net/core/utils.c

   1 /*
   2  *      Generic address resultion entity
   3  *
   4  *      Authors:
   5  *      net_random Alan Cox
   6  *      net_ratelimit Andi Kleen
   7  *      in{4,6}_pton YOSHIFUJI Hideaki, Copyright (C)2006 USAGI/WIDE Project
   8  *
   9  *      Created by Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
  10  *
  11  *      This program is free software; you can redistribute it and/or
  12  *      modify it under the terms of the GNU General Public License
  13  *      as published by the Free Software Foundation; either version
  14  *      2 of the License, or (at your option) any later version.
  15  */
  16
  17 #include <linux/module.h>
  18 #include <linux/jiffies.h>
  19 #include <linux/kernel.h>
  20 #include <linux/inet.h>
  21 #include <linux/mm.h>
  22 #include <linux/net.h>
  23 #include <linux/string.h>
  24 #include <linux/types.h>
  25 #include <linux/random.h>
  26 #include <linux/percpu.h>
  27 #include <linux/init.h>
  28 #include <net/sock.h>
  29
  30 #include <asm/byteorder.h>
  31 #include <asm/system.h>
  32 #include <asm/uaccess.h>
  33
  34 int net_msg_warn __read_mostly = 1;
  35 EXPORT_SYMBOL(net_msg_warn);
  36
  37 DEFINE_RATELIMIT_STATE(net_ratelimit_state, 5 * HZ, 10);
  38 /*
  39  * All net warning printk()s should be guarded by this function.
  40  */
  41 int net_ratelimit(void)
  42 {
  43         return __ratelimit(&net_ratelimit_state);
  44 }
  45 EXPORT_SYMBOL(net_ratelimit);
  46
  47 /*
  48  * Convert an ASCII string to binary IP.
  49  * This is outside of net/ipv4/ because various code that uses IP addresses
  50  * is otherwise not dependent on the TCP/IP stack.
  51  */
  52
  53 __be32 in_aton(const char *str)
  54 {
  55         unsigned long l;
  56         unsigned int val;
  57         int i;
  58
  59         l = 0;
  60         for (i = 0; i < 4; i++)
  61         {
  62                 l <<= 8;
  63                 if (*str != '\0')
  64                 {
  65                         val = 0;
  66                         while (*str != '\0' && *str != '.' && *str != '\n')
  67                         {
  68                                 val *= 10;
  69                                 val += *str - '0';
  70                                 str++;
  71                         }
  72                         l |= val;
  73                         if (*str != '\0')
  74                                 str++;
  75                 }
  76         }
  77         return(htonl(l));
  78 }
  79
  80 EXPORT_SYMBOL(in_aton);
  81
  82 #define IN6PTON_XDIGIT          0x00010000
  83 #define IN6PTON_DIGIT           0x00020000
  84 #define IN6PTON_COLON_MASK      0x00700000
  85 #define IN6PTON_COLON_1         0x00100000      /* single : requested */
  86 #define IN6PTON_COLON_2         0x00200000      /* second : requested */
  87 #define IN6PTON_COLON_1_2       0x00400000      /* :: requested */
  88 #define IN6PTON_DOT             0x00800000      /* . */
  89 #define IN6PTON_DELIM           0x10000000
  90 #define IN6PTON_NULL            0x20000000      /* first/tail */
  91 #define IN6PTON_UNKNOWN         0x40000000
  92
  93 static inline int xdigit2bin(char c, int delim)
  94 {
  95         if (c == delim || c == '\0')
  96                 return IN6PTON_DELIM;
  97         if (c == ':')
  98                 return IN6PTON_COLON_MASK;
  99         if (c == '.')
 100                 return IN6PTON_DOT;
 101         if (c >= '0' && c <= '9')
 102                 return (IN6PTON_XDIGIT | IN6PTON_DIGIT| (c - '0'));
 103         if (c >= 'a' && c <= 'f')
 104                 return (IN6PTON_XDIGIT | (c - 'a' + 10));
 105         if (c >= 'A' && c <= 'F')
 106                 return (IN6PTON_XDIGIT | (c - 'A' + 10));
 107         if (delim == -1)
 108                 return IN6PTON_DELIM;
 109         return IN6PTON_UNKNOWN;
 110 }
 111
 112 int in4_pton(const char *src, int srclen,
 113              u8 *dst,
 114              int delim, const char **end)
 115 {
 116         const char *s;
 117         u8 *d;
 118         u8 dbuf[4];
 119         int ret = 0;
 120         int i;
 121         int w = 0;
 122
 123         if (srclen < 0)
 124                 srclen = strlen(src);
 125         s = src;
 126         d = dbuf;
 127         i = 0;
 128         while(1) {
 129                 int c;
 130                 c = xdigit2bin(srclen > 0 ? *s : '\0', delim);
 131                 if (!(c & (IN6PTON_DIGIT | IN6PTON_DOT | IN6PTON_DELIM | IN6PTON_COLON_MASK))) {
 132                         goto out;
 133                 }
 134                 if (c & (IN6PTON_DOT | IN6PTON_DELIM | IN6PTON_COLON_MASK)) {
 135                         if (w == 0)
 136                                 goto out;
 137                         *d++ = w & 0xff;
 138                         w = 0;
 139                         i++;
 140                         if (c & (IN6PTON_DELIM | IN6PTON_COLON_MASK)) {
 141                                 if (i != 4)
 142                                         goto out;
 143                                 break;
 144                         }
 145                         goto cont;
 146                 }
 147                 w = (w * 10) + c;
 148                 if ((w & 0xffff) > 255) {
 149                         goto out;
 150                 }
 151 cont:
 152                 if (i >= 4)
 153                         goto out;
 154                 s++;
 155                 srclen--;
 156         }
 157         ret = 1;
 158         memcpy(dst, dbuf, sizeof(dbuf));
 159 out:
