CFNetwork Programming Guide

CFNetwork封装了具体的网路实现，可以通过CFxxx等api来简单的实现操作
CFNetwork也是基于core foundation的两个API,CFSocket和CFStream



CFSocket是基于BSD socket的抽象，使用CFSocketCreate、CFSocketCreateWithNative
CFSocketCreateRunLoopSource、CFRunLoopAddSource方法创建CFSocket
CFStream提供两种抽象的Stream类型，一种是CFReadStream，一种是CFWriteStream.

使用CFStream读写流数据跟读取UNIX文件类似，首先指定stream的类型（内存、文件、socket等）
然后打开流，进行读写操作。避免主线程阻塞，使用异步方法来读取流。
CFStream支持SSL加密，通过设置kCFStreamPropertySSLSettings属性来设置。



CFNetwork有几种API组成，每种指定着一种网络协议。每种协议的API定义都是类似的
CFFTP API：
1：从ftp服务器中下载文件
2：上传文件到ftp服务器
3：在ftp服务器上创建文件
4：Download a directory listing from an FTP server

CFHTTP API：

CFHTTPAuthentication API支持四种认证方案：
Basic
Digest
NT LAN Manager (NTLM)
Simple and Protected GSS-API Negotiation Mechanism (SPNEGO)

CFHost API处理步骤：
1：创建一个CFHost对象
2：解析CFHost对象
3：获取地址、host名称等信息
4：销毁CFHost对象

CFNetServices API（使用Bonjour服务需要CFNetServices API）

CFNetDiagnostics API（当网络有问题的时候，可以通过这个API来快速定位问题）

//流的读操作

//创建一个读的流:
CFReadStreamRef myReadStream = CFReadStreamCreateWithFile(kCFAllocatorDefault,
fileURL);
//打开一个读的流
if (!CFReadStreamOpen(myReadStream)) {
CFStreamError myErr = CFReadStreamGetError(myReadStream);
// An error has occurred.
if (myErr.domain == kCFStreamErrorDomainPOSIX) {
// Interpret myErr.error as a UNIX errno.
} else if (myErr.domain == kCFStreamErrorDomainMacOSStatus) {
// Interpret myErr.error as a MacOS error code.
OSStatus macError = (OSStatus)myErr.error;
// Check other error domains.
}
}
//从流中读取数据
CFIndex numBytesRead;
do {
UInt8 buf[myReadBufferSize]; // define myReadBufferSize as desired
numBytesRead = CFReadStreamRead(myReadStream, buf, sizeof(buf));
if( numBytesRead > 0 ) {
handleBytes(buf, numBytesRead);
} else if( numBytesRead < 0 ) {
CFStreamError error = CFReadStreamGetError(myReadStream);
reportError(error);
}
} while( numBytesRead > 0 );
//关闭流
CFReadStreamClose(myReadStream);
CFRelease(myReadStream);
myReadStream = NULL;

//流的写操作

CFWriteStreamRef myWriteStream =
CFWriteStreamCreateWithFile(kCFAllocatorDefault, fileURL);
if (!CFWriteStreamOpen(myWriteStream)) {
CFStreamError myErr = CFWriteStreamGetError(myWriteStream);
// An error has occurred.
if (myErr.domain == kCFStreamErrorDomainPOSIX) {
// Interpret myErr.error as a UNIX errno.
} else if (myErr.domain == kCFStreamErrorDomainMacOSStatus) {
// Interpret myErr.error as a MacOS error code.
OSStatus macError = (OSStatus)myErr.error;
// Check other error domains.
}
}
UInt8 buf[] = "Hello, world";
CFIndex bufLen = (CFIndex)strlen(buf);
while (!done) {
CFIndex bytesWritten = CFWriteStreamWrite(myWriteStream, buf, (CFIndex)bufLen);
if (bytesWritten < 0) {
CFStreamError error = CFWriteStreamGetError(myWriteStream);
reportError(error);
} else if (bytesWritten == 0) {
if (CFWriteStreamGetStatus(myWriteStream) == kCFStreamStatusAtEnd) {
done = TRUE;
}
} else if (bytesWritten != bufLen) {
// Determine how much has been written and adjust the buffer
bufLen = bufLen - bytesWritten;
memmove(buf, buf + bytesWritten, bufLen);
// Figure out what went wrong with the write stream
CFStreamError error = CFWriteStreamGetError(myWriteStream);
reportError(error);
}
}
CFWriteStreamClose(myWriteStream);
CFRelease(myWriteStream);
myWriteStream = NULL;

