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 <jo@mein.io>
  13
  14 --- a/pppd/Makefile.linux
  15 +++ b/pppd/Makefile.linux
  16 @@ -51,6 +51,9 @@ 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 @@ -214,6 +217,14 @@ LIBS    += -lpcap -L$(STAGING_DIR)/usr/l
  27  CFLAGS  += -DPPP_FILTER -I$(STAGING_DIR)/usr/include
  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 @@ -56,6 +56,7 @@
  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 @@ -168,6 +169,13 @@ static int setlogfile(char **);
  52  static int loadplugin(char **);
  53  #endif
  54
  55 +#ifdef PPP_PRECOMPILED_FILTER
  56 +#include "pcap_pcc.h"
  57 +static int setprecompiledpassfilter(char **);
  58 +static int setprecompiledactivefilter(char **);
  59 +#undef PPP_FILTER
  60 +#endif
  61 +
  62  #ifdef PPP_FILTER
  63  static int setpassfilter(char **);
  64  static int setactivefilter(char **);
  65 @@ -360,6 +368,14 @@ 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 @@ -1468,6 +1484,27 @@ callfile(char **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(char **argv)
  91 +{
  92 +    return pcap_pre_compiled (*argv, &pass_filter);
  93 +}
  94 +
  95 +/*
  96 + * setactivefilter - Set the active filter for packets
  97 + */
  98 +static int
  99 +setprecompiledactivefilter(char **argv)
 100 +{
 101 +    return pcap_pre_compiled (*argv, &active_filter);
 102 +}
 103 +#endif
 104 +
 105  #ifdef PPP_FILTER
 106  /*
 107   * setpassfilter - Set the pass filter for packets
 108 --- /dev/null
 109 +++ b/pppd/pcap_pcc.c
 110 @@ -0,0 +1,74 @@
 111 +#include <pcap.h>
 112 +#include <pcap-bpf.h>
 113 +#include <stdio.h>
 114 +#include <stdlib.h>
 115 +#include <string.h>
 116 +#include <errno.h>
 117 +#include "pppd.h"
 118 +
 119 +int pcap_pre_compiled (char * fname, struct bpf_program *p)
 120 +{
 121 +    char buf[128];
 122 +    int line = 0, size = 0, index=0, ret=1;
 123 +    FILE *f = fopen (fname, "r");
 124 +    if (!f)
 125 +    {
 126 +       option_error("error opening precompiled active-filter '%s': %s",
 127 +                    fname, strerror (errno));
 128 +       return 0;
 129 +    }
 130 +    while (fgets (buf, 127, f))
 131 +    {
 132 +       line++;
 133 +       if (*buf == '#')
 134 +           continue;
 135 +       if (size)
 136 +       {
 137 +           /*
 138 +             struct bpf_insn {
 139 +             u_short   code;
 140 +             u_char    jt;
 141 +             u_char    jf;
 142 +             bpf_int32 k;
 143 +             }
 144 +           */
 145 +           struct bpf_insn * insn = & p->bf_insns[index];
 146 +           unsigned code, jt, jf, k;
 147 +           if (sscanf (buf, "%u %u %u %u", &code, &jt, &jf, &k) != 4)
 148 +           {
 149 +               goto err;
 150 +           }
 151 +           insn->code = code;
 152 +           insn->jt = jt;
 153 +           insn->jf = jf;
 154 +           insn->k  = k;
 155 +           index++;
 156 +       }
 157 +       else
 158 +       {
 159 +           if (sscanf (buf, "%u", &size) != 1)
 160 +           {
 161 +               goto err;
 162 +           }
 163 +           p->bf_len = size;
 164 +           p->bf_insns = (struct bpf_insn *)
 165 +               malloc (size * sizeof (struct bpf_insn));
 166 +       }
 167 +    }
 168 +    if (size != index)
 169 +    {
 170 +       option_error("error in precompiled active-filter,"
 171 +                    " expected %d expressions, got %dn",
 172 +                    size, index);
 173 +       ret = 0;
 174 +    }
 175 +    fclose(f);
 176 +    return ret;
 177 +
 178 +err:
 179 +  option_error("error in precompiled active-filter"
 180 +              " expression line %s:%d (wrong size)\n",
 181 +              fname, line);
 182 +  fclose (f);
 183 +  return 0;
 184 +}
 185 --- /dev/null
 186 +++ b/pppd/pcap_pcc.h
 187 @@ -0,0 +1,7 @@
 188 +#ifndef PCAP_PCC_H
 189 +#define PCAP_PCC_H
 190 +
 191 +#include <pcap.h>
 192 +
 193 +int pcap_pre_compiled (char * fname, struct bpf_program *p);
 194 +#endif /* PCAP_PCC_H */