irc: a bitchx/irssi-style IRC client

irc HOST [NICK] - connects over the kernel TCP stack (DNS-resolves the
host), registers, and runs a live client on the 40x18 LCD.

UI, within the terminal's means (no cursor addressing - just \r + \b):
messages scroll above a fixed irssi-style input line '[#chan] text_'
redrawn in place; long input scrolls horizontally. The elders' formats:
<nick> msg, <nick:#c> off-channel, *nick* private, -nick- notice,
* nick action, >target< outbound, -!- server/status. Keys come from both
the OSK (SELECT) and the console ring (pollcon), so a hub can drive it.

Commands: /join /part /msg /me /nick /quit /raw, plus bare text to the
current channel. Handles PING (PONG + a wink), CTCP ACTION/VERSION,
JOIN/PART/QUIT/KICK/NICK, 332/353 topic+names, and 433 nick-in-use
(auto-appends _). Registers on bank 32 as program id 30.

Note: gbos doesn't zero C statics, so main() inits its state explicitly;
the local TCP port is randomized (DIV) to dodge a stale server-side
half-open from an unclean prior exit. Tested end to end against a small
ircd through gbhub: full MOTD burst, join, channel + private messages,
actions, and bot replies all render correctly.

4 files changed, 384 insertions, 1 deletions

diff --git a/Makefile b/Makefile
index 99160dc..bc0eac7 100644
--- a/Makefile
+++ b/Makefile
@@ -20,7 +20,7 @@ $(BUILD)/%.o: src/%.asm | $(BUILD)
 # C programs: compiled with SDCC into ROM-bank blobs and INCBIN'd by programs.asm
 CBLOBS := c/chello.bin c/echo.bin c/true.bin c/false.bin c/uname.bin \
           c/pid.bin c/cat.bin c/wc.bin c/head.bin c/args.bin \
-          c/ls.bin c/save.bin c/rm.bin c/sh.bin c/ps.bin c/kill.bin c/spin.bin c/blk.bin c/mkdir.bin c/count.bin c/ptest.bin c/necho.bin c/wget.bin c/chat.bin c/netd.bin c/ping.bin c/nslookup.bin c/dhcp.bin
+          c/ls.bin c/save.bin c/rm.bin c/sh.bin c/ps.bin c/kill.bin c/spin.bin c/blk.bin c/mkdir.bin c/count.bin c/ptest.bin c/necho.bin c/wget.bin c/chat.bin c/netd.bin c/ping.bin c/nslookup.bin c/dhcp.bin c/irc.bin
 $(BUILD)/programs.o: $(CBLOBS)
 
 # C programs also depend on the shared libc sources
diff --git a/c/irc.c b/c/irc.c
new file mode 100644
index 0000000..817471e
--- /dev/null
+++ b/c/irc.c
@@ -0,0 +1,375 @@
+#include "resolve.h"
+/* irc HOST [NICK] - a bitchx/irssi-flavored IRC client on 40x18 columns.
+   The kernel owns TCP; this owns the protocol and the screen.
+
+   UI: messages scroll above; the bottom line is an irssi-style input line
+   "[#chan] text_" redrawn in place with \r (the terminal has no cursor
+   addressing - \r + overprint is the entire trick). Long input scrolls
+   horizontally like irssi. Keys come from the OSK (SELECT toggles it) and
+   from the console ring (pollcon), so a hub can type into the client too.
+
+   Formats, straight from the elders:
+     <nick> text        channel message      * nick text   CTCP ACTION
+     <nick:#c> text     msg to a non-current channel
+     *nick* text        private msg          >target< text  outbound /msg
+     -nick- text        notice               -!- text       server/status  */
+
+/* seg first + large: the arg string lives at 0xA000 and the first static
+   lands on it; args are copied out in main() before seg is ever written. */
+static unsigned char seg[220];      /* one TCP segment from the kernel   */
+static char line[240];              /* server line accumulator           */
+static unsigned char llen;
+static char input[140];             /* the input line being typed        */
+static unsigned char inlen;
+static unsigned char drawn;         /* chars currently drawn on input row */
+static char nick[16];
+static char target[32];             /* current channel/query, "" = none  */
+static char sbuf[200];              /* outgoing IRC line builder         */
+static unsigned char slen;
+static unsigned char namebuf[64];
+static unsigned char dst[4];
+static unsigned char sock;
+static unsigned char quitting;
+
+/* ---- tiny string helpers (SDCC libc is us) ------------------------------- */
+static unsigned char sceq(const char *a, const char *b) {   /* case-insens. */
+    unsigned char ca, cb;
+    for (;;) {
+        ca = (unsigned char)*a++; cb = (unsigned char)*b++;
+        if (ca >= 'a' && ca <= 'z') ca -= 32;
+        if (cb >= 'a' && cb <= 'z') cb -= 32;
+        if (ca != cb) return 0;
+        if (!ca) return 1;
+    }
+}
+static void scpy(char *d, const char *s, unsigned char max) {
+    unsigned char i;
+    for (i = 0; s[i] && i < (unsigned char)(max - 1); i++) d[i] = s[i];
+    d[i] = 0;
+}
+
+/* ---- outgoing IRC lines --------------------------------------------------- */
+static void sc(const char *s) {           /* append to sbuf */
+    while (*s && slen < 197) sbuf[slen++] = *s++;
+}
+static void sfin(void) {                  /* CRLF + send */
+    sbuf[slen++] = '\r'; sbuf[slen++] = '\n';
+    net_send(sock, sbuf, slen);
+    slen = 0;
+}
+
+/* ---- the input line ------------------------------------------------------- */
+/* erase what's drawn on the bottom row, park at col 0 */
+static void row_clear(void) {
+    unsigned char i;
+    putc('\r');
+    for (i = 0; i < drawn; i++) putc(' ');
+    putc('\r');
+    drawn = 0;
+}
+/* redraw "[target] tail-of-input_"; keep total < 40 so it never wraps */
+static void row_draw(void) {
+    unsigned char pl, vis, i;
+    const char *t = target[0] ? target : "(status)";
+    row_clear();
+    putc('[');
+    for (pl = 0; t[pl] && pl < 12; pl++) putc(t[pl]);
+    putc(']'); putc(' ');
+    pl += 3;                              /* prompt width */
+    vis = 39 - pl - 1;                    /* room for text (cursor gets 1) */
+    i = (inlen > vis) ? (unsigned char)(inlen - vis) : 0;
+    for (; i < inlen; i++) putc(input[i]);
+    drawn = pl + ((inlen > vis) ? vis : inlen);
+}
+/* print a message line above the input line */
+static void say(const char *s) {
+    row_clear();
+    puts(s); nl();
+    row_draw();
+}
+static void say2(const char *a, const char *b) {
+    row_clear();
+    puts(a); puts(b); nl();
+    row_draw();
+}
+static void say3(const char *a, const char *b, const char *c) {
+    row_clear();
+    puts(a); puts(b); puts(c); nl();
+    row_draw();
+}
+
+/* ---- server line parsing -------------------------------------------------- */
+/* split "pfx!user@host" -> pfx nick only (in place) */
+static void bang(char *p) {
+    while (*p && *p != '!') p++;
+    *p = 0;
+}
+static unsigned char isnum(const char *c) {
+    return c[0] >= '0' && c[0] <= '9';
+}
+
+static void handle(char *l) {
+    char *pfx = (char *)"", *cmd, *arg, *txt = (char *)"";
+    char *p = l;
+
+    if (*p == ':') {                       /* :prefix */
+        pfx = ++p;
+        while (*p && *p != ' ') p++;
+        if (*p) *p++ = 0;
+    }
