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toa: support inet6 socket -> inet socket #670

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toa: support inet6 socket -> inet socket #670

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27adf8d
toa: support inet6 socket -> inet socket
invalid-email-address Nov 2, 2020
8c4ea56
Merge pull request #728 from iqiyi/devel
ywc689 Apr 28, 2021
e094c9d
Merge pull request #757 from iqiyi/devel
ywc689 Sep 1, 2021
9c21f80
Merge branch 'iqiyi:master' into master
limeix Oct 29, 2021
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31 changes: 23 additions & 8 deletions kmod/toa/toa.c
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Original file line number Diff line number Diff line change
Expand Up @@ -456,14 +456,29 @@ inet_getname_toa(struct socket *sock, struct sockaddr *uaddr,
ntohs(tdata.port));
sin->sin_port = tdata.port;
sin->sin_addr.s_addr = tdata.ip;
} else { /* sk_user_data doesn't belong to us */
TOA_INC_STATS(ext_stats,
GETNAME_TOA_MISMATCH_CNT);
TOA_DBG("inet_getname_toa: invalid toa data, "
"ip "TOA_NIPQUAD_FMT" port %u opcode %u "
"opsize %u\n",
TOA_NIPQUAD(tdata.ip), ntohs(tdata.port),
tdata.opcode, tdata.opsize);
} else {
struct toa_ip6_entry* ptr_ip6_entry = sk->sk_user_data;
struct toa_ip6_data* ptr_ip6_data = &ptr_ip6_entry->toa_data;

if (TCPOPT_TOA == ptr_ip6_data->opcode &&
TCPOLEN_IP6_TOA == ptr_ip6_data->opsize) {
TOA_INC_STATS(ext_stats, GETNAME_TOA_OK_CNT);
TOA_DBG("inet_getname_toa: set new sockaddr, ip "
TOA_NIPQUAD_FMT" -> "TOA_NIPQUAD_FMT
", port %u -> %u\n",
TOA_NIPQUAD(sin->sin_addr.s_addr),
TOA_NIPQUAD(ptr_ip6_data->in6_addr.s6_addr32[3]), ntohs(sin->sin_port),
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The IPv6 address is truncated to fit the IPv4 address size. Is the truncated address more meaningful than the original IP address derived from inet_getname.

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IPv4-mapped IPv6 address

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  1. If toa_data stores the ipv4-mapped ipv6 address, and this is the only case, you should validate the address format to ensure its has ::ffff:x.x.xx format.
  2. Do you have the case that the client address in toa_data is ipv4-mapped ipv6 address. The toa data is inserted by DPVS without considering socket's address family. I don't think there exists a case where toa_data contains ipv4-mapped address.

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场景大概是这样：
用户是IPv4，DPVS上配置的RS地址也是IPv4，RS真实监听的只有IPv6，但是可能会通过setsockopt改成AF_INET类型。
这个虽然不常见，但是RFC允许只监听IPv6的服务接收IPv4的连接。
这种场景下，当连接进来时，在RS上的TOA module看来，这是一个IPv6的监听，所以会把这个IPv4地址map成IPv6地址放到sk_user_data里（代码373行）。
然后RS上层应用看出来这是个V4的连接，然后调用setsockopt接口把连接类型改为V4，然后再获取对端地址的时候就会调用TOA module中的inet_getname_toa了。
目前，inet_getname_toa没有考虑这种情况，因此拿不到用户地址。

针对你上述两个异议的回答：

  1. 如果userdata里是一个正常的IPv6地址，那场景应该是NAT64
  2. 这个场景是我们真实遇到的；如上面所述，这个地址不是DPVS放进来的，而是TOA自己把V4 map 成V6，放到sk_user_data里的

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场景大概是这样： 用户是IPv4，DPVS上配置的RS地址也是IPv4，RS真实监听的只有IPv6，但是可能会通过setsockopt改成AF_INET类型。 这个虽然不常见，但是RFC允许只监听IPv6的服务接收IPv4的连接。 这种场景下，当连接进来时，在RS上的TOA module看来，这是一个IPv6的监听，所以会把这个IPv4地址map成IPv6地址放到sk_user_data里（代码373行）。 然后RS上层应用看出来这是个V4的连接，然后调用setsockopt接口把连接类型改为V4，然后再获取对端地址的时候就会调用TOA module中的inet_getname_toa了。 目前，inet_getname_toa没有考虑这种情况，因此拿不到用户地址。

针对你上述两个异议的回答：

  1. 如果userdata里是一个正常的IPv6地址，那场景应该是NAT64
  2. 这个场景是我们真实遇到的；如上面所述，这个地址不是DPVS放进来的，而是TOA自己把V4 map 成V6，放到sk_user_data里的

”RFC允许只监听IPv6的服务接收IPv4的连接“这个和 ”通过setsockopt改成AF_INET类型“没有关系吧？”通过setsockopt改成AF_INET类型“是另外一个场景的需求？

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我的理解是，setsockopt之所以支持把AF_INET6的socket改成AF_INET4，就是为了实现这个RFC。

ntohs(ptr_ip6_data->port));
sin->sin_port = ptr_ip6_data->port;
sin->sin_addr.s_addr = ptr_ip6_data->in6_addr.s6_addr32[3]; // trans v6 to v4
} else { /* sk_user_data doesn't belong to us */
TOA_INC_STATS(ext_stats,GETNAME_TOA_MISMATCH_CNT);
TOA_DBG("inet_getname_toa: invalid toa data, "
"ip "TOA_NIPQUAD_FMT" port %u opcode %u "
"opsize %u\n",
TOA_NIPQUAD(tdata.ip), ntohs(tdata.port),
tdata.opcode, tdata.opsize);
}
}
} else {
TOA_INC_STATS(ext_stats, GETNAME_TOA_BYPASS_CNT);
Expand Down