Specialized logging functions; can control debug

configure.ac

@@ -1,11 +1,36 @@
 AC_INIT([WrapSix], [0.1.99.0], [xhire@mujmalysvet.cz])
 AM_INIT_AUTOMAKE([-Wall -Werror])
+
+# prevent automatic adding of "-g -O2" to CFLAGS
+OLD_CFLAGS=$CFLAGS
 AC_PROG_CC
+CFLAGS=$OLD_CFLAGS
+
 AC_CONFIG_FILES([
 	Makefile
 	src/Makefile
 ])
 
-CFLAGS="-g -ggdb -O0 -pipe -pedantic -Wshadow -Wall -Wextra -Wno-missing-field-initializers -Wno-unused-parameter -Wold-style-definition -Wdeclaration-after-statement -Wmissing-declarations -Wmissing-prototypes -Wredundant-decls -Wmissing-noreturn -Wshadow -Wpointer-arith -Wcast-align -Wwrite-strings -Winline -Wformat-nonliteral -Wformat-security -Wswitch-enum -Wswitch-default -Winit-self -Wmissing-include-dirs -Wundef -Waggregate-return -Wmissing-format-attribute -Wnested-externs -Wunsafe-loop-optimizations"
+###
+# Configuration options
+###
+
+AC_ARG_ENABLE([debug],
+	      AS_HELP_STRING([--enable-debug], [enable debugging]),
+	      [debug=$enableval],
+	      [debug=no])
+
+if test "x$debug" = "xyes"; then
+	AM_CFLAGS="${AM_CFLAGS} -g -ggdb -O0 -pipe -pedantic -Wshadow -Wall -Wextra -Wno-missing-field-initializers -Wno-unused-parameter -Wold-style-definition -Wdeclaration-after-statement -Wmissing-declarations -Wmissing-prototypes -Wredundant-decls -Wshadow -Wpointer-arith -Wcast-align -Wwrite-strings -Winline -Wformat-nonliteral -Wformat-security -Wswitch-enum -Wswitch-default -Winit-self -Wmissing-include-dirs -Wundef -Waggregate-return -Wnested-externs -Wunsafe-loop-optimizations"
+	AC_DEFINE([DEBUG])
+else
+        AM_CFLAGS="${AM_CFLAGS} -O2"
+fi
+
+###
+# Final commands
+###
+
+AC_SUBST([AM_CFLAGS])
 
 AC_OUTPUT

src/Makefile.am

@@ -7,6 +7,7 @@ wrapsix_wrapper_SOURCES = \
 			  icmp.c icmp.h \
 			  ipv4.c ipv4.h \
 			  ipv6.c ipv6.h \
+			  log.c log.h \
 			  nat.c nat.h \
 			  radixtree.c radixtree.h \
 			  tcp.c tcp.h \

src/arp.c

@@ -18,11 +18,11 @@
 
 #include <net/ethernet.h>	/* ETHERTYPE_* */
 #include <netinet/in.h>		/* htons */
-#include <stdio.h>
 #include <stdlib.h>		/* malloc */
 #include <string.h>		/* memcmp, memset */
 
 #include "arp.h"
+#include "log.h"
 #include "transmitter.h"
 #include "wrapper.h"
 
@@ -32,8 +32,8 @@
  * @param	ethq	Ethernet header of the packet
  * @param	payload	Data of the packet
  *
- * @return		0 for success
+ * @return	0 for success
- * @return		1 for failure
+ * @return	1 for failure
  */
 int arp(struct s_ethernet *ethq, char *payload)
 {
@@ -51,7 +51,7 @@ int arp(struct s_ethernet *ethq, char *payload)
 
 	/* test if this packet belongs to us */
 	if (memcmp(&wrapsix_ipv4_addr, &arpq->ip_dest, 4)) {
-		printf("[Debug] This is unfamiliar packet\n");
+		log_debug("This is unfamiliar ARP packet");
 		return 1;
 	}
 
@@ -60,7 +60,7 @@ int arp(struct s_ethernet *ethq, char *payload)
 
 	/* allocate enough memory */
 	if ((packet = (unsigned char *) malloc(ARP_PACKET_SIZE)) == NULL) {
-		fprintf(stderr, "[Error] Lack of free memory\n");
+		log_error("Lack of free memory");
 		return 1;
 	}
 	memset(packet, 0x0, ARP_PACKET_SIZE);

src/checksum.c

@@ -17,13 +17,13 @@
  */
 
 #include <netinet/in.h>		/* htonl */
-#include <stdio.h>
 #include <stdlib.h>		/* malloc */
 #include <string.h>		/* memcpy */
 
 #include "checksum.h"
 #include "ipv4.h"
 #include "ipv6.h"
+#include "log.h"
 
