Map addresses back to hostnames

Makefile

@@ -1,5 +1,5 @@
 -include make.conf
-OBJS := parser.o main.o redsocks.o log.o http-connect.o socks4.o socks5.o http-relay.o base.o base64.o md5.o http-auth.o utils.o redudp.o dnstc.o gen/version.o
+OBJS := parser.o main.o redsocks.o log.o http-connect.o socks4.o socks5.o http-relay.o base.o base64.o md5.o http-auth.o utils.o redudp.o dnstc.o rdns.o gen/version.o
 ifeq ($(DBG_BUILD),1)
 OBJS += debug.o
 endif

hash.h

@@ -0,0 +1,85 @@
+#ifndef _LINUX_HASH_H
+#define _LINUX_HASH_H
+/* Fast hashing routine for ints,  longs and pointers.
+   (C) 2002 Nadia Yvette Chambers, IBM */
+
+/*
+ * Knuth recommends primes in approximately golden ratio to the maximum
+ * integer representable by a machine word for multiplicative hashing.
+ * Chuck Lever verified the effectiveness of this technique:
+ * http://www.citi.umich.edu/techreports/reports/citi-tr-00-1.pdf
+ *
+ * These primes are chosen to be bit-sparse, that is operations on
+ * them can use shifts and additions instead of multiplications for
+ * machines where multiplications are slow.
+ */
+
+// #include <asm/types.h>
+// #include <linux/compiler.h>
+#include <limits.h>
+
+/* 2^31 + 2^29 - 2^25 + 2^22 - 2^19 - 2^16 + 1 */
+#define GOLDEN_RATIO_PRIME_32 0x9e370001UL
+/*  2^63 + 2^61 - 2^57 + 2^54 - 2^51 - 2^18 + 1 */
+#define GOLDEN_RATIO_PRIME_64 0x9e37fffffffc0001UL
+
+#if __WORDSIZE == 32
+#define GOLDEN_RATIO_PRIME GOLDEN_RATIO_PRIME_32
+#define hash_long(val, bits) hash_32(val, bits)
+#elif __WORDSIZE == 64
+#define hash_long(val, bits) hash_64(val, bits)
+#define GOLDEN_RATIO_PRIME GOLDEN_RATIO_PRIME_64
+#else
+#error Wordsize not 32 or 64
+#endif
+
+typedef unsigned int u32;
+typedef unsigned long long u64;
+
+static __always_inline u64 hash_64(u64 val, unsigned int bits)
+{
+	u64 hash = val;
+
+	/*  Sigh, gcc can't optimise this alone like it does for 32 bits. */
+	u64 n = hash;
+	n <<= 18;
+	hash -= n;
+	n <<= 33;
+	hash -= n;
+	n <<= 3;
+	hash += n;
+	n <<= 3;
+	hash -= n;
+	n <<= 4;
+	hash += n;
+	n <<= 2;
+	hash += n;
+
+	/* High bits are more random, so use them. */
+	return hash >> (64 - bits);
+}
+
+static inline u32 hash_32(u32 val, unsigned int bits)
+{
+	/* On some cpus multiply is faster, on others gcc will do shifts */
+	u32 hash = val * GOLDEN_RATIO_PRIME_32;
+
+	/* High bits are more random, so use them. */
+	return hash >> (32 - bits);
+}
+
+static inline unsigned long hash_ptr(const void *ptr, unsigned int bits)
+{
+	return hash_long((unsigned long)ptr, bits);
+}
+
+static inline u32 hash32_ptr(const void *ptr)
+{
+	unsigned long val = (unsigned long)ptr;
+
+#if BITS_PER_LONG == 64
+	val ^= (val >> 32);
+#endif
+	return (u32)val;
+}
+#endif /* _LINUX_HASH_H */

