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Merge bitcoin/bitcoin#21756: Avoid calling getnameinfo when formatting IPv6 addresses in CNetAddr::ToStringIP

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54548bae80 net: Avoid calling getnameinfo when formatting IPv6 addresses in CNetAddr::ToStringIP (practicalswift)
c10f27fdb2 net: Make IPv6ToString do zero compression as described in RFC 5952 (practicalswift)

Pull request description:

  Avoid calling `getnameinfo` when formatting IPv6 addresses in `CNetAddr::ToStringIP`.

  Fixes #21466.
  Fixes #21967.

  The IPv4 case was fixed in #21564.

ACKs for top commit:
  laanwj:
    Code review ACK 54548bae80
  vasild:
    ACK 54548bae80

Tree-SHA512: 8404e458b29efdb7bf78b91adc075d05e0385969d1532cccaa2c7cb69cd77411c42d95fcefc4000137b9f2076fe395731c7d9844b7d42b58a6d3bec69eed6fce
This commit is contained in:
W. J. van der Laan 2021-05-17 12:52:02 +02:00
commit 7b87fca930
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1 changed files with 48 additions and 20 deletions
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54
src/netaddress.cpp
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@ -556,11 +556,12 @@ static std::string IPv4ToString(Span<const uint8_t> a)
return strprintf("%u.%u.%u.%u", a[0], a[1], a[2], a[3]); return strprintf("%u.%u.%u.%u", a[0], a[1], a[2], a[3]);
} }
// Return an IPv6 address text representation with zero compression as described in RFC 5952
// ("A Recommendation for IPv6 Address Text Representation").
static std::string IPv6ToString(Span<const uint8_t> a) static std::string IPv6ToString(Span<const uint8_t> a)
{ {
assert(a.size() == ADDR_IPV6_SIZE); assert(a.size() == ADDR_IPV6_SIZE);
// clang-format off const std::array groups{
return strprintf("%x:%x:%x:%x:%x:%x:%x:%x",
ReadBE16(&a[0]), ReadBE16(&a[0]),
ReadBE16(&a[2]), ReadBE16(&a[2]),
ReadBE16(&a[4]), ReadBE16(&a[4]),
@ -568,8 +569,44 @@ static std::string IPv6ToString(Span<const uint8_t> a)
ReadBE16(&a[8]), ReadBE16(&a[8]),
ReadBE16(&a[10]), ReadBE16(&a[10]),
ReadBE16(&a[12]), ReadBE16(&a[12]),
ReadBE16(&a[14])); ReadBE16(&a[14]),
// clang-format on };
// The zero compression implementation is inspired by Rust's std::net::Ipv6Addr, see
// https://github.com/rust-lang/rust/blob/cc4103089f40a163f6d143f06359cba7043da29b/library/std/src/net/ip.rs#L1635-L1683
struct ZeroSpan {
size_t start_index{0};
size_t len{0};
};
// Find longest sequence of consecutive all-zero fields. Use first zero sequence if two or more
// zero sequences of equal length are found.
ZeroSpan longest, current;
for (size_t i{0}; i < groups.size(); ++i) {
if (groups[i] != 0) {
current = {i + 1, 0};
continue;
}
current.len += 1;
if (current.len > longest.len) {
longest = current;
}
}
std::string r;
r.reserve(39);
for (size_t i{0}; i < groups.size(); ++i) {
// Replace the longest sequence of consecutive all-zero fields with two colons ("::").
if (longest.len >= 2 && i >= longest.start_index && i < longest.start_index + longest.len) {
if (i == longest.start_index) {
r += "::";
}
continue;
}
r += strprintf("%s%x", ((!r.empty() && r.back() != ':') ? ":" : ""), groups[i]);
}
return r;
} }
std::string CNetAddr::ToStringIP() const std::string CNetAddr::ToStringIP() const
@ -578,15 +615,6 @@ std::string CNetAddr::ToStringIP() const
case NET_IPV4: case NET_IPV4:
return IPv4ToString(m_addr); return IPv4ToString(m_addr);
case NET_IPV6: { case NET_IPV6: {
CService serv(*this, 0);
struct sockaddr_storage sockaddr;
socklen_t socklen = sizeof(sockaddr);
if (serv.GetSockAddr((struct sockaddr*)&sockaddr, &socklen)) {
char name[1025] = "";
if (!getnameinfo((const struct sockaddr*)&sockaddr, socklen, name,
sizeof(name), nullptr, 0, NI_NUMERICHOST))
return std::string(name);
}
return IPv6ToString(m_addr); return IPv6ToString(m_addr);
} }
case NET_ONION: case NET_ONION: