fix segfault in DNS mapping lookup code

the allocatorthread got pointers to RAM which were reallocated
behind the back, and if realloc() couldn't grow in-place, lead
to segfaults in applications that do a lot of DNS-lookups such
as webbrowsers.

closes #66
closes #31

thanks to @ravomavain for tracking down the issue.

Makefile

@@ -16,8 +16,8 @@ sysconfdir=$(prefix)/etc
 SRCS = $(sort $(wildcard src/*.c))
 OBJS = $(SRCS:.c=.o)
 LOBJS = src/nameinfo.o src/version.o \
-        src/core.o src/common.o src/libproxychains.o src/shm.o \
+        src/core.o src/common.o src/libproxychains.o \
-        src/allocator_thread.o src/ip_type.o src/stringdump.o \
+        src/allocator_thread.o src/ip_type.o \
         src/hostsreader.o src/hash.o src/debug.o
 
 GENH = src/version.h

src/allocator_thread.c

@@ -10,12 +10,10 @@
 #include <stddef.h>
 #include <errno.h>
 #include "allocator_thread.h"
-#include "shm.h"
 #include "debug.h"
 #include "ip_type.h"
 #include "mutex.h"
 #include "hash.h"
-#include "stringdump.h"
 
 /* stuff for our internal translation table */
 
@@ -30,6 +28,12 @@ typedef struct {
 	string_hash_tuple** list;
 } internal_ip_lookup_table;
 
+static void *dumpstring(char* s, size_t len) {
+	char* p = malloc(len);
+	if(p) memcpy(p, s, len);
+	return p;
+}
+
 pthread_mutex_t internal_ips_lock;
 internal_ip_lookup_table *internal_ips = NULL;
 internal_ip_lookup_table internal_ips_buf;

src/core.c

@@ -37,7 +37,6 @@
 
 #include "core.h"
 #include "common.h"
-#include "shm.h"
 #include "allocator_thread.h"
 
 extern int tcp_read_time_out;

src/libproxychains.c

@@ -95,15 +95,12 @@ static void* load_sym(char* symname, void* proxyfunc) {
 
 #define SETUP_SYM(X) do { true_ ## X = load_sym( # X, X ); } while(0)
 
-#include "shm.h"
 #include "allocator_thread.h"
-#include "stringdump.h"
 
 const char *proxychains_get_version(void);
 
 static void do_init(void) {
 	srand(time(NULL));
-	dumpstring_init(); // global string garbage can
 	core_initialize();
 	at_init();
 

src/shm.c

@@ -1,53 +0,0 @@
-#include <assert.h>
-#include <string.h>
-#include <limits.h>
-#include <string.h>
-#include <stdlib.h>
-#ifndef PAGE_SIZE
-#define PAGE_SIZE 4096
-#endif
-#include "shm.h"
-#include "debug.h"
-
-#if 0
-#include <sys/mman.h>
-#include <sys/ipc.h>
-#include <sys/shm.h>
-
-/* allocates shared memory which can be accessed from the parent and its childs */
-void *shm_realloc(void* old, size_t old_size, size_t new_size) {
-	//PFUNC();
-	void *nu = mmap(NULL, new_size, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANON, -1, 0);
-	if(old) {
-		if(!nu) return NULL;
-		assert(new_size >= old_size);
-		memcpy(nu, old, old_size);
-		munmap(old, old_size);
-	}
-	return nu;
-}
-#endif
-
-void stringpool_init(struct stringpool* sp) {
-	PFUNC();
-	memset(sp, 0, sizeof *sp);
-}
-
-char* stringpool_add(struct stringpool *sp, char* s, size_t len) {
-	//PFUNC();
-	if(len > sp->alloced - sp->used) {
-		size_t newsz = sp->used + len;
-		size_t inc = PAGE_SIZE - (newsz % PAGE_SIZE);
-		newsz += (inc == PAGE_SIZE) ? 0 : inc;
-		void* p = realloc(sp->start, newsz);
-		if(p) {
-			sp->start = p;
-			sp->alloced = newsz;
-		} else 
-			return 0;
-	}
-	char* ret = sp->start + sp->used;
-	memcpy(ret, s, len);
-	sp->used += len;
-	return ret;
-}

src/shm.h

@@ -1,17 +0,0 @@
-#ifndef SHM_H
-#define SHM_H
-#include <unistd.h>
-
-struct stringpool {
-	size_t alloced;
-	size_t used;
-	char* start;
-};
-
-void stringpool_init(struct stringpool* sp);
-char* stringpool_add(struct stringpool *sp, char* s, size_t len);
-#if 0
-void *shm_realloc(void* old, size_t old_size, size_t new_size);
-#endif
-//RcB: DEP "shm.c"
-#endif

src/stringdump.c

@@ -1,13 +0,0 @@
-#include "stringdump.h"
-#include "debug.h"
-
-struct stringpool mem;
-
-char *dumpstring(char* s, size_t len) {
-	PFUNC();
-	return stringpool_add(&mem, s, len);
-}
-
-void dumpstring_init(void) {
-	stringpool_init(&mem);
-}

src/stringdump.h

@@ -1,12 +0,0 @@
-#ifndef STRINGDUMP_H
-#define STRINGDUMP_H
-
-#include "shm.h"
-#include <unistd.h>
-
-char *dumpstring(char* s, size_t len);
-void dumpstring_init(void);
-
-//RcB: DEP "stringdump.h"
-
-#endif