解析並綁定到IPv6地址

Question

我編寫了一個程序來解析地址或主機名，然后嘗試在listen(2)模式下綁定到該地址。 出於某些奇怪的原因，我無法使用IPv6地址，該程序在調用bind(2)后僅以“無效參數”失敗。 使用IPv4，一切都可以按我預期的方式工作，名稱得到解析，地址僅轉換為二進制格式。

資源

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <netdb.h>
#include <unistd.h>

static int
resolve_addr (const char *hostname, const char *service, int family, struct addrinfo **result)
{
    struct addrinfo addr_hint;

    memset (&addr_hint, 0, sizeof (struct addrinfo));

    addr_hint.ai_socktype = SOCK_STREAM;
    addr_hint.ai_flags = AI_PASSIVE | AI_NUMERICSERV | AI_ADDRCONFIG;
    addr_hint.ai_family = family;

    return getaddrinfo (hostname, service, &addr_hint, result);
}

int
main (int argc, char *argv[])
{
    struct addrinfo *addr;
    int rval, sock, opt_val;

    rval = resolve_addr (argv[1], argv[2], AF_UNSPEC, &addr);

    if ( rval != 0 ){
        fprintf (stderr, "%s\n", gai_strerror (rval));
        return 1;
    }

    sock = socket (addr->ai_family, addr->ai_socktype | SOCK_NONBLOCK, addr->ai_protocol);

    if ( sock == -1 ){
        fprintf (stderr, "error socket: %s\n", strerror (errno));
        return 1;
    }

    if ( setsockopt (sock, SOL_SOCKET, SO_REUSEADDR, &opt_val, sizeof (opt_val)) == -1 ){
        fprintf (stderr, "error setsockopt: %s\n", strerror (errno));
        return 1;
    }

    if ( bind (sock, (struct sockaddr*) addr->ai_addr, sizeof (struct sockaddr)) == -1 ){
        fprintf (stderr, "error bind: %s\n", strerror (errno));
        return 1;
    }

    if ( listen (sock, 32) == -1 ){
        fprintf (stderr, "error listen: %s\n", strerror (errno));
        return 1;
    }

    sleep (120);

    freeaddrinfo (addr);
    close (sock);

    return 0;
}

用法

1. ./test_bind localhost 8888 # works
2. ./test_bind 0.0.0.0 8888 # works
3. ./test_bind 127.0.0.1 8888 # works
4. ./test_bind :: 8888 # does not work: Invalid argument
5. ./test_bind ::1 8888 # does not work: Invalid argument

邊注

我使用netcat來確定系統是否有問題，但是以下命令可以運行：

ncat -l :: 8888

在netstat中可以看到：

tcp6 0 0 :::8888 :::* LISTEN

Answer 1

我更新了代碼，IPv4和IPv6均已解析並成功綁定。問題出在bind(2)函數的第三個參數中，該參數根據結構大小計算地址的大小，而不是使用getaddrinfo的值結果。

我替換了該行：

if ( bind (sock, (struct sockaddr*) addr->ai_addr, sizeof (struct sockaddr)) == -1 ){

有：

if ( bind (sock, (struct sockaddr*) addr->ai_addr, addr->ai_addrlen) == -1 ){

全文

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netdb.h>
#include <unistd.h>

static int
resolve_addr (const char *hostname, const char *service, int family, struct addrinfo **result)
{
    struct addrinfo addr_hint;

    memset (&addr_hint, 0, sizeof (struct addrinfo));

    addr_hint.ai_socktype = SOCK_STREAM;
    addr_hint.ai_flags = AI_PASSIVE | AI_NUMERICSERV | AI_ADDRCONFIG;
    addr_hint.ai_family = family;

    return getaddrinfo (hostname, service, &addr_hint, result);
}


int
main (int argc, char *argv[])
{
    struct addrinfo *addr;
    int rval, sock, opt_val;

    rval = resolve_addr (argv[1], argv[2], AF_UNSPEC, &addr);

    if ( rval != 0 ){
        fprintf (stderr, "%s\n", gai_strerror (rval));
        return 1;
    }

    sock = socket (addr->ai_family, addr->ai_socktype | SOCK_NONBLOCK, addr->ai_protocol);

    if ( sock == -1 ){
        fprintf (stderr, "error socket: %s\n", strerror (errno));
        return 1;
    }

    opt_val = 1;

    if ( setsockopt (sock, SOL_SOCKET, SO_REUSEADDR, &opt_val, sizeof (opt_val)) == -1 ){
        fprintf (stderr, "error setsockopt: %s\n", strerror (errno));
        return 1;
    }

    if ( bind (sock, (struct sockaddr*) addr->ai_addr, addr->ai_addrlen) == -1 ){
        fprintf (stderr, "error bind: %s\n", strerror (errno));
        return 1;
    }

    if ( listen (sock, 32) == -1 ){
        fprintf (stderr, "error listen: %s\n", strerror (errno));
        return 1;
    }

    sleep (120);

    freeaddrinfo (addr);
    close (sock);

    return 0;
}