 /**
  * General checksum computation function
@@ -31,7 +31,7 @@
  * @param	data	Pointer to data of which to compute the checksum
  * @param	length	Length of the data (in bytes)
  *
- * @return		Checksum
+ * @return	Checksum
  */
 unsigned short checksum(const void *data, int length)
 {
@@ -76,7 +76,7 @@ unsigned short checksum(const void *data, int length)
  * 				number of octets
  * @param	new_len		Length of new data
  *
- * @return			Updated checksum
+ * @return	Updated checksum
  */
 unsigned short checksum_update(unsigned short old_sum,
 			       unsigned short *old_data, short old_len,
@@ -116,7 +116,7 @@ unsigned short checksum_update(unsigned short old_sum,
  * @param	proto	Protocol in the payload
  * @param	payload	Pointer to payload data
  *
- * @return		Checksum
+ * @return	Checksum
  */
 unsigned short checksum_ipv4(struct s_ipv4_addr ip_src,
 			     struct s_ipv4_addr ip_dest,
@@ -128,7 +128,7 @@ unsigned short checksum_ipv4(struct s_ipv4_addr ip_src,
 	unsigned short		 sum;
 
 	if ((buffer = malloc(sizeof(struct s_ipv4_pseudo) + length)) == NULL) {
-		fprintf(stderr, "[Error] Lack of free memory\n");
+		log_error("Lack of free memory");
 		return 0;
 	}
 
@@ -158,7 +158,7 @@ unsigned short checksum_ipv4(struct s_ipv4_addr ip_src,
  * @param	proto	Protocol in the payload
  * @param	payload	Pointer to payload data
  *
- * @return		Checksum
+ * @return	Checksum
  */
 unsigned short checksum_ipv6(struct s_ipv6_addr ip_src,
 			     struct s_ipv6_addr ip_dest,
@@ -170,7 +170,7 @@ unsigned short checksum_ipv6(struct s_ipv6_addr ip_src,
 	unsigned short		 sum;
 
 	if ((buffer = malloc(sizeof(struct s_ipv6_pseudo) + length)) == NULL) {
-		fprintf(stderr, "[Error] Lack of free memory\n");
+		log_error("Lack of free memory");
 		return 0;
 	}
 
@@ -202,7 +202,7 @@ unsigned short checksum_ipv6(struct s_ipv6_addr ip_src,
  * @param	ip4_dest	New destination IPv4 address
  * @param	new_port	New transport layer address (port)
  *
- * @return			Checksum
+ * @return	Checksum
  */
 unsigned short checksum_ipv4_update(unsigned short old_sum,
 				    struct s_ipv6_addr ip6_src,
@@ -241,7 +241,7 @@ unsigned short checksum_ipv4_update(unsigned short old_sum,
  * @param	ip6_dest	New destination IPv6 address
  * @param	new_port	New transport layer address (port)
  *
- * @return			Checksum
+ * @return	Checksum
  */
 unsigned short checksum_ipv6_update(unsigned short old_sum,
 				    struct s_ipv4_addr ip4_src,

src/icmp.c

@@ -18,13 +18,13 @@
 
 #include <net/ethernet.h>	/* ETHERTYPE_* */
 #include <netinet/in.h>		/* htons */
-#include <stdio.h>
 #include <stdlib.h>		/* malloc */
 #include <string.h>		/* memcpy, memset */
 
 #include "checksum.h"
 #include "icmp.h"
 #include "ipv6.h"
+#include "log.h"
 #include "nat.h"
 #include "transmitter.h"
 #include "wrapper.h"
@@ -65,7 +65,7 @@ int icmp_ipv4(struct s_ethernet *eth4, struct s_ipv4 *ip4,
 
 	if (icmp->checksum != orig_checksum) {
 		/* packet is corrupted and shouldn't be processed */
-		printf("[Debug] Wrong checksum\n");
+		log_debug("Wrong checksum");
 		return 1;
 	}
 
@@ -81,8 +81,8 @@ int icmp_ipv4(struct s_ethernet *eth4, struct s_ipv4 *ip4,
 					    0, echo->id);
 
 			if (connection == NULL) {
-				printf("[Debug] Incoming connection wasn't "
+				log_debug("Incoming connection wasn't found in "
-				       "found in NAT\n");
+					  "NAT");
 				return 1;
 			}
 
@@ -94,8 +94,8 @@ int icmp_ipv4(struct s_ethernet *eth4, struct s_ipv4 *ip4,
 			break;
 
 		default:
-			printf("[Debug] ICMPv4 Type: unknown [%d/0x%x]\n",
+			log_debug("ICMPv4 Type: unknown [%d/0x%x]",
-			       icmp->type, icmp->type);
+				  icmp->type, icmp->type);
 			return 1;
 	}
 
