最新live555优化扩展ipv6功能支持苹果版本应用上架AppStore

live555的发展历史实在是非常悠久，保守估计已经发展了至少18年以上了，同时，这也导致了live555在很多架构和考虑上面不能满足现代化的多线程、ipv6方面的需求，虽然官方也开启了对ipv6功能支持的众筹，但是已经很久了，预计很长时间内是不会有这个计划支持了，因为要改动的地方还真是蛮多的：

今天我们要来聊一下我们在live555扩展IPv6方面是怎么做到的！

设计过程

1. IPV4 地址
   rtsp://192.168.1.100:554/ch1
   rtsp://admin:[email protected]:554/ch1

2. IPV6 地址
   rtsp://[2001:0:9d38:953c:38b0:d177:88d8:a5e0]:554/ch1
   rtsp://admin:12345@[2001:0:9d38:953c:38b0:d177:88d8:a5e0]:554/ch1

3. 支持IPv6修改步骤
   增加live_ipv4_ipv6.h和live_ipv4_ipv6.cpp两个文件
   用途: 在live所有用到类型为netAddressBits的文件中,包含该头文件,针对ipv4和ipv6进行不同的处理;

• live_ipv4_ipv6.h

  #ifndef __LIVE_IPV4_IPV6
  #define __LIVE_IPV4_IPV6

  typedef enum LIVE_IPVER_ENUM
  {
  LIVE_IP_VER_4 = 0,
  LIVE_IP_VER_6
  }LIVE_IP_VER_ENUM;

  extern LIVE_IP_VER_ENUM live_ip_ver;

  #endif

• live_ipv4_ipv6.cpp

  #include “live_ipv4_ipv6.h”
  LIVE_IP_VER_ENUM live_ip_ver = LIVE_IP_VER_6;

• NetAddress.hh

增加以下定义, 并注释掉typedef u_int32_t netAddressBits;

typedef struct __LIVE_NET_ADDRESS_INADDR
{
	struct in_addr sin_addr;
	struct in6_addr sin6_addr;

	__LIVE_NET_ADDRESS_INADDR()
	{
		sin_addr.s_addr = INADDR_ANY;
		sin6_addr = in6addr_any;
	};

}LIVE_NET_ADDRESS_INADDR;

//typedef u_int32_t netAddressBits;	//注释掉该句,在所有用到netAddressBits的地方，均用LIVE_NET_ADDRESS_INADDR替代;

//增加以下定义
typedef struct __LIVE_NET_ADDRESS_SOCKADDR_IN
{
	struct sockaddr_in	saddr4;
	struct sockaddr_in6	saddr6;
}LIVE_NET_ADDRESS_SOCKADDR_IN;

将所有struct in_addr 改为 LIVE_NET_ADDRESS, 除了以下几处:
void AddressString::init(struct in_addr addr)

将所有struct sockaddr_in 改为 LIVE_NET_ADDRESS_SOCKADDR_IN;

在EasyRTSPClient的live555中，将调用到LIVE_NET_ADDRESS_SOCKADDR_IN的函数，增加一个参数,用于标识是IPv4还是IPv6;
从调用以下代码开始，进行区分，用于标识该客户端需要使用IPv4还是IPv6进行连接;

Boolean RTSPClient::parseRTSPURL(UsageEnvironment& env, char const* url,
				 char*& username, char*& password,
				 NetAddress& address,
				 portNumBits& portNum,
				 char const** urlSuffix) {

		do {
		// Parse the URL as "rtsp://[<username>[:<password>]@]<server-address-or-name>[:<port>][/<stream-name>]"
		char const* prefix = "rtsp://";
		unsigned const prefixLength = 7;
		if (_strncasecmp(url, prefix, prefixLength) != 0) {
			env.setResultMsg("URL is not of the form \"", prefix, "\"");
			break;
		}

		unsigned const parseBufferSize = 100;
		char parseBuffer[parseBufferSize] = {0};
		char const* from = &url[prefixLength];

		// Check whether "<username>[:<password>]@" occurs next.
		// We do this by checking whether '@' appears before the end of the URL, or before the first '/'.
		username = password = NULL; // default return values
		char const* colonPasswordStart = NULL;
		char const* p;
        //此处检查字符[
		for (p = from; *p != '\0' && *p != '/' && *p != '['; ++p) {
			if (*p == ':' && colonPasswordStart == NULL) {
		colonPasswordStart = p;
			} else if (*p == '@') {
		// We found <username> (and perhaps <password>).  Copy them into newly-allocated result strings:
		if (colonPasswordStart == NULL) colonPasswordStart = p;

		char const* usernameStart = from;
		unsigned usernameLen = colonPasswordStart - usernameStart;
		username = new char[usernameLen + 1] ; // allow for the trailing '\0'
		copyUsernameOrPasswordStringFromURL(username, usernameStart, usernameLen);

		char const* passwordStart = colonPasswordStart;
		if (passwordStart < p) ++passwordStart; // skip over the ':'
		unsigned passwordLen = p - passwordStart;
		password = new char[passwordLen + 1]; // allow for the trailing '\0'
		copyUsernameOrPasswordStringFromURL(password, passwordStart, passwordLen);

		from = p + 1; // skip over the '@'
		break;
			}
		}

		// Next, parse <server-address-or-name>
		char* to = &parseBuffer[0];
		unsigned i;

		live_ip_ver = LIVE_IP_VER_4;	//默认为IPv4
		if (*from == '[')		//如果地址是以符号[开头，则为IPv6  因为ipv6的地址是以符号[开头
		{
			live_ip_ver = LIVE_IP_VER_6;
		}

		if (live_ip_ver == LIVE_IP_VER_6)
		{
			*from ++;	//  跳过符号[
			for (i = 0; i < parseBufferSize; ++i) {
				if (*from == '\0' || *from == ']' || *from == '/') {
			// We've completed parsing the address
			*to = '\0';
			break;
				}
				*to++ = *from++;
			}
			if (i == parseBufferSize) {
				env.setResultMsg("URL is too long");
				break;
			}

			*from ++;		//  跳过符号]
		}
		else		//IPV4
		{
			for (i = 0; i < parseBufferSize; ++i) {
				if (*from == '\0' || *from == ':' || *from == '/') {
			// We've completed parsing the address
			*to = '\0';
			break;
				}
				*to++ = *from++;
			}
			if (i == parseBufferSize) {
				env.setResultMsg("URL is too long");
				break;
			}
		}
		//rtsp://[2001:0:9d38:953c:14b3:7a:3f57:fe40]:554/ch1
		//strcpy(parseBuffer, "2001:0:9d38:953c:38b0:d177:88d8:a5e0");

		NetAddressList addresses(parseBuffer);
		if (addresses.numAddresses() == 0) {
			env.setResultMsg("Failed to find network address for \"",
					parseBuffer, "\"");
			break;
		}
		address = *(addresses.firstAddress());

		portNum = 554; // default value

		char nextChar = *from;
		if (nextChar == ':') {
			int portNumInt;
			if (sscanf(++from, "%d", &portNumInt) != 1) {
		env.setResultMsg("No port number follows ':'");
		break;
			}
			if (portNumInt < 1 || portNumInt > 65535) {
		env.setResultMsg("Bad port number");
		break;
			}
			portNum = (portNumBits)portNumInt;
			while (*from >= '0' && *from <= '9') ++from; // skip over port number
		}

		// The remainder of the URL is the suffix:
		if (urlSuffix != NULL) *urlSuffix = from;

		return True;
		} while (0);

  return False;
}

其中, live_ip_ver 为全局变量，用于标识该IP地址类型;
后面用到struct sockaddr_in 和 struct in_addr 的地方， 使用LIVE_NET_ADDRESS_SOCKADDR_IN来区分，并进行相应的处理;

live555中，就不能使用live_ip_ver这个全局变量了, 因为要同时兼容IPv4和IPv6, 将在下篇说明；

重要性

live555的ipv6技术虽然是很小的一个点，但是在越来越物联网的现在，无论是上架AppStore还是投标竞标，ipv6都将成为一个关键的技术点；