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don't warn for DHCP release commands

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This commit is contained in:
Martin Michelsen
2023-10-13 10:07:43 -07:00
parent 0a3528b978
commit 7d95efa803
1 changed files with 40 additions and 32 deletions
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src/IPStackSimulator.cc
+40 -32
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@@ -401,6 +401,9 @@ void IPStackSimulator::on_client_udp_frame(
if (dhcp.magic != 0x63825363) { if (dhcp.magic != 0x63825363) {
throw runtime_error("incorrect DHCP magic cookie"); throw runtime_error("incorrect DHCP magic cookie");
} }
if (dhcp.opcode != 1) { // Request
throw runtime_error("DHCP packet is not a request");
}
unordered_map<uint8_t, string> option_data; unordered_map<uint8_t, string> option_data;
for (;;) { for (;;) {
@@ -412,14 +415,17 @@ void IPStackSimulator::on_client_udp_frame(
option_data.emplace(option, r.read(size)); option_data.emplace(option, r.read(size));
} }
if (dhcp.opcode == 1) { // Request uint8_t command = 0;
uint8_t command = 0; try {
try { command = option_data.at(53).at(0);
command = option_data.at(53).at(0); } catch (const out_of_range&) {
} catch (const out_of_range&) { throw runtime_error("client did not send a DHCP command option");
throw runtime_error("client did not send a DHCP command option"); }
}
if (command == 7) {
// Release IP address (we just ignore these)
} else if ((command == 1) || (command == 3)) {
// Populate the client's addresses // Populate the client's addresses
c->mac_addr = dhcp.client_hardware_address.data(); c->mac_addr = dhcp.client_hardware_address.data();
c->ipv4_addr = 0x0A000105; // 10.0.1.5 c->ipv4_addr = 0x0A000105; // 10.0.1.5
@@ -495,7 +501,7 @@ void IPStackSimulator::on_client_udp_frame(
r_data = std::move(w.str()); r_data = std::move(w.str());
} else { } else {
throw runtime_error("unknown DHCP command"); throw runtime_error("client sent unknown DHCP command");
} }
} else if (fi.udp->dest_port == 53) { // DNS } else if (fi.udp->dest_port == 53) { // DNS
@@ -510,34 +516,36 @@ void IPStackSimulator::on_client_udp_frame(
throw runtime_error("UDP packet is not DHCP or DNS"); throw runtime_error("UDP packet is not DHCP or DNS");
} }
r_ipv4.size = sizeof(IPv4Header) + sizeof(UDPHeader) + r_data.size(); if (!r_data.empty()) {
r_udp.size = sizeof(UDPHeader) + r_data.size(); r_ipv4.size = sizeof(IPv4Header) + sizeof(UDPHeader) + r_data.size();
r_ipv4.checksum = FrameInfo::computed_ipv4_header_checksum(r_ipv4); r_udp.size = sizeof(UDPHeader) + r_data.size();
r_udp.checksum = FrameInfo::computed_udp4_checksum( r_ipv4.checksum = FrameInfo::computed_ipv4_header_checksum(r_ipv4);
r_ipv4, r_udp, r_data.data(), r_data.size()); r_udp.checksum = FrameInfo::computed_udp4_checksum(
r_ipv4, r_udp, r_data.data(), r_data.size());
struct evbuffer* out_buf = bufferevent_get_output(c->bev.get()); struct evbuffer* out_buf = bufferevent_get_output(c->bev.get());
if (ip_stack_simulator_log.should_log(LogLevel::DEBUG)) { if (ip_stack_simulator_log.should_log(LogLevel::DEBUG)) {
string remote_str = this->str_for_ipv4_netloc(fi.ipv4->src_addr, fi.udp->src_port); string remote_str = this->str_for_ipv4_netloc(fi.ipv4->src_addr, fi.udp->src_port);
ip_stack_simulator_log.debug("Sending UDP response to %s", remote_str.c_str()); ip_stack_simulator_log.debug("Sending UDP response to %s", remote_str.c_str());
print_data(stderr, r_data); print_data(stderr, r_data);
} }
uint16_t frame_size = sizeof(r_ether) + sizeof(r_ipv4) + sizeof(r_udp) + r_data.size(); uint16_t frame_size = sizeof(r_ether) + sizeof(r_ipv4) + sizeof(r_udp) + r_data.size();
evbuffer_add(out_buf, &frame_size, 2); evbuffer_add(out_buf, &frame_size, 2);
evbuffer_add(out_buf, &r_ether, sizeof(r_ether)); evbuffer_add(out_buf, &r_ether, sizeof(r_ether));
evbuffer_add(out_buf, &r_ipv4, sizeof(r_ipv4)); evbuffer_add(out_buf, &r_ipv4, sizeof(r_ipv4));
evbuffer_add(out_buf, &r_udp, sizeof(r_udp)); evbuffer_add(out_buf, &r_udp, sizeof(r_udp));
evbuffer_add(out_buf, r_data.data(), r_data.size()); evbuffer_add(out_buf, r_data.data(), r_data.size());
if (this->pcap_text_log_file) { if (this->pcap_text_log_file) {
StringWriter w; StringWriter w;
w.write(&r_ether, sizeof(r_ether)); w.write(&r_ether, sizeof(r_ether));
w.write(&r_ipv4, sizeof(r_ipv4)); w.write(&r_ipv4, sizeof(r_ipv4));
w.write(&r_udp, sizeof(r_udp)); w.write(&r_udp, sizeof(r_udp));
w.write(r_data.data(), r_data.size()); w.write(r_data.data(), r_data.size());
this->log_frame(w.str()); this->log_frame(w.str());
}
} }
} }