@@ -103,7 +103,7 @@ int icmp_ipv4(struct s_ethernet *eth4, struct s_ipv4 *ip4,
 	if ((packet = (unsigned char *) malloc(sizeof(struct s_ethernet) +
 					       sizeof(struct s_ipv6) +
 					       payload_size)) == NULL) {
-		fprintf(stderr, "[Error] Lack of free memory\n");
+		log_error("Lack of free memory");
 		return 1;
 	}
 	eth6 = (struct s_ethernet *) packet;
@@ -177,7 +177,7 @@ int icmp_ipv6(struct s_ethernet *eth6, struct s_ipv6 *ip6, char *payload)
 
 	if (icmp->checksum != orig_checksum) {
 		/* packet is corrupted and shouldn't be processed */
-		printf("[Debug] Wrong checksum\n");
+		log_debug("Wrong checksum");
 		return 1;
 	}
 
@@ -192,8 +192,8 @@ int icmp_ipv6(struct s_ethernet *eth6, struct s_ipv6 *ip6, char *payload)
 					     echo->id, 0);
 
 			if (connection == NULL) {
-				printf("[Debug] Error! Outgoing connection "
+				log_warn("Outgoing connection wasn't "
-				       "wasn't found/created in NAT!\n");
+					 "found/created in NAT!");
 				return 1;
 			}
 
@@ -213,15 +213,15 @@ int icmp_ipv6(struct s_ethernet *eth6, struct s_ipv6 *ip6, char *payload)
 					(struct s_icmp_ndp_ns *) icmp_data);
 
 		default:
-			printf("[Debug] ICMPv6 Type: unknown [%d/0x%x]\n",
+			log_debug("ICMPv6 Type: unknown [%d/0x%x]",
-			       icmp->type, icmp->type);
+				  icmp->type, icmp->type);
 			return 1;
 	}
 
 	/* allocate memory for translated packet */
 	if ((packet = (unsigned char *) malloc(sizeof(struct s_ipv4) +
 					       htons(ip6->len))) == NULL) {
-		fprintf(stderr, "[Error] Lack of free memory\n");
+		log_error("Lack of free memory");
 		return 1;
 	}
 	ip4 = (struct s_ipv4 *) packet;
@@ -280,7 +280,7 @@ int icmp_ndp(struct s_ethernet *ethq, struct s_ipv6 *ipq,
 
 	/* first check whether the request belongs to us */
 	if (memcmp(&wrapsix_ipv6_prefix, &ndp_ns->target, 12) != 0) {
-		printf("[Debug] [NDP] This is unfamiliar packet\n");
+		log_debug("This is unfamiliar NDP packet");
 		return 1;
 	}
 
@@ -290,7 +290,7 @@ int icmp_ndp(struct s_ethernet *ethq, struct s_ipv6 *ipq,
 				sizeof(struct s_icmp) + \
 				sizeof(struct s_icmp_ndp_na)
 	if ((packet = (unsigned char *) malloc(NDP_PACKET_SIZE)) == NULL) {
-		fprintf(stderr, "[Error] Lack of free memory\n");
+		log_error("Lack of free memory");
 		return 1;
 	}
 	memset(packet, 0x0, NDP_PACKET_SIZE);

src/ipv4.c

@@ -17,11 +17,11 @@
  */
 
 #include <netinet/in.h>		/* IPPROTO_* */
-#include <stdio.h>
 #include <string.h>		/* memcmp */
 
 #include "icmp.h"
 #include "ipv4.h"
+#include "log.h"
 #include "tcp.h"
 #include "udp.h"
 #include "wrapper.h"
@@ -47,7 +47,7 @@ int ipv4(struct s_ethernet *eth, char *packet)
 
 	/* test if this packet belongs to us */
 	if (memcmp(&wrapsix_ipv4_addr, &ip->ip_dest, 4) != 0) {
-		printf("[Debug] [IPv4] This is unfamiliar packet\n");
+		log_debug("This is unfamiliar IPv4 packet");
 		return 1;
 	}
 
@@ -58,17 +58,17 @@ int ipv4(struct s_ethernet *eth, char *packet)
 
 	switch (ip->proto) {
 		case IPPROTO_TCP:
-			printf("[Debug] IPv4 Protocol: TCP\n");
+			log_debug("IPv4 Protocol: TCP");
 			return tcp_ipv4(eth, ip, payload, data_size);
 		case IPPROTO_UDP:
-			printf("[Debug] IPv4 Protocol: UDP\n");
+			log_debug("IPv4 Protocol: UDP");
 			return udp_ipv4(eth, ip, payload, data_size);
 		case IPPROTO_ICMP:
-			printf("[Debug] IPv4 Protocol: ICMP\n");
+			log_debug("IPv4 Protocol: ICMP");
 			return icmp_ipv4(eth, ip, payload, data_size);
 		default:
-			printf("[Debug] IPv4 Protocol: unknown [%d/0x%x]\n",
+			log_debug("IPv4 Protocol: unknown [%d/0x%x]",
-			       ip->proto, ip->proto);
+				  ip->proto, ip->proto);
 			return 1;
 	}
 }

src/ipv6.c

@@ -17,11 +17,11 @@
  */
 
 #include <netinet/in.h>		/* IPPROTO_* */
-#include <stdio.h>
 #include <string.h>		/* memcmp */
 
