如何正确克隆struct addrinfo

Question

我需要克隆一个现有的struct addrinfo指针。我已经写了下面的代码来克隆它。虽然从功能的角度来看它工作得很好，但当我释放克隆的strutc addrinfo指针时，我得到了内存泄漏。

struct addrinfo * transport_clone_addrinfo(struct addrinfo *src)
{
    struct addrinfo *dst;

    if(src == NULL)
    {
        return NULL;
    }

    dst = calloc(1, sizeof(struct addrinfo));
    dst->ai_next = NULL;

    dst->ai_flags = 0; 
    dst->ai_family = src->ai_family;
    dst->ai_socktype = src->ai_socktype;
    dst->ai_protocol = src->ai_protocol;
    dst->ai_canonname = NULL;
    dst->ai_addrlen = src->ai_addrlen;
    dst->ai_addr = malloc(src->ai_addrlen);
    memcpy(dst->ai_addr, src->ai_addr, src->ai_addrlen);

    return dst;
}

int main(int argc, char **argv)
{
    char *ip = "192.168.1.10";
    unsigned short port = 5555;
    int index;
    int ret_val = -1;
    char service[8];
    struct addrinfo hints;
    struct addrinfo *rp = NULL;
    struct addrinfo *rp2;

    index = sprintf(service, "%u", port);
    service[index] = 0;

    if(true)
    {
        memset(&hints, 0, sizeof(struct addrinfo));
        hints.ai_family = AF_INET;
        ret_val = getaddrinfo(ip, NULL, &hints, &rp);
    }
    else
    {
        ret_val = getaddrinfo(ip, service, NULL, &rp);
    }

    if(ret_val != 0)
    {
        printf("\ngetaddrinfo failed\n");
    }

    rp2 = transport_clone_addrinfo(rp);

    freeaddrinfo(rp);
    freeaddrinfo(rp2);

    return 0;
}

有了这一点，从功能上讲，它工作得很好。但是valgrind报告了以下代码行的内存泄漏。

dst->ai_addr = malloc(src->ai_addrlen);

然后我检查了freeaddrinfo代码，我发现struct addrinfo的ai_addr成员没有显式释放。

也许我在克隆的时候遗漏了一些东西。有人能帮我理解如何正确克隆struct addrinfo吗？

有没有可以克隆struct addrinfo的C api？

Answer 1

实际上，getaddrinfo的实现有一个诀窍，它会为rp分配整个内存(sizeof (struct addrinfo) + ai_addrlen)，所以freeaddrinfo只会释放rp和rp.ai_canonname。