Split custom demo data into its own file/feature

Copyright note: the stuff Bill wrote is all still in the other file.

5 files changed, 180 insertions, 127 deletions

diff --git a/src/democustom.c b/src/democustom.c
new file mode 100644
index 0000000..0a1174f
--- /dev/null
+++ b/src/democustom.c
@@ -0,0 +1,138 @@
+/*
+ * Copyright © 2022 Michael Smith <mikesmiffy128@gmail.com>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED “AS IS” AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+ * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+ * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+ * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+ * OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+ * PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <stdbool.h>
+
+#include "bitbuf.h"
+#include "con_.h"
+#include "democustom.h"
+#include "demorec.h"
+#include "engineapi.h"
+#include "errmsg.h"
+#include "gamedata.h"
+#include "intdefs.h"
+#include "mem.h"
+#include "ppmagic.h"
+#include "vcall.h"
+
+static int nbits_msgtype, nbits_datalen;
+
+// The engine allows usermessages up to 255 bytes, we add 2 bytes of overhead,
+// and then there's the leading bits before that too (see create_message)
+static char bb_buf[DEMOCUSTOM_MSG_MAX + 4];
+static struct bitbuf bb = {
+	bb_buf, sizeof(bb_buf), sizeof(bb_buf) * 8, 0, false, false, "SST"
+};
+
+static void create_message(struct bitbuf *msg, const void *buf, int len) {
+	// The way we pack our custom demo data is via a user message packet with
+	// type "HudText" - this causes the client to do a text lookup which will
+	// simply silently fail on invalid keys. By making the first byte null
+	// (creating an empty string), we get the rest of the packet to stick in
+	// whatever other data we want.
+	//
+	// Notes from Uncrafted:
+	// > But yeah the data you want to append is as follows:
+	// > - 6 bits (5 bits in older versions) for the message type - should be 23
+	// >   for user message
+	bitbuf_appendbits(msg, 23, nbits_msgtype);
+	// > - 1 byte for the user message type - should be 2 for HudText
+	bitbuf_appendbyte(msg, 2);
+	// > - ~~an int~~ 11 or 12 bits for the length of your data in bits,
+	bitbuf_appendbits(msg, len * 8, nbits_datalen); // NOTE: assuming len <= 254
+	// > - your data
+	// [first the aforementioned null byte, plus an arbitrary marker byte to
+	// avoid confusion when parsing the demo later...
+	bitbuf_appendbyte(msg, 0);
+	bitbuf_appendbyte(msg, 0xAC);
+	// ... and then just the data itself]
+	bitbuf_appendbuf(msg, buf, len);
+	// Thanks Uncrafted, very cool!
+}
+
+typedef void (*VCALLCONV WriteMessages_func)(void *this, struct bitbuf *msg);
+static WriteMessages_func WriteMessages = 0;
+
+void democustom_write(const void *buf, int len) {
+	create_message(&bb, buf, len);
+	WriteMessages(demorecorder, &bb);
+	bitbuf_reset(&bb);
+}
+
+// This finds the CDemoRecorder::WriteMessages() function, which takes a raw
+// network packet, wraps it up in the appropriate demo framing format and writes
+// it out to the demo file being recorded.
+static bool find_WriteMessages(void) {
+	// TODO(compat): probably rewrite this to just scan for a call instruction!
+	const uchar *insns = (*(uchar ***)demorecorder)[vtidx_RecordPacket];
+	// RecordPacket calls WriteMessages pretty much right away:
+	// 56           push  esi
+	// 57           push  edi
+	// 8B F1        mov   esi,ecx
+	// 8D BE        lea   edi,[esi + 0x68c]
+	// 8C 06 00 00
+	// 57           push  edi
+	// E8           call  CDemoRecorder_WriteMessages
+	// B0 EF FF FF
+	// So we just double check the byte pattern...
+	static const uchar bytes[] =
+#ifdef _WIN32
+		HEXBYTES(56, 57, 8B, F1, 8D, BE, 8C, 06, 00, 00, 57, E8);
+#else
+#warning This is possibly different on Linux too, have a look!
+		{-1, -1, -1, -1, -1, -1};
+#endif
+	if (!memcmp(insns, bytes, sizeof(bytes))) {
+		ssize off = mem_loadoffset(insns + sizeof(bytes));
+		// ... and then offset is relative to the address of whatever is _after_
+		// the call instruction... because x86.
+		WriteMessages = (WriteMessages_func)(insns + sizeof(bytes) + 4 + off);
+		return true;
+	}
+	return false;
+}
+
+DECL_VFUNC_DYN(int, GetEngineBuildNumber)
+
+bool democustom_init(void) {
+	if (!has_vtidx_GetEngineBuildNumber || !has_vtidx_RecordPacket) {
+		errmsg_errorx("missing gamedata entries for this engine");
+		return false;
+	}
+
+	// More UncraftedkNowledge:
+	// > yeah okay so [the usermessage length is] 11 bits if the demo protocol
+	// > is 11 or if the game is l4d2 and the network protocol is 2042.
+	// > otherwise it's 12 bits
+	// > there might be some other l4d2 versions where it's 11 but idk
+	// So here we have to figure out the network protocol version!
+	// NOTE: assuming engclient != null as GEBN index relies on client version
+	int buildnum = VCALL(engclient, GetEngineBuildNumber);
+	// condition is redundant until other GetEngineBuildNumber offsets are added
+	// if (GAMETYPE_MATCHES(L4D2)) {
+		nbits_msgtype = 6;
+		// based on Some Code I Read, buildnum *should* be the protocol version,
+		// however L4D2 returns the actual game version instead, because sure
+		// why not. The only practical difference though is that the network
+		// protocol froze after 2042, so we just have to do a >=. No big deal
+		// really.
+		if (buildnum >= 2042) nbits_datalen = 11; else nbits_datalen = 12;
+	// }
+
+	return find_WriteMessages();
+}
+
+// vi: sw=4 ts=4 noet tw=80 cc=80
diff --git a/src/democustom.h b/src/democustom.h
new file mode 100644
index 0000000..9f9bbe9
--- /dev/null
+++ b/src/democustom.h
@@ -0,0 +1,35 @@
+/*
+ * Copyright © 2022 Michael Smith <mikesmiffy128@gmail.com>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED “AS IS” AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+ * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+ * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+ * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+ * OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+ * PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#ifndef INC_DEMOCUSTOM_H
+#define INC_DEMOCUSTOM_H
+
+#include <stdbool.h>
+
+/* maximum length of a custom demo message, in bytes */
+#define DEMOCUSTOM_MSG_MAX 253
+
+/*
+ * Write a block of up to DEMOWRITER_MSG_MAX bytes into the currently recording
+ * demo - NOT bounds checked, caller MUST ensure length is okay!
+ */
+void democustom_write(const void *buf, int len);
+
+bool democustom_init(void);
+
+#endif
+
+// vi: sw=4 ts=4 noet tw=80 cc=80
diff --git a/src/demorec.c b/src/demorec.c
index b4a674d..1fb5e8e 100644
--- a/src/demorec.c
+++ b/src/demorec.c
@@ -18,9 +18,7 @@
 #include <stdbool.h>
 #include <string.h>
 