 #include "icmp.h"
 #include "ipv6.h"
+#include "log.h"
 #include "tcp.h"
 #include "udp.h"
 #include "wrapper.h"
@@ -47,23 +47,23 @@ int ipv6(struct s_ethernet *eth, char *packet)
 	/* test if this packet belongs to us */
 	if (memcmp(&wrapsix_ipv6_prefix, &ip->ip_dest, 12) != 0 &&
 	    memcmp(&ndp_multicast_addr,  &ip->ip_dest, 13) != 0) {
-		printf("[Debug] [IPv6] This is unfamiliar packet\n");
+		log_debug("This is unfamiliar IPv6 packet");
 		return 1;
 	}
 
 	switch (ip->next_header) {
 		case IPPROTO_TCP:
-			printf("[Debug] IPv6 Protocol: TCP\n");
+			log_debug("IPv6 Protocol: TCP");
 			return tcp_ipv6(eth, ip, payload);
 		case IPPROTO_UDP:
-			printf("[Debug] IPv6 Protocol: UDP\n");
+			log_debug("IPv6 Protocol: UDP");
 			return udp_ipv6(eth, ip, payload);
 		case IPPROTO_ICMPV6:
-			printf("[Debug] IPv6 Protocol: ICMP\n");
+			log_debug("IPv6 Protocol: ICMP");
 			return icmp_ipv6(eth, ip, payload);
 		default:
-			printf("[Debug] IPv6 Protocol: unknown [%d/0x%x]\n",
+			log_debug("IPv6 Protocol: unknown [%d/0x%x]",
-			       ip->next_header, ip->next_header);
+				  ip->next_header, ip->next_header);
 			return 1;
 	}
 }

src/log.c

@@ -0,0 +1,100 @@
+/*
+ *  WrapSix
+ *  Copyright (C) 2008-2012  Michal Zima <xhire@mujmalysvet.cz>
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU Affero General Public License as
+ *  published by the Free Software Foundation, either version 3 of the
+ *  License, or (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU Affero General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Affero General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stdarg.h>
+#include <stdio.h>
+
+#include "log.h"
+
+/**
+ * Logs debugging stuff to stdout, but only when compiled with debug enabled.
+ *
+ * @param	msg	Formatted message
+ * @param	...	Parameters to be included in the message
+ */
+void log_debug(const char *msg, ...)
+{
+#ifdef DEBUG
+	va_list args;
+
+	fprintf(stdout, "[Debug] ");
+
+	va_start(args, msg);
+	vfprintf(stdout, msg, args);
+	va_end(args);
+
+	fprintf(stdout, "\n");
+#endif /* DEBUG */
+}
+
+/**
+ * Logs information to stdout.
+ *
+ * @param	msg	Formatted message
+ * @param	...	Parameters to be included in the message
+ */
+void log_info(const char *msg, ...)
+{
+	va_list args;
+
+	fprintf(stdout, "[Info] ");
+
+	va_start(args, msg);
+	vfprintf(stdout, msg, args);
+	va_end(args);
+
+	fprintf(stdout, "\n");
+}
+
+/**
+ * Logs warnings to stderr.
+ *
+ * @param	msg	Formatted message
+ * @param	...	Parameters to be included in the message
+ */
+void log_warn(const char *msg, ...)
+{
+	va_list args;
+
+	fprintf(stderr, "[Warning] ");
+
+	va_start(args, msg);
+	vfprintf(stderr, msg, args);
+	va_end(args);
+
+	fprintf(stderr, "\n");
+}
+
+/**
+ * Logs errors to stderr.
+ *
+ * @param	msg	Formatted message
+ * @param	...	Parameters to be included in the message
+ */
+void log_error(const char *msg, ...)
+{
+	va_list args;
+
+	fprintf(stderr, "[Error] ");
+
+	va_start(args, msg);
+	vfprintf(stderr, msg, args);
+	va_end(args);
+
+	fprintf(stderr, "\n");
+}

src/log.h

@@ -0,0 +1,27 @@
+/*
+ *  WrapSix
+ *  Copyright (C) 2008-2012  Michal Zima <xhire@mujmalysvet.cz>
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU Affero General Public License as
+ *  published by the Free Software Foundation, either version 3 of the
+ *  License, or (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU Affero General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Affero General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef LOG_H
+#define LOG_H
+
+void log_debug(const char *msg, ...);
+void log_info(const char *msg, ...);
+void log_warn(const char *msg, ...);
+void log_error(const char *msg, ...);
+
+#endif /* LOG_H */

src/nat.c

@@ -16,13 +16,13 @@
  *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#include <stdio.h>
 #include <stdlib.h>		/* malloc */
 #include <time.h>		/* time */
 
 #include "ethernet.h"
 #include "ipv4.h"
 #include "ipv6.h"
+#include "log.h"
 #include "nat.h"
 #include "radixtree.h"
 #include "wrapper.h"
@@ -120,7 +120,7 @@ struct s_nat *nat_out(radixtree_t *nat_proto6, radixtree_t *nat_proto4,
 		/* if no connection is found, let's create one */
 		if ((connection =
 		    (struct s_nat *) malloc(sizeof(struct s_nat))) == NULL) {
-			fprintf(stderr, "[Error] Lack of free memory\n");
+			log_error("Lack of free memory");
 			return NULL;
 		}
 
@@ -198,7 +198,7 @@ struct s_nat *nat_in(radixtree_t *nat_proto4, struct s_ipv4_addr ipv4_src,
  * @param	id		Fragment identification
  * @param	nat		Connection to save
  *
- * @return			Connection
+ * @return	Connection
  */
 struct s_nat *nat_in_fragments(radixtree_t *nat_proto4,
 			       struct s_ipv4_addr ipv4_src,

src/radixtree.c

@@ -16,10 +16,10 @@
  *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#include <stdio.h>		/* fprintf */
 #include <stdlib.h>		/* free, malloc */
 #include <string.h>		/* memcpy */
 
+#include "log.h"
 #include "radixtree.h"
 
 /**
@@ -32,7 +32,7 @@ radixtree_t *radixtree_create(void)
 	radixtree_t *radixtree;
 
 	if ((radixtree = (radixtree_t *) malloc(sizeof(radixtree_t))) == NULL) {
-		fprintf(stderr, "[Error] Lack of free memory\n");
+		log_error("Lack of free memory");
 		return NULL;
 	}
 	memset(radixtree, 0, sizeof(radixtree_t));
@@ -207,7 +207,7 @@ void *radixtree_lookup(radixtree_t *root,
  * @param	count	Variable into which is put information about number of
  * 			chunks produced
  *
- * @return		Array of chunks
+ * @return	Array of chunks
  */
 unsigned char *radixtree_chunker(void *data, unsigned char size, unsigned char *count)
 {
@@ -220,7 +220,7 @@ unsigned char *radixtree_chunker(void *data, unsigned char size, unsigned char *
 	memcpy(count, &counter, sizeof(unsigned char));
 
 	if ((chunks = (unsigned char *) malloc(counter * sizeof(unsigned char))) == NULL) {
-		fprintf(stderr, "[Error] Lack of free memory\n");
+		log_error("Lack of free memory");
 		return NULL;
 	}
 

src/tcp.c

@@ -18,7 +18,6 @@
 
 #include <net/ethernet.h>	/* ETHERTYPE_* */
 #include <netinet/in.h>		/* htons */
-#include <stdio.h>
 #include <stdlib.h>		/* malloc */
 #include <string.h>		/* memcpy */
 
@@ -26,6 +25,7 @@
 #include "ethernet.h"
 #include "ipv4.h"
 #include "ipv6.h"
+#include "log.h"
 #include "nat.h"
 #include "tcp.h"
 #include "transmitter.h"
@@ -78,7 +78,7 @@ int tcp_ipv4(struct s_ethernet *eth4, struct s_ipv4 *ip4, char *payload,
 			if (tcp->checksum != orig_checksum) {
 				/* packet is corrupted and shouldn't be
 				 * processed */
-				printf("[Debug] Wrong checksum\n");
+				log_debug("Wrong checksum");
 				return 1;
 			}
 		}
@@ -88,8 +88,7 @@ int tcp_ipv4(struct s_ethernet *eth4, struct s_ipv4 *ip4, char *payload,
 				    tcp->port_src, tcp->port_dest);
 
 		if (connection == NULL) {
-			printf("[Debug] Incoming connection wasn't found in "
+			log_debug("Incoming connection wasn't found in NAT");
-			       "NAT\n");
 			return 1;
 		}
 
@@ -105,7 +104,7 @@ int tcp_ipv4(struct s_ethernet *eth4, struct s_ipv4 *ip4, char *payload,
 		    MTU + sizeof(struct s_ethernet) :
 		    sizeof(struct s_ethernet) + sizeof(struct s_ipv6) +
 		    payload_size)) == NULL) {
-			fprintf(stderr, "[Error] Lack of free memory\n");
+			log_error("Lack of free memory");
 			return 1;
 		}
 		eth6 = (struct s_ethernet *) packet;
@@ -201,8 +200,8 @@ int tcp_ipv4(struct s_ethernet *eth4, struct s_ipv4 *ip4, char *payload,
 					      ip4->id, NULL);
 
 		if (connection == NULL) {
-			printf("[Debug] Incoming connection wasn't found in "
+			log_debug("Incoming connection wasn't found in "
-			       "fragments table\n");
+				  "fragments table");
 			return 1;
 		}
 
