From f048c6a2255cb7827f9f1d0bb1327e3fdcbe24d1 Mon Sep 17 00:00:00 2001
From: Matt Corallo <git@bluematt.me>
Date: Sat, 25 Nov 2023 17:45:16 +0000
Subject: [PATCH] Add new v2 encoding which should be simpler to parse

---
 split.c | 48 ++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 44 insertions(+), 4 deletions(-)

diff --git a/split.c b/split.c
index 8e484d0..1d70a2c 100644
--- a/split.c
+++ b/split.c
@@ -34,6 +34,9 @@ int main(int argc, char* argv[]) {
 	size_t linelen = 0;
 	getline(&hex, &linelen, stdin);
 	size_t len = strlen(hex);
+	// len should include a \n but otherwise be a multiple of header_len
+	assert(len % 2 == 1);
+	assert((len-1)/2 % header_len == 0);
 
 	if (start_height < total_height - 1) {
 		int prev_chunk_count = (total_height - 1) / 10000;
@@ -60,7 +63,48 @@ int main(int argc, char* argv[]) {
 	assert(write(out_fd, hex + ((len / header_len / 2) - 1) * header_len * 2, header_len * 2) == header_len * 2);
 	assert(write(out_fd, "\n", 1) == 1);
 
+	// We add one byte for the version and then divide (rounding up) by 14 bytes per IPv6.
+	int addr_count = (header_len + 1 + 13) / 14;
 	for (int i = 0; i < len / header_len / 2; i++) {
+		int zttl = ttl - i;
+		if (zttl < 60) { zttl = 60; }
+
+		for (int j = 0; j < addr_count; j++) {
+			char fmt[7*5];
+			memset(fmt, 0, sizeof(fmt));
+			for (int k = 0; k < 7; k++) {
+				char* target = fmt + k * 5;
+				int start = j*14*2 + k*4 - 2;
+				int count = header_len*2 - start;
+				if (start < 0) {
+					start = 0;
+					target[0] = '0';
+					target[1] = '1';
+					target += 2;
+					if (count > 2) count = 2;
+				}
+				if (count < 0) {
+					fmt[k*5] = '0';
+					continue;
+				}
+				if (count > 4) count = 4;
+				assert(count % 2 == 0);
+				memcpy(target, &hex[i * header_len*2 + start], count);
+				if (count < 4 && start != 0) {
+					target[2] = '0';
+					target[3] = '0';
+				}
+			}
+			dprintf(out_fd, "v2.%d	%d	IN	AAAA	260%d:%s:%s:%s:%s:%s:%s:%s\n",
+				start_height + i, zttl, j,
+				&fmt[0 * 5],
+				&fmt[1 * 5],
+				&fmt[2 * 5],
+				&fmt[3 * 5],
+				&fmt[4 * 5],
+				&fmt[5 * 5],
+				&fmt[6 * 5]);
+		}
 		if (header_len == 80) {
 			for (int j = 0; j < 6; j++) {
 				char fmt[7*5];
@@ -82,8 +126,6 @@ int main(int argc, char* argv[]) {
 				memcpy(fmt + 4*5, &hex[i * header_len*2 + 3*4 + offs], 4);
 				memcpy(fmt + 5*5, &hex[i * header_len*2 + 4*4 + offs], 4);
 				memcpy(fmt + 6*5, &hex[i * header_len*2 + 5*4 + offs], 4);
-				int zttl = ttl - i;
-				if (zttl < 60) { zttl = 60; }
 				dprintf(out_fd, "%d	%d	IN	AAAA	2001:%d%s:%s:%s:%s:%s:%s:%s\n",
 					start_height + i, zttl, j,
 					&fmt[0 * 5],
@@ -116,8 +158,6 @@ int main(int argc, char* argv[]) {
 					fmt[5*5] = '0';
 					fmt[6*5] = '0';
 				}
-				int zttl = ttl - i;
-				if (zttl < 60) { zttl = 60; }
 				dprintf(out_fd, "%d	%d	IN	AAAA	2001:%d%s:%s:%s:%s:%s:%s:%s\n",
 					start_height + i, zttl, j,
 					&fmt[0 * 5],
-- 
2.30.2