wowana.me

website source

commit 8a89605017f86042f36777e65c41cdb31a582960
parent ae45281eb1cd8f5c0607e2e8052c86a61a4ae860
Author: opal hart <opal@wowana.me>
Date:   Tue, 24 Nov 2020 04:26:01 +0000

add fp.c -- fingerprint colourisation tool

used to generate coloured fingerprints on
<https://wowana.me/pages/omemo.xht>, uses openkeychain / dino algorithm
so people can easily compare fingerprints manually

Diffstat:
M
.gitignore
 | 
1
+
M
Makefile
 | 
11
++++++++---
A
src/fp.c
 | 
146
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

3 files changed, 155 insertions(+), 3 deletions(-)
diff --git a/.gitignore b/.gitignore
@@ -1,3 +1,4 @@
+/scripts/fp
 /out/**
 !/out/.well-known/
 !/out/cloudflare-warning.svg
diff --git a/Makefile b/Makefile
@@ -1,8 +1,9 @@
 .PHONY := all check clean upload
 BLOGSRC := $(wildcard src/blog/*.md)
-SRC := $(wildcard src/*.md src/mirrors/*.md) $(BLOGSRC)
-OBJ := $(SRC:%.md=%.part.xht) src/blog/index.part.xht
-FINAL := $(OBJ:src/%.part.xht=out/%.xht) out/blog/index.xht out/blog/feed.atom
+SRC := $(wildcard src/*.md src/pages/*.md src/mirrors/*.md) $(BLOGSRC)
+XHT_OBJ := $(SRC:%.md=%.part.xht) src/blog/index.part.xht
+OBJ := $(XHT_OBJ)
+FINAL := $(XHT_OBJ:src/%.part.xht=out/%.xht) out/blog/index.xht out/blog/feed.atom
 MARKDOWN := hoedown --xhtml
 
 .INTERMEDIATE: $(OBJ)
@@ -36,3 +37,7 @@ out/%.xht: src/%.part.xht src/header.inc src/footer.inc
 
 out/blog/feed.atom: $(BLOGSRC:%.md=%.part.xht)
 	./scripts/feed $$(ls -1t $^) > $@
+
+scripts/fp: CFLAGS += -Wno-implicit-int
+scripts/fp: src/fp.c
+	$(CC) -o $@ $< $(CFLAGS) -lcrypto
diff --git a/src/fp.c b/src/fp.c
@@ -0,0 +1,146 @@
+#include <errno.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <openssl/sha.h>
+
+struct colour {
+	unsigned char r;
+	unsigned char g;
+	unsigned char b;
+};
+
+int main (int, char**);
+static usage (const char*, int);
+static html_format_fp (const char*);
+bool take_four (char*, const char*);
+static from_hex (const char*);
+struct colour get_colour (int);
+unsigned char uchar_min (unsigned char, unsigned char);
+
+int main (int argc, char** argv)
+{
+	if (argc < 2)
+		return usage(argv[0], 1);
+	int ret;
+	while (--argc && !( ret = html_format_fp(argv[1]) ))
+		++argv;
+	if (!ret)
+		puts("");
+	return ret;
+}
+
+usage (const char* arg0, int exit)
+{
+	fputs("Usage: ", stdout);
+	fputs(arg0, stdout);
+	puts(" <fingerprint>");
+	return exit;
+}
+
+html_format_fp (const char* fp)
+{
+	const char* ptr = fp;
+	bool insert_space = false;
+	while (*ptr) {
+		char buf[5];
+		if (!take_four(buf, ptr))
+			return 1;
+		int val = from_hex(buf);
+		if (val < 0)
+			return 1;
+		struct colour c = get_colour(val);
+		fputs("<span style='color:#", stdout);
+		printf("%02x%02x%02x", c.r, c.g, c.b);
+		fputs("'>", stdout);
+		fputs(buf, stdout);
+		fputs("</span>", stdout);
+		if (insert_space)
+			fputs(" ", stdout);
+		insert_space = !insert_space;
+		ptr += 4;
+	}
+	return 0;
+}
+
+bool take_four (char* buf, const char* str)
+{
+	if (strlen(str) < 4) {
+		fputs("string length of value `", stderr);
+		fputs(str, stderr);
+		fputs("' is not divisible by four\n", stderr);
+		return false;
+	}
+	strncpy(buf, str, 4);
+	return true;
+}
+
+/* expects 'str' in range of 0x0000 ~ 0xFFFF.
+ * returns negative value on error
+ */
+from_hex (const char* str)
+{
+	errno = 0;
+	long val = strtol(str, NULL, 16);
+	if (errno) {
+		perror("in from_hex(): strtol");
+		return -1;
+	}
+	else if (val > 0xFFFF) {
+		fputs("BUG: value `", stderr);
+		fputs(str, stderr);
+		fputs("' is greater than 0xFFFF\n", stderr);
+		return -1;
+	}
+	else if (val < 0x0000) {
+		fputs("BUG: value `", stderr);
+		fputs(str, stderr);
+		fputs("' is negative\n", stderr);
+		return -1;
+	}
+	else return (int) val;
+}
+
+/* algorithm stolen from Dino, in turn stolen from OpenKeyChain */
+struct colour get_colour (int val)
+{
+	unsigned char bytes[2] = {
+		(unsigned char) ((val >> 8) & 0xff - 128),
+		(unsigned char) (val & 0xff - 128),
+	};
+	unsigned char* hash = SHA1(bytes, sizeof bytes, NULL);
+	struct colour c = {
+		.r = hash[0],
+		.g = hash[1],
+		.b = hash[2],
+	};
+	if (0 == (c.r | c.g | c.b))
+		c.r = c.g = c.b = 1;
+	double brightness =
+	 (.2126 * c.r) +
+	 (.7152 * c.g) +
+	 (.0722 * c.b);
+	if (brightness < 80.) {
+		double factor = 80. / brightness;
+#define brighten(which) which = uchar_min(255, (unsigned char) (which * factor))
+		brighten(c.r);
+		brighten(c.g);
+		brighten(c.b);
+#undef brighten
+	}
+	else if (brightness > 180) {
+		double factor = 180. / brightness;
+#define darken(which) which = (unsigned char) (which * factor)
+		darken(c.r);
+		darken(c.g);
+		darken(c.b);
+#undef darken
+	}
+	return c;
+}
+
+unsigned char uchar_min (unsigned char a, unsigned char b)
+{
+	return (a<b)? a : b;
+}