@@ -213,7 +212,7 @@ int tcp_ipv4(struct s_ethernet *eth4, struct s_ipv4 *ip4, char *payload,
 		    MTU + sizeof(struct s_ethernet) :
 		    sizeof(struct s_ethernet) + sizeof(struct s_ipv6) +
 		    sizeof(struct s_ipv6_fragment) + payload_size)) == NULL) {
-			fprintf(stderr, "[Error] Lack of free memory\n");
+			log_error("Lack of free memory");
 			return 1;
 		}
 		eth6 = (struct s_ethernet *) packet;
@@ -311,7 +310,7 @@ int tcp_ipv4(struct s_ethernet *eth4, struct s_ipv4 *ip4, char *payload,
 
 		/* if this is the last fragment, remove the entry from table */
 		if (!(ip4->flags_offset & htons(IPV4_FLAG_MORE_FRAGMENTS))) {
-			printf("[Debug] Removing fragment entry\n");
+			log_debug("Removing fragment entry");
 			nat_in_fragments_cleanup(nat4_tcp_fragments,
 						 ip4->ip_src, ip4->id);
 		}
@@ -354,7 +353,7 @@ int tcp_ipv6(struct s_ethernet *eth6, struct s_ipv6 *ip6, char *payload)
 
 	if (tcp->checksum != orig_checksum) {
 		/* packet is corrupted and shouldn't be processed */
-		printf("[Debug] Wrong checksum\n");
+		log_debug("Wrong checksum");
 		return 1;
 	}
 
@@ -364,15 +363,14 @@ int tcp_ipv6(struct s_ethernet *eth6, struct s_ipv6 *ip6, char *payload)
 			     tcp->port_src, tcp->port_dest);
 
 	if (connection == NULL) {
-		printf("[Debug] Error! Outgoing connection wasn't "
+		log_warn("Outgoing connection wasn't found/created in NAT");
-		       "found/created in NAT!\n");
 		return 1;
 	}
 
 	/* allocate memory for translated packet */
 	if ((packet = (unsigned char *) malloc(sizeof(struct s_ipv4) +
 	    htons(ip6->len))) == NULL) {
-		fprintf(stderr, "[Error] Lack of free memory\n");
+		log_error("Lack of free memory");
 		return 1;
 	}
 	ip4 = (struct s_ipv4 *) packet;

src/transmitter.c

@@ -22,11 +22,12 @@
 				 * sendto */
 #include <netinet/in.h>		/* htons */
 #include <netpacket/packet.h>	/* sockaddr_ll, PACKET_OTHERHOST */
-#include <stdio.h>		/* fprintf, stderr, perror */
+#include <stdio.h>		/* perror */
 #include <string.h>		/* memcpy */
 #include <unistd.h>		/* close */
 
 #include "ipv4.h"
+#include "log.h"
 #include "transmitter.h"
 #include "wrapper.h"
 
@@ -38,8 +39,8 @@ int			sock, sock_ipv4;
  * Initialize sockets and all needed properties. Should be called only once on
  * program startup.
  *
- * @return		0 for success
+ * @return	0 for success
- * @return		1 for failure
+ * @return	1 for failure
  */
 int transmission_init(void)
 {
@@ -54,7 +55,7 @@ int transmission_init(void)
 
 	/* initialize RAW socket */
 	if ((sock = socket(AF_PACKET, SOCK_RAW, htons(ETH_P_ALL))) == -1) {
-		fprintf(stderr, "[Error] Couldn't open RAW socket.\n");
+		log_error("Couldn't open RAW socket.");
 		perror("socket()");
 		return 1;
 	}
@@ -62,8 +63,7 @@ int transmission_init(void)
 	/* bind the socket to the interface */
 	if (setsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE, &interface,
 	    sizeof(struct ifreq)) == -1) {
-		fprintf(stderr, "[Error] Couldn't bind the socket to the "
+		log_error("Couldn't bind the socket to the interface.");
-				"interface.\n");
 		perror("setsockopt()");
 		return 1;
 	}
@@ -76,7 +76,7 @@ int transmission_init(void)
 
