Added ability to announce presence

Signed-off-by: tyrolyean <tyrolyean@tyrolyean.net>

include/attach.h

@@ -21,15 +21,7 @@
 #include <stdint.h>
 #include <stddef.h>
 
-struct email_t{
-	char* message;
-	/* From the below values you can say pretty much anything about the 
-	 * message. The line delimiting body and header is left out. The header
-	 * len includes the last \r\n of the header. If header len is zero,
-	 * there was no clear distinction between header and body...
-	 */
-	size_t header_len, body_offset, message_length;
-};
+#include "mail.h"
 
 struct email_t mail_from_text(char* message, size_t length);
 void redetect_body_head(struct email_t* mail);

include/config.h

@@ -26,4 +26,6 @@ extern uint16_t listen_port, forward_port;
 
 extern int abort_on_pgp, abort_on_dkim;
 
+extern char* instance_id;
+
 #endif /* CONFIG_H */

include/mail.h

@@ -0,0 +1,37 @@
+/*
+ * mail.h - Mail editing toolset
+ * The author licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ * 
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+#ifndef MAIL_H
+#define MAIL_H
+
+#include <stdint.h>
+#include <stddef.h>
+
+struct email_t{
+	char* message;
+	/* From the below values you can say pretty much anything about the 
+	 * message. The line delimiting body and header is left out. The header
+	 * len includes the last \r\n of the header. If header len is zero,
+	 * there was no clear distinction between header and body...
+	 */
+	size_t header_len, body_offset, message_length;
+};
+
+int append_header(struct email_t* mail, const char* key, const char* value);
+int append_to_header(struct email_t* mail, const char* pair);
+
+#endif /* MAIL_H */

include/tools.h

@@ -20,7 +20,7 @@
 
 #include <stddef.h>
 
-const char* insert_string(char * destination, const char* source, 
+char* insert_string(char * destination, const char* source, 
 	size_t dest_orig_len, size_t offset);
 
 

src/attach.c

@@ -19,6 +19,7 @@
 #include "attach.h"
 #include "detect.h"
 #include "config.h"
+#include "mail.h"
 
 #include <string.h>
 #include <stdio.h>
@@ -94,6 +95,10 @@ char* attach_files(char* message, size_t len){
 		return email.message;
 	}
 
+	/* Now we can start the real work! */
+	
+	/* Announce our presence via header */
+	append_header(&email,"X-Mailattached", instance_id);
 	return email.message;
 }
 

src/config.c

@@ -14,7 +14,11 @@
  * specific language governing permissions and limitations
  * under the License.
  */
+
 #include "config.h"
 
+#include <stddef.h>
+
 uint16_t listen_port = 4269, forward_port = 4270;
 int abort_on_pgp = true, abort_on_dkim = true;
+char* instance_id = NULL;

src/detect.c

@@ -58,6 +58,7 @@ bool detect_dkim(struct email_t* mail){
 		if(strcasestr(mail->message, dkim_signatures[i]) != NULL
 				&& strcasestr(mail->message, dkim_signatures[i])
 				<= (mail->message+mail->header_len)){
+			/* DKIM only happens inside the header, not the body! */
 			points++;
 		}
 		

src/mail.c

@@ -0,0 +1,77 @@
+/*
+ * mail.c - Mail editing toolset
+ * The author licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ * 
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+#include "mail.h"
+#include "tools.h"
+
+#include <string.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+int append_header(struct email_t* mail, const char* key, const char* value){
+	
+	if(mail == NULL || key == NULL || value == NULL){
+		return -1;
+	}
+	const char* in_between = ": ";
+	size_t len = strlen(key) + strlen(value) + strlen(in_between) + 1;
+	char* buffer = malloc(len);
+	
+	if(buffer == NULL){
+		return -1;
+	}
+	
+	memset(buffer, 0, len);
+	strcat(buffer, key);
+	strcat(buffer, in_between);
+	strcat(buffer, value);
+	if(append_to_header(mail, buffer) < 0){
+		free(buffer);
+		return -1;
+	}
+	
+	free(buffer);
+
+	return 0;
+
+}
+
+
+int append_to_header(struct email_t* mail, const char* pair){
+
+	if(pair == NULL || mail == NULL){
+		return -1;
+	}
+
+	char *buffer = malloc(strlen(pair) + 3);
+	if(buffer == NULL){
+		return -1;
+	}
+	memset(buffer, 0, strlen(pair) + 3);
+	buffer[0] = '\r';
+	buffer[1] = '\n';
+	strcat(buffer, pair);
+
+	mail->message=insert_string(mail->message, buffer, strlen(buffer), 
+		mail->header_len);
+	free(buffer);
+
+	return 0;
+
+}
+

src/main.c

@@ -7,6 +7,9 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <getopt.h>
+#include <string.h>
+#include <unistd.h>
+#include <limits.h>
 
 #include "network.h"
 #include "config.h"
@@ -27,12 +30,13 @@ int main(int argc, char* argv[]){
 			{"noabort-dkim",no_argument, &abort_on_dkim,0},
 			{"in-port",	required_argument, 0, 'i'},
 			{"out-port",	required_argument, 0, 'o'},
+			{"instance-id",	required_argument, 0, 'n'},
 			{0, 0, 0, 0}
 		};
 		/* getopt_long stores the option index here. */
 		int option_index = 0;
 
-		c = getopt_long (argc, argv, "i:o:pd",
+		c = getopt_long (argc, argv, "n:i:o:pd",
 			       long_options, &option_index);
 
 		/* Detect the end of the options. */
@@ -50,6 +54,10 @@ int main(int argc, char* argv[]){
 		case 'o':
 			forward_port = atoi(optarg);
 			break;
+			
+		case 'n':
+			instance_id = optarg;
+			break;
 
 		case '?':
 			/* getopt_long already printed an error message. */
@@ -61,6 +69,17 @@ int main(int argc, char* argv[]){
 		}
 	}
 
+	/* If not already specified, populate the instance ID with the sytem 
+	 * hostname.
+	 */
+	if(instance_id == NULL){
+		instance_id = malloc(HOST_NAME_MAX + 1);
+		memset(instance_id, 0, HOST_NAME_MAX + 1);
+		if(gethostname(instance_id, HOST_NAME_MAX) < 0){
+			perror("gethostname failed! set instance id manually");
+		}
+	}
+
 	printf("Incoming port: %u outgoing port: %u on loopback interface\n",
 		 listen_port, forward_port);
 
@@ -69,6 +88,9 @@ int main(int argc, char* argv[]){
 
 	printf("Ignoring DKIM signed messages: %s\n",
 		abort_on_dkim ? "true" : "false");
+	
+	printf("Instance id for messages: %s\n",
+		instance_id);
 
 	if(init_net() < 0){
 		return EXIT_FAILURE;

src/network.c

@@ -248,7 +248,8 @@ int init_net(){
 	serveraddr.sin_port = htons((unsigned short)listen_port);
 
 	if (bind(parentfd, (struct sockaddr *) &serveraddr,
-	   sizeof(serveraddr)) < 0) {
+		sizeof(serveraddr)) < 0) {
+		
 		perror("ERROR on binding");
 		return -1;
 	}

src/tools.c

@@ -24,7 +24,7 @@
 /* Takes a string destination and inserts at the given point offset the string
  * in source. Really more like a stringcat with shifting the end. 
  * dest_orig_len is without '\0'*/
-const char* insert_string(char * destination, const char* source, 
+char* insert_string(char * destination, const char* source, 
 	size_t dest_orig_len, size_t offset){
 
 	if(source == NULL|| dest_orig_len < offset){