد بایتی که خوانده و در buf ذخیره شده است.
-مثال برای ارسال و دریافت یک پیغام از سمت سرور با کلاینت telnet
-<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 "3435"
-#define BACKLOG 120
-#define BUFSIZE 1000
-int main()
-{
-    int status, sockopt;
-    fprintf(stdout, "Configuring local address ...\n");
-    struct addrinfo hints;
-    memset(&hints, 0, sizeof(hints));
-    hints.ai_flags = AI_PASSIVE;
-    hints.ai_family = AF_INET6;
-    hints.ai_socktype = SOCK_STREAM;
-    struct addrinfo *bind_address, *rp;
-    status = getaddrinfo(NULL, PORT, &hints, &bind_address);
-    if (status != 0) {
-        fprintf(stderr, "getaddrinfo() error: %s\n", gai_strerror(status));
-        exit(EXIT_FAILURE);
-    }
-    int listen_socket;
-    for (rp = bind_address; rp != NULL; rp = rp->ai_next) {
-        fprintf(stdout, "Creating socket ...\n");
-        listen_socket = socket(rp->ai_family, rp->ai_socktype,
-                                rp->ai_protocol);
-        if (listen_socket == -1) {
-            perror("socket() error ");
-            continue;
-        }
-        sockopt = 1;
-        status = setsockopt(listen_socket, SOL_SOCKET, SO_REUSEADDR,
-                            (void*)&sockopt, sizeof(sockopt));
-        if (status == -1) {
-            perror("setsockopt() SO_REUSEADDR error ");
-            exit(EXIT_FAILURE);
-        }
-        sockopt = 0;
-        status = setsockopt(listen_socket, IPPROTO_IPV6, IPV6_V6ONLY,
-                            (void*)&sockopt, sizeof(sockopt));
-        if (status == -1) {
-            perror("setsockopt() IPV6_V6ONLY error ");
-            exit(EXIT_FAILURE);
-        }
-        fprintf(stdout, "Binding socket to local address ...\n");
-        status = bind(listen_socket, rp->ai_addr, rp->ai_addrlen);
-        if (status == -1) {
-            perror("bind() error ");
-            continue;
-        }
-        break;
-    }
-    freeaddrinfo(bind_address);
-    if (rp == NULL) {
-        fprintf(stderr, "Failed to bind()\n");
-        exit(EXIT_FAILURE);
-    }
-    fprintf(stdout, "Listening ...\n");
-    status = listen(listen_socket, BACKLOG);
-    if (status == -1) {
-        perror("listen() error ");
-        exit(EXIT_FAILURE);
-    }
-    fprintf(stdout, "Waiting for connections ...\n");
-    fflush(stdout);
-    int client_socket;
-    struct sockaddr_storage client_addr;
-    socklen_t client_addrlen = sizeof(client_addr);
-    client_socket = accept(listen_socket, (struct sockaddr *)&client_addr,
-                    &client_addrlen);
-    if (client_socket == -1) {
-        perror("accept() error ");
-        exit(EXIT_FAILURE);
-    }
-    char *ipver, ipstr[INET6_ADDRSTRLEN];
-    void *addr;
-    if (client_addr.ss_family == AF_INET) {
-        ipver = "IPv4";
-        addr = &(((struct sockaddr_in *)&client_addr)->sin_addr);
-    } else if (client_addr.ss_family == AF_INET6) {
-        ipver = "IPv6";
-        addr = &(((struct sockaddr_in6 *)&client_addr)->sin6_addr);
-    } else {
-        ipver = "Unknown";
-    }
-    inet_ntop(client_addr.ss_family, addr, ipstr, sizeof(ipstr));
-    printf("Client is connected from %s address %s\n", ipver, ipstr);
-    printf("Reading client request ...\n");
-    ssize_t readlen;
-    char readbuf[BUFSIZE];
-    readlen = recv(client_socket, readbuf, BUFSIZE, 0);
-    if (readlen < 1) {
-        fprintf(stderr, "Error Reading client request\n");
-        if(readlen == -1)
-            perror("recv() error ");
-        exit(EXIT_FAILURE);
-    }
-    // null terminating client message
-    if(readlen > 0 && readlen < BUFSIZE)
-        readbuf[readlen] = 0;
-    else
-        readbuf[0] = 0;
-    fprintf(stdout, "Cleint message:\n---\n%s\n---\n", readbuf);
-    fprintf(stdout, "Sending message to cleint...\n");
-    char *msg = "Hello world\n";
-    status = send(client_socket, msg, strlen(msg), 0);
-    if (status == -1)
-        perror("send() error ");
-    else
-        fprintf(stdout, "Byte sent = %d\n", status);
-    printf("Closing connection...\n");
-    close(client_socket);
-    printf("Closing listening socket...\n");
-    close(listen_socket);
-    printf("Finished.\n");
-    return 0;
-}
-</code>
-کلاینت
-  $ telnet 127.0.0.1 3435
-  Trying 127.0.0.1...
