package/network/services/ppp/patches/310-precompile_filter.patch

   1 pppd: Implement support for precompiled pcap filters
   2
   3 This patch implements support for precompiled pcap filters which is useful to
   4 support dial-on-demand on memory constrained embedded devices without having
   5 to link the full libpcap into pppd to generate the filters during runtime.
   6
   7 Two new options are introduced; "precompiled-pass-filter" specifies a pre-
   8 compiled filter file containing rules to match packets which should be passed,
   9 "precompiled-active-filter" specifies a filter file containing rules to match
  10 packets which are treated as active.
  11
  12 Signed-off-by: Jo-Philipp Wich <jow@openwrt.org>
  13
  14 --- a/pppd/Makefile.linux
  15 +++ b/pppd/Makefile.linux
  16 @@ -50,6 +50,9 @@ MPPE=y
  17  # and that the kernel driver support PPP packet filtering.
  18  #FILTER=y
  19
  20 +# Support for precompiled filters
  21 +PRECOMPILED_FILTER=y
  22 +
  23  # Uncomment the next line to enable multilink PPP (enabled by default)
  24  # Linux distributions: Please leave multilink ENABLED in your builds
  25  # of pppd!
  26 @@ -183,6 +186,14 @@ CFLAGS  += -DPPP_FILTER -I$(STAGING_DIR)
  27  endif
  28  endif
  29
  30 +ifdef PRECOMPILED_FILTER
  31 +PPPDSRCS += pcap_pcc.c
  32 +HEADERS  += pcap_pcc.h
  33 +PPPDOBJS += pcap_pcc.o
  34 +LIBS   += $(STAGING_DIR)/usr/lib/libpcap.a
  35 +CFLAGS += -DPPP_FILTER -DPPP_PRECOMPILED_FILTER -I$(STAGING_DIR)/usr/include
  36 +endif
  37 +
  38  ifdef HAVE_INET6
  39       PPPDSRCS += ipv6cp.c eui64.c
  40       HEADERS  += ipv6cp.h eui64.h
  41 --- a/pppd/options.c
  42 +++ b/pppd/options.c
  43 @@ -57,6 +57,7 @@
  44
  45  #ifdef PPP_FILTER
  46  #include <pcap.h>
  47 +#include <pcap-bpf.h>
  48  /*
  49   * There have been 3 or 4 different names for this in libpcap CVS, but
  50   * this seems to be what they have settled on...
  51 @@ -165,6 +166,13 @@ static int setlogfile __P((char **));
  52  static int loadplugin __P((char **));
  53  #endif
  54
  55 +#ifdef PPP_PRECOMPILED_FILTER
  56 +#include "pcap_pcc.h"
  57 +static int setprecompiledpassfilter __P((char **));
  58 +static int setprecompiledactivefilter __P((char **));
  59 +#undef PPP_FILTER
  60 +#endif
  61 +
  62  #ifdef PPP_FILTER
  63  static int setpassfilter __P((char **));
  64  static int setactivefilter __P((char **));
  65 @@ -344,6 +352,14 @@ option_t general_options[] = {
  66        "set filter for active pkts", OPT_PRIO },
  67  #endif
  68
  69 +#ifdef PPP_PRECOMPILED_FILTER
  70 +    { "precompiled-pass-filter", 1, setprecompiledpassfilter,
  71 +      "set precompiled filter for packets to pass", OPT_PRIO },
  72 +
  73 +    { "precompiled-active-filter", 1, setprecompiledactivefilter,
  74 +      "set precompiled filter for active pkts", OPT_PRIO },
  75 +#endif
  76 +
  77  #ifdef MAXOCTETS
  78      { "maxoctets", o_int, &maxoctets,
  79        "Set connection traffic limit",
  80 @@ -1488,6 +1504,29 @@ callfile(argv)
  81      return ok;
  82  }
  83
  84 +#ifdef PPP_PRECOMPILED_FILTER
  85 +/*
