Add a slack.com CGI front-end

Makefile

@@ -1,5 +1,5 @@
 CFLAGS = -Wall -Werror
-TARGETS = bot factoids
+TARGETS = bot factoids slack.cgi
 
 all: $(TARGETS)
 
@@ -9,6 +9,8 @@ all: $(TARGETS)
 src/bot:
 src/factoids: src/factoids.o src/cdb.o src/cdbmake.o
 
+src/slack.cgi: src/slack.cgi.o src/cgi.o
+
 .PHONY: clean
 clean:
 	rm -f $(TARGETS) $(addprefix src/, $(TARGETS)) src/*.o

src/cgi.c

@@ -0,0 +1,189 @@
+/*
+ * This software has been authored by an employee or employees of Los
+ * Alamos National Security, LLC, operator of the Los Alamos National
+ * Laboratory (LANL) under Contract No. DE-AC52-06NA25396 with the U.S.
+ * Department of Energy.  The U.S. Government has rights to use,
+ * reproduce, and distribute this software.  The public may copy,
+ * distribute, prepare derivative works and publicly display this
+ * software without charge, provided that this Notice and any statement
+ * of authorship are reproduced on all copies.  Neither the Government
+ * nor LANS makes any warranty, express or implied, or assumes any
+ * liability or responsibility for the use of this software.  If
+ * software is modified to produce derivative works, such modified
+ * software should be clearly marked, so as not to confuse it with the
+ * version available from LANL.
+ */
+
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+
+#include "cgi.h"
+
+#define POST_MAX 4000
+
+static int is_cgi  = 0;
+static char **argv = NULL;
+
+static int
+read_char_argv()
+{
+  static int   arg = 0;
+  static char *p;
+
+  if (NULL == argv) {
+    return EOF;
+  }
+
+  if (0 == arg) {
+    arg = 1;
+    p = argv[1];
+  }
+
+  if (! p) {
+    return EOF;
+  } else if (! *p) {
+    arg += 1;
+    p = argv[arg];
+    return '&';
+  }
+
+  return *(p++);
+}
+
+static int
+read_char_stdin()
+{
+  static long inlen = -1;
+
+  if (-1 == inlen) {
+    char *p = getenv("CONTENT_LENGTH");
+    if (p) {
+      inlen = atoi(p);
+      if (inlen > POST_MAX) {
+        inlen = POST_MAX;
+      }
+      if (inlen < 0) {
+        inlen = 0;
+      }
+    } else {
+      inlen = 0;
+    }
+  }
+
+  if (inlen) {
+    inlen -= 1;
+    return getchar();
+  }
+  return EOF;
+}
+
+static int
+read_char_query_string()
+{
+  static char *p = (char *)-1;
+
+  if ((char *)-1 == p) {
+    p = getenv("QUERY_STRING");
+  }
+
+  if (! p) {
+    return EOF;
+  } else if (! *p) {
+    return EOF;
+  } else {
+    return *(p++);
+  }
+}
+
+static int (* read_char)() = read_char_argv;
+
+int
+cgi_init(char *global_argv[])
+{
+  char *rm = getenv("REQUEST_METHOD");
+
+  if (! rm) {
+    read_char = read_char_argv;
+    argv = global_argv;
+  } else if (0 == strcmp(rm, "POST")) {
+    read_char = read_char_stdin;
+    is_cgi = 1;
+  } else if (0 == strcmp(rm, "GET")) {
+    read_char = read_char_query_string;
+    is_cgi = 1;
+  } else {
+    printf(("405 Method not allowed\r\n"
+            "Allow: GET, POST\r\n"
+            "Content-type: text/plain\r\n"
+            "\r\n"
+            "%s is not allowed.\n"),
+           rm);
+    return -1;
+  }
+
+  return 0;
+}
+
+static char
+tonum(int c)
+{
+  if ((c >= '0') && (c <= '9')) {
+    return c - '0';
+  }
+  if ((c >= 'a') && (c <= 'f')) {
+    return 10 + c - 'a';
+  }
+  if ((c >= 'A') && (c <= 'F')) {
+    return 10 + c - 'A';
+  }
+  return 0;
+}
+
+static char
+read_hex()
+{
+  int a = read_char();
+  int b = read_char();
+
+  return tonum(a)*16 + tonum(b);
+}
+
+/* Read a key or a value.  Since & and = aren't supposed to appear
+   outside of boundaries, we can use the same function for both.
+*/
+size_t
+cgi_item(char *str, size_t maxlen)
+{
+  int    c;
+  size_t pos = 0;
+
+  while (1) {
+    c = read_char();
+    switch (c) {
+      case EOF:
+      case '=':
+      case '&':
+        str[pos] = '\0';
+        return pos;
+      case '%':
+        c = read_hex();
+        break;
+      case '+':
+        c = ' ';
+        break;
+    }
+    if (pos < maxlen - 1) {
+      str[pos] = c;
+      pos += 1;
+    }
+  }
+}
+
+void
+cgi_header(char *content_type)
+{
+    if (is_cgi) {
+        printf("Content-type: %s\r\n\r\n", content_type);
+    }
+}

