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extract igmp into its own static library

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This commit is contained in:
Ian Gulliver
2026-05-01 13:47:22 -07:00
parent a56e034bfb
commit 71c07957f8
4 changed files with 13 additions and 1 deletions
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109
src/igmp.cpp
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@@ -1,109 +0,0 @@
#include "igmp.h"
#include <vector>
#include "eth.h"
#include "ipv4.h"
#include "parse_buffer.h"
#include "prepend_buffer.h"
namespace igmp {
struct group_entry {
ipv4::ip4_addr ip;
eth::mac_addr mac;
};
static std::vector<group_entry> groups;
eth::mac_addr mac_for_ip(const ipv4::ip4_addr& group) {
return {0x01, 0x00, 0x5E,
static_cast<uint8_t>(group[1] & 0x7F), group[2], group[3]};
}
bool is_member(const ipv4::ip4_addr& ip) {
if (ip == ALL_HOSTS) return true;
for (auto& g : groups)
if (g.ip == ip) return true;
return false;
}
bool is_member_mac(const eth::mac_addr& mac) {
static constexpr eth::mac_addr ALL_HOSTS_MAC = {0x01, 0x00, 0x5E, 0x00, 0x00, 0x01};
if (mac == ALL_HOSTS_MAC) return true;
for (auto& g : groups)
if (g.mac == mac) return true;
return false;
}
static void send_report(const ipv4::ip4_addr& group) {
prepend_buffer<4096> buf;
prepend_report(buf, eth::get_mac(), ipv4::get_ip(), group);
eth::send_raw(buf.span());
}
void join(const ipv4::ip4_addr& group) {
for (auto& g : groups)
if (g.ip == group) return;
groups.push_back({group, mac_for_ip(group)});
send_report(group);
}
void send_all_reports() {
for (auto& g : groups)
send_report(g.ip);
}
void handle(std::span<const uint8_t> frame, span_writer& tx) {
parse_buffer pb(frame);
pb.consume<eth::header>();
auto* ip = pb.consume<ipv4::header>();
if (!ip) return;
size_t options_len = ip->header_len() - sizeof(ipv4::header);
if (options_len > 0 && !pb.skip(options_len)) return;
auto* msg = pb.consume<message>();
if (!msg) return;
if (msg->type != 0x11) return;
if (msg->group == ipv4::ip4_addr{0, 0, 0, 0}) {
for (auto& g : groups)
send_report(g.ip);
} else {
for (auto& g : groups) {
if (g.ip == msg->group) {
send_report(g.ip);
break;
}
}
}
}
void init() {
ipv4::register_protocol(2, handle);
eth::register_mac_filter(is_member_mac);
ipv4::register_addr_filter(is_member);
}
bool parse_report(std::span<const uint8_t> frame, ipv4::ip4_addr& group) {
parse_buffer pb(frame);
auto* eth_hdr = pb.consume<eth::header>();
if (!eth_hdr) return false;
if (eth_hdr->ethertype != eth::ETH_IPV4) return false;
auto* ip = pb.consume<ipv4::header>();
if (!ip) return false;
if ((ip->ver_ihl >> 4) != 4) return false;
if (ip->protocol != 2) return false;
size_t options_len = ip->header_len() - sizeof(ipv4::header);
if (options_len > 0 && !pb.skip(options_len)) return false;
auto* msg = pb.consume<message>();
if (!msg) return false;
if (msg->type != 0x16) return false;
group = msg->group;
return true;
}
} // namespace igmp