成功扩展live555支持ipv6,同时支持RTSPServer & RTSPClient

live555对ipv6的扩展

从live555的官网看live555的发展历史，实在是历史悠久，保守估计已经发展了至少16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：

，在上一期中我们已经为live555的多线程开了个头《经过两个多月的攻关，终于搞定了live555多线程并稳定压测通过》，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

IPV4 地址

rtsp://192.168.1.100:554/ch1
rtsp://admin:12345@192.168.1.100:554/ch1

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

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 != '' && *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 ''
        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 ''
        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 == '' || *from == ']' || *from == '/') {
            // We've completed parsing the address
            *to = '';
            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 == '' || *from == ':' || *from == '/') {
            // We've completed parsing the address
            *to = '';
            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；

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