iprange: rework ip range parsing functions

The previous parsing functions had a few problems:

  * They did accept negative numbers in addresses (e.g. 192.0.2.-5).

  * They relied on C undefined behaviour for detecting /0 prefix
    length: "mask = htonl(~((1 << (32 - m)) - 1)" was wrong for m = 0,
    because that resulted in a left shift of 32 bits, on a 32 bit wide
    value (the right operand of a bitwise shift operator must be
    strictly smaller than the width of the promoted left operand).

  * They misinterpreted /32 prefixes as disable requests. In fact, due
    to the undefined behaviour described above, /0 and /32 prefix
    lengths were represented in the same way by parse1(), that is, with
    an iprange_t structure where ->begin == ->end. Therefore
    load_ranges() had no way to distinguish between them and did
    disable the module in both cases.

This patch fixes these issues and brings the following improvements:

  * It uses getaddrinfo() to parse IP addresses, so it accept (almost)
    all IPv4 representations and is more easily extensible to IPv6 in
    the future.

  * It warns when the IP address used in CIDR notation is not the first
    address in the range (e.g. the first address of 192.0.2.1/24 is
    192.0.2.0, not 192.0.2.1).

  * It doesn't _exit() on parsing failures, thus making the functions
    usable in an EV_CONFIG_RELOAD handler.

While there, the unfinished tunnel_ranges code, which was already
commented, has been removed.

Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>

1 files changed, 27 insertions, 0 deletions

diff --git a/accel-pppd/utils.c b/accel-pppd/utils.c
index 81b4c993..3b87ee16 100644
--- a/accel-pppd/utils.c
+++ b/accel-pppd/utils.c
@@ -1,7 +1,9 @@
 #include <errno.h>
+#include <netdb.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
+#include <netinet/in.h>
 
 #include "triton.h"
 #include "utils.h"
@@ -35,6 +37,31 @@ int __export u_readlong(long int *dst, const char *src,
         }
 }
 
+int __export u_parse_ip4addr(const char *src, struct in_addr *addr,
+			     const char **err_msg)
+{
+	struct addrinfo hint = {
+		.ai_flags = AI_NUMERICHOST,
+		.ai_family = AF_INET,
+		.ai_socktype = 0,
+		.ai_protocol = 0,
+	};
+	struct addrinfo *ainfo;
+	int err;
+
+	err = getaddrinfo(src, NULL, &hint, &ainfo);
+	if (err) {
+		*err_msg = gai_strerror(err);
+		return err;
+	}
+
+	*addr = ((struct sockaddr_in *)ainfo->ai_addr)->sin_addr;
+
+	freeaddrinfo(ainfo);
+
+	return 0;
+}
+
 int __export u_randbuf(void *buf, size_t buf_len, int *err)
 {
 	uint8_t *u8buf = buf;