src/cgi.h

@@ -0,0 +1,10 @@
+#ifndef __CGI_H_
+#define __CGI_H_
+
+#include <stddef.h>
+
+int cgi_init(char *global_argv[]);
+size_t cgi_item(char *str, size_t maxlen);
+void cgi_header(char *content_type);
+
+#endif

src/slack.cgi.c

@@ -0,0 +1,95 @@
+#include <stdlib.h>
+#include <string.h>
+#include <stdbool.h>
+#include <unistd.h> // only for chdir
+#include <stdio.h>
+
+#include "cgi.h"
+
+void
+jputchar(char c)
+{
+	if (c == '\n') {
+		printf("\\n");
+	} else if (c < 0x20) {
+		printf("\%04x", c);
+	} else if ((c == '\\') || (c == '"')) {
+		putchar('\\');
+		putchar(c);
+	} else {
+		putchar(c);
+	}
+}
+
+int
+main(int argc, char *argv[])
+{
+	char key[80];
+	char val[2000];
+	
+	bool its_me = false;
+	
+	cgi_init(argv);
+	
+	for (;;) {
+		size_t len;
+		
+		len = cgi_item(key, sizeof(key));
+		len = cgi_item(val, sizeof(val));
+		
+		if (0 == len) {
+			break;
+		}
+		
+		if (0 == strcmp(key, "user_id")) {
+			if (0 == strcmp(val, "USLACKBOT")) {
+				its_me = true;
+			}
+		} else if (0 == strcmp(key, "channel_name")) {
+			char chan[40];
+			
+			snprintf(chan, sizeof(chan), "#%s", val);
+			setenv("forum", chan, true);
+		} else if (0 == strcmp(key, "user_name")) {
+			setenv("sender", val, true);
+		} else if (0 == strcmp(key, "text")) {
+			setenv("text", val, true);
+		} 
+	}
+	
+	cgi_header("text/json");
+	
+	if (its_me) {
+		printf("{}");
+		return 0;
+	}
+	
+	setenv("command", "PRIVMSG", true);
+	
+	chdir("/home/neale/bot/zinc");
+	{
+		FILE *p = popen("./handler", "r");
+		int newlines = 0;
+		
+		printf("{\"text\": \"");
+		for (;;) {
+			int c = fgetc(p);
+			
+			if (EOF == c) {
+				break;
+			} else if ('\n' == c) {
+				newlines += 1;
+			} else {
+				for (; newlines > 0; newlines -= 1) {
+					jputchar('\n');
+				}
+				jputchar(c);
+			}
+		}
+		printf("\"}\n");
+		
+		pclose(p);
+	}
+
+	return 0;
+}