hashtable.h

@@ -0,0 +1,157 @@
+/*
+ * Statically sized hash table implementation
+ * (C) 2012  Sasha Levin <[email protected]>
+ */
+
+#ifndef _LINUX_HASHTABLE_H
+#define _LINUX_HASHTABLE_H
+
+#include "list.h"
+// #include <linux/types.h>
+// #include <linux/kernel.h>
+#include "hash.h"
+
+static unsigned int ilog2( unsigned int x )
+{
+  unsigned int ans = 0 ;
+  while( x>>=1 ) ans++;
+  return ans ;
+}
+
+#define DEFINE_HASHTABLE(name, bits)						\
+	struct hlist_head_t name[1 << (bits)] =					\
+			{ [0 ... ((1 << (bits)) - 1)] = HLIST_HEAD_INIT }
+
+#define DECLARE_HASHTABLE(name, bits)                                   	\
+	struct hlist_head_t name[1 << (bits)]
+
+#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
+#define HASH_SIZE(name) (ARRAY_SIZE(name))
+#define HASH_BITS(name) ilog2(HASH_SIZE(name))
+
+/* Use hash_32 when possible to allow for fast 32bit hashing in 64bit kernels. */
+#define hash_min(val, bits)							\
+	(sizeof(val) <= 4 ? hash_32(val, bits) : hash_long(val, bits))
+
+static inline void __hash_init(struct hlist_head_t *ht, unsigned int sz)
+{
+	unsigned int i;
+
+	for (i = 0; i < sz; i++)
+		INIT_HLIST_HEAD(&ht[i]);
+}
+
+/**
+ * hash_init - initialize a hash table
+ * @hashtable: hashtable to be initialized
+ *
+ * Calculates the size of the hashtable from the given parameter, otherwise
+ * same as hash_init_size.
+ *
+ * This has to be a macro since HASH_BITS() will not work on pointers since
+ * it calculates the size during preprocessing.
+ */
+#define hash_init(hashtable) __hash_init(hashtable, HASH_SIZE(hashtable))
+
+/**
+ * hash_add - add an object to a hashtable
+ * @hashtable: hashtable to add to
+ * @node: the &struct hlist_node of the object to be added
+ * @key: the key of the object to be added
+ */
+#define hash_add(hashtable, node, key)						\
+	hlist_add_head(node, &hashtable[hash_min(key, HASH_BITS(hashtable))])
+
+/**
+ * hash_hashed - check whether an object is in any hashtable
+ * @node: the &struct hlist_node of the object to be checked
+ */
+static inline bool hash_hashed(struct hlist_node_t *node)
+{
+	return !hlist_unhashed(node);
+}
+
+static inline bool __hash_empty(struct hlist_head_t *ht, unsigned int sz)
+{
+	unsigned int i;
+
+	for (i = 0; i < sz; i++)
+		if (!hlist_empty(&ht[i]))
+			return false;
+
+	return true;
+}
+
+/**
+ * hash_empty - check whether a hashtable is empty
+ * @hashtable: hashtable to check
+ *
+ * This has to be a macro since HASH_BITS() will not work on pointers since
+ * it calculates the size during preprocessing.
+ */
+#define hash_empty(hashtable) __hash_empty(hashtable, HASH_SIZE(hashtable))
+
+/**
+ * hash_del - remove an object from a hashtable
+ * @node: &struct hlist_node of the object to remove
+ */
+static inline void hash_del(struct hlist_node_t *node)
+{
+	hlist_del_init(node);
+}
+
+/**
+ * hash_for_each - iterate over a hashtable
+ * @name: hashtable to iterate
+ * @bkt: integer to use as bucket loop cursor
+ * @node: the &struct list_head to use as a loop cursor for each entry
+ * @obj: the type * to use as a loop cursor for each entry
+ * @member: the name of the hlist_node within the struct
+ */
+#define hash_for_each(name, bkt, node, obj, member)				\
+	for ((bkt) = 0, node = NULL; node == NULL && (bkt) < HASH_SIZE(name); (bkt)++)\
+		hlist_for_each_entry(obj, node, &name[bkt], member)
+
+/**
+ * hash_for_each_safe - iterate over a hashtable safe against removal of
+ * hash entry
+ * @name: hashtable to iterate
+ * @bkt: integer to use as bucket loop cursor
+ * @node: the &struct list_head to use as a loop cursor for each entry
+ * @tmp: a &struct used for temporary storage
+ * @obj: the type * to use as a loop cursor for each entry
+ * @member: the name of the hlist_node within the struct
+ */
+#define hash_for_each_safe(name, bkt, node, tmp, obj, member)			\
+	for ((bkt) = 0, node = NULL; node == NULL && (bkt) < HASH_SIZE(name); (bkt)++)\
+		hlist_for_each_entry_safe(obj, node, tmp, &name[bkt], member)
+
+/**
+ * hash_for_each_possible - iterate over all possible objects hashing to the
+ * same bucket
+ * @name: hashtable to iterate
+ * @obj: the type * to use as a loop cursor for each entry
+ * @node: the &struct list_head to use as a loop cursor for each entry
+ * @member: the name of the hlist_node within the struct
+ * @key: the key of the objects to iterate over
+ */
+#define hash_for_each_possible(name, obj, node, member, key)			\
+	hlist_for_each_entry(obj, node,	&name[hash_min(key, HASH_BITS(name))], member)
+
+/**
+ * hash_for_each_possible_safe - iterate over all possible objects hashing to the
+ * same bucket safe against removals
+ * @name: hashtable to iterate
+ * @obj: the type * to use as a loop cursor for each entry
+ * @node: the &struct list_head to use as a loop cursor for each entry
+ * @tmp: a &struct used for temporary storage
+ * @member: the name of the hlist_node within the struct
+ * @key: the key of the objects to iterate over
+ */
+#define hash_for_each_possible_safe(name, obj, node, tmp, member, key)		\
+	hlist_for_each_entry_safe(obj, node, tmp,				\
+		&name[hash_min(key, HASH_BITS(name))], member)
+
+
+#endif
+

http-connect.c

@@ -30,6 +30,7 @@
 #include "log.h"
 #include "redsocks.h"
 #include "http-auth.h"
+#include "rdns.h"
 
 typedef enum httpc_state_t {
 	httpc_new,
@@ -246,7 +247,7 @@ static struct evbuffer *httpc_mkconnect(redsocks_client *client)
 
 	// TODO: do accurate evbuffer_expand() while cleaning up http-auth
 	len = evbuffer_add_printf(buff, "CONNECT %s:%u HTTP/1.0\r\n",
-		inet_ntoa(client->destaddr.sin_addr),
+		get_hostname_for_addr(inet_ntoa(client->destaddr.sin_addr)),
 		ntohs(client->destaddr.sin_port));
 	if (len < 0) {
 		redsocks_log_errno(client, LOG_ERR, "evbufer_add_printf");