  86 + * setprecompiledpassfilter - Set the pass filter for packets using a
  87 + * precompiled expression
  88 + */
  89 +static int
  90 +setprecompiledpassfilter(argv)
  91 +    char **argv;
  92 +{
  93 +    return pcap_pre_compiled (*argv, &pass_filter);
  94 +}
  95 +
  96 +/*
  97 + * setactivefilter - Set the active filter for packets
  98 + */
  99 +static int
 100 +setprecompiledactivefilter(argv)
 101 +    char **argv;
 102 +{
 103 +    return pcap_pre_compiled (*argv, &active_filter);
 104 +}
 105 +#endif
 106 +
 107  #ifdef PPP_FILTER
 108  /*
 109   * setpassfilter - Set the pass filter for packets
 110 --- /dev/null
 111 +++ b/pppd/pcap_pcc.c
 112 @@ -0,0 +1,74 @@
 113 +#include <pcap.h>
 114 +#include <pcap-bpf.h>
 115 +#include <stdio.h>
 116 +#include <stdlib.h>
 117 +#include <string.h>
 118 +#include <errno.h>
 119 +#include "pppd.h"
 120 +
 121 +int pcap_pre_compiled (char * fname, struct bpf_program *p)
 122 +{
 123 +    char buf[128];
 124 +    int line = 0, size = 0, index=0, ret=1;
 125 +    FILE *f = fopen (fname, "r");
 126 +    if (!f)
 127 +    {
 128 +       option_error("error opening precompiled active-filter '%s': %s",
 129 +                    fname, strerror (errno));
 130 +       return 0;
 131 +    }
 132 +    while (fgets (buf, 127, f))
 133 +    {
 134 +       line++;
 135 +       if (*buf == '#')
 136 +           continue;
 137 +       if (size)
 138 +       {
 139 +           /*
 140 +             struct bpf_insn {
 141 +             u_short   code;
 142 +             u_char    jt;
 143 +             u_char    jf;
 144 +             bpf_int32 k;
 145 +             }
 146 +           */
 147 +           struct bpf_insn * insn = & p->bf_insns[index];
 148 +           unsigned code, jt, jf, k;
 149 +           if (sscanf (buf, "%u %u %u %u", &code, &jt, &jf, &k) != 4)
 150 +           {
 151 +               goto err;
 152 +           }
 153 +           insn->code = code;
 154 +           insn->jt = jt;
 155 +           insn->jf = jf;
 156 +           insn->k  = k;
 157 +           index++;
 158 +       }
 159 +       else
 160 +       {
 161 +           if (sscanf (buf, "%u", &size) != 1)
 162 +           {
 163 +               goto err;
 164 +           }
 165 +           p->bf_len = size;
 166 +           p->bf_insns = (struct bpf_insn *)
 167 +               malloc (size * sizeof (struct bpf_insn));
 168 +       }
 169 +    }
 170 +    if (size != index)
 171 +    {
 172 +       option_error("error in precompiled active-filter,"
 173 +                    " expected %d expressions, got %dn",
 174 +                    size, index);
 175 +       ret = 0;
 176 +    }
 177 +    fclose(f);
 178 +    return ret;
 179 +
 180 +err:
 181 +  option_error("error in precompiled active-filter"
 182 +              " expression line %s:%d (wrong size)\n",
 183 +              fname, line);
 184 +  fclose (f);
 185 +  return 0;
 186 +}
 187 --- /dev/null
 188 +++ b/pppd/pcap_pcc.h
 189 @@ -0,0 +1,7 @@
 190 +#ifndef PCAP_PCC_H
 191 +#define PCAP_PCC_H
 192 +
 193 +#include <pcap.h>
 194 +
 195 +int pcap_pre_compiled (char * fname, struct bpf_program *p);
 196 +#endif /* PCAP_PCC_H */