MINOR: contrib/iprange: add a network IP range to mask converter

This tool has remained uncommitted in my development tree for almost a year.
Just minor polish and commit.

It can be used to convert some geolocation IP lists to ACLs.

contrib/iprange/Makefile

@@ -0,0 +1,13 @@
+CC       = gcc
+OPTIMIZE = -O3
+LDFLAGS  = -s
+
+OBJS     = iprange
+
+all: $(OBJS)
+
+%: %.c
+	$(CC) $(LDFLAGS) $(OPTIMIZE) -o $@ $^
+
+clean:
+	rm -f $(OBJS) *.o *.a *~

contrib/iprange/iprange.c

@@ -0,0 +1,187 @@
+/*
+ * network range to IP+mask converter
+ *
+ * Copyright 2011-2012 Willy Tarreau <w@1wt.eu>
+ *
+ * This program reads lines starting by two IP addresses and outputs them with
+ * the two IP addresses replaced by a netmask covering the range between these
+ * IPs (inclusive). When multiple ranges are needed, as many lines are emitted.
+ * The IP addresses may be delimited by spaces, tabs or commas. Quotes are
+ * stripped, and lines beginning with a sharp character ('#') are ignored. The
+ * IP addresses may be either in the dotted format or represented as a 32-bit
+ * integer value in network byte order.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <arpa/inet.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define MAXLINE 1024
+
+/* returns a string version of an IPv4 address in host order */
+static const char *get_ipv4_addr(unsigned int addr)
+{
+	struct in_addr a;
+
+	a.s_addr = ntohl(addr);
+	return inet_ntoa(a);
+}
+
+/* print all networks present between address <low> and address <high> in
+ * cidr format, followed by <eol>.
+ */
+static void convert_range(unsigned int low, unsigned int high, const char *eol)
+{
+	int bit;
+
+	if (low == high) {
+		/* single value */
+		printf("%s%s\n", get_ipv4_addr(low), eol);
+		return;
+	}
+	else if (low > high) {
+		int swap = low;
+		low = high;
+		high = swap;
+	}
+
+	if (low == high + 1) {
+		/* full range */
+		printf("0.0.0.0/0%s\n", eol);
+		return;
+	}
+	//printf("low=%08x high=%08x\n", low, high);
+
+	bit = 0;
+	while (bit < 32 && low + (1 << bit) - 1 <= high) {
+		/* enlarge mask */
+		if (low & (1 << bit)) {
+			/* can't aggregate anymore, dump and retry from the same bit */
+			printf("%s/%d%s\n", get_ipv4_addr(low), 32-bit, eol);
+			low += (1 << bit);
+		}
+		else {
+			/* try to enlarge the mask as much as possible first */
+			bit++;
+			//printf("  ++bit=%d\n", bit);
+		}
+	}
+	//printf("stopped 1 at low=%08x, bit=%d\n", low, bit);
+
+	bit = 31;
+	while (bit >= 0 && high - low + 1 != 0) {
+		/* shrink mask */
+		if ((high - low + 1) & (1 << bit)) {
+			/* large bit accepted, dump and go on from the same bit */
+			//printf("max: %08x/%d\n", low, 32-bit);
+			printf("%s/%d%s\n", get_ipv4_addr(low), 32-bit, eol);
+			low += (1 << bit);
+		}
+		else {
+			bit--;
+			//printf("  --bit=%d, low=%08x\n", bit, low);
+		}
+	}
+	//printf("stopped at low=%08x\n", low);
+}
+
+static void usage(const char *argv0)
+{
+	fprintf(stderr,
+	        "Usage: %s < iplist.csv\n"
+	        "\n"
+	        "This program reads lines starting by two IP addresses and outputs them with\n"
+	        "the two IP addresses replaced by a netmask covering the range between these\n"
+	        "IPs (inclusive). When multiple ranges are needed, as many lines are emitted.\n"
+	        "The IP addresses may be delimited by spaces, tabs or commas. Quotes are\n"
+	        "stripped, and lines beginning with a sharp character ('#') are ignored. The\n"
+	        "IP addresses may be either in the dotted format or represented as a 32-bit\n"
+	        "integer value in network byte order.\n"
+		"\n", argv0);
+}
+
+main(int argc, char **argv)
+{
+	char line[MAXLINE];
+	int l, lnum;
+	char *lb, *le, *hb, *he, *err;
+	struct in_addr src_addr, dst_addr;
+	unsigned int sa, da;
+
+	if (argc > 1) {
+		usage(argv[0]);
+		exit(1);
+	}
+
+	lnum = 0;
+	while (fgets(line, sizeof(line), stdin) != NULL) {
+		l = strlen(line);
+		if (l && line[l - 1] == '\n')
+			line[--l] = '\0';
+
+		lnum++;
+		/* look for the first field which must be the low address of a range,
+		 * in dotted IPv4 format or as an integer. spaces and commas are
+		 * considered as delimiters, quotes are removed.
+		 */
+		for (lb = line; *lb == ' ' || *lb == '\t' || *lb == ',' || *lb == '"'; lb++);
+		if (!*lb || *lb == '#')
+			continue;
+		for (le = lb + 1; *le != ' ' && *le != '\t' && *le != ',' && *le != '"' && *le; le++);
+		if (!*le)
+			continue;
+		/* we have the low address between lb(included) and le(excluded) */
+		*(le++) = 0;
+
+		for (hb = le; *hb == ' ' || *hb == '\t' || *hb == ',' || *hb == '"'; hb++);
+		if (!*hb || *hb == '#')
+			continue;
+		for (he = hb + 1; *he != ' ' && *he != '\t' && *he != ',' && *he != '"' && *he; he++);
+		if (!*he)
+			continue;
+		/* we have the high address between hb(included) and he(excluded) */
+		*(he++) = 0;
+
+		/* we want to remove a possible ending quote and a possible comma,
+		 * not more.
+		 */
+		while (*he == '"')
+			*(he++) = ' ';
+		while (*he == ',' || *he == ' ' || *he == '\t')
+			*(he++) = ' ';
+
+		/* if the trailing string is not empty, prefix it with a space */
+		if (*(he-1) == ' ')
+			he--;
+
+		if (inet_pton(AF_INET, lb, &src_addr) <= 0) {
+			/* parsing failed, retry with a plain numeric IP */
+			src_addr.s_addr = ntohl(strtoul(lb, &err, 10));
+			if (err && *err) {
+				fprintf(stderr, "Failed to parse source address <%s> at line %d, skipping line\n", lb, lnum);
+				continue;
+			}
+		}
+
+		if (inet_pton(AF_INET, hb, &dst_addr) <= 0) {
+			/* parsing failed, retry with a plain numeric IP */
+			dst_addr.s_addr = ntohl(strtoul(hb, &err, 10));
+			if (err && *err) {
+				fprintf(stderr, "Failed to parse destination address <%s> at line %d, skipping line\n", hb, lnum);
+				continue;
+			}
+		}
+
+		sa = htonl(src_addr.s_addr);
+		da = htonl(dst_addr.s_addr);
+		convert_range(sa, da, he);
+	}
+}