net_user.c

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/*
 * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
 * Licensed under the GPL
 */

#include <stdio.h>
#include <unistd.h>
#include <stdarg.h>
#include <errno.h>
#include <stddef.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <net_user.h>
#include <os.h>
#include <um_malloc.h>

int tap_open_common(void *dev, char *gate_addr)
{
    int tap_addr[4];

    if (gate_addr == NULL)
        return 0;
    if (sscanf(gate_addr, "%d.%d.%d.%d", &tap_addr[0],
          &tap_addr[1], &tap_addr[2], &tap_addr[3]) != 4) {
        printk(UM_KERN_ERR "Invalid tap IP address - '%s'\n",
               gate_addr);
        return -EINVAL;
    }
    return 0;
}

void tap_check_ips(char *gate_addr, unsigned char *eth_addr)
{
    int tap_addr[4];

    if ((gate_addr != NULL) &&
        (sscanf(gate_addr, "%d.%d.%d.%d", &tap_addr[0],
            &tap_addr[1], &tap_addr[2], &tap_addr[3]) == 4) &&
        (eth_addr[0] == tap_addr[0]) &&
        (eth_addr[1] == tap_addr[1]) &&
        (eth_addr[2] == tap_addr[2]) &&
        (eth_addr[3] == tap_addr[3])) {
        printk(UM_KERN_ERR "The tap IP address and the UML eth IP "
               "address must be different\n");
    }
}

/* Do reliable error handling as this fails frequently enough. */
void read_output(int fd, char *output, int len)
{
    int remain, ret, expected;
    char c;
    char *str;

    if (output == NULL) {
        output = &c;
        len = sizeof(c);
    }

    *output = '\0';
    ret = read(fd, &remain, sizeof(remain));

    if (ret != sizeof(remain)) {
        if (ret < 0)
            ret = -errno;
        expected = sizeof(remain);
        str = "length";
        goto err;
    }

    while (remain != 0) {
        expected = (remain < len) ? remain : len;
        ret = read(fd, output, expected);
        if (ret != expected) {
            if (ret < 0)
                ret = -errno;
            str = "data";
            goto err;
        }
        remain -= ret;
    }

    return;

err:
    if (ret < 0)
        printk(UM_KERN_ERR "read_output - read of %s failed, "
               "errno = %d\n", str, -ret);
    else
        printk(UM_KERN_ERR "read_output - read of %s failed, read only "
               "%d of %d bytes\n", str, ret, expected);
}

int net_read(int fd, void *buf, int len)
{
    int n;

    n = read(fd,  buf,  len);

    if ((n < 0) && (errno == EAGAIN))
        return 0;
    else if (n == 0)
        return -ENOTCONN;
    return n;
}

int net_recvfrom(int fd, void *buf, int len)
{
    int n;

    CATCH_EINTR(n = recvfrom(fd,  buf,  len, 0, NULL, NULL));
    if (n < 0) {
        if (errno == EAGAIN)
            return 0;
        return -errno;
    }
    else if (n == 0)
        return -ENOTCONN;
    return n;
}

int net_write(int fd, void *buf, int len)
{
    int n;

    n = write(fd, buf, len);

    if ((n < 0) && (errno == EAGAIN))
        return 0;
    else if (n == 0)
        return -ENOTCONN;
    return n;
}

int net_send(int fd, void *buf, int len)
{
    int n;

    CATCH_EINTR(n = send(fd, buf, len, 0));
    if (n < 0) {
        if (errno == EAGAIN)
            return 0;
        return -errno;
    }
    else if (n == 0)
        return -ENOTCONN;
    return n;
}

int net_sendto(int fd, void *buf, int len, void *to, int sock_len)
{
    int n;

    CATCH_EINTR(n = sendto(fd, buf, len, 0, (struct sockaddr *) to,
                   sock_len));
    if (n < 0) {
        if (errno == EAGAIN)
            return 0;
        return -errno;
    }
    else if (n == 0)
        return -ENOTCONN;
    return n;
}

struct change_pre_exec_data {
    int close_me;
    int stdout;
};

static void change_pre_exec(void *arg)
{
    struct change_pre_exec_data *data = arg;

    close(data->close_me);
    dup2(data->stdout, 1);
}

static int change_tramp(char **argv, char *output, int output_len)
{
    int pid, fds[2], err;
    struct change_pre_exec_data pe_data;

    err = os_pipe(fds, 1, 0);
    if (err < 0) {
        printk(UM_KERN_ERR "change_tramp - pipe failed, err = %d\n",
               -err);
        return err;
    }
    pe_data.close_me = fds[0];
    pe_data.stdout = fds[1];
    pid = run_helper(change_pre_exec, &pe_data, argv);

    if (pid > 0)    /* Avoid hang as we won't get data in failure case. */
        read_output(fds[0], output, output_len);

    close(fds[0]);
    close(fds[1]);

    if (pid > 0)
        helper_wait(pid);
    return pid;
}

static void change(char *dev, char *what, unsigned char *addr,
           unsigned char *netmask)
{
    char addr_buf[sizeof("255.255.255.255\0")];
    char netmask_buf[sizeof("255.255.255.255\0")];
    char version[sizeof("nnnnn\0")];
    char *argv[] = { "uml_net", version, what, dev, addr_buf,
             netmask_buf, NULL };
    char *output;
    int output_len, pid;

    sprintf(version, "%d", UML_NET_VERSION);
    sprintf(addr_buf, "%d.%d.%d.%d", addr[0], addr[1], addr[2], addr[3]);
    sprintf(netmask_buf, "%d.%d.%d.%d", netmask[0], netmask[1],
        netmask[2], netmask[3]);

    output_len = UM_KERN_PAGE_SIZE;
    output = uml_kmalloc(output_len, UM_GFP_KERNEL);
    if (output == NULL)
        printk(UM_KERN_ERR "change : failed to allocate output "
               "buffer\n");

    pid = change_tramp(argv, output, output_len);
    if (pid < 0) {
        kfree(output);
        return;
    }

    if (output != NULL) {
        printk("%s", output);
        kfree(output);
    }
}

void open_addr(unsigned char *addr, unsigned char *netmask, void *arg)
{
    change(arg, "add", addr, netmask);
}

void close_addr(unsigned char *addr, unsigned char *netmask, void *arg)
{
    change(arg, "del", addr, netmask);
}

char *split_if_spec(char *str, ...)
{
    char **arg, *end;
    va_list ap;

    va_start(ap, str);
    while ((arg = va_arg(ap, char **)) != NULL) {
        if (*str == '\0')
            return NULL;
        end = strchr(str, ',');
        if (end != str)
            *arg = str;
        if (end == NULL)
            return NULL;
        *end++ = '\0';
        str = end;
    }
    va_end(ap);
    return str;
}