-#include "bitbuf.h"
 #include "con_.h"
-#include "demorec.h"
 #include "engineapi.h"
 #include "errmsg.h"
 #include "gamedata.h"
@@ -37,7 +35,7 @@
 DEF_CVAR(sst_autorecord, "Continuously record demos even after reconnecting", 1,
 		CON_ARCHIVE | CON_HIDDEN)
 
-static void *demorecorder;
+void *demorecorder;
 static int *demonum;
 static bool *recording;
 static bool wantstop = false;
@@ -252,114 +250,4 @@ void demorec_end(void) {
 	cmd_stop->cb = orig_stop_cb;
 }
 
-// custom data writing stuff is a separate feature, defined below. it we can't
-// find WriteMessage, we can still probably do the auto recording stuff above
-
-static int nbits_msgtype, nbits_datalen;
-
-// The engine allows usermessages up to 255 bytes, we add 2 bytes of overhead,
-// and then there's the leading bits before that too (see create_message)
-static char bb_buf[DEMOREC_CUSTOM_MSG_MAX + 4];
-static struct bitbuf bb = {
-	bb_buf, sizeof(bb_buf), sizeof(bb_buf) * 8, 0, false, false, "SST"
-};
-
-static void create_message(struct bitbuf *msg, const void *buf, int len) {
-	// The way we pack our custom demo data is via a user message packet with
-	// type "HudText" - this causes the client to do a text lookup which will
-	// simply silently fail on invalid keys. By making the first byte null
-	// (creating an empty string), we get the rest of the packet to stick in
-	// whatever other data we want.
-	//
-	// Notes from Uncrafted:
-	// > But yeah the data you want to append is as follows:
-	// > - 6 bits (5 bits in older versions) for the message type - should be 23
-	// >   for user message
-	bitbuf_appendbits(msg, 23, nbits_msgtype);
-	// > - 1 byte for the user message type - should be 2 for HudText
-	bitbuf_appendbyte(msg, 2);
-	// > - ~~an int~~ 11 or 12 bits for the length of your data in bits,
-	bitbuf_appendbits(msg, len * 8, nbits_datalen); // NOTE: assuming len <= 254
-	// > - your data
-	// [first the aforementioned null byte, plus an arbitrary marker byte to
-	// avoid confusion when parsing the demo later...
-	bitbuf_appendbyte(msg, 0);
-	bitbuf_appendbyte(msg, 0xAC);
-	// ... and then just the data itself]
-	bitbuf_appendbuf(msg, buf, len);
-	// Thanks Uncrafted, very cool!
-}
-
-typedef void (*VCALLCONV WriteMessages_func)(void *this, struct bitbuf *msg);
-static WriteMessages_func WriteMessages = 0;
-
-void demorec_writecustom(void *buf, int len) {
-	create_message(&bb, buf, len);
-	WriteMessages(demorecorder, &bb);
-	bitbuf_reset(&bb);
-}
-
-// This finds the CDemoRecorder::WriteMessages() function, which takes a raw
-// network packet, wraps it up in the appropriate demo framing format and writes
-// it out to the demo file being recorded.
-static bool find_WriteMessages(void) {
-	// TODO(compat): probably rewrite this to just scan for a call instruction!
-	const uchar *insns = (*(uchar ***)demorecorder)[vtidx_RecordPacket];
-	// RecordPacket calls WriteMessages pretty much right away:
-	// 56           push  esi
-	// 57           push  edi
-	// 8B F1        mov   esi,ecx
-	// 8D BE        lea   edi,[esi + 0x68c]
-	// 8C 06 00 00
-	// 57           push  edi
-	// E8           call  CDemoRecorder_WriteMessages
-	// B0 EF FF FF
-	// So we just double check the byte pattern...
-	static const uchar bytes[] =
-#ifdef _WIN32
