python - 不允许操作 : Server-setsockopt() error for SO_BINDTODEVICE

Question

我有这个负责处理数据包的c可执行文件。我正在尝试使用 setsockopt 将接口(interface)绑定(bind)到我的套接字 sockfd

#define MULTICAST

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <sys/types.h>
#include <sys/time.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <time.h>
#include <sys/ioctl.h>
#include <net/if.h>

#define TS_PACKET_SIZE 188

long long int usecDiff(struct timeval* time_stop, struct timeval* time_start)
{
    long long int temp = 0;
    long long int utemp = 0;

    if (time_stop && time_start) {
        if (time_stop->tv_usec >= time_start->tv_usec) {
            utemp = time_stop->tv_usec - time_start->tv_usec;    
            temp = time_stop->tv_sec - time_start->tv_sec;
        } else {
            utemp = time_stop->tv_usec + 1000000 - time_start->tv_usec;       
            temp = time_stop->tv_sec - 1 - time_start->tv_sec;
        }
        if (temp >= 0 && utemp >= 0) {
            temp = (temp * 1000000) + utemp;
            } else {
            fprintf(stderr, "start time %ld.%ld is after stop time %ld.%ld\n", time_start->tv_sec, time_start->tv_usec, time_stop->tv_sec, time_stop->tv_usec);
            temp = -1;
        }
    } else {
        fprintf(stderr, "memory is garbaged?\n");
        temp = -1;
    }
        return temp;
}


int main (int argc, char *argv[]) {

    int sockfd;
    int len;
    int sent;
    int transport_fd;
    struct sockaddr_in addr;
    unsigned long int packet_size;   
    char* tsfile;
    unsigned char* send_buf;
    unsigned int bitrate;
    unsigned long long int packet_time;
    unsigned long long int real_time;    
    struct timeval time_start;
    struct timeval time_stop;
    struct timespec nano_sleep_packet;
    char *opt; // "eth0" or "eth1"

    memset(&addr, 0, sizeof(addr));
    memset(&time_start, 0, sizeof(time_start));
    memset(&time_stop, 0, sizeof(time_stop));
    memset(&nano_sleep_packet, 0, sizeof(nano_sleep_packet));

    if(argc < 6 ) {
    fprintf(stderr, "Usage: %s file.ts ipaddr port bitrate [ts_packet_per_ip_packet]\n", argv[0]);
    fprintf(stderr, "ts_packet_per_ip_packet default is 7\n");
    fprintf(stderr, "bit rate refers to transport stream bit rate\n");
    fprintf(stderr, "zero bitrate is 100.000.000 bps\n");
    fprintf(stderr, "This is the modified file\n");
    return 0;
    } else {
    tsfile = argv[1];
    addr.sin_family = AF_INET;
    addr.sin_addr.s_addr = inet_addr(argv[2]);
    addr.sin_port = htons(atoi(argv[3]));
    bitrate = atoi(argv[4]);
    opt = argv[5];
    if (bitrate <= 0) {
        bitrate = 100000000;
    }
    //To be modified : original arguments are 5 and have to be increased by one
    if (argc >= 7) {
        packet_size = strtoul(argv[5], 0, 0) * TS_PACKET_SIZE;
    } else {
        packet_size = 7 * TS_PACKET_SIZE;
    }
    }

    sockfd = socket(AF_INET, SOCK_DGRAM, 0);
    if(sockfd < 0) {
    perror("socket(): error ");
    return 0;
    } 
    struct ifreq ifr;

    memset(&ifr, 0, sizeof(ifr));
    //snprintf(ifr.ifr_name, sizeof(ifr.ifr_name), opt); //
    setsockopt(sockfd, SOL_SOCKET, SO_BINDTODEVICE, opt, strlen(opt)); // 6 is the size of MAC address in bytes
    ioctl(sockfd, SIOCGIFINDEX, &ifr);
    if (setsockopt(sockfd, SOL_SOCKET, SO_BINDTODEVICE, (void *)&ifr, sizeof(ifr)) < 0) {
    perror("Server-setsockopt() error for SO_BINDTODEVICE");
    close(sockfd);
    return 0;
    }

