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-rw-r--r--src/nyancat.c113
1 files changed, 88 insertions, 25 deletions
diff --git a/src/nyancat.c b/src/nyancat.c
index 46cd6c1..5f4c702 100644
--- a/src/nyancat.c
+++ b/src/nyancat.c
@@ -47,29 +47,55 @@
#include <signal.h>
#include <time.h>
#include <setjmp.h>
+
+/*
+ * telnet.h contains some #defines for the various
+ * commands, escape characters, and modes for telnet.
+ * (it surprises some people that telnet is, really,
+ * a protocol, and not just raw text transmission)
+ */
#include "telnet.h"
-/* The animation frames are stored separately. */
+/*
+ * The animation frames are stored separately in
+ * this header so they don't clutter the core source
+ */
#include "animation.h"
-/* The color palette is not yet set */
+/*
+ * Color palette to use for final output
+ * Specifically, this should be either control sequences
+ * or raw characters (ie, for vt220 mode)
+ */
char * colors[256] = {NULL};
+
/*
* For most modes, we ouput spaces, but for some
- * we will use block characters.
+ * we will use block characters (or even nothing)
*/
char * output = " ";
-/* Telnet mode? */
+/*
+ * Are we currently in telnet mode?
+ */
int telnet = 0;
-/* I refuse to include libm */
-double log10(double x) {
- int val = (int)x;
+/*
+ * Environment to use for setjmp/longjmp
+ * when breaking out of options handler
+ */
+jmp_buf environment;
+
+
+/*
+ * I refuse to include libm to keep this low
+ * on external dependencies.
+ * */
+int digits(int val) {
int d = 1, c;
if (val >= 0) for (c = 10; c <= val; c *= 10) d++;
else for (c = -10 ; c >= val; c *= 10) d++;
- return (c < 0) ? (double)++d : (double)d;
+ return (c < 0) ? ++d : d;
}
/*
@@ -90,8 +116,6 @@ void SIGINT_handler(int sig){
exit(0);
}
-jmp_buf environment;
-
/*
* Handle the alarm which breaks us off of options
* handling if we didn't receive a terminal
@@ -102,16 +126,23 @@ void SIGALRM_handler(int sig) {
/* Unreachable */
}
+/*
+ * Telnet requires us to send a specific sequence
+ * for a line break (\r\000\n), so let's make it happy.
+ */
void newline(int n) {
int i = 0;
for (i = 0; i < n; ++i) {
- if (telnet) {
- putc('\r', stdout);
- putc(0, stdout);
- putc('\n', stdout);
- } else {
- putc('\n', stdout);
- }
+ /* We will send `n` linefeeds to the client */
+ if (telnet) {
+ /* Send the telnet newline sequence */
+ putc('\r', stdout);
+ putc(0, stdout);
+ putc('\n', stdout);
+ } else {
+ /* Send a regular line feed */
+ putc('\n', stdout);
+ }
}
}
@@ -155,6 +186,10 @@ void set_options() {
telnet_willack[NEW_ENVIRON] = DO;
}
+/*
+ * Send a command (cmd) to the telnet client
+ * Also does special handling for DO/DONT/WILL/WONT
+ */
void send_command(int cmd, int opt) {
/* Send a command to the telnet client */
if (cmd == DO || cmd == DONT) {
@@ -234,6 +269,8 @@ int main(int argc, char ** argv) {
/* End of extended option mode */
sb_mode = 0;
if (sb[0] == TTYPE) {
+ /* This was a response to the TTYPE command, meaning
+ * that this should be a terminal type */
alarm(0);
strcpy(term, &sb[2]);
goto ready;
@@ -249,6 +286,7 @@ int main(int argc, char ** argv) {
/* Will / Won't Negotiation */
opt = getchar();
if (!telnet_willack[opt]) {
+ /* We default to WONT */
telnet_willack[opt] = WONT;
}
send_command(telnet_willack[opt], opt);
@@ -264,6 +302,7 @@ int main(int argc, char ** argv) {
/* Do / Don't Negotation */
opt = getchar();
if (!telnet_options[opt]) {
+ /* We default to DONT */
telnet_options[opt] = DONT;
}
send_command(telnet_options[opt], opt);
@@ -281,7 +320,7 @@ int main(int argc, char ** argv) {
memset(sb, 0, 1024);
break;
case IAC:
- /* Connection Closed During Negotiation */
+ /* IAC IAC? That's probably not right. */
done = 1;
break;
default:
@@ -290,6 +329,13 @@ int main(int argc, char ** argv) {
} else if (sb_mode) {
/* Extended Option Mode -> Accept character */
if (sb_len < 1023) {
+ /* Append this character to the SB string,
+ * but only if it doesn't put us over
+ * our limit; honestly, we shouldn't hit
+ * the limit, as we're only collecting characters
+ * for a terminal type, but better safe than
+ * sorry (and vulernable).
+ */
sb[sb_len] = i;
sb_len++;
}
@@ -298,11 +344,20 @@ int main(int argc, char ** argv) {
}
}
} else {
- /* Otherwise, we were run standalone, find the terminal type from the environement */
+ /* We are running standalone, retrieve the
+ * terminal type from the environment. */
char * nterm = getenv("TERM");
strcpy(term, nterm);
}
+ /*
+ * Labels. Yes, and I used a goto.
+ * If you're going to complain about this, you
+ * really need to reevaluate your approach to getting
+ * things done. This works, it works well, and there
+ * is absolutely, positively nothing wrong with using
+ * goto in C, so I'm going to do it.
+ */
ready:
/* Convert the entire terminal string to lower case */
@@ -478,10 +533,10 @@ ready:
time_t start, current;
time(&start);
- int playing = 1;
- size_t i = 0;
- char last = 0;
- size_t y, x;
+ int playing = 1; /* Animation should continue [left here for modifications] */
+ size_t i = 0; /* Current frame # */
+ char last = 0; /* Last color index rendered */
+ size_t y, x; /* x/y coordinates of what we're drawing */
while (playing) {
/* Render the frame */
for (y = MIN_ROW; y < MAX_ROW; ++y) {
@@ -503,15 +558,23 @@ ready:
/* End of row, send newline */
newline(1);
}
+ /* Get the current time for the "You have nyaned..." string */
time(&current);
double diff = difftime(current, start);
- double nLen = log10(diff);
- int width = (80 - 29 - (int)nLen) / 2;
+ /* Now count the length of the time difference so we can center */
+ int nLen = int(diff);
+ int width = (80 - 29 - nLen) / 2;
+ /* Spit out some spaces so that we're actually centered */
while (width) {
printf(" ");
width--;
}
+ /* You have nyaned for [n] seconds!
+ * The \033[J ensures that the rest of the line has the dark blue
+ * background, and the \033[1;37m ensures that our text is bright white
+ */
printf("\033[1;37mYou have nyaned for %0.0f seconds!\033[J", diff);
+ /* Reset the last color so that the escape sequences rewrite */
last = 0;
/* Update frame crount */
++i;