+    cmd = p;                               /* command */
+    while (*p && *p != ' ') p++;
+    if (*p) *p++ = 0;
+    arg = p;                               /* params, then :trailing */
+    while (*p) {
+        if (*p == ':' && (p == arg || p[-1] == 0)) { txt = p + 1; p[-1] = 0; break; }
+        if (*p == ' ') *p = 0;
+        p++;
+    }
+    /* arg = first param (NUL-joined list), txt = trailing */
+
+    if (sceq(cmd, "PING")) {
+        slen = 0; sc("PONG :"); sc(txt[0] ? txt : arg); sfin();
+        say("-!- Ping? Pong!");
+        return;
+    }
+    bang(pfx);
+    if (sceq(cmd, "PRIVMSG")) {
+        char *dest = arg;
+        unsigned char act = 0;
+        if (txt[0] == 1) {                 /* CTCP */
+            char *e = txt + 1;
+            while (*e && *e != 1) e++;
+            *e = 0; txt++;
+            if (txt[0]=='A'&&txt[1]=='C'&&txt[2]=='T'&&txt[3]=='I'&&txt[4]=='O'&&txt[5]=='N'&&txt[6]==' ') {
+                act = 1; txt += 7;
+            } else if (txt[0]=='V') {      /* VERSION */
+                slen = 0; sc("NOTICE "); sc(pfx); sc(" :\001VERSION gbos:sl0pboy:GameBoyColor\001"); sfin();
+                return;
+            } else return;
+        }
+        row_clear();
+        if (act)                { puts("* "); puts(pfx); putc(' '); }
+        else if (sceq(dest, nick)) { putc('*'); puts(pfx); puts("* "); }
+        else if (sceq(dest, target)) { putc('<'); puts(pfx); puts("> "); }
+        else                    { putc('<'); puts(pfx); putc(':'); puts(dest); puts("> "); }
+        puts(txt); nl();
+        row_draw();
+        return;
+    }
+    if (sceq(cmd, "NOTICE")) {
+        row_clear();
+        putc('-'); puts(pfx[0] ? pfx : "server"); puts("- "); puts(txt); nl();
+        row_draw();
+        return;
+    }
+    if (sceq(cmd, "JOIN")) {
+        char *ch = txt[0] ? txt : arg;
+        if (sceq(pfx, nick)) {
+            scpy(target, ch, sizeof(target));
+            say2("-!- now talking in ", target);
+        } else say3("-!- ", pfx, " has joined");
+        return;
+    }
+    if (sceq(cmd, "PART")) {
+        if (sceq(pfx, nick)) { target[0] = 0; say("-!- you left"); }
+        else say3("-!- ", pfx, " has left");
+        return;
+    }
+    if (sceq(cmd, "QUIT")) { say3("-!- ", pfx, " has quit"); return; }
+    if (sceq(cmd, "KICK")) {
+        char *ch = arg, *who = arg;
+        while (*who) who++;
+        who++;                              /* param 2: the victim */
+        if (sceq(who, nick)) { target[0] = 0; say2("-!- you were kicked from ", ch); }
+        else say3("-!- ", who, " was kicked");
+        return;
+    }
+    if (sceq(cmd, "NICK")) {
+        char *nn = txt[0] ? txt : arg;
+        if (sceq(pfx, nick)) scpy(nick, nn, sizeof(nick));
+        row_clear();
+        puts("-!- "); puts(pfx); puts(" is now known as "); puts(nn); nl();
+        row_draw();
+        return;
+    }
+    if (isnum(cmd)) {
+        if (cmd[0]=='4'&&cmd[1]=='3'&&cmd[2]=='3') {   /* nick in use */
+            unsigned char n = strlen(nick);
+            if (n < 14) { nick[n] = '_'; nick[n+1] = 0; }
+            slen = 0; sc("NICK "); sc(nick); sfin();
+            say2("-!- nick in use, trying ", nick);
+            return;
+        }
+        if (cmd[0]=='3'&&cmd[1]=='3'&&cmd[2]=='2') {   /* topic */
+            say2("-!- topic: ", txt);
+            return;
+        }
+        if (cmd[0]=='3'&&cmd[1]=='5'&&cmd[2]=='3') {   /* names */
+            say2("-!- users: ", txt);
+            return;
+        }
+        if (cmd[1]=='3'&&cmd[0]=='3') return;          /* 333 topic-by: skip */
+        if (txt[0]) say2("-!- ", txt);                 /* motd & friends */
+        return;
+    }
+    /* anything else: show it raw-ish, bitchx would too */
+    if (txt[0]) say3(cmd, " ", txt);
+}
+
+/* accumulate TCP bytes into lines */
+static void feed(unsigned char *b, unsigned char n) {
+    unsigned char i;
+    for (i = 0; i < n; i++) {
+        char c = (char)b[i];
+        if (c == '\r') continue;
+        if (c == '\n') { line[llen] = 0; if (llen) handle(line); llen = 0; }
+        else if (llen < 239) line[llen++] = c;
+    }
+}
+
+/* ---- typed input ---------------------------------------------------------- */
+static void run_cmd(char *t) {
+    char *a = t;
+    while (*a && *a != ' ') a++;
+    if (*a) *a++ = 0;                      /* t = /cmd, a = rest */
+
+    if (sceq(t, "/join") || sceq(t, "/j")) {
+        if (!*a) { say("-!- join what?"); return; }
+        slen = 0; sc("JOIN "); sc(a); sfin();
+        return;
+    }
+    if (sceq(t, "/part") || sceq(t, "/p")) {
+        slen = 0; sc("PART "); sc(*a ? a : target); sfin();
+        return;
+    }
+    if (sceq(t, "/msg")) {
+        char *m = a;