 	/* initialize RAW IPv4 socket */
 	if ((sock_ipv4 = socket(AF_INET, SOCK_RAW, IPPROTO_RAW)) == -1) {
-		fprintf(stderr, "[Error] Couldn't open RAW IPv4 socket.\n");
+		log_error("Couldn't open RAW IPv4 socket.");
 		perror("socket()");
 		return 1;
 	}
@@ -84,8 +84,7 @@ int transmission_init(void)
 	/* we will provide our own IPv4 header */
 	if (setsockopt(sock_ipv4, IPPROTO_IP, IP_HDRINCL, &on,
 	    sizeof(on)) == -1) {
-		fprintf(stderr, "[Error] Couldn't apply the socket "
+		log_error("Couldn't apply the socket settings.");
-				"settings.\n");
 		perror("setsockopt()");
 		return 1;
 	}
@@ -96,15 +95,14 @@ int transmission_init(void)
 /**
  * Close sockets. Should be called only once on program shutdown.
  *
- * @return		0 for success
+ * @return	0 for success
- * @return		1 for failure
+ * @return	1 for failure
  */
 int transmission_quit(void)
 {
 	/* close the socket */
 	if (close(sock) || close(sock_ipv4)) {
-		fprintf(stderr, "[Error] Couldn't close the transmission "
+		log_warn("Couldn't close the transmission sockets.");
-				"sockets.\n");
 		perror("close()");
 		return 1;
 	} else {
@@ -118,14 +116,14 @@ int transmission_quit(void)
  * @param	data	Raw packet data, including ethernet header
  * @param	length	Length of the whole packet in bytes
  *
- * @return		0 for success
+ * @return	0 for success
- * @return		1 for failure
+ * @return	1 for failure
  */
 int transmit_raw(unsigned char *data, unsigned int length)
 {
 	if (sendto(sock, data, length, 0, (struct sockaddr *) &socket_address,
 	    sizeof(struct sockaddr_ll)) != (int) length) {
-		fprintf(stderr, "[Error] Couldn't send a RAW packet.\n");
+		log_error("Couldn't send a RAW packet.");
 		perror("sendto()");
 		return 1;
 	}
@@ -141,8 +139,8 @@ int transmit_raw(unsigned char *data, unsigned int length)
  * 			including IPv4 header
  * @param	length	Length of the whole packet in bytes
  *
- * @return		0 for success
+ * @return	0 for success
- * @return		1 for failure
+ * @return	1 for failure
  */
 int transmit_ipv4(struct s_ipv4_addr *ip, unsigned char *data,
 		  unsigned int length)
@@ -154,7 +152,7 @@ int transmit_ipv4(struct s_ipv4_addr *ip, unsigned char *data,
 	if (sendto(sock_ipv4, data, length, 0,
 	    (struct sockaddr *) &socket_address_ipv4,
 	    sizeof(struct sockaddr)) != (int) length) {
-		fprintf(stderr, "[Error] Couldn't send an IPv4 packet.\n");
+		log_error("Couldn't send an IPv4 packet.");
 		perror("sendto()");
 		return 1;
 	}

src/udp.c

@@ -18,7 +18,6 @@
 
 #include <net/ethernet.h>	/* ETHERTYPE_* */
 #include <netinet/in.h>		/* htons */
-#include <stdio.h>
 #include <stdlib.h>		/* malloc */
 #include <string.h>		/* memcpy */
 
@@ -26,6 +25,7 @@
 #include "ethernet.h"
 #include "ipv4.h"
 #include "ipv6.h"
+#include "log.h"
 #include "nat.h"
 #include "transmitter.h"
 #include "udp.h"
@@ -68,7 +68,7 @@ int udp_ipv4(struct s_ethernet *eth4, struct s_ipv4 *ip4, char *payload,
 
 		if (udp->checksum != orig_checksum) {
 			/* packet is corrupted and shouldn't be processed */
-			printf("[Debug] Wrong checksum\n");
+			log_debug("Wrong checksum");
 			return 1;
 		}
 	}
@@ -77,7 +77,7 @@ int udp_ipv4(struct s_ethernet *eth4, struct s_ipv4 *ip4, char *payload,
 	connection = nat_in(nat4_udp, ip4->ip_src, udp->port_src, udp->port_dest);
 
 	if (connection == NULL) {
-		printf("[Debug] Incoming connection wasn't found in NAT\n");
+		log_debug("Incoming connection wasn't found in NAT");
 		return 1;
 	}
 
@@ -85,7 +85,7 @@ int udp_ipv4(struct s_ethernet *eth4, struct s_ipv4 *ip4, char *payload,
 	if ((packet = (unsigned char *) malloc(sizeof(struct s_ethernet) +
 					       sizeof(struct s_ipv6) +
 					       payload_size)) == NULL) {
-		fprintf(stderr, "[Error] Lack of free memory\n");
+		log_error("Lack of free memory");
 		return 1;
 	}
 	eth6 = (struct s_ethernet *) packet;
@@ -168,7 +168,7 @@ int udp_ipv6(struct s_ethernet *eth6, struct s_ipv6 *ip6, char *payload)
 
 	if (udp->checksum != orig_checksum) {
 		/* packet is corrupted and shouldn't be processed */
-		printf("[Debug] Wrong checksum\n");
+		log_debug("Wrong checksum");
 		return 1;
 	}
 
@@ -178,15 +178,14 @@ int udp_ipv6(struct s_ethernet *eth6, struct s_ipv6 *ip6, char *payload)
 			     udp->port_src, udp->port_dest);
 
 	if (connection == NULL) {
-		printf("[Debug] Error! Outgoing connection wasn't "
+		log_warn("Outgoing connection wasn't found/created in NAT!");
-		       "found/created in NAT!\n");
 		return 1;
 	}
 
