From 235c2c4f4df84aeff5b9452a39cc7818690f436a Mon Sep 17 00:00:00 2001 From: evgeny Date: Sun, 25 Oct 2026 22:28:36 +0100 Subject: [PATCH] Bound IPv4 packet dump reads and handle fragments --- src/transport_layer/packet_dump.c | 231 ++++++++++++------------------ src/transport_layer/packet_dump.h | 17 ++- 2 files changed, 99 insertions(+), 149 deletions(-) diff --git a/src/transport_layer/packet_dump.c b/src/transport_layer/packet_dump.c index 55232db9..d9fbc989 100644 --- a/src/transport_layer/packet_dump.c +++ b/src/transport_layer/packet_dump.c @@ -5,167 +5,112 @@ static const char* tcp_flags_to_str(uint8_t flags) { static char buf[32]; - int pos = 0; - buf[0] = '\0'; - - if (flags & 0x01) { pos += snprintf(buf + pos, sizeof(buf) - pos, "FIN,"); } - if (flags & 0x02) { pos += snprintf(buf + pos, sizeof(buf) - pos, "SYN,"); } - if (flags & 0x04) { pos += snprintf(buf + pos, sizeof(buf) - pos, "RST,"); } - if (flags & 0x08) { pos += snprintf(buf + pos, sizeof(buf) - pos, "PSH,"); } - if (flags & 0x10) { pos += snprintf(buf + pos, sizeof(buf) - pos, "ACK,"); } - if (flags & 0x20) { pos += snprintf(buf + pos, sizeof(buf) - pos, "URG,"); } - if (flags & 0x40) { pos += snprintf(buf + pos, sizeof(buf) - pos, "ECE,"); } - if (flags & 0x80) { pos += snprintf(buf + pos, sizeof(buf) - pos, "CWR,"); } - - if (pos > 0 && buf[pos - 1] == ',') { - buf[pos - 1] = '\0'; + static const char* const names[] = {"FIN", "SYN", "RST", "PSH", "ACK", "URG", "ECE", "CWR"}; + size_t pos = 0; + for (unsigned i = 0; i < 8; i++) { + if (!(flags & (1u << i))) continue; + if (pos) buf[pos++] = ','; + memcpy(buf + pos, names[i], 3); + pos += 3; } - - if (buf[0] == '\0') { - return "none"; - } - return buf; + buf[pos] = '\0'; + return pos ? buf : "none"; } char* dump_ip_packet_to_buffer(const uint8_t* data, size_t len) { static char buffer[1024]; - buffer[0] = '\0'; - + if (!data) { + snprintf(buffer, sizeof(buffer), "Missing IP packet: len=%zu", len); + goto invalid; + } if (len < 20) { - snprintf(buffer, sizeof(buffer), "Packet too small: %zd bytes", len); - return buffer; + snprintf(buffer, sizeof(buffer), "Packet too small: %zu bytes", len); + goto invalid; + } + if ((data[0] >> 4) != 4) { + snprintf(buffer, sizeof(buffer), "Non-IPv4 packet: version=%u len=%zu", (unsigned)(data[0] >> 4), len); + goto invalid; } - uint8_t version = (data[0] >> 4) & 0x0F; - if (version != 4) { - snprintf(buffer, sizeof(buffer), "Non-IPv4 packet: %zd bytes", len); - return buffer; + size_t ihl = (data[0] & 0x0f) * 4u; + if (ihl < 20) { + snprintf(buffer, sizeof(buffer), "Invalid IP header length: ihl=%zu len=%zu", ihl, len); + goto invalid; } - - uint8_t ihl = (data[0] & 0x0F) * 4; - if (len < ihl) { - snprintf(buffer, sizeof(buffer), "Truncated IP header: %zd bytes", len); - return buffer; + if (ihl > len) { + snprintf(buffer, sizeof(buffer), "Truncated IP header: ihl=%zu len=%zu", ihl, len); + goto invalid; + } + size_t total_len = ((unsigned)data[2] << 8) | data[3]; + if (total_len < ihl) { + snprintf(buffer, sizeof(buffer), "Invalid IP total length: total=%zu ihl=%zu", total_len, ihl); + goto invalid; + } + if (total_len > len) { + snprintf(buffer, sizeof(buffer), "Truncated IPv4 packet: total=%zu len=%zu", total_len, len); + goto invalid; } + char src[24], dst[24], details[128] = "", fragment[64] = ""; + snprintf(src, sizeof(src), "%u.