[U-Boot] [RFC PATCH v2 4/5] lib/net_utils.c: add string_to_ip6

Chris Packham
2013-01-18T01:35:31Z

From: Chris Packham <chris.packham@alliedtelesis.co.nz>

string_to_ip6 parses an IPv6 address from a string. Parsing v6 addresses
is a bit more complicated than parsing v4 because there are a number of
different formats that can be used.

Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>

---
I'm sure the parsing can be better and done in less code with only a
single pass but I haven't yet figured it out. The main problem is that
"::" can represent a variable number of contiguous "0000:" so when
parsing "::" we can't tell how many half words to skip.

Changes in v2: None

include/net6.h | 3 ++
lib/net_utils.c | 115 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 118 insertions(+)

diff --git a/include/net6.h b/include/net6.h
index bdb4326..55ab187 100644
--- a/include/net6.h
+++ b/include/net6.h
@@ -53,4 +53,7 @@ static inline int ipv6_addr_is_isatap(const IP6addr_t *a)
return (a->u6_addr32[2] | htonl(0x02000000)) == htonl(0x02005EFE);
}

+/* Convert a string to an ipv6 address */
+extern int string_to_ip6(const char *s, IP6addr_t *addr);
+
#endif /* __NET6_H__ */
diff --git a/lib/net_utils.c b/lib/net_utils.c
index 2b20ccb..a8de103 100644
--- a/lib/net_utils.c
+++ b/lib/net_utils.c
@@ -27,6 +27,8 @@
*/

#include <common.h>
+#include <net6.h>
+#include <linux/ctype.h>

IPaddr_t string_to_ip(const char *s)
{
@@ -49,3 +51,116 @@ IPaddr_t string_to_ip(const char *s)

return (htonl(addr));
}
+
+/**
+ * Parses an IP6addr_t from the given string. IPv6 address parsing is a bit
+ * more complicated than v4 due to the flexible format and some of the special
+ * cases (e.g. v4 mapped).
+ *
+ * Examples of valid strings:
+ * 2001:db8::0:1234:1
+ * 2001:0db8:0000:0000:0000:0000:1234:0001
+ * ::1
+ * ::ffff:192.168.1.1
+ *
+ * Examples of invalid strings
+ * 2001:db8::0::0 (:: can only appear once)
+ * 2001:db8:192.168.1.1::1 (v4 part can only appear at the end)
+ * 192.168.1.1 (we don't implicity map v4)
+ */
+int string_to_ip6(const char *strpt, IP6addr_t *addrpt)
+{
+ IP6addr_t *in6_val = addrpt;
+ int colon_count = 0;
+ int found_double_colon = 0;
+ int xstart = 0; /* first zero (double colon) */
+ int len = 7; /* numbers of zero words the double colon represents */
+ int i;
+ const char *s = strpt;
+
+ if (strpt == NULL)
+ return 0;
+
+ /* First pass, verify the syntax and locate the double colon */
+ for (;;) {
+ while (isxdigit((int)*s))
+ s++;
+ if (*s == '\0')
+ break;
+ if (*s != ':') {
+ if (*s == '.' && len >= 2) {
+ while (s != strpt && *(s-1) != ':')
+ --s;
+ if (string_to_ip(s) != 0) {
+ len -= 2;
+ break;
+ }
+ }
+ /* This could be a valid address */
+ break;
+ }
+ if (s == strpt) {
+ /* The address begins with a colon */
+ if (*++s != ':')
+ /* Must start with a double colon or a number */
+ goto out_err;
+ } else {
+ s++;
+ if (found_double_colon)
+ len--;
+ else
+ xstart++;
+ }
+
+ if (*s == ':') {
+ if (found_double_colon)
+ /* Two double colons are not allowed */
+ goto out_err;
+ found_double_colon = 1;
+ len -= xstart;
+ s++;
+ }
+
+ if (++colon_count == 7)
+ /* Found all colons */
+ break;
+ }
+
+ if (colon_count == 0 || colon_count > 7)
+ goto out_err;
+ if (*--s == ':')
+ len++;
+
+ /* Second pass, read the address */
+ s = strpt;
+ for (i = 0; i < 8; i++) {
+ int val = 0;
+ char *end;
+
+ if (found_double_colon && i >= xstart && i < xstart + len) {
+ addrpt->u6_addr16[i] = 0;
+ continue;
+ }
+ while (*s == ':')
+ s++;
+
+ if (i == 6 && isdigit((int)*s)) {
+ IPaddr_t v4 = string_to_ip(s);
+ if (v4 != 0) {
+ /* Ending with :IPv4-address */
+ addrpt->u6_addr32[3] = v4;
+ break;
+ }
+ }
+
+ val = simple_strtoul(s, &end, 16);
+ if (*end != '\0' && *end != ':')
+ goto out_err;
+ addrpt->u6_addr16[i] = htons(val);
+ s = end;
+ }
+ return 0;
+
+out_err:
+ return -1;
+}
--
1.7.12.rc2.16.g034161a