在数据转化的时候，如果是同步的，那么就有可能会阻塞主线程，有两种方式可以避免：
1：使用run loop（查看Threading Programming Guide）：注册run loop的通知方法，然后在对应的事件上发起通知。
2：使用Polling（轮训）

//创建一个socket，读流
CFStreamCreatePairWithSocketToCFHost(kCFAllocatorDefault, host, port,
&myReadStream, NULL);
//创建一个容器，主要为了回调方法用
CFStreamClientContext myContext = {0, myPtr, myRetain, myRelease, myCopyDesc};
//创建run loop
CFOptionFlags registeredEvents = kCFStreamEventHasBytesAvailable |
kCFStreamEventErrorOccurred | kCFStreamEventEndEncountered;
if (CFReadStreamSetClient(myReadStream, registeredEvents, myCallBack, &myContext))
{
CFReadStreamScheduleWithRunLoop(myReadStream, CFRunLoopGetCurrent(),
kCFRunLoopCommonModes);
}
//创建一个非阻塞的读流
if (!CFReadStreamOpen(myReadStream)) {
CFStreamError myErr = CFReadStreamGetError(myReadStream);
if (myErr.error != 0) {
// An error has occurred.
if (myErr.domain == kCFStreamErrorDomainPOSIX) {
// Interpret myErr.error as a UNIX errno.
strerror(myErr.error);
} else if (myErr.domain == kCFStreamErrorDomainMacOSStatus) {
OSStatus macError = (OSStatus)myErr.error;
}
// Check other domains.
} else
// start the run loop
CFRunLoopRun();
}

//网络请求回调方法
void myCallBack (CFReadStreamRef stream, CFStreamEventType event, void *myPtr) {
switch(event) {
case kCFStreamEventHasBytesAvailable:
// It is safe to call CFReadStreamRead; it won’t block because bytes
// are available.
UInt8 buf[BUFSIZE];
CFIndex bytesRead = CFReadStreamRead(stream, buf, BUFSIZE);
if (bytesRead > 0) {
handleBytes(buf, bytesRead);
}
// It is safe to ignore a value of bytesRead that is less than or
// equal to zero because these cases will generate other events.
break;
case kCFStreamEventErrorOccurred:
CFStreamError error = CFReadStreamGetError(stream);
reportError(error);
CFReadStreamUnscheduleFromRunLoop(stream, CFRunLoopGetCurrent(),
kCFRunLoopCommonModes);
CFReadStreamClose(stream);
CFRelease(stream);
break;
case kCFStreamEventEndEncountered:
reportCompletion();
CFReadStreamUnscheduleFromRunLoop(stream, CFRunLoopGetCurrent(),
kCFRunLoopCommonModes);
CFReadStreamClose(stream);
CFRelease(stream);
break;
}
}

//一般情况下，不建议使用轮训来处理读写流的操作

//轮训一个读流
while (!done) {
if (CFReadStreamHasBytesAvailable(myReadStream)) {
UInt8 buf[BUFSIZE];
CFIndex bytesRead = CFReadStreamRead(myReadStream, buf, BUFSIZE);
if (bytesRead < 0) {
CFStreamError error = CFReadStreamGetError(myReadStream);
reportError(error);
} else if (bytesRead == 0) {
if (CFReadStreamGetStatus(myReadStream) == kCFStreamStatusAtEnd) {
done = TRUE;
}
} else {
handleBytes(buf, bytesRead);
}
} else {
// ...do something else while you wait...
}
}

//轮训一个写的流
UInt8 buf[] = "Hello, world";
UInt32 bufLen = strlen(buf);
while (!done) {
if (CFWriteStreamCanAcceptBytes(myWriteStream)) {
int bytesWritten = CFWriteStreamWrite(myWriteStream, buf, strlen(buf));
if (bytesWritten < 0) {
CFStreamError error = CFWriteStreamGetError(myWriteStream);
reportError(error);
} else if (bytesWritten == 0) {
if (CFWriteStreamGetStatus(myWriteStream) == kCFStreamStatusAtEnd)
{
done = TRUE;
}
} else if (bytesWritten != strlen(buf)) {
// Determine how much has been written and adjust the buffer
bufLen = bufLen - bytesWritten;
memmove(buf, buf + bytesWritten, bufLen);
// Figure out what went wrong with the write stream
CFStreamError error = CFWriteStreamGetError(myWriteStream);
reportError(error);
}
} else {
// ...do something else while you wait...
}
}