-		HEXBYTES(56, 57, 8B, F1, 8D, BE, 8C, 06, 00, 00, 57, E8);
-#else
-#warning This is possibly different on Linux too, have a look!
-		{-1, -1, -1, -1, -1, -1};
-#endif
-	if (!memcmp(insns, bytes, sizeof(bytes))) {
-		ssize off = mem_loadoffset(insns + sizeof(bytes));
-		// ... and then offset is relative to the address of whatever is _after_
-		// the call instruction... because x86.
-		WriteMessages = (WriteMessages_func)(insns + sizeof(bytes) + 4 + off);
-		return true;
-	}
-	return false;
-}
-
-DECL_VFUNC_DYN(int, GetEngineBuildNumber)
-
-bool demorec_custom_init(void) {
-	if (!has_vtidx_GetEngineBuildNumber || !has_vtidx_RecordPacket) {
-		errmsg_errorx("custom: missing gamedata entries for this engine");
-		return false;
-	}
-
-	// More UncraftedkNowledge:
-	// > yeah okay so [the usermessage length is] 11 bits if the demo protocol
-	// > is 11 or if the game is l4d2 and the network protocol is 2042.
-	// > otherwise it's 12 bits
-	// > there might be some other l4d2 versions where it's 11 but idk
-	// So here we have to figure out the network protocol version!
-	// NOTE: assuming engclient != null as GEBN index relies on client version
-	int buildnum = VCALL(engclient, GetEngineBuildNumber);
-	// condition is redundant until other GetEngineBuildNumber offsets are added
-	// if (GAMETYPE_MATCHES(L4D2)) {
-		nbits_msgtype = 6;
-		// based on Some Code I Read, buildnum *should* be the protocol version,
-		// however L4D2 returns the actual game version instead, because sure
-		// why not. The only practical difference though is that the network
-		// protocol froze after 2042, so we just have to do a >=. No big deal
-		// really.
-		if (buildnum >= 2042) nbits_datalen = 11; else nbits_datalen = 12;
-	// }
-
-	return find_WriteMessages();
-}
-
 // vi: sw=4 ts=4 noet tw=80 cc=80
diff --git a/src/demorec.h b/src/demorec.h
index a18bea4..7306c0a 100644
--- a/src/demorec.h
+++ b/src/demorec.h
@@ -20,20 +20,12 @@
 
 #include <stdbool.h>
 
+/* For internal use by democustom */
+extern void *demorecorder;
+
 bool demorec_init(void);
 void demorec_end(void);
 
-bool demorec_custom_init(void);
-
-/* maximum length of a custom demo message, in bytes */
-#define DEMOREC_CUSTOM_MSG_MAX 253
-
-/*
- * Write a block of up to DEMOWRITER_MSG_MAX bytes into the currently recording
- * demo - NOT bounds checked, caller MUST ensure length is okay!
- */
-void demorec_writecustom(void *buf, int len);
-
 #endif
 
 // vi: sw=4 ts=4 noet tw=80 cc=80
diff --git a/src/sst.c b/src/sst.c
index 7246e89..4182b09 100644
--- a/src/sst.c
+++ b/src/sst.c
@@ -26,6 +26,7 @@
 #include "alias.h"
 #include "autojump.h"
 #include "con_.h"
+#include "democustom.h"
 #include "demorec.h"
 #include "engineapi.h"
 #include "errmsg.h"
@@ -209,11 +210,10 @@ static const char *updatenotes = "\
 static void do_featureinit(void) {
 	bool has_bind = bind_init();
 	if (has_bind) has_ac = ac_init();
-	bool has_alias = alias_init();
+	alias_init();
 	has_autojump = autojump_init();
 	has_demorec = demorec_init();
-	// not enabling demorec_custom yet - kind of incomplete and currently unused
-	//if (has_demorec) demorec_custom_init();
+	if (has_demorec) democustom_init();
 	bool has_ent = ent_init();
 	has_fov = fov_init(has_ent);
 	if (has_ent) l4dwarp_init();