+        while (*m && *m != ' ') m++;
+        if (*m) *m++ = 0;
+        if (!*a || !*m) { say("-!- /msg nick text"); return; }
+        slen = 0; sc("PRIVMSG "); sc(a); sc(" :"); sc(m); sfin();
+        row_clear();
+        putc('>'); puts(a); puts("< "); puts(m); nl();
+        row_draw();
+        return;
+    }
+    if (sceq(t, "/me")) {
+        if (!target[0]) { say("-!- no channel"); return; }
+        slen = 0; sc("PRIVMSG "); sc(target); sc(" :\001ACTION "); sc(a); sc("\001"); sfin();
+        row_clear();
+        puts("* "); puts(nick); putc(' '); puts(a); nl();
+        row_draw();
+        return;
+    }
+    if (sceq(t, "/nick")) {
+        if (!*a) { say("-!- /nick newnick"); return; }
+        slen = 0; sc("NICK "); sc(a); sfin();
+        return;
+    }
+    if (sceq(t, "/quit")) {
+        slen = 0; sc("QUIT :"); sc(*a ? a : "sl0pboy out"); sfin();
+        quitting = 1;
+        return;
+    }
+    if (sceq(t, "/raw") || sceq(t, "/quote")) {
+        slen = 0; sc(a); sfin();
+        return;
+    }
+    say("-!- commands: /join /part /msg /me /nick /quit /raw");
+}
+
+static void submit(void) {
+    input[inlen] = 0;
+    if (!inlen) return;
+    if (input[0] == '/') {
+        inlen = 0;
+        run_cmd(input);
+        row_draw();
+        return;
+    }
+    if (!target[0]) { inlen = 0; say("-!- join a channel first (/join #gb)"); return; }
+    slen = 0; sc("PRIVMSG "); sc(target); sc(" :"); sc(input); sfin();
+    row_clear();
+    putc('<'); puts(nick); puts("> "); puts(input); nl();
+    inlen = 0;
+    row_draw();
+}
+
+static void key(unsigned char c) {
+    if (c == '\n' || c == '\r') { submit(); return; }
+    if (c == 8 || c == 127) {
+        if (inlen) { inlen--; row_draw(); }
+        return;
+    }
+    if (c < 32) return;
+    if (inlen < 139) { input[inlen++] = (char)c; row_draw(); }
+}
+
+/* ---- main ----------------------------------------------------------------- */
+void main(void) {
+    char *argp;
+    unsigned char i, n, idle;
+
+    /* gbos does not zero C statics (crt0 zeroes nothing; fork inherits the
+       parent's RAM bank) - initialize every piece of state explicitly */
+    llen = inlen = drawn = slen = quitting = 0;
+    target[0] = 0;
+
+    argp = getargs();                      /* copy args before seg is used */
+    for (i = 0; argp[i] && i < 63; i++) namebuf[i] = (unsigned char)argp[i];
+    namebuf[i] = 0;
+
+    /* split "HOST [NICK]" */
+    scpy(nick, "sl0pboy", sizeof(nick));
+    for (i = 0; namebuf[i]; i++)
+        if (namebuf[i] == ' ') {
+            namebuf[i] = 0;
+            if (namebuf[i+1]) scpy(nick, (char *)namebuf + i + 1, sizeof(nick));
+            break;
+        }
+    if (!namebuf[0]) {
+        puts("usage: irc HOST [NICK]     (port 6667)"); nl();
+        puts("  then: /join #chan, SELECT = keyboard"); nl();
+        sexit(1);
+    }
+
+    if (!resolve((char *)namebuf, dst)) {
+        puts("irc: cannot resolve "); puts((char *)namebuf); nl(); sexit(1);
+    }
+
+    sock = net_socket(SOCK_TCP);
+    if (sock == 0xFF) { puts("irc: no socket"); nl(); sexit(1); }
+    /* vary the local port per run (DIV timer noise): a fixed port can hit a
+       stale half-dead connection at the server after an unclean exit */
+    net_bind(sock, 41000 + ((unsigned int)*(volatile unsigned char *)0xFF04 << 2) + getpid());
+    puts("-!- connecting to "); puts((char *)namebuf); puts(":6667"); nl();
+    if (net_connect(sock, dst, 6667) == 0xFF) {
+        puts("irc: connect failed"); nl(); net_close(sock); sexit(1);
+    }
+
+    slen = 0; sc("NICK "); sc(nick); sfin();
+    slen = 0; sc("USER gbos 0 * :sl0pboy on gbos"); sfin();
+    puts("-!- registering as "); puts(nick);
+    puts(" (SELECT = keyboard)"); nl();
+    row_draw();
+
+    idle = 0;
+    for (;;) {
+        n = net_recv_nb(sock, seg, (unsigned char)sizeof(seg));
+        if (n == 0) { say("-!- disconnected"); break; }
+        if (n != 0xFE && n != 0xFF) {      /* got a segment: drain hard */
+            feed(seg, n);
+            idle = 0;
+            continue;
+        }
+        if (quitting) { say("-!- quit"); break; }
+        i = pollin();                      /* OSK */
+        if (!i) i = pollcon();             /* hub-injected console bytes */
+        if (i) { key(i); idle = 0; continue; }
+        if (++idle >= 4) { msleep(20); idle = 4; }   /* settle when idle */
+    }
+    net_close(sock);
+    row_clear();
+    sexit(0);
+}
diff --git a/include/gbos.inc b/include/gbos.inc
index 55f0681..92d8732 100644
--- a/include/gbos.inc
+++ b/include/gbos.inc
@@ -258,5 +258,6 @@ DEF PROG_NETD   EQU 26
 DEF PROG_PING   EQU 27
 DEF PROG_NSLOOKUP EQU 28
 DEF PROG_DHCP   EQU 29
+DEF PROG_IRC    EQU 30
 
