Console work + modem.c

packages/p2/bin/p2console

@@ -8,6 +8,7 @@ if ! [ -f $BASE/salt ]; then
     dd if=/dev/urandom count=1 | md5sum - > $BASE/salt
 fi
 clear
+printf '\017'
 read salt < $BASE/salt
 
 esc () {
@@ -64,15 +65,40 @@ elif ! [ -d $BASE/$hash ]; then
     fini
 fi
 
+clear
+
 read -r name < $BASE/$hash/.name
-printf "%s answer: " "$name"
+
+printf 'Welcome back, %s.\n' "$name"
+
+while true; do
+    printf "p2> "
     read -r answer
-echo
+
+    case "$answer" in
+        \?|help)
+            cat <<EOD
+                         Help
+----------------------------------------------------------
+
+Type "quit" to leave the p2 shell.
+
+Any other string is checked as an answer.  If the answer
+is correct, you are awarded points and the scoreboard will
+update within 10 seconds.  Check the puzzles overview to
+see if your answer unlocked a new puzzle.
+EOD
+            continue
+            ;;
+        quit)
+            break
+            ;;
+    esac
 
     match=$(awk -v ans="$answer" '(substr($0, length($1)+2) == ans) { print substr(FILENAME, 6, length(FILENAME)-17) " " $1; }' /opt/*/answers.txt)
     if [ -z "$match" ]; then
-    echo "That is not a correct answer."
-    fini
+        echo 'That is not a correct answer.  Type "help" for help.'
+        continue
     fi
     
     cat=${match% *}
@@ -86,6 +112,5 @@ else
         # run puzzles.cgi
         # update scoreboard
     fi
-
-fini
+done
 

packages/p2/src/Makefile

@@ -0,0 +1 @@
+modem:

packages/p2/src/modem.c

@@ -0,0 +1,60 @@
+#include <unistd.h>
+#include <stdlib.h>
+
+#define NOISE_PROB 300
+#define NOISE_BITS 16
+
+int badbits = 0;
+
+char
+line_noise(char c)
+{
+    int i = 7;
+
+    while (badbits && (i >= 0)) {
+        c = c ^ ((rand() % 2) << i);
+        badbits -= 1;
+        i -= 1;
+    }
+
+    if (rand() % NOISE_PROB == 0) {
+        badbits = rand() % NOISE_BITS;
+    }
+
+    return c;
+}
+
+int
+main(int argc, char *argv[])
+{
+    char c;
+    ssize_t ret;
+    int baud = 0;
+    useconds_t usec;
+
+    if (argv[1]) {
+        baud = atoi(argv[1]);
+    }
+    if (! baud) {
+        baud = 1200;
+    }
+
+    srandom(getpid());
+
+    /* 
+      N81 uses 1 stop bit, and 1 parity bit.  That works out to
+       exactly 10 bits per byte.
+     */
+    usec = 10000000 / baud;
+
+    while (1) {
+        ret = read(0, &c, 1);
+        if (ret != 1) {
+            break;
+        }
+        c = line_noise(c);
+        write(1, &c, 1);
+        usleep(usec);
+    }
+    return 0;
+}