Highlight URLs with control and follow with click

config.def.h

@@ -525,3 +525,14 @@ static char ascii_printable[] =
 	" !\"#$%&'()*+,-./0123456789:;<=>?"
 	"@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_"
 	"`abcdefghijklmnopqrstuvwxyz{|}~";
+
+/*
+ * Open urls starting with urlprefixes, contatining urlchars
+ * by passing as ARG1 to urlhandler.
+ */
+char* urlhandler = "xdg-open";
+char urlchars[] =
+	"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+	"abcdefghijklmnopqrstuvwxyz"
+	"0123456789-._~:/?#@!$&'*+,;=%";
+char* urlprefixes[] = {"http://", "https://", NULL};

st.c

@@ -643,6 +643,95 @@ getsel(void)
 	return str;
 }
 
+char *
+strstrany(char* s, char** strs) {
+	char *match;
+	for (int i = 0; strs[i]; i++) {
+		if ((match = strstr(s, strs[i]))) {
+			return match;
+		}
+	}
+	return NULL;
+}
+
+void
+highlighturls(void)
+{
+	char *match;
+	char *linestr = calloc(sizeof(char), term.col+1); /* assume ascii */
+	for (int i = term.top; i < term.bot; i++) {
+		int url_start = -1;
+		for (int j = 0; j < term.col; j++) {
+			if (term.line[i][j].u < 127) {
+				linestr[j] = term.line[i][j].u;
+			}
+			linestr[term.col] = '\0';
+		}
+		while ((match = strstrany(linestr + url_start + 1, urlprefixes))) {
+			url_start = match - linestr;
+			for (int c = url_start; c < term.col && strchr(urlchars, linestr[c]); c++) {
+				term.line[i][c].mode |= ATTR_URL;
+				tsetdirt(i, c);
+			}
+		}
+	}
+	free(linestr);
+}
+
+void
+unhighlighturls(void)
+{
+	for (int i = term.top; i < term.bot; i++) {
+		for (int j = 0; j < term.col; j++) {
+			Glyph* g = &term.line[i][j];
+			if (g->mode & ATTR_URL) {
+				g->mode &= ~ATTR_URL;
+				tsetdirt(i, j);
+			}
+		}
+	}
+	return;
+}
+
+void
+followurl(int x, int y) {
+	char *linestr = calloc(sizeof(char), term.col+1); /* assume ascii */
+	char *match;
+	for (int i = 0; i < term.col; i++) {
+		if (term.line[x][i].u < 127) {
+			linestr[i] = term.line[x][i].u;
+		}
+		linestr[term.col] = '\0';
+	}
+	int url_start = -1;
+	while ((match = strstrany(linestr + url_start + 1, urlprefixes))) {
+		url_start = match - linestr;
+		int url_end = url_start;
+		for (int c = url_start; c < term.col && strchr(urlchars, linestr[c]); c++) {
+			url_end++;
+		}
+		if (url_start <= y && y < url_end) {
+			linestr[url_end] = '\0';
+			break;
+		}
+	}
+	if (url_start == -1) {
+		free(linestr);
+		return;
+	}
+
+	pid_t chpid;
+	if ((chpid = fork()) == 0) {
+		if (fork() == 0)
+			execlp(urlhandler, urlhandler, linestr + url_start, NULL);
+		exit(1);
+	}
+	if (chpid > 0)
+		waitpid(chpid, NULL, 0);
+	free(linestr);
+	unhighlighturls();
+}
+
 void
 selclear(void)
 {

st.h

@@ -35,6 +35,7 @@ enum glyph_attribute {
 	ATTR_WIDE       = 1 << 9,
 	ATTR_WDUMMY     = 1 << 10,
 	ATTR_BOLD_FAINT = ATTR_BOLD | ATTR_FAINT,
+	ATTR_URL	= 1 << 14,
 };
 
 enum selection_mode {
@@ -110,6 +111,10 @@ void selextend(int, int, int, int);
 int selected(int, int);
 char *getsel(void);
 
+void highlighturls(void);
+void unhighlighturls(void);
+void followurl(int, int);
+
 size_t utf8encode(Rune, char *);
 
 void *xmalloc(size_t);
@@ -130,6 +135,10 @@ extern unsigned int tabspaces;
 extern unsigned int defaultfg;
 extern unsigned int defaultbg;
 extern unsigned int defaultcs;
+extern char *urlhandler;
+extern char urlchars[];
+extern char *urlprefixes[];
+extern int nurlprefixes;
 
 char **externalcopycmd();
 char **externalpastecmd();

x.c

@@ -203,6 +203,7 @@ static void usage(void);
 
 static void (*handler[LASTEvent])(XEvent *) = {
 	[KeyPress] = kpress,
+	[KeyRelease] = kpress,
 	[ClientMessage] = cmessage,
 	[ConfigureNotify] = resize,
 	[VisibilityNotify] = visibility,
@@ -465,6 +466,15 @@ mouseaction(XEvent *e, uint release)
 	/* ignore Button<N>mask for Button<N> - it's set on release */
 	uint state = e->xbutton.state & ~buttonmask(e->xbutton.button);
 
+	if (release == 0 &&
+	    e->xbutton.button == Button1 &&
+	    (match(ControlMask, state) ||
+	     match(ControlMask, state & ~forcemousemod))) {
+		followurl(evrow(e), evcol(e));
+		return 1;
+	}
+
+
 	for (ms = mshortcuts; ms < mshortcuts + LEN(mshortcuts); ms++) {
 		if (ms->release == release &&
 		    ms->button == e->xbutton.button &&
@@ -1527,7 +1537,7 @@ xdrawglyphfontspecs(const XftGlyphFontSpec *specs, Glyph base, int len, int x, i
 	XftDrawGlyphFontSpec(xw.draw, fg, specs, len);
 
 	/* Render underline and strikethrough. */
-	if (base.mode & ATTR_UNDERLINE) {
+	if (base.mode & ATTR_UNDERLINE || base.mode & ATTR_URL) {
 		XftDrawRect(xw.draw, fg, winx, winy + dc.font.ascent * chscale + 1,
 				width, 1);
 	}
@@ -1897,6 +1907,18 @@ kpress(XEvent *ev)
 		                                      == finish) normalMode();
 		return;
 	}
+
+        /* 0. highlight URLs when control held */
+	if (ksym == XK_Control_L) {
+		highlighturls();
+	} else if (ev->type == KeyRelease && e->keycode == XKeysymToKeycode(e->display, XK_Control_L)) {
+		unhighlighturls();
+	}
+
+	/* KeyRelease not relevant to shortcuts */
+	if (ev->type == KeyRelease)
+		return;
+
 	/* 1. shortcuts */
 	for (bp = shortcuts; bp < shortcuts + LEN(shortcuts); bp++) {
 		if (ksym == bp->keysym && match(bp->mod, e->state)) {