http请求

//创建一个http request请求
CFStringRef bodyString = CFSTR(""); // Usually used for POST data
CFDataRef bodyData = CFStringCreateExternalRepresentation(kCFAllocatorDefault,
bodyString, kCFStringEncodingUTF8, 0);
CFStringRef headerFieldName = CFSTR("X-My-Favorite-Field");
CFStringRef headerFieldValue = CFSTR("Dreams");
CFStringRef url = CFSTR("http://www.apple.com");
CFURLRef myURL = CFURLCreateWithString(kCFAllocatorDefault, url, NULL);
CFStringRef requestMethod = CFSTR("GET");
CFHTTPMessageRef myRequest =
CFHTTPMessageCreateRequest(kCFAllocatorDefault, requestMethod, myURL,CFDataRef bodyDataExt = CFStringCreateExternalRepresentation(kCFAllocatorDefault,
bodyData, kCFStringEncodingUTF8, 0);
CFHTTPMessageSetBody(myRequest, bodyDataExt);
CFHTTPMessageSetHeaderFieldValue(myRequest, headerFieldName, headerFieldValue);
CFDataRef mySerializedRequest = CFHTTPMessageCopySerializedMessage(myRequest);

//release请求
CFRelease(myRequest);
CFRelease(myURL);
CFRelease(url);
CFRelease(mySerializedRequest);
myRequest = NULL;
mySerializedRequest = NULL;
Communicating with HTTP Servers
Creating a CFHTTP Request
2012-

http相应

//反序列化信息
CFHTTPMessageRef myMessage = CFHTTPMessageCreateEmpty(kCFAllocatorDefault, TRUE);
if (!CFHTTPMessageAppendBytes(myMessage, &data, numBytes)) {
//Handle parsing error
}
//反序列化成功
if (CFHTTPMessageIsHeaderComplete(myMessage)) {
// Perform processing.
}
//反序列化之后可以调用CFHTTPMessageCopyBody等方法获取对应的数据

//通过读的流，序列化一个http请求
CFStringRef url = CFSTR("http://www.apple.com");
CFURLRef myURL = CFURLCreateWithString(kCFAllocatorDefault, url, NULL);
CFStringRef requestMethod = CFSTR("GET");
CFHTTPMessageRef myRequest = CFHTTPMessageCreateRequest(kCFAllocatorDefault,
requestMethod, myUrl, kCFHTTPVersion1_1);
CFHTTPMessageSetBody(myRequest, bodyData);
CFHTTPMessageSetHeaderFieldValue(myRequest, headerField, value);
CFReadStreamRef myReadStream = CFReadStreamCreateForHTTPRequest(kCFAllocatorDefault,
myRequest);
CFReadStreamOpen(myReadStream);

//通过CFReadStreamCopyProperty，监听响应
CFHTTPMessageRef myResponse =
(CFHTTPMessageRef)CFReadStreamCopyProperty(myReadStream,
kCFStreamPropertyHTTPResponseHeader);
//返回响应code
UInt32 myErrCode = CFHTTPMessageGetResponseStatusCode(myResponse);
//重定向流
CFReadStreamClose(myReadStream);
CFReadStreamRef myReadStream =
CFReadStreamCreateForHTTPRequest(kCFAllocatorDefault, myRequest);
if (CFReadStreamSetProperty(myReadStream, kCFStreamPropertyHTTPShouldAutoredirect,
kCFBooleanTrue) == false) {
// something went wrong, exit
}
CFReadStreamOpen(myReadStream);

//关闭流就相当于关闭了这个请求

Authenticating HTTP Servers
如果一个http服务器返回401或者407，那么表示服务端需要认证，请求中需要带上证书，在API中，证书放在CFHTTPAuthentication对象中。

//创建一个authentication对象
if (!authentication) {
CFHTTPMessageRef responseHeader =
(CFHTTPMessageRef) CFReadStreamCopyProperty(
readStream,
kCFStreamPropertyHTTPResponseHeader
);
// Get the authentication information from the response.
authentication = CFHTTPAuthenticationCreateFromResponse(NULL, responseHeader);
CFRelease(responseHeader);
}