    transport_fd = open(tsfile, O_RDONLY);
    if(transport_fd < 0) {
    fprintf(stderr, "can't open file %s\n", tsfile);
    close(sockfd);
    return 0;
    } 

    int completed = 0;
    send_buf = malloc(packet_size);
    packet_time = 0;
    real_time = 0;

    gettimeofday(&time_start, 0);
    while (!completed) {

        gettimeofday(&time_stop, 0);
        real_time = usecDiff(&time_stop, &time_start);
        if (real_time * bitrate > packet_time * 1000000) { /* theorical bits against sent bits */
        len = read(transport_fd, send_buf, packet_size);
        if(len < 0) {
            fprintf(stderr, "ts file read error \n");
            completed = 1;
        } else if (len == 0) {
            fprintf(stderr, "ts sent done\n");
                completed = 1;
        } else {
            sent = sendto(sockfd, send_buf, len, 0, (struct sockaddr *)&addr, sizeof(struct sockaddr_in));
            if(sent <= 0) {
            perror("send(): error ");
            completed = 1;
            } else {
            packet_time += packet_size * 8;
            }
        }
        } else {
            nanosleep(&nano_sleep_packet, 0);
        }
    }

    close(transport_fd);
    close(sockfd);
    free(send_buf);
    return 0;    
}

我在 Python 脚本中使用 subprocess.Popen() 调用此文件，如下所示

self.proc.append(subprocess.Popen(["tsudpsend", "/dev/stdin", out_address, str(port), "10000000", "eth0"], stdin=self.proc[-1].stdout, stderr=open("/home/cayman/log.txt", "w")))

当我检查管道输出时，我发现了以下错误:

Server-setsockopt() error for SO_BINDTODEVICE: Operation not permitted

我花了一些时间研究 this thread我看到的建议很少，但都是徒劳的。谁能指导我如何解决这个问题。谢谢。

Answer 1

SO_BINDTODEVICE 的问题是您必须是 root 才能使用它。如果我以 root 身份运行您的代码，我不会收到该错误。

您需要做的是通过 getifaddrs 获取接口(interface)列表并循环遍历接口(interface)列表，直到名称与您想要的相匹配。然后，您提取有问题的 IPv4 地址，并使用它在 bind 调用中填充 sockaddr_in。

struct sockaddr_in bind_addr;
memset(&bind_addr, 0, sizeof(bind_addr);
bind_addr.sin_family = AF_INET;
bind_addr.sin_port = htons(atoi(argv[3]));

...

struct ifaddrs *ifa, *ifa_tmp;
if (getifaddrs(&ifa) == -1) {
    perror("getifaddrs failed");
    exit(1);
}
ifa_tmp = ifa;
while (ifa_tmp) {
    if (!strcmp(ifa_tmp->ifa_name, opt) && 
            ifa_tmp->ifa_addr && (ifa_tmp->ifa_addr->sa_family == AF_INET)) {
        printf("addr = %s\n", 
            inet_ntoa(((struct sockaddr_in *)ifa_tmp->ifa_addr)->sin_addr);
        bind_addr.sin_addr.s_addr = 
            ((struct sockaddr_in *)ifa_tmp->ifa_addr)->sin_addr.s_addr;
        break;
    }
    ifa_tmp = ifa_tmp->ifa_next;
}
freeifaddrs(ifa);

if (bind_addr.sin_addr.s_addr == 0) {
    printf("interface not found\n");
    exit(1);
}

...

if (bind(sockfd, (struct sockaddr *)&bind_addr, sizeof(bind_addr)) != 0) {
    perror("bind failed");
    exit(1);
}

...