 160         if (end)
 161                 *end = s;
 162         return ret;
 163 }
 164
 165 EXPORT_SYMBOL(in4_pton);
 166
 167 int in6_pton(const char *src, int srclen,
 168              u8 *dst,
 169              int delim, const char **end)
 170 {
 171         const char *s, *tok = NULL;
 172         u8 *d, *dc = NULL;
 173         u8 dbuf[16];
 174         int ret = 0;
 175         int i;
 176         int state = IN6PTON_COLON_1_2 | IN6PTON_XDIGIT | IN6PTON_NULL;
 177         int w = 0;
 178
 179         memset(dbuf, 0, sizeof(dbuf));
 180
 181         s = src;
 182         d = dbuf;
 183         if (srclen < 0)
 184                 srclen = strlen(src);
 185
 186         while (1) {
 187                 int c;
 188
 189                 c = xdigit2bin(srclen > 0 ? *s : '\0', delim);
 190                 if (!(c & state))
 191                         goto out;
 192                 if (c & (IN6PTON_DELIM | IN6PTON_COLON_MASK)) {
 193                         /* process one 16-bit word */
 194                         if (!(state & IN6PTON_NULL)) {
 195                                 *d++ = (w >> 8) & 0xff;
 196                                 *d++ = w & 0xff;
 197                         }
 198                         w = 0;
 199                         if (c & IN6PTON_DELIM) {
 200                                 /* We've processed last word */
 201                                 break;
 202                         }
 203                         /*
 204                          * COLON_1 => XDIGIT
 205                          * COLON_2 => XDIGIT|DELIM
 206                          * COLON_1_2 => COLON_2
 207                          */
 208                         switch (state & IN6PTON_COLON_MASK) {
 209                         case IN6PTON_COLON_2:
 210                                 dc = d;
 211                                 state = IN6PTON_XDIGIT | IN6PTON_DELIM;
 212                                 if (dc - dbuf >= sizeof(dbuf))
 213                                         state |= IN6PTON_NULL;
 214                                 break;
 215                         case IN6PTON_COLON_1|IN6PTON_COLON_1_2:
 216                                 state = IN6PTON_XDIGIT | IN6PTON_COLON_2;
 217                                 break;
 218                         case IN6PTON_COLON_1:
 219                                 state = IN6PTON_XDIGIT;
 220                                 break;
 221                         case IN6PTON_COLON_1_2:
 222                                 state = IN6PTON_COLON_2;
 223                                 break;
 224                         default:
 225                                 state = 0;
 226                         }
 227                         tok = s + 1;
 228                         goto cont;
 229                 }
 230
 231                 if (c & IN6PTON_DOT) {
 232                         ret = in4_pton(tok ? tok : s, srclen + (int)(s - tok), d, delim, &s);
 233                         if (ret > 0) {
 234                                 d += 4;
 235                                 break;
 236                         }
 237                         goto out;
 238                 }
 239
 240                 w = (w << 4) | (0xff & c);
 241                 state = IN6PTON_COLON_1 | IN6PTON_DELIM;
 242                 if (!(w & 0xf000)) {
 243                         state |= IN6PTON_XDIGIT;
 244                 }
 245                 if (!dc && d + 2 < dbuf + sizeof(dbuf)) {
 246                         state |= IN6PTON_COLON_1_2;
 247                         state &= ~IN6PTON_DELIM;
 248                 }
 249                 if (d + 2 >= dbuf + sizeof(dbuf)) {
 250                         state &= ~(IN6PTON_COLON_1|IN6PTON_COLON_1_2);
 251                 }
 252 cont:
 253                 if ((dc && d + 4 < dbuf + sizeof(dbuf)) ||
 254                     d + 4 == dbuf + sizeof(dbuf)) {
 255                         state |= IN6PTON_DOT;
 256                 }
 257                 if (d >= dbuf + sizeof(dbuf)) {
 258                         state &= ~(IN6PTON_XDIGIT|IN6PTON_COLON_MASK);
 259                 }
 260                 s++;
 261                 srclen--;
 262         }
 263
 264         i = 15; d--;
 265
 266         if (dc) {
 267                 while(d >= dc)
 268                         dst[i--] = *d--;
 269                 while(i >= dc - dbuf)
 270                         dst[i--] = 0;
 271                 while(i >= 0)
 272                         dst[i--] = *d--;
 273         } else
 274                 memcpy(dst, dbuf, sizeof(dbuf));
 275
 276         ret = 1;
 277 out:
 278         if (end)
 279                 *end = s;
 280         return ret;
 281 }
 282
 283 EXPORT_SYMBOL(in6_pton);
 284
 285 void inet_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb,
 286                               __be32 from, __be32 to, int pseudohdr)
 287 {
 288         __be32 diff[] = { ~from, to };
 289         if (skb->ip_summed != CHECKSUM_PARTIAL) {
 290                 *sum = csum_fold(csum_partial(diff, sizeof(diff),
 291                                 ~csum_unfold(*sum)));
 292                 if (skb->ip_summed == CHECKSUM_COMPLETE && pseudohdr)
 293                         skb->csum = ~csum_partial(diff, sizeof(diff),
 294                                                 ~skb->csum);
 295         } else if (pseudohdr)
 296                 *sum = ~csum_fold(csum_partial(diff, sizeof(diff),
 297                                 csum_unfold(*sum)));
 298 }
 299 EXPORT_SYMBOL(inet_proto_csum_replace4);