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| #include <stdint.h>
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| #include <stddef.h>
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| #include <stdio.h>
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| #include <arpa/inet.h>
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| #define MARLBORG_MAGIC 0x4D425748
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| typedef enum {
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| MSG_HEARTBEAT = 0x01,
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| MSG_RULE_INSTALL = 0x02,
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| MSG_STATE_SYNC = 0x03
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| } marlborg_msg_type_t;
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|
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| typedef enum {
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| ERR_NONE = 0,
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| ERR_TRUNCATED = -1,
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| ERR_BAD_MAGIC = -2,
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| ERR_INVALID_TYPE = -3,
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| ERR_LENGTH_MISMATCH = -4
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| } parse_error_t;
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|
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| #pragma pack(push, 1)
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| typedef struct {
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| uint32_t magic;
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| uint8_t type;
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| uint16_t length;
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| uint8_t payload[];
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| } m_header_t;
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|
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| typedef struct {
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| uint32_t rule_priority;
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| uint16_t s_bh_fixed;
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| uint16_t h_measured_fixed;
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| uint8_t signature[64];
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| } rule_install_payload_t;
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|
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| typedef struct {
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| uint16_t s_bh_fixed;
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| uint16_t h_current_fixed;
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| uint32_t chain_length;
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| uint32_t step_count;
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| uint8_t latest_hash[32];
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| } state_sync_payload_t;
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| #pragma pack(pop)
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|
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| parse_error_t parse_marlborg_frame(const uint8_t* buffer, size_t len) {
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| if (len < sizeof(m_header_t)) return ERR_TRUNCATED;
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| const m_header_t* header = (const m_header_t*)buffer;
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| if (ntohl(header->magic) != MARLBORG_MAGIC) return ERR_BAD_MAGIC;
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| uint16_t expected_len = ntohs(header->length);
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| if (len < (sizeof(m_header_t) + expected_len)) return ERR_LENGTH_MISMATCH;
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|
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| switch (header->type) {
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| case MSG_HEARTBEAT:
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| printf("[HEARTBEAT] alive\n");
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| return ERR_NONE;
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|
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| case MSG_RULE_INSTALL: {
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| if (expected_len != sizeof(rule_install_payload_t)) return ERR_LENGTH_MISMATCH;
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| const rule_install_payload_t* p = (const rule_install_payload_t*)header->payload;
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| uint32_t prio = ntohl(p->rule_priority);
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| uint16_t s_bh = ntohs(p->s_bh_fixed);
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| uint16_t h_meas = ntohs(p->h_measured_fixed);
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| printf("[AUTH GATE] Rule Install -> Prio: %u, S_BH: %u, H_meas: %u\n",
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| prio, s_bh, h_meas);
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| if (h_meas > s_bh) {
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| printf("[AUTH GATE] REJECTED: entropy overflow (%u > %u)\n", h_meas, s_bh);
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| return ERR_NONE;
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| }
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| printf("[AUTH GATE] Entropy OK, forwarding to signature verification\n");
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| return ERR_NONE;
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| }
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| case MSG_STATE_SYNC: {
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| if (expected_len != sizeof(state_sync_payload_t)) return ERR_LENGTH_MISMATCH;
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| const state_sync_payload_t* p = (const state_sync_payload_t*)header->payload;
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| printf("[STATE SYNC] S_BH=%u H=%u chain_len=%u step=%u\n",
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| ntohs(p->s_bh_fixed),
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| ntohs(p->h_current_fixed),
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| ntohl(p->chain_length),
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| ntohl(p->step_count));
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| return ERR_NONE;
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| }
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|
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| default:
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| return ERR_INVALID_TYPE;
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| }
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| }
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