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DHCPClient: Don't reject packets smaller than the max size

Browse source 
It's acceptable to have less padding in a packet, the only requirement
is to have a single byte of 'END' in the DHCP fields.
This commit is contained in:
AnotherTest 2021-02-15 21:36:57 +03:30 • committed by Andreas Kling
parent c0703f48fe
commit 3440dbb1fc
2 changed files with 8 additions and 4 deletions
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6
Userland/Services/DHCPClient/DHCPv4Client.cpp
View file

@ -53,7 +53,9 @@ static void send(const InterfaceDescriptor& iface, const DHCPv4Packet& packet, C
dst.sin_addr.s_addr = IPv4Address { 255, 255, 255, 255 }.to_u32();
memset(&dst.sin_zero, 0, sizeof(dst.sin_zero));
dbgln_if(DHCPV4CLIENT_DEBUG, "sendto({} bound to {}, ..., {} at {}) = ...?", fd, iface.m_ifname, dst.sin_addr.s_addr, dst.sin_port);
auto rc = sendto(fd, &packet, sizeof(packet), 0, (sockaddr*)&dst, sizeof(dst));
dbgln_if(DHCPV4CLIENT_DEBUG, "sendto({}) = {}", fd, rc);
if (rc < 0) {
dbgln("sendto failed with {}", strerror(errno));
// FIXME: what do we do here?
@ -113,8 +115,8 @@ DHCPv4Client::DHCPv4Client(Vector<InterfaceDescriptor> ifnames)
m_server->on_ready_to_receive = [this] {
auto buffer = m_server->receive(sizeof(DHCPv4Packet));
dbgln("Received {} bytes", buffer.size());
if (buffer.size() != sizeof(DHCPv4Packet)) {
dbgln("we expected {} bytes, this is a bad packet", sizeof(DHCPv4Packet));
if (buffer.size() < sizeof(DHCPv4Packet) - DHCPV4_OPTION_FIELD_MAX_LENGTH + 1 || buffer.size() > sizeof(DHCPv4Packet)) {
dbgln("we expected {}-{} bytes, this is a bad packet", sizeof(DHCPv4Packet) - DHCPV4_OPTION_FIELD_MAX_LENGTH + 1, sizeof(DHCPv4Packet));
return;
}
auto& packet = *(DHCPv4Packet*)buffer.data();