Initial commit

3 files changed, 327 insertions, 0 deletions

diff --git a/src/Makefile.am b/src/Makefile.am
new file mode 100644
index 0000000..840bffc
--- /dev/null
+++ b/src/Makefile.am
@@ -0,0 +1,35 @@
+# This file is part of nss-dontstalkme.
+#
+# Copyright 2014 Guido Günther
+# 
+# nss-dontstalkme is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public License
+# as published by the Free Software Foundation, either version 2.1 of
+# the License, or (at your option) any later version.
+#
+# nss-dontstalkme is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with nss-dontstalkme. If not, If not, see
+# <http://www.gnu.org/licenses/>.
+
+include $(top_srcdir)/flymake.mk
+
+ACLOCAL_AMFLAGS = -I m4
+
+lib_LTLIBRARIES = libnss_dontstalkme.la
+
+AM_CPPFLAGS = -include $(top_builddir)/config.h
+
+libnss_dontstalkme_la_SOURCES = \
+	nss-dontstalkme.c
+
+libnss_dontstalkme_la_LDFLAGS = \
+	-avoid-version \
+	-module \
+	-export-dynamic \
+	-shrext .so.2
+
diff --git a/src/nss-dontstalkme.c b/src/nss-dontstalkme.c
new file mode 100644
index 0000000..39bf34b
--- /dev/null
+++ b/src/nss-dontstalkme.c
@@ -0,0 +1,292 @@
+/*
+ * nss-dontstalkme: Return localhost for tracking host IPs
+ *
+ * Copyright (C) 2014 Guido Günther
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307  USA
+ *
+ * Author: Guido Günther <agx@sigxcpu.org>
+ *
+ * Heavily inspired by nss-myhostname.c which is
+ * Copyright 2008-2011 Lennart Poettering
+ */
+
+#include <assert.h>
+#include <nss.h>
+#include <limits.h>
+#include <string.h>
+#include <sys/types.h>
+#include <netdb.h>
+#include <errno.h>
+#include <net/if.h>
+
+/* We use 127.0.2.1 as returned address */
+#define LOCALADDRESS_IPV4 (htonl(0x7F000201))
+#define LOCALADDRESS_IPV6 &in6addr_loopback
+#define LOOPBACK_INTERFACE "lo"
+
+#define ALIGN(a) (((a+sizeof(void*)-1)/sizeof(void*))*sizeof(void*))
+#define _public_ __attribute__ ((visibility("default")))
+#define ARRAY_CARDINALITY(Array) (sizeof(Array) / sizeof(*(Array)))
+
+/* The hosts we blacklist */
+const char* stalkers[] =  { "www.google-analytics.com",
+                            "ssl.google-analytics.com",
+                          };
+
+enum nss_status _nss_dontstalkme_gethostbyname4_r(const char *name,
+                                                  struct gaih_addrtuple **pat,
+                                                  char *buffer, size_t buflen,
+                                                  int *errnop, int *h_errnop,
+                                                  int32_t *ttlp) _public_;
+
+enum nss_status _nss_dontstalkme_gethostbyname3_r(const char *name,
+                                                  int af,
+                                                  struct hostent *host,
+                                                  char *buffer, size_t buflen,
+                                                  int *errnop, int *h_errnop,
+                                                  int32_t *ttlp,
+                                                  char **canonp) _public_;
+
+enum nss_status _nss_dontstalkme_gethostbyname2_r(const char *name,
+                                                  int af,
+                                                  struct hostent *host,
+                                                  char *buffer, size_t buflen,
+                                                  int *errnop, int *h_errnop) _public_;
+
+enum nss_status _nss_dontstalkme_gethostbyname_r(const char *name,
+                                                 struct hostent *host,
+                                                 char *buffer, size_t buflen,
+                                                 int *errnop, int *h_errnop) _public_;
+
+
+enum nss_status
+_nss_dontstalkme_gethostbyname4_r(const char *name,
+                                 struct gaih_addrtuple **pat,
+                                 char *buffer, size_t buflen,
+                                 int *errnop, int *h_errnop,
+                                 int32_t *ttlp)
+{
+    unsigned lo_ifi;
+    size_t l, idx, ms;
+    char *r_name;
+    unsigned int  i;
+    struct gaih_addrtuple *r_tuple, *r_tuple_prev = NULL;
+
+    lo_ifi = if_nametoindex(LOOPBACK_INTERFACE);
+
+    for (i = 0; i < ARRAY_CARDINALITY(stalkers); i++) {
+        if (!strcasecmp(stalkers[i], name)) {
+            break;
+        }
+    }
+    if (i == ARRAY_CARDINALITY(stalkers)) {
+        *errnop = ENOENT;
+        *h_errnop = HOST_NOT_FOUND;
+        return NSS_STATUS_NOTFOUND;
+    }
+
+    l = strlen(name);
+    ms = ALIGN(l+1)+ALIGN(sizeof(struct gaih_addrtuple))*2;
+    if (buflen < ms) {
+        *errnop = ENOMEM;
+        *h_errnop = NO_RECOVERY;
+        return NSS_STATUS_TRYAGAIN;
+    }
+
+    /* First, fill in hostname */
+    r_name = buffer;
+    l = strlen(name);
+    memcpy(r_name, name, l+1);
+    idx = ALIGN(l+1);
+
+    /* Second, fill in IPv6 tuple */
+    r_tuple = (struct gaih_addrtuple*) (buffer + idx);
+    r_tuple->next = r_tuple_prev;
+    r_tuple->name = r_name;
+    r_tuple->family = AF_INET6;
+    memcpy(r_tuple->addr, LOCALADDRESS_IPV6, 16);
+    r_tuple->scopeid = (uint32_t) lo_ifi;
+
+    idx += ALIGN(sizeof(struct gaih_addrtuple));
+    r_tuple_prev = r_tuple;
+
+    /* Third, fill in IPv4 tuple */
+    r_tuple = (struct gaih_addrtuple*) (buffer + idx);
+    r_tuple->next = r_tuple_prev;
+    r_tuple->name = r_name;
+    r_tuple->family = AF_INET;
+    *(uint32_t*) r_tuple->addr = LOCALADDRESS_IPV4;
+    r_tuple->scopeid = (uint32_t) lo_ifi;
+
+    idx += ALIGN(sizeof(struct gaih_addrtuple));
+    r_tuple_prev = r_tuple;
+
+    /* Verify the size matches */
+    assert(idx == ms);
+
+    *pat = r_tuple_prev;
+
+    if (ttlp)
+        *ttlp = 0;
+
+    return NSS_STATUS_SUCCESS;
+}
+
+static inline size_t 
+proto_address_size(int proto)
+{
+    assert(proto == AF_INET || proto == AF_INET6);
+    return proto == AF_INET6 ? 16 : 4;
+}
+
+static enum nss_status
+fill_in_hostent(const char *hn,
+                int af,
+                struct hostent *result,
+                char *buffer, size_t buflen,
+                int *errnop, int *h_errnop,
+                int32_t *ttlp,
+                char **canonp)
+{
+
+    size_t l, idx, ms;
+    char *r_addr, *r_name, *r_aliases, *r_addr_list;
+    size_t alen;
+
+    alen = proto_address_size(af);
+
+    l = strlen(hn);
+    ms = ALIGN(l+1)+
+        sizeof(char*)+
+        ALIGN(alen)+
+        2*sizeof(char*);
+
+    if (buflen < ms) {
+        *errnop = ENOMEM;
+        *h_errnop = NO_RECOVERY;
+        return NSS_STATUS_TRYAGAIN;
+    }
+
+    /* First, fill in hostname */
+    r_name = buffer;
+    memcpy(r_name, hn, l+1);
+    idx = ALIGN(l+1);
+
+    /* Second, create (empty) aliases array */
+    r_aliases = buffer + idx;
+    *(char**) r_aliases = NULL;
+    idx += sizeof(char*);
+
+    /* Third, add addresses */
+    r_addr = buffer + idx;
+    if (af == AF_INET)
+        *(uint32_t*) r_addr = LOCALADDRESS_IPV4;
+    else
+        memcpy(r_addr, LOCALADDRESS_IPV6, 16);
+
+    idx += ALIGN(alen);
+
+    /* Fourth, add address pointer array */
+    r_addr_list = buffer + idx;
+    ((char**) r_addr_list)[0] = r_addr;
+    ((char**) r_addr_list)[1] = NULL;
+    idx += 2*sizeof(char*);
+
+    /* Verify the size matches */
+    assert(idx == ms);
+
+    result->h_name = r_name;
+    result->h_aliases = (char**) r_aliases;
+    result->h_addrtype = af;
+    result->h_length = alen;
+    result->h_addr_list = (char**) r_addr_list;
+
+    if (ttlp)
+        *ttlp = 0;
+
+    if (canonp)
+        *canonp = r_name;
+
+    return NSS_STATUS_SUCCESS;
+}
+
+
+enum nss_status
+_nss_dontstalkme_gethostbyname3_r(const char *name,
+                                 int af,
+                                 struct hostent *host,
+                                 char *buffer, size_t buflen,
+                                 int *errnop, int *h_errnop,
+                                 int32_t *ttlp,
+                                 char **canonp)
+{
+    unsigned int i;
+
+    if (af == AF_UNSPEC)
+        af = AF_INET;
+
+    if (af != AF_INET && af != AF_INET6) {
+        *errnop = EAFNOSUPPORT;
+        *h_errnop = NO_DATA;
+        return NSS_STATUS_UNAVAIL;
+    }
+
+    for (i = 0; i < ARRAY_CARDINALITY(stalkers); i++) {
+        if (!strcasecmp(stalkers[i], name)) {
+            break;
+        }
+    }
+    if (i == ARRAY_CARDINALITY(stalkers)) {
+        *errnop = ENOENT;
+        *h_errnop = HOST_NOT_FOUND;
+        return NSS_STATUS_NOTFOUND;
+    }
+
+    return fill_in_hostent(name, af, host, buffer, buflen, errnop, h_errnop, ttlp, canonp);
+}
+
+
+enum nss_status
+_nss_dontstalkme_gethostbyname2_r(const char *name,
+                                 int af,
+                                 struct hostent *host,
+                                 char *buffer, size_t buflen,
+                                 int *errnop, int *h_errnop)
+{
+    return _nss_dontstalkme_gethostbyname3_r(name,
+                                            af,
+                                            host,
+                                            buffer, buflen,
+                                            errnop, h_errnop,
+                                            NULL,
+                                            NULL);
+}
+
+
+enum nss_status
+ _nss_dontstalkme_gethostbyname_r(const char *name,
+                                 struct hostent *host,
+                                 char *buffer, size_t buflen,
+                                 int *errnop, int *h_errnop)
+{
+    return _nss_dontstalkme_gethostbyname3_r(name,
+                                            AF_UNSPEC,
+                                            host,
+                                            buffer, buflen,
+                                            errnop, h_errnop,
+                                            NULL,
+                                            NULL);
+}
diff --git a/src/nss-dontstalkme.h b/src/nss-dontstalkme.h
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/src/nss-dontstalkme.h