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net_user.c

/*
 * 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 "kern_constants.h"
#include "os.h"
#include "um_malloc.h"
#include "user.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, 0, "change_tramp");
      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 = 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) 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;
}

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