//判断这个authentication是否验证
CFStreamError err;
if (!authentication) {
// the newly created authentication object is bad, must return
return;
} else if (!CFHTTPAuthenticationIsValid(authentication, &err)) {// destroy authentication and credentials
if (credentials) {
CFRelease(credentials);
credentials = NULL;
}
CFRelease(authentication);
authentication = NULL;
// check for bad credentials (to be treated separately)
if (err.domain == kCFStreamErrorDomainHTTP &&
(err.error == kCFStreamErrorHTTPAuthenticationBadUserName
|| err.error == kCFStreamErrorHTTPAuthenticationBadPassword))
{
retryAuthorizationFailure(&authentication);
return;
} else {
errorOccurredLoadingImage(err);
}
}
//如果找到证书，那么使用它
else {
cancelLoad();
if (credentials) {
resumeWithCredentials();
}
// are a user name & password needed?
else if (CFHTTPAuthenticationRequiresUserNameAndPassword(authentication))
{
CFStringRef realm = NULL;
CFURLRef url = CFHTTPMessageCopyRequestURL(request);
// check if you need an account domain so you can display it if necessary
if (!CFHTTPAuthenticationRequiresAccountDomain(authentication)) {
realm = CFHTTPAuthenticationCopyRealm(authentication);
}
// ...prompt user for user name (user), password (pass)
// and if necessary domain (domain) to give to the server...
// Guarantee values
if (!user) user = CFSTR("");
if (!pass) pass = CFSTR("");
CFDictionarySetValue(credentials, kCFHTTPAuthenticationUsername, user);
CFDictionarySetValue(credentials, kCFHTTPAuthenticationPassword, pass);
// Is an account domain needed? (used currently for NTLM only)
if (CFHTTPAuthenticationRequiresAccountDomain(authentication)) {
if (!domain) domain = CFSTR("");
CFDictionarySetValue(credentials,kCFHTTPAuthenticationAccountDomain, domain);
}
if (realm) CFRelease(realm);
CFRelease(url);
}
else {
resumeWithCredentials();
}
}
//发起拥有证书的请求
void resumeWithCredentials() {
// Apply whatever credentials we've built up to the old request
if (!CFHTTPMessageApplyCredentialDictionary(request, authentication,
credentials, NULL)) {
errorOccurredLoadingImage();
} else {
// Now that we've updated our request, retry the load
loadRequest();
}
}

把证书放在内存中

//创建一个array来放不同的证书
CFMutableArrayRef authArray;
//创建一个证书的映射
CFMutableDictionaryRef credentialsDict;
//修改映射
CFDictionaryRemoveValue(credentialsDict, authentication);
//寻找一个合适的证书
CFHTTPAuthenticationRef findAuthenticationForRequest {
int i, c = CFArrayGetCount(authArray);
for (i = 0; i < c; i ++) {
CFHTTPAuthenticationRef auth = (CFHTTPAuthenticationRef)
CFArrayGetValueAtIndex(authArray, i);
if (CFHTTPAuthenticationAppliesToRequest(auth, request)) {
return auth;
}
}
return NULL;
}
//获取证书
credentials = CFDictionaryGetValue(credentialsDict, authentication);

持久化证书存储

CFMutableDictionaryRef findCredentialsForAuthentication(
CFHTTPAuthenticationRef auth);
void saveCredentialsForRequest(void);
//如果证书不在缓存中，那么从钥匙串中寻找
didFind =
SecKeychainFindInternetPassword(NULL,
strlen(host), host,
realm ? strlen(realm) : 0, realm,
0, NULL,
path ? strlen(path) : 0, path,
port,
protocolType,
authenticationType,
0, NULL,
&itemRef);

//从钥匙串中加载服务器证书
if (didFind == noErr) {
SecKeychainAttribute attr;
SecKeychainAttributeList attrList;
UInt32 length;
void *outData;
// To set the account name attribute
attr.tag = kSecAccountItemAttr;
attr.length = 0;
attr.data = NULL;
attrList.count = 1;
attrList.attr = &attr;
if (SecKeychainItemCopyContent(itemRef, NULL, &attrList, &length, &outData)
== noErr) {
// attr.data is the account (username) and outdata is the password
CFStringRef username =
CFStringCreateWithBytes(kCFAllocatorDefault, attr.data,
attr.length, kCFStringEncodingUTF8, false);
CFStringRef password =
CFStringCreateWithBytes(kCFAllocatorDefault, outData, length,
kCFStringEncodingUTF8, false);
SecKeychainItemFreeContent(&attrList, outData);
// create credentials dictionary and fill it with the user name & password
credentials =
CFDictionaryCreateMutable(NULL, 0,
&kCFTypeDictionaryKeyCallBacks,
&kCFTypeDictionaryValueCallBacks);
CFDictionarySetValue(credentials, kCFHTTPAuthenticationUsername,
username);
CFDictionarySetValue(credentials, kCFHTTPAuthenticationPassword,
password);
CFRelease(username);
CFRelease(password);
}
CFRelease(itemRef);
}