-  Connected to 127.0.0.1.
-  Escape character is '^]'.
-  this is a test message
-  Hello world
-  Connection closed by foreign host.
-خروجی سرور
-  Configuring local address ...
-  Creating socket ...
-  Binding socket to local address ...
-  Listening ...
-  Waiting for connections ...
-  Client is connected from IPv6 address ::ffff:127.0.0.1
-  Reading client request ...
-  Cleint message:
-  ---
-  this is a test message
-  ---
-  Sending message to cleint...
-  Byte sent = 12
-  Closing connection...
-  Closing listening socket...
-  Finished.
-کلاینت جایگزین telnet در مثال بالا
-<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>
-#define PORT "3435"
-#define SERVER "127.0.0.1"
-#define BUFSIZE 250
-int main()
-{
-    char *msg = "This is a test message.";
-    int status, sockfd;
-    printf("Configuring local address ...\n");
-    struct addrinfo hints, *res, *rp;
-    memset(&hints, 0, sizeof(hints));
-    hints.ai_family = AF_INET;
-    hints.ai_socktype = SOCK_STREAM;
-    status = getaddrinfo(SERVER, 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) {
-        printf("Creating socket ...\n");
-        sockfd = socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol);
-        if (sockfd == -1) {
-            perror("socket() error ");
-            continue;
-        }
-        printf("Connecting to server ...\n");
-        status = connect(sockfd, rp->ai_addr, rp->ai_addrlen);
-        if (status == -1) {
-            perror("connect() error ");
-            close(sockfd);
-            continue;
-        }
-        break;
-    }
-    freeaddrinfo(res);
-    if (rp == NULL) {
-        fprintf(stderr, "Could not connect() \n");
-        exit(EXIT_FAILURE);
-    }
-    printf("Sending message to server ...\n");
-    status = send(sockfd, msg, strlen(msg), 0);
-    if (status == -1)
-        perror("send() error ");
-    else
-        printf("Byte sent = %d\n", status);
-    printf("Reading server message ...\n");
-    char buf[BUFSIZE];
-    status = recv(sockfd, buf, BUFSIZE, 0);
-    if (status < 1) {
-        fprintf(stderr, "Error reading client message.\n");
-        if (status == -1)
-            perror("recv() error ");
-    }
-    // null terminating client message
-    if (status > 0 && status < BUFSIZE)
-        buf[status] = 0;
-    else
-        buf[0] = 0;
-    if (strlen(buf) > 0)
-        printf("Client message:\n---\n%s\n---\n");
-    printf("Closing connection ...\n");
-    close(sockfd);
-    printf("Finished.\n");
-    return 0;
-}
-</code>
-خروجی کلاینت
-  Configuring local address ...
-  Creating socket ...
-  Connecting to server ...
-  Sending message to server ...
-  Byte sent = 23
-  Reading server message ...
-  Client message:
-  ---
-  Hello world
-  ---
-  Closing connection ...
-  Finished.
-خروجی سرور
-  Configuring local address ...
-  Creating socket ...
-  Binding socket to local address ...
-  Listening ...
-  Waiting for connections ...
-  Client is connected from IPv6 address ::ffff:127.0.0.1
-  Reading client request ...
-  Cleint message:
-  ---
-  This is a test message.
-  ---
-  Sending message to cleint...
-  Byte sent = 12
-  Closing connection...
-  Closing listening socket...
-  Finished.