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fishhook nwlog_legacy_v to avoid log spam on websocket reconnect

Reviewed By: mmmulani, javache

Differential Revision: D5570896

fbshipit-source-id: be98f500434bd2a0113b9abca20c9f21102c09d1
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emilsjolander authored and facebook-github-bot committed Aug 8, 2017
1 parent 898790d commit 878b7e42fae990df745af2db6ac50cbac8a8ce1c
@@ -11,11 +11,27 @@
#import <React/RCTConvert.h>
#import <React/RCTDefines.h>
#import <fishhook/fishhook.h>
#import "RCTSRWebSocket.h"
#if RCT_DEV // Only supported in dev mode
static void (*orig_nwlog_legacy_v)(int, char*, va_list);
static void my_nwlog_legacy_v(int level, char *format, va_list args) {
static const uint buffer_size = 256;
static char buffer[buffer_size];
va_list copy;
va_copy(copy, args);
vsnprintf(buffer, buffer_size, format, copy);
va_end(copy);
if (strstr(buffer, "nw_connection_get_connected_socket_block_invoke") == NULL) {
orig_nwlog_legacy_v(level, format, args);
}
}
@interface RCTReconnectingWebSocket () <RCTSRWebSocketDelegate>
@end
@@ -26,6 +42,16 @@ @implementation RCTReconnectingWebSocket {
@synthesize delegate = _delegate;
+ (void)load
{
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
rebind_symbols((struct rebinding[1]){
{"nwlog_legacy_v", my_nwlog_legacy_v, (void *)&orig_nwlog_legacy_v}
}, 1);
});
}
- (instancetype)initWithURL:(NSURL *)url
{
if (self = [super init]) {
@@ -9,6 +9,7 @@
/* Begin PBXBuildFile section */
1338BBE01B04ACC80064A9C9 /* RCTSRWebSocket.m in Sources */ = {isa = PBXBuildFile; fileRef = 1338BBDD1B04ACC80064A9C9 /* RCTSRWebSocket.m */; };
1338BBE11B04ACC80064A9C9 /* RCTWebSocketExecutor.m in Sources */ = {isa = PBXBuildFile; fileRef = 1338BBDF1B04ACC80064A9C9 /* RCTWebSocketExecutor.m */; };
13526A521F362F7F0008EF00 /* libfishhook.a in Frameworks */ = {isa = PBXBuildFile; fileRef = 13526A511F362F7F0008EF00 /* libfishhook.a */; };
2D3B5F3D1D9B165B00451313 /* RCTSRWebSocket.m in Sources */ = {isa = PBXBuildFile; fileRef = 1338BBDD1B04ACC80064A9C9 /* RCTSRWebSocket.m */; };
2D3B5F3E1D9B165B00451313 /* RCTWebSocketExecutor.m in Sources */ = {isa = PBXBuildFile; fileRef = 1338BBDF1B04ACC80064A9C9 /* RCTWebSocketExecutor.m */; };
2D3B5F3F1D9B165B00451313 /* RCTWebSocketObserver.m in Sources */ = {isa = PBXBuildFile; fileRef = 3DB9106E1C74B1ED00838BBE /* RCTWebSocketObserver.m */; };
@@ -24,6 +25,7 @@
1338BBDD1B04ACC80064A9C9 /* RCTSRWebSocket.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = RCTSRWebSocket.m; sourceTree = "<group>"; };
1338BBDE1B04ACC80064A9C9 /* RCTWebSocketExecutor.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = RCTWebSocketExecutor.h; sourceTree = "<group>"; };
1338BBDF1B04ACC80064A9C9 /* RCTWebSocketExecutor.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = RCTWebSocketExecutor.m; sourceTree = "<group>"; };
13526A511F362F7F0008EF00 /* libfishhook.a */ = {isa = PBXFileReference; lastKnownFileType = archive.ar; name = libfishhook.a; path = "libfishhook.a"; sourceTree = "<group>"; };
2D2A28881D9B049200D4039D /* libRCTWebSocket-tvOS.a */ = {isa = PBXFileReference; explicitFileType = archive.ar; includeInIndex = 0; path = "libRCTWebSocket-tvOS.a"; sourceTree = BUILT_PRODUCTS_DIR; };
3C86DF461ADF2C930047B81A /* libRCTWebSocket.a */ = {isa = PBXFileReference; explicitFileType = archive.ar; includeInIndex = 0; path = libRCTWebSocket.a; sourceTree = BUILT_PRODUCTS_DIR; };
3C86DF7A1ADF695F0047B81A /* RCTWebSocketModule.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = RCTWebSocketModule.h; sourceTree = "<group>"; };
@@ -34,7 +36,26 @@
A12E9E2D1E5DEC4E0029001B /* RCTReconnectingWebSocket.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = RCTReconnectingWebSocket.m; sourceTree = "<group>"; };
/* End PBXFileReference section */
/* Begin PBXFrameworksBuildPhase section */
13526A4F1F362F770008EF00 /* Frameworks */ = {
isa = PBXFrameworksBuildPhase;
buildActionMask = 2147483647;
files = (
13526A521F362F7F0008EF00 /* libfishhook.a in Frameworks */,
);
runOnlyForDeploymentPostprocessing = 0;
};
/* End PBXFrameworksBuildPhase section */
/* Begin PBXGroup section */
13526A501F362F7F0008EF00 /* Frameworks */ = {
isa = PBXGroup;
children = (
13526A511F362F7F0008EF00 /* libfishhook.a */,
);
name = Frameworks;
sourceTree = "<group>";
};
3C86DF3D1ADF2C930047B81A = {
isa = PBXGroup;
children = (
@@ -49,6 +70,7 @@
3C86DF7A1ADF695F0047B81A /* RCTWebSocketModule.h */,
3C86DF7B1ADF695F0047B81A /* RCTWebSocketModule.m */,
3C86DF471ADF2C930047B81A /* Products */,
13526A501F362F7F0008EF00 /* Frameworks */,
);
indentWidth = 2;
sourceTree = "<group>";
@@ -87,6 +109,7 @@
buildConfigurationList = 3C86DF5A1ADF2C930047B81A /* Build configuration list for PBXNativeTarget "RCTWebSocket" */;
buildPhases = (
3C86DF421ADF2C930047B81A /* Sources */,
13526A4F1F362F770008EF00 /* Frameworks */,
);
buildRules = (
);
View
@@ -0,0 +1,22 @@
// Copyright (c) 2013, Facebook, Inc.
