Skeleton for quic initial message parser

2025-12-31 03:38:07 +03:00 · 2024-08-13 01:59:47 +03:00
parent d5db8c18e5
commit 4a8f0d18a9
2 changed files with 250 additions and 0 deletions
--- a/quic.c
+++ b/quic.c
@@ -0,0 +1,137 @@
+#include "quic.h"
+
+static const uint32_t supported_versions[] = {
+	1,		// version 1, RFC 9000
+	0x6b3343cf,	// version 2, RFC 9369
+};
+
+/**
+ * Packet number.
+ */
+struct quic_pnumber {
+	uint8_t d1;
+	uint8_t d2;
+	uint8_t d3;
+	uint8_t d4;
+};
+
+uint64_t quic_parse_varlength(uint8_t *variable, uint64_t *mlen) {
+	if (mlen && *mlen == 0) return 0;
+	uint64_t vr = (*variable & 0x3F);
+	uint8_t len = 1 << (*variable >> 6);
+
+	if (mlen) {
+		if (*mlen < len) return 0;
+		*mlen = len;
+	}
+
+	++variable;
+	for (uint8_t i = 1; i < len; i++) {
+		vr = (vr << 8) + *variable;
+		++variable;
+	}
+
+	return vr;
+}
+
+int quic_parse_data(uint8_t *raw_payload, uint32_t raw_payload_len,
+		struct quic_lhdr **qch, uint32_t *qch_len,
+		struct quic_cids *qci,
+		uint8_t **payload, uint32_t *plen) {
+	if (	raw_payload == NULL || 
+		raw_payload_len < sizeof(struct quic_lhdr)) 
+		goto invalid_packet;
+
+	struct quic_lhdr *nqch = (struct quic_lhdr *)raw_payload;
+	uint32_t left_len = raw_payload_len - sizeof(struct quic_lhdr);
+	uint8_t *cur_rawptr = raw_payload + sizeof(struct quic_lhdr);
+	if (!nqch->fixed)
+		return -EPROTO;
+
+	uint8_t found = 0;
+	for (uint8_t i = 0; i < sizeof(supported_versions); i++) {
+		if (nqch->version == supported_versions[i]) {
+			found = 1;
+		}
+	}
+
+	if (!found) 
+		return -EPROTO;
+
+	if (left_len < 2) goto invalid_packet;
+	struct quic_cids nqci = {0};
+
+	nqci.dst_len = *cur_rawptr++;
+	left_len--;
+	if (left_len < nqci.dst_len) goto invalid_packet;
+	nqci.dst_id = cur_rawptr;
+	cur_rawptr += nqci.dst_len;
+	left_len -= nqci.dst_len;
+
+	nqci.src_len = *cur_rawptr++;
+	left_len--;
+	if (left_len < nqci.src_len) goto invalid_packet;
+	nqci.src_id = cur_rawptr;
+	cur_rawptr += nqci.src_len;
+	left_len -= nqci.src_len;
+
+	if (qch) *qch = nqch;
+	if (qch_len) {
+		*qch_len = sizeof(struct quic_lhdr) + 
+			nqci.src_len + nqci.dst_len;
+	}
+	if (qci) *qci = nqci;
+	if (payload) *payload = cur_rawptr;
+	if (plen) *plen = left_len;
+
+	return 0;
+
+invalid_packet:
+	return -EINVAL;
+}
+
+int quic_parse_initial_message(uint8_t *inpayload, uint32_t inplen,
+			const struct quic_lhdr *qch, 
+			struct quici_hdr *qhdr,
+			uint8_t **payload, uint32_t *plen) {
+	if (inplen < 3) goto invalid_packet;
+	struct quici_hdr nqhdr;
+
+	uint8_t *cur_ptr = inpayload;
+	uint32_t left_len = inplen;
+	uint64_t tlen = left_len;
+
+	nqhdr.token_len = quic_parse_varlength(cur_ptr, &tlen);
+	nqhdr.token = cur_ptr + tlen;
+	
+	if (left_len < nqhdr.token_len + tlen) 
+		goto invalid_packet;
+	cur_ptr += tlen + nqhdr.token_len;
+	left_len -= tlen + nqhdr.token_len;
+
+	tlen = left_len;
+	nqhdr.length = quic_parse_varlength(cur_ptr, &tlen);
+
+	if (left_len != nqhdr.length + tlen && 
+		left_len <= qch->number_length + 1)
+		goto invalid_packet;
+
+	uint32_t packet_number = 0;
+
+	for (uint8_t i = 0; i <= qch->number_length; i++) {
+		packet_number = (packet_number << 8) + *cur_ptr++;
+		left_len--;
+	}
+
+	nqhdr.packet_number = packet_number;
+
+	if (qhdr) *qhdr = nqhdr;
+	if (payload) *payload = cur_ptr;
+	if (plen) *plen = left_len;
+
+	return 0;
+
+invalid_packet:
+	lgerror("QUIC invalid Initial packet", -EINVAL);
+	return -EINVAL;
+}