第10章 Network Namespace基础

// namespace_create.c
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/wait.h>
#include <sys/utsname.h>

int main() {
    pid_t pid;
    
    // 创建子进程
    pid = fork();
    if (pid == 0) {
        // 子进程：创建新的网络Namespace
        if (unshare(CLONE_NEWNET) < 0) {
            perror("unshare");
            exit(1);
        }
        
        // 在新的Namespace中执行命令
        execl("/bin/bash", "bash", NULL);
    } else if (pid > 0) {
        // 父进程：等待子进程
        wait(NULL);
    } else {
        perror("fork");
        return 1;
    }
    
    return 0;
}

// veth_create.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include <linux/if_link.h>

int create_veth_pair(const char *name1, const char *name2) {
    int sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
    if (sock < 0) {
        perror("socket");
        return -1;
    }
    
    // 创建veth pair
    struct ifreq ifr;
    strcpy(ifr.ifr_name, name1);
    ifr.ifr_data = (char*)name2;
    
    if (ioctl(sock, SIOCSIFNAME, &ifr) < 0) {
        perror("ioctl");
        close(sock);
        return -1;
    }
    
    close(sock);
    return 0;
}

int main() {
    if (create_veth_pair("veth0", "veth1") < 0) {
        return 1;
    }
    
    printf("veth pair created: veth0 <-> veth1\n");
    return 0;
}

// container_network.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/wait.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include <arpa/inet.h>

int create_namespace(const char *name) {
    char cmd[256];
    snprintf(cmd, sizeof(cmd), "ip netns add %s", name);
    return system(cmd);
}

int create_veth_pair(const char *name1, const char *name2) {
    char cmd[256];
    snprintf(cmd, sizeof(cmd), "ip link add %s type veth peer name %s", name1, name2);
    return system(cmd);
}

int move_interface_to_namespace(const char *ifname, const char *nsname) {
    char cmd[256];
    snprintf(cmd, sizeof(cmd), "ip link set %s netns %s", ifname, nsname);
    return system(cmd);
}

int configure_interface(const char *nsname, const char *ifname, const char *ip) {
    char cmd[256];
    snprintf(cmd, sizeof(cmd), "ip netns exec %s ip addr add %s dev %s", nsname, ip, ifname);
    if (system(cmd) != 0) return -1;
    
    snprintf(cmd, sizeof(cmd), "ip netns exec %s ip link set %s up", nsname, ifname);
    return system(cmd);
}

int main() {
    // 创建两个Namespace
    if (create_namespace("ns1") != 0) {
        printf("Failed to create ns1\n");
        return 1;
    }
    
    if (create_namespace("ns2") != 0) {
        printf("Failed to create ns2\n");
        return 1;
    }
    
    // 创建veth pair
    if (create_veth_pair("veth1", "veth2") != 0) {
        printf("Failed to create veth pair\n");
        return 1;
    }
    
    // 移动接口到Namespace
    if (move_interface_to_namespace("veth1", "ns1") != 0) {
        printf("Failed to move veth1 to ns1\n");
        return 1;
    }
    
    if (move_interface_to_namespace("veth2", "ns2") != 0) {
        printf("Failed to move veth2 to ns2\n");
        return 1;
    }
    
    // 配置IP地址
    if (configure_interface("ns1", "veth1", "10.0.0.1/24") != 0) {
        printf("Failed to configure veth1\n");
        return 1;
    }
    
    if (configure_interface("ns2", "veth2", "10.0.0.2/24") != 0) {
        printf("Failed to configure veth2\n");
        return 1;
    }
    
    printf("Container network created successfully!\n");
    printf("Test connectivity:\n");
    printf("sudo ip netns exec ns1 ping 10.0.0.2\n");
    
    return 0;
}