     ENDC
diff --git a/src/programs.asm b/src/programs.asm
index e89fe0c..36f9d02 100644
--- a/src/programs.asm
+++ b/src/programs.asm
@@ -130,6 +130,9 @@ ProgNslookup:
 SECTION "prog_dhcp",   ROMX[$4000], BANK[31]
 ProgDhcp:
     INCBIN "c/dhcp.bin"
+SECTION "prog_irc",    ROMX[$4000], BANK[32]
+ProgIrc:
+    INCBIN "c/irc.bin"
 
 ; -----------------------------------------------------------------------------
 ; PROG_SH (bank 3) - the shell, now written in C (c/sh.c): parses >/</| and
@@ -232,6 +235,8 @@ ProgramTable::
     dw ProgNslookup
     db LOW(BANK(ProgDhcp)), HIGH(BANK(ProgDhcp))
     dw ProgDhcp
+    db LOW(BANK(ProgIrc)), HIGH(BANK(ProgIrc))
+    dw ProgIrc
 
 ; -----------------------------------------------------------------------------
 ; NameTable (ROM0) - command name -> program id, searched by sys_lookup.
@@ -298,4 +303,6 @@ NameTable::
     db PROG_NSLOOKUP
     db "dhcp", 0
     db PROG_DHCP
+    db "irc", 0
+    db PROG_IRC
     db 0