// All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
// * Redistributions of source code must retain the above copyright notice,
// this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above copyright notice,
// this list of conditions and the following disclaimer in the documentation
// and/or other materials provided with the distribution.
// * Neither the name Facebook nor the names of its contributors may be used to
// endorse or promote products derived from this software without specific
// prior written permission.
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
@@ -0,0 +1,75 @@
# fishhook
__fishhook__ is a very simple library that enables dynamically rebinding symbols in Mach-O binaries running on iOS in the simulator and on device. This provides functionality that is similar to using [`DYLD_INTERPOSE`][interpose] on OS X. At Facebook, we've found it useful as a way to hook calls in libSystem for debugging/tracing purposes (for example, auditing for double-close issues with file descriptors).
[interpose]: http://opensource.apple.com/source/dyld/dyld-210.2.3/include/mach-o/dyld-interposing.h "<mach-o/dyld-interposing.h>"
## Usage
Once you add `fishhook.h`/`fishhook.c` to your project, you can rebind symbols as follows:
```Objective-C
#import <dlfcn.h>
#import <UIKit/UIKit.h>
#import "AppDelegate.h"
#import "fishhook.h"
static int (*orig_close)(int);
static int (*orig_open)(const char *, int, ...);
int my_close(int fd) {
printf("Calling real close(%d)\n", fd);
return orig_close(fd);
}
int my_open(const char *path, int oflag, ...) {
va_list ap = {0};
mode_t mode = 0;
if ((oflag & O_CREAT) != 0) {
// mode only applies to O_CREAT
va_start(ap, oflag);
mode = va_arg(ap, int);
va_end(ap);
printf("Calling real open('%s', %d, %d)\n", path, oflag, mode);
return orig_open(path, oflag, mode);
} else {
printf("Calling real open('%s', %d)\n", path, oflag);
return orig_open(path, oflag, mode);
}
}
int main(int argc, char * argv[])
{
@autoreleasepool {
rebind_symbols((struct rebinding[2]){{"close", my_close, (void *)&orig_close}, {"open", my_open, (void *)&orig_open}}, 2);
// Open our own binary and print out first 4 bytes (which is the same
// for all Mach-O binaries on a given architecture)
int fd = open(argv[0], O_RDONLY);
uint32_t magic_number = 0;
read(fd, &magic_number, 4);
printf("Mach-O Magic Number: %x \n", magic_number);
close(fd);
return UIApplicationMain(argc, argv, nil, NSStringFromClass([AppDelegate class]));
}
}
```
### Sample output
```
Calling real open('/var/mobile/Applications/161DA598-5B83-41F5-8A44-675491AF6A2C/Test.app/Test', 0)
Mach-O Magic Number: feedface
Calling real close(3)
...
```
## How it works
`dyld` binds lazy and non-lazy symbols by updating pointers in particular sections of the `__DATA` segment of a Mach-O binary. __fishhook__ re-binds these symbols by determining the locations to update for each of the symbol names passed to `rebind_symbols` and then writing out the corresponding replacements.
For a given image, the `__DATA` segment may contain two sections that are relevant for dynamic symbol bindings: `__nl_symbol_ptr` and `__la_symbol_ptr`. `__nl_symbol_ptr` is an array of pointers to non-lazily bound data (these are bound at the time a library is loaded) and `__la_symbol_ptr` is an array of pointers to imported functions that is generally filled by a routine called `dyld_stub_binder` during the first call to that symbol (it's also possible to tell `dyld` to bind these at launch). In order to find the name of the symbol that corresponds to a particular location in one of these sections, we have to jump through several layers of indirection. For the two relevant sections, the section headers (`struct section`s from `<mach-o/loader.h>`) provide an offset (in the `reserved1` field) into what is known as the indirect symbol table. The indirect symbol table, which is located in the `__LINKEDIT` segment of the binary, is just an array of indexes into the symbol table (also in `__LINKEDIT`) whose order is identical to that of the pointers in the non-lazy and lazy symbol sections. So, given `struct section nl_symbol_ptr`, the corresponding index in the symbol table of the first address in that section is `indirect_symbol_table[nl_symbol_ptr->reserved1]`. The symbol table itself is an array of `struct nlist`s (see `<mach-o/nlist.h>`), and each `nlist` contains an index into the string table in `__LINKEDIT` which where the actual symbol names are stored. So, for each pointer `__nl_symbol_ptr` and `__la_symbol_ptr`, we are able to find the corresponding symbol and then the corresponding string to compare against the requested symbol names, and if there is a match, we replace the pointer in the section with the replacement.
The process of looking up the name of a given entry in the lazy or non-lazy pointer tables looks like this:
![Visual explanation](http://i.imgur.com/HVXqHCz.png)
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