使用 XFRM_MSG_NEWSA 在 C 代码中添加 SA

以下是使用 XFRM_MSG_NEWSA 消息在 C 代码中添加 SA 的示例：

#include <linux/xfrm.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <unistd.h>
#include <string.h>
#include <stdio.h>
#include <errno.h>

int main() {
    int sockfd = socket(AF_INET6, SOCK_RAW, IPPROTO_RAW);
    if (sockfd < 0) {
        perror("socket() failed");
        return 1;
    }

    // 设置 SA 参数
    struct xfrm_usersa_info sa_info;
    memset(&sa_info, 0, sizeof(sa_info));
    sa_info.family = AF_INET6;
    sa_info.saddr.a6[0] = 0x20010DB8;
    sa_info.saddr.a6[1] = 0x00000000;
    sa_info.saddr.a6[2] = 0x00000000;
    sa_info.saddr.a6[3] = 0x00000001;
    sa_info.id.proto = IPPROTO_ESP;
    sa_info.id.spi = 12345;
    sa_info.reqid = 0;
    sa_info.mode = XFRM_MODE_TRANSPORT;
    sa_info.flags = XFRM_STATE_ESN;
    sa_info.aalgos = 0;
    sa_info.ealgos = 0;
    sa_info.calgos = 0;
    sa_info.encap = 0;
    sa_info.mark.v = 0;

    // 构建 XFRM 请求消息
    char buf[512];
    memset(buf, 0, sizeof(buf));
    struct nlmsghdr *nlh = (struct nlmsghdr *)buf;
    struct xfrm_userpolicy_info *policy = (struct xfrm_userpolicy_info *)(buf + NLMSG_ALIGN(sizeof(*nlh)));
    struct xfrm_user_tmpl *tmpl = (struct xfrm_user_tmpl *)(buf + NLMSG_ALIGN(sizeof(*nlh)) + NLMSG_ALIGN(sizeof(*policy)));
    struct xfrm_usersa_info *sa = (struct xfrm_usersa_info *)(buf + NLMSG_ALIGN(sizeof(*nlh)) + NLMSG_ALIGN(sizeof(*policy)) + NLMSG_ALIGN(sizeof(*tmpl)));
    nlh->nlmsg_flags = NLM_F_REQUEST | NLM_F_CREATE;
    nlh->nlmsg_type = XFRM_MSG_NEWSA;
    nlh->nlmsg_len = NLMSG_ALIGN(sizeof(*nlh)) + NLMSG_ALIGN(sizeof(*policy)) + NLMSG_ALIGN(sizeof(*tmpl)) + NLMSG_ALIGN(sizeof(*sa));
    policy->family = AF_INET6;
    policy->dir = XFRM_POLICY_OUT;
    policy->sel.family = AF_INET6;
    policy->sel.prefixlen_d = 128;
    policy->sel.prefixlen_s = 128;
    policy->sel.saddr.a6[0] = 0x20010DB8;
    policy->sel.saddr.a6[1] = 0x00000000;
    policy->sel.saddr.a6[2] = 0x00000000;
    policy->sel.saddr.a6[3] = 0x00000001;
    policy->sel.daddr.a6[0] = 0x20010DB8;
    policy->sel.daddr.a6[1] = 0x00000000;
    policy->sel.daddr.a6[2] = 0x00000000;
    policy->sel.daddr.a6[3] = 0x00000002;
    policy->action = XFRM_POLICY_ALLOW;
    tmpl->family = AF_INET6;
    tmpl->saddr.a6[0] = 0x20010DB8;
    tmpl->saddr.a6[1] = 0x00000000;
    tmpl->saddr.a6[2] = 0x00000000;
    tmpl->saddr.a6[3] = 0x00000001;
    tmpl->id.proto = IPPROTO_ESP;
    tmpl->id.spi = 12345;
    tmpl->reqid = 0;
    tmpl->mode = XFRM_MODE_TRANSPORT;
    tmpl->share = XFRM_SHARE_UNIQUE;
    tmpl->aalgos = 0;
    tmpl->ealgos = 0;
    tmpl->calgos = 0;
    tmpl->encap_family = 0;
    sa->family = AF_INET6;
    sa->saddr.a6[0] = 0x20010DB8;
    sa->saddr.a6[1] = 0x00000000;
    sa->saddr.a6[2] = 0x00000000;
    sa->saddr.a6[3] = 0x00000001;
    sa->id.proto = IPPROTO_ESP;
    sa->id.spi = 12345;
    sa->reqid = 0;
    sa->mode = XFRM_MODE_TRANSPORT;
    sa->flags = XFRM_STATE_ESN;
    sa->aalgos = 0;
    sa->ealgos = 0;
    sa->calgos = 0;
    sa->encap = 0;
    sa->mark.v = 0;

    // 发送 XFRM 请求消息
    struct sockaddr_nl nladdr;
    memset(&nladdr, 0, sizeof(nladdr));
    nladdr.nl_family = AF_NETLINK;
    if (sendto(sockfd, buf, nlh->nlmsg_len, 0, (struct sockaddr *)&nladdr, sizeof(nladdr)) < 0) {
        perror("sendto() failed");
        close(sockfd);
        return 1;
    }

    close(sockfd);
    return 0;
}

该代码使用原始套接字创建了一个 IPv6 套接字，并使用 XFRM_MSG_NEWSA 消息来创建一个新的 SA，同时还创建了一个新的策略，并将 SA 和策略绑定在一起。需要注意的是，此代码仅用于示例和学习目的。实际上，创建 SA 和策略需要根据特定的网络环境和安全需求进行配置和管理，这需要更多的专业知识和经验。

更多信息：

注意：

此代码示例仅用于演示目的，可能需要进行调整才能适应您的特定需求。
在使用 XFRM API 创建 SA 和策略时，请务必遵循最佳实践，并确保您的配置符合安全要求。
建议您仔细阅读 XFRM 文档，并参考相关资源以深入了解 XFRM 框架。