 	/* allocate memory for translated packet */
 	packet_size = sizeof(struct s_ipv4) + htons(ip6->len);
 	if ((packet = (unsigned char *) malloc(packet_size)) == NULL) {
-		fprintf(stderr, "[Error] Lack of free memory\n");
+		log_error("Lack of free memory");
 		return 1;
 	}
 	ip4 = (struct s_ipv4 *) packet;

src/wrapper.c

@@ -22,7 +22,6 @@
 #include <netpacket/packet.h>	/* struct packet_mreq, struct sockaddr_ll */
 #include <netinet/in.h>		/* htons */
 #include <net/ethernet.h>	/* ETHERTYPE_* */
-#include <stdio.h>
 #include <stdlib.h>		/* srand */
 #include <string.h>		/* strncpy */
 #include <sys/ioctl.h>		/* ioctl, SIOCGIFINDEX */
@@ -33,6 +32,7 @@
 #include "ethernet.h"
 #include "ipv4.h"
 #include "ipv6.h"
+#include "log.h"
 #include "nat.h"
 #include "transmitter.h"
 #include "wrapper.h"
@@ -63,16 +63,18 @@ int main(int argc, char **argv)
 	int	length;
 	char	buffer[MTU];
 
+	log_info(PACKAGE_STRING " is starting");
+
 	/* initialize the socket for sniffing */
 	if ((sniff_sock = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL))) == -1) {
-		fprintf(stderr, "[Error] Unable to create listening socket\n");
+		log_error("Unable to create listening socket");
 		return 1;
 	}
 
 	/* get the interface */
 	strncpy(interface.ifr_name, INTERFACE, IFNAMSIZ);
 	if (ioctl(sniff_sock, SIOCGIFINDEX, &interface) == -1) {
-		fprintf(stderr, "[Error] Unable to get the interface\n");
+		log_error("Unable to get the interface");
 		return 1;
 	}
 
@@ -82,11 +84,11 @@ int main(int argc, char **argv)
 
 		/* reinitialize the interface */
 		if (ioctl(sniff_sock, SIOCGIFINDEX, &interface) == -1) {
-			fprintf(stderr, "[Error] Unable to reinitialize the interface\n");
+			log_error("Unable to reinitialize the interface");
 			return 1;
 		}
 	} else {
-		fprintf(stderr, "[Error] Unable to get the interface's HW address\n");
+		log_error("Unable to get the interface's HW address");
 		return 1;
 	}
 
@@ -95,7 +97,7 @@ int main(int argc, char **argv)
 	pmr.mr_ifindex = interface.ifr_ifindex;
 	pmr.mr_type = PACKET_MR_PROMISC;
 	if (setsockopt(sniff_sock, SOL_PACKET, PACKET_ADD_MEMBERSHIP, (char *) &pmr, sizeof(pmr)) == -1) {
-		fprintf(stderr, "[Error] Unable to set the promiscuous mode on the interface\n");
+		log_error("Unable to set the promiscuous mode on the interface");
 		return 1;
 	}
 
@@ -111,7 +113,7 @@ int main(int argc, char **argv)
 
 	/* initiate sending socket */
 	if (transmission_init()) {
-		fprintf(stderr, "[Error] Unable to initiate sending socket\n");
+		log_error("Unable to initiate sending socket");
 		return 1;
 	}
 
@@ -125,7 +127,7 @@ int main(int argc, char **argv)
 	for (;;) {
 		addr_size = sizeof(addr);
 		if ((length = recv(sniff_sock, buffer, MTU, 0)) == -1) {
-			fprintf(stderr, "[Error] Unable to retrieve data from socket\n");
+			log_error("Unable to retrieve data from socket");
 			return 1;
 		}
 
@@ -141,7 +143,7 @@ int main(int argc, char **argv)
 
 	/* unset the promiscuous mode */
 	if (setsockopt(sniff_sock, SOL_PACKET, PACKET_DROP_MEMBERSHIP, (char *) &pmr, sizeof(pmr)) == -1) {
-		fprintf(stderr, "[Error] Unable to unset the promiscuous mode on the interface\n");
+		log_error("Unable to unset the promiscuous mode on the interface");
 		/* do not call `return` here as we want to close the socket too */
 	}
 
@@ -162,16 +164,16 @@ int process(char *packet)
 
 	switch (htons(eth->type)) {
 		case ETHERTYPE_IP:
-			printf("[Debug] HW Protocol: IPv4\n");
+			log_debug("HW Protocol: IPv4");
 			return ipv4(eth, payload);
 		case ETHERTYPE_IPV6:
-			printf("[Debug] HW Protocol: IPv6\n");
+			log_debug("HW Protocol: IPv6");
 			return ipv6(eth, payload);
 		case ETHERTYPE_ARP:
-			printf("[Debug] HW Protocol: ARP\n");
+			log_debug("HW Protocol: ARP");
 			return arp(eth, payload);
 		default:
-			printf("[Debug] HW Protocol: unknown [%d/0x%04x]\n",
+			log_debug("HW Protocol: unknown [%d/0x%04x]",
 			       htons(eth->type), htons(eth->type));
 			return 1;
 	}