//修改钥匙串的实体
// Set the attribute to the account name
attr.tag = kSecAccountItemAttr;
attr.length = strlen(username);
attr.data = (void*)username;
// Modify the keychain entry
SecKeychainItemModifyContent(itemRef, &attrList, strlen(password),
(void *)password);
//保存钥匙串实体
SecKeychainAddInternetPassword(NULL,strlen(host), host,
realm ? strlen(realm) : 0, realm,
strlen(username), username,
path ? strlen(path) : 0, path,
port,
protocolType,
authenticationType,
strlen(password), password,
&itemRef);

FTP Servers

//流的结构
typedef struct MyStreamInfo {
CFWriteStreamRef writeStream;
CFReadStreamRef readStream;
CFDictionaryRef proxyDict;
SInt64 fileSize;
UInt32 totalBytesWritten;
UInt32 leftOverByteCount;
UInt8 buffer[kMyBufferSize];
} MyStreamInfo;

//从读流中写数据
bytesRead = CFReadStreamRead(info->readStream, info->buffer, kMyBufferSize);
//...make sure bytesRead > 0 ...
bytesWritten = 0;
while (bytesWritten < bytesRead) {
CFIndex result;
result = CFWriteStreamWrite(info->writeStream, info->buffer + bytesWritten,
bytesRead - bytesWritten);
if (result <= 0) {
fprintf(stderr, "CFWriteStreamWrite returned %ld\n", result);
goto exit;
}
bytesWritten += result;
}
info->totalBytesWritten += bytesWritten;

//上传文件
do {
// Check for leftover data
if (info->leftOverByteCount > 0) {
bytesRead = info->leftOverByteCount;
} else {
// Make sure there is no error reading from the file
bytesRead = CFReadStreamRead(info->readStream, info->buffer,
kMyBufferSize);
if (bytesRead < 0) {
fprintf(stderr, "CFReadStreamRead returned %ld\n", bytesRead);
goto exit;
}
totalBytesRead += bytesRead;
}
// Write the data to the write stream
bytesWritten = CFWriteStreamWrite(info->writeStream, info->buffer, bytesRead);
if (bytesWritten > 0) {
info->totalBytesWritten += bytesWritten;
// Store leftover data until kCFStreamEventCanAcceptBytes event occurs
again
if (bytesWritten < bytesRead) {
info->leftOverByteCount = bytesRead - bytesWritten;
memmove(info->buffer, info->buffer + bytesWritten,
info->leftOverByteCount);
} else {
info->leftOverByteCount = 0;
}
} else {
if (bytesWritten < 0)
fprintf(stderr, "CFWriteStreamWrite returned %ld\n", bytesWritten);
break;
}
} while (CFWriteStreamCanAcceptBytes(info->writeStream));

创建一个远程目录

下载目录清单

//从目录清单下载数据
// If previous call had unloaded data
int offset = info->leftOverByteCount;
// Load data from the read stream, accounting for the offset
bytesRead = CFReadStreamRead(info->readStream, info->buffer + offset,
kMyBufferSize - offset);
if (bytesRead < 0) {
fprintf(stderr, "CFReadStreamRead returned %ld\n", bytesRead);
break;
} else if (bytesRead == 0) {
break;
}
bufSize = bytesRead + offset;
totalBytesRead += bufSize;

//下载整个目录并且解析
do
{
bufRemaining = info->buffer + totalBytesConsumed;
bytesConsumed = CFFTPCreateParsedResourceListing(NULL, bufRemaining,
bufSize, &parsedDict);
if (bytesConsumed > 0) {
// Make sure CFFTPCreateParsedResourceListing was able to properly
// parse the incoming data
if (parsedDict != NULL) {
// ...Print out data from parsedDict...
CFRelease(parsedDict);
}
totalBytesConsumed += bytesConsumed;
bufSize -= bytesConsumed;
info->leftOverByteCount = bufSize;
} else if (bytesConsumed == 0) {
// This is just in case. It should never happen due to the large buffer
size
info->leftOverByteCount = bufSize;
totalBytesRead -= info->leftOverByteCount;
memmove(info->buffer, bufRemaining, info->leftOverByteCount);
} else if (bytesConsumed == -1) {
fprintf(stderr, "CFFTPCreateParsedResourceListing parse failure\n");
// ...Break loop and cleanup...
}
} while (bytesConsumed > 0);

使用网络诊断

case kCFStreamEventErrorOccurred:
CFNetDiagnosticRef diagRef =
CFNetDiagnosticCreateWithStreams(NULL, stream, NULL);
(void)CFNetDiagnosticDiagnoseProblemInteractively(diagRef);
CFStreamError error = CFReadStreamGetError(stream);
reportError(error);
CFReadStreamClose(stream);
CFRelease(stream);
break;