%u.%u.%u", data[12], data[13], data[14], data[15]); + snprintf(dst, sizeof(dst), "%u.%u.%u.%u", data[16], data[17], data[18], data[19]); uint8_t protocol = data[9]; - uint32_t src_ip = *(uint32_t*)&data[12]; - uint32_t dst_ip = *(uint32_t*)&data[16]; + const char* name = protocol == 6 ? "TCP" : protocol == 17 ? "UDP" : protocol == 1 ? "ICMP" : "UNKNOWN"; + unsigned frag = ((unsigned)data[6] << 8) | data[7]; + unsigned frag_offset = (frag & 0x1fff) * 8u; + int more_fragments = (frag & 0x2000) != 0; + if (frag_offset || more_fragments) + snprintf(fragment, sizeof(fragment), " fragment offset=%u MF=%d", frag_offset, more_fragments); - char src_str[16], dst_str[16]; - snprintf(src_str, sizeof(src_str), "%u.%u.%u.%u", - (src_ip) & 0xFF, (src_ip >> 8) & 0xFF, - (src_ip >> 16) & 0xFF, (src_ip >> 24) & 0xFF); - snprintf(dst_str, sizeof(dst_str), "%u.%u.%u.%u", - (dst_ip) & 0xFF, (dst_ip >> 8) & 0xFF, - (dst_ip >> 16) & 0xFF, (dst_ip >> 24) & 0xFF); - - const char* proto_name = "UNKNOWN"; - uint16_t src_port = 0, dst_port = 0; - char proto_info[128] = {'\0'}; - int is_special_proto = 0; - - if (protocol == 6 && len >= ihl + 20) { - proto_name = "TCP"; - src_port = (data[ihl] << 8) | data[ihl + 1]; - dst_port = (data[ihl + 2] << 8) | data[ihl + 3]; - - uint32_t seq_num = ((uint32_t)data[ihl + 4] << 24) | - ((uint32_t)data[ihl + 5] << 16) | - ((uint32_t)data[ihl + 6] << 8) | - ((uint32_t)data[ihl + 7]); - uint32_t ack_num = ((uint32_t)data[ihl + 8] << 24) | - ((uint32_t)data[ihl + 9] << 16) | - ((uint32_t)data[ihl + 10] << 8) | - ((uint32_t)data[ihl + 11]); - uint8_t flags = data[ihl + 13]; - uint16_t window = (data[ihl + 14] << 8) | data[ihl + 15]; - - snprintf(proto_info, sizeof(proto_info), "[%s] seq=%u ack=%u win=%u", - tcp_flags_to_str(flags), seq_num, ack_num, window); - is_special_proto = 1; - - } else if (protocol == 17 && len >= ihl + 8) { - proto_name = "UDP"; - src_port = (data[ihl] << 8) | data[ihl + 1]; - dst_port = (data[ihl + 2] << 8) | data[ihl + 3]; - uint16_t udp_len = (data[ihl + 4] << 8) | data[ihl + 5]; - - snprintf(proto_info, sizeof(proto_info), "len=%u", udp_len); - is_special_proto = 1; - - } else if (protocol == 1 && len >= ihl + 8) { - proto_name = "ICMP"; - uint8_t icmp_type = data[ihl]; - uint16_t icmp_id = (data[ihl + 4] << 8) | data[ihl + 5]; - uint16_t icmp_seq = (data[ihl + 6] << 8) | data[ihl + 7]; - if (icmp_type == 0) { - snprintf(proto_info, sizeof(proto_info), "echo_reply seq=%u id=%u", icmp_seq, icmp_id); - } else if (icmp_type == 8) { - snprintf(proto_info, sizeof(proto_info), "echo_request seq=%u id=%u", icmp_seq, icmp_id); + const uint8_t* payload = data + ihl; + size_t payload_len = total_len - ihl; + unsigned required = protocol == 6 ? 20 : (protocol == 17 || protocol == 1) ? 8 : 0; + if (!frag_offset && payload_len < required) { + snprintf(details, sizeof(details), "%s header: available=%zu required=%u", + more_fragments ? "partial" : "truncated", payload_len, required); + if (more_fragments) DEBUG_DEBUG(DEBUG_CATEGORY_DUMP, "packet_dump: %s %s", name, details); + else DEBUG_WARN(DEBUG_CATEGORY_DUMP, "packet_dump: %s %s", name, details); + } else if (!frag_offset && (protocol == 6 || protocol == 17)) { + unsigned src_port = ((unsigned)payload[0] << 8) | payload[1]; + unsigned dst_port = ((unsigned)payload[2] << 8) | payload[3]; + size_t src_len = strlen(src), dst_len = strlen(dst); + snprintf(src + src_len, sizeof(src) - src_len, ":%u", src_port); + snprintf(dst + dst_len, sizeof(dst) - dst_len, ":%u", dst_port); + if (protocol == 6) { + uint32_t seq = ((uint32_t)payload[4] << 24) | ((uint32_t)payload[5] << 16) | + ((uint32_t)payload[6] << 8) | payload[7]; + uint32_t ack = ((uint32_t)payload[8] << 24) | ((uint32_t)payload[9] << 16) | + ((uint32_t)payload[10] << 8) | payload[11]; + unsigned window = ((unsigned)payload[14] << 8) | payload[15]; + snprintf(details, sizeof(details), "[%s] seq=%u ack=%u win=%u", tcp_flags_to_str(payload[13]), seq, ack, window); } else { - snprintf(proto_info, sizeof(proto_info), "type=%u code=%u", icmp_type, data[ihl + 1]); + unsigned udp_len = ((unsigned)payload[4] << 8) | payload[5]; + snprintf(details, sizeof(details), "len=%u", udp_len); } - is_special_proto = 1; + } else if (!frag_offset && protocol == 1) { + unsigned type = payload[0]; + if (type == 0 || type == 8) { + unsigned id = ((unsigned)payload[4] << 8) | payload[5]; + unsigned seq = ((unsigned)payload[6] << 8) | payload[7]; + snprintf(details, sizeof(details), "%s seq=%u id=%u", type == 0 ? "echo_reply" : "echo_request", seq, id); + } else snprintf(details, sizeof(details), "type=%u code=%u", type, payload[1]); } - if (is_special_proto && proto_info[0] != '\0') { - if (src_port > 0 && dst_port > 0) { - int offset = snprintf(buffer, sizeof(buffer), "IPv4 %s %s:%d -> %s:%d (%zd bytes) %s", - proto_name, src_str, src_port, dst_str, dst_port, len, proto_info); - if (offset > 0 && offset < (int)sizeof(buffer) - 50) { - snprintf(buffer + offset, sizeof(buffer) - offset, " data: " - "%02x%02x%02x%02x%02x%02x%02x%02x " - "%02x%02x%02x%02x%02x%02x%02x%02x " - "%02x%02x%02x%02x%02x%02x%02x%02x " - "%02x%02x%02x%02x%02x%02x%02x%02x", - data[ihl + 0], data[ihl + 1], data[ihl + 2], data[ihl + 3], - data[ihl + 4], data[ihl + 5], data[ihl + 6], data[ihl + 7], - data[ihl + 8], data[ihl + 9], data[ihl + 10], data[ihl + 11], - data[ihl + 12], data[ihl + 13], data[ihl + 14], data[ihl + 15], - data[ihl + 16], data[ihl + 17], data[ihl + 18], data[ihl + 19], - data[ihl + 20], data[ihl + 21], data[ihl + 22], data[ihl + 23], - data[ihl + 24], data[ihl + 25], data[ihl + 26], data[ihl + 27], - data[ihl + 28], data[ihl + 29], data[ihl + 30], data[ihl + 31]); - } - } else { - int offset = snprintf(buffer, sizeof(buffer), "IPv4 %s %s -> %s (%zd bytes) %s", - proto_name, src_str, dst_str, len, proto_info); - if (offset > 0 && offset < (int)sizeof(buffer) - 50) { - snprintf(buffer + offset, sizeof(buffer) - offset, " data: " - "%02x%02x%02x%02x%02x%02x%02x%02x " - "%02x%02x%02x%02x%02x%02x%02x%02x " - "%02x%02x%02x%02x%02x%02x%02x%02x " - "%02x%02x%02x%02x%02x%02x%02x%02x", - data[ihl + 0], data[ihl + 1], data[ihl + 2], data[ihl + 3], - data[ihl + 4], data[ihl + 5], data[ihl + 6], data[ihl + 7], - data[ihl + 8], data[ihl + 9], data[ihl + 10], data[ihl + 11], - data[ihl + 12], data[ihl + 13], data[ihl + 14], data[ihl + 15], - data[ihl + 16], data[ihl + 17], data[ihl + 18], data[ihl + 19], - data[ihl + 20], data[ihl + 21], data[ihl + 22], data[ihl + 23], - data[ihl + 24], data[ihl + 25], data[ihl + 26], data[ihl + 27], - data[ihl + 28], data[ihl + 29], data[ihl + 30], data[ihl + 31]); - } - } - } else { - int offset = snprintf(buffer, sizeof(buffer), "IPv4 %s %s:%d -> %s:%d (%zd bytes) data: " - "%02x%02x%02x%02x%02x%02x%02x%02x " - "%02x%02x%02x%02x%02x%02x%02x%02x " - "%02x%02x%02x%02x%02x%02x%02x%02x " - "%02x%02x%02x%02x%02x%02x%02x%02x", - proto_name, src_str, src_port, dst_str, dst_port, len, - data[ihl + 0], data[ihl + 1], data[ihl + 2], data[ihl + 3], - data[ihl + 4], data[ihl + 5], data[ihl + 6], data[ihl + 7], - data[ihl + 8], data[ihl + 9], data[ihl + 10], data[ihl + 11], - data[ihl + 12], data[ihl + 13], data[ihl + 14], data[ihl + 15], - data[ihl + 16], data[ihl + 17], data[ihl + 18], data[ihl + 19], - data[ihl + 20], data[ihl + 21], data[ihl + 22], data[ihl + 23], - data[ihl + 24], data[ihl + 25], data[ihl + 26], data[ihl + 27], - data[ihl + 28], data[ihl + 29], data[ihl + 30], data[ihl + 31]); - if (offset > 0 && offset < (int)sizeof(buffer)) { - buffer[offset] = '\0'; - } + /* Максимум 32 байта, три пробела между группами и завершающий NUL. */ + static const char hex_digits[] = "0123456789abcdef"; + char hex[68]; + size_t count = payload_len < 32 ? payload_len : 32, pos = 0; + for (size_t i = 0; i < count; i++) { + if (i && i % 8 == 0) hex[pos++] = ' '; + hex[pos++] = hex_digits[payload[i] >> 4]; + hex[pos++] = hex_digits[payload[i] & 0x0f]; } + hex[pos] = '\0'; + snprintf(buffer, sizeof(buffer), "IPv4 %s %s -> %s (%zu bytes)%s%s%s data: %s", + name, src, dst, total_len, details[0] ? " " : "", details, fragment, hex); + return buffer; +invalid: + DEBUG_WARN(DEBUG_CATEGORY_DUMP, "packet_dump: %s", buffer); return buffer; } diff --git a/src/transport_layer/packet_dump.h b/src/transport_layer/packet_dump.h index 51c27548..e6937a1c 100644 --- a/src/transport_layer/packet_dump.h +++ b/src/transport_layer/packet_dump.h @@ -1,20 +1,25 @@ /* packet_dump — текстовая сводка IPv4-пакета: адреса, транспортные поля и короткий hex-фрагмент. * Принимает IP-пакет без ETCP-заголовка. Результат в общем static-буфере перезаписывается каждым вызовом; - * его не освобождать, для хранения скопировать. Модуль не потокобезопасен и сам в лог не пишет. - * Известный дефект: hex-дамп читает 32 байта после IHL без проверки остатка len; - * текущая реализация небезопасна для коротких пакетов (см. doc/tasks.md). */ + * его не освобождать, для хранения скопировать. Модуль не потокобезопасен. + * Ошибки входа отражаются в строке и логируются в категории dump; штатный результат логирует вызывающий. */ #ifndef PACKET_DUMP_H #define PACKET_DUMP_H -#include +#include #include -#include -#include "../lib/platform_compat.h" #ifdef __cplusplus extern "C" { #endif +/* data — начало IPv4-пакета, len — доступные байты; выравнивание не требуется, NULL даёт диагностику. + * Проверяет version/IHL/total length; при усечённом IP-пакете возвращает только причину ошибки. + * При len > total length игнорирует хвост; размер в строке — total length. + * Выводит до 32 байт после IHL (включая транспортный заголовок), ограниченных total length. + * TCP/UDP/ICMP разбирает только при нулевом fragment offset и наличии 20/8/8 байт; + * короткий транспортный заголовок отмечает в строке, сохраняя доступный hex-дамп. + * Fragment offset выводит в байтах, MF — 0/1. Не проверяет checksum/полную корректность транспорта. + * Возвращает общий static char[1024], всегда NUL-терминированный; не освобождать и не изменять. */ char* dump_ip_packet_to_buffer(const uint8_t* data, size_t len); #ifdef __cplusplus