提交

Pods/AliyunOSSiOS/AliyunOSSSDK/OSSHttpdns.m

@@ -0,0 +1,147 @@
+//
+//  OSSHttpdns.m
+//  AliyunOSSiOS
+//
+//  Created by zhouzhuo on 5/1/16.
+//  Copyright © 2016 zhouzhuo. All rights reserved.
+//
+
+#import "OSSLog.h"
+#import "OSSHttpdns.h"
+#import "OSSIPv6Adapter.h"
+
+NSString * const OSS_HTTPDNS_SERVER_IP = @"203.107.1.1";
+NSString * const OSS_HTTPDNS_SERVER_PORT = @"80";
+
+NSString * const ACCOUNT_ID = @"181345";
+NSTimeInterval const MAX_ENDURABLE_EXPIRED_TIME_IN_SECOND = 60; // The DNS entry's expiration time in seconds. After it expires, the entry is invalid.
+NSTimeInterval const PRERESOLVE_IN_ADVANCE_IN_SECOND = 10; // Once the remaining valid time of an DNS entry is less than this number, issue a DNS request to prefetch the data.
+
+@interface IpObject : NSObject
+
+@property (nonatomic, copy) NSString * ip;
+@property (nonatomic, assign) NSTimeInterval expiredTime;
+
+@end
+
+@implementation IpObject
+@end
+
+
+@implementation OSSHttpdns {
+    NSMutableDictionary * gHostIpMap;
+    NSMutableSet * penddingSet;
+}
+
++ (instancetype)sharedInstance {
+    static OSSHttpdns * sharedInstance = nil;
+    static dispatch_once_t onceToken;
+    dispatch_once(&onceToken, ^{
+        sharedInstance = [OSSHttpdns new];
+    });
+    return sharedInstance;
+}
+
+- (instancetype)init {
+    if (self = [super init]) {
+        gHostIpMap = [NSMutableDictionary new];
+        penddingSet = [NSMutableSet new];
+    }
+    return self;
+}
+
+/**
+ *  OSS SDK specific
+ *
+ *  @param host it needs strictly follow the domain's format, such as oss-cn-hangzhou.aliyuncs.com
+ *
+ *  @return an ip in the ip list of the resolved host.
+ */
+- (NSString *)asynGetIpByHost:(NSString *)host {
+    IpObject * ipObject = [gHostIpMap objectForKey:host];
+    if (!ipObject) {
+
+        // if the host is not resolved, asynchronously resolve it and return nil
+        [self resolveHost:host];
+        return nil;
+    } else if ([[NSDate date] timeIntervalSince1970] - ipObject.expiredTime > MAX_ENDURABLE_EXPIRED_TIME_IN_SECOND) {
+
+        // If the entry is expired, asynchronously resolve it and return nil.
+        [self resolveHost:host];
+        return nil;
+    } else if (ipObject.expiredTime -[[NSDate date] timeIntervalSince1970] < PRERESOLVE_IN_ADVANCE_IN_SECOND) {
+
+        // If the entry is about to expire, asynchronously resolve it and return the current value.
+        [self resolveHost:host];
+        return ipObject.ip;
+    } else {
+
+        // returns the current result.
+        return ipObject.ip;
+    }
+}
+
+/**
+ *  resolve the host asynchronously
+
+ *  If the host is being resolved, the call will be skipped.
+ *
+ *  @param host the host to resolve
+ */
+- (void)resolveHost:(NSString *)host {
+
+    @synchronized (self) {
+        if ([penddingSet containsObject:host]) {
+            return;
+        } else {
+            [penddingSet addObject:host];
+        }
+    }
+
+    NSURL * url = [NSURL URLWithString:[NSString stringWithFormat:@"https://%@/%@/d?host=%@", [[OSSIPv6Adapter getInstance] handleIpv4Address:OSS_HTTPDNS_SERVER_IP], ACCOUNT_ID, host]];
+    NSURLSession * session = [NSURLSession sharedSession];
+
+    NSURLSessionDataTask * dataTask = [session dataTaskWithURL:url completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
+
+        IpObject * ipObject = nil;
+        NSUInteger statusCode = ((NSHTTPURLResponse *)response).statusCode;
+        if (statusCode != 200) {
+            OSSLogError(@"Httpdns resolve host: %@ failed, responseCode: %lu", host, (unsigned long)statusCode);
+        } else {
+            NSError *error = nil;
+            NSDictionary *json = nil;
+            if (data != nil){
+                json = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:&error];
+            }
+            
+            if (error != nil || json == nil){
+                return;
+            }
+
+            NSTimeInterval expiredTime = [[NSDate new] timeIntervalSince1970] + [[json objectForKey:@"ttl"] longLongValue];
+
+            NSArray *ips = [json objectForKey:@"ips"];
+            if (ips == nil || [ips count] == 0) {
+                OSSLogError(@"Httpdns resolve host: %@ failed, ip list empty.", host);
+            } else {
+                NSString * ip = ips[0];
+                ipObject = [IpObject new];
+                ipObject.expiredTime = expiredTime;
+                ipObject.ip = ip;
+                OSSLogDebug(@"Httpdns resolve host: %@ success, ip: %@, expiredTime: %lf", host, ipObject.ip, ipObject.expiredTime);
+            }
+        }
+
+        @synchronized (self) {
+            if (ipObject) {
+                gHostIpMap[host] = ipObject;
+            }
+
+            [penddingSet removeObject:host];
+        }
+    }];
+
+    [dataTask resume];
+}
+
+@end