Add support for nftables

.gitignore

@@ -7,3 +7,4 @@
 /deb
 *.deb
 *.minisig
+*.qcow2

Makefile

@@ -3,22 +3,24 @@ PREFIX ?= /usr/local
 BINDIR = $(PREFIX)/bin
 SYSTEMDDIR ?= /etc/systemd
 
-all: reaction ip46tables
+all: reaction ip46tables nft46
 
 clean:
 	rm -f reaction ip46tables reaction.deb deb reaction.minisig ip46tables.minisig reaction.deb.minisig
 
-ip46tables: ip46tables.d/ip46tables.c
-	$(CC) -s -static ip46tables.d/ip46tables.c -o ip46tables
+ip46tables: helpers_c/ip46tables.c
+	$(CC) -s -static helpers_c/ip46tables.c -o ip46tables
+
+nft46: helpers_c/nft46.c
+	$(CC) -s -static helpers_c/nft46.c -o nft46
 
 reaction: app/* reaction.go go.mod go.sum
 	CGO_ENABLED=0 go build -buildvcs=false -ldflags "-s -X main.version=`git tag --sort=v:refname | tail -n1` -X main.commit=`git rev-parse --short HEAD`"
 
-reaction.deb: reaction ip46tables
-	chmod +x reaction ip46tables
+reaction.deb: reaction ip46tables nft46
+	chmod +x reaction ip46tables nft46
 	mkdir -p deb/reaction/usr/bin/ deb/reaction/usr/sbin/ deb/reaction/lib/systemd/system/
-	cp reaction deb/reaction/usr/bin/
-	cp ip46tables deb/reaction/usr/sbin/
+	cp reaction ip46tables nft46 deb/reaction/usr/bin/
 	cp config/reaction.debian.service deb/reaction/lib/systemd/system/reaction.service
 	cp -r DEBIAN/ deb/reaction/DEBIAN
 	sed -e "s/LAST_TAG/`git tag --sort=v:refname | tail -n1`/" -e "s/Version: v/Version: /" -i deb/reaction/DEBIAN/*
@@ -26,12 +28,13 @@ reaction.deb: reaction ip46tables
 	mv deb/reaction.deb reaction.deb
 	rm -rf deb/
 
-signatures: reaction.deb reaction ip46tables
-	minisign -Sm ip46tables reaction reaction.deb
+signatures: reaction.deb reaction ip46tables nft46
+	minisign -Sm ip46tables nft46 reaction reaction.deb
 
 install: all
 	install -m755 reaction $(DESTDIR)$(BINDIR)
 	install -m755 ip46tables $(DESTDIR)$(BINDIR)
+	install -m755 nft46 $(DESTDIR)$(BINDIR)
 
 install_systemd: install
 	install -m644 config/reaction.debian.service $(SYSTEMDDIR)/system/reaction.service

helpers_c/nft46.c

@@ -0,0 +1,97 @@
+#include<ctype.h>
+#include<errno.h>
+#include<stdio.h>
+#include<stdlib.h>
+#include<string.h>
+#include<unistd.h>
+
+// nft46 'add element inet reaction ipvXbans { 1.2.3.4 }' → nft 'add element inet reaction ipv4bans { 1.2.3.4 }'
+// nft46 'add element inet reaction ipvXbans { a:b::c:d }' → nft 'add element inet reaction ipv6bans { a:b::c:d }'
+//
+// the character X is replaced by 4 or 6 depending on the address family of the specified IP
+//
+// Limitations:
+// - nft46 must receive exactly one argument
+// - only one IP must be given per command
+// - the IP must be between { braces }
+
+int isIPv4(char *tab, int len) {
+	int i;
+	// IPv4 addresses are at least 7 chars long
+	if (len < 7 || !isdigit(tab[0]) || !isdigit(tab[len-1])) {
+			return 0;
+	}
+	// Each char must be a digit or a dot between 2 digits
+	for (i=1; i<len-1; i++) {
+		if (!isdigit(tab[i]) && !(tab[i] == '.' && isdigit(tab[i-1]) && isdigit(tab[i+1]))) {
+			return 0;
+		}
+	}
+	return 1;
+}
+
+int isIPv6(char *tab, int len) {
+	int i;
+	// IPv6 addresses are at least 3 chars long
+	if (len < 3) {
+		return 0;
+	}
+	// Each char must be a digit, :, a-f, or A-F
+	for (i=0; i<len; i++) {
+		if (!isdigit(tab[i]) && tab[i] != ':' && !(tab[i] >= 'a' && tab[i] <= 'f') && !(tab[i] >= 'A' && tab[i] <= 'F')) {
+			return 0;
+		}
+	}
+	return 1;
+}
+
+int findchar(char *tab, char c, int i, int len) {
+	while (i < len && tab[i] != c) i++;
+	if (i == len) {
+		printf("nft46: one %c must be present", c);
+		exit(1);
+	}
+	return i;
+}
+
+void adapt_args(char *tab) {
+	int i, len, X, startIP, endIP, startedIP;
+	X = startIP = endIP = -1;
+	startedIP = 0;
+	len = strlen(tab);
+	i = 0;
+	X = i = findchar(tab, 'X', i, len);
+	startIP = i = findchar(tab, '{', i, len);
+	while (startIP + 1 <= (i = findchar(tab, ' ', i, len))) startIP = i + 1;
+	i = startIP;
+	endIP = i = findchar(tab, ' ', i, len) - 1;
+
+	if (isIPv4(tab+startIP, endIP-startIP+1)) {
+		tab[X] = '4';
+		return;
+	}
+
+	if (isIPv6(tab+startIP, endIP-startIP+1)) {
+		tab[X] = '6';
+		return;
+	}
+
+	printf("nft46: no IP address found\n");
+	exit(1);
+}
+
+int exec(char *str, char **argv) {
+	argv[0] = str;
+	execvp(str, argv);
+	// returns only if fails
+	printf("nft46: exec failed %d\n", errno);
+}
+
+int main(int argc, char **argv) {
+	if (argc != 2) {
+		printf("nft46: Exactly one argument must be given\n");
+		exit(1);
+	}
+	adapt_args(argv[1]);
+	exec("nft", argv);
+}