udhcpd: support decoding of option 120 "SIP servers". Closes bug 737

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

4 files changed, 83 insertions, 44 deletions

diff --git a/networking/udhcp/Config.in b/networking/udhcp/Config.in
index fd2a61c..34adf35 100644
--- a/networking/udhcp/Config.in
+++ b/networking/udhcp/Config.in
@@ -92,7 +92,8 @@ config FEATURE_UDHCP_RFC3397
 	depends on UDHCPD || UDHCPC
 	help
 	  If selected, both client and server will support passing of domain
-	  search lists via option 119, specified in RFC3397.
+	  search lists via option 119, specified in RFC 3397,
+	  and SIP servers option 120, specified in RFC 3361.
 
 config UDHCPC_DEFAULT_SCRIPT
 	string "Absolute path to config script"
diff --git a/networking/udhcp/common.c b/networking/udhcp/common.c
index adbcd77..77d7fd5 100644
--- a/networking/udhcp/common.c
+++ b/networking/udhcp/common.c
@@ -50,7 +50,8 @@ const struct dhcp_option dhcp_options[] = {
 //TODO: not a string, but a set of LASCII strings:
 //	{ OPTION_STRING                           , 0x4D }, /* DHCP_USER_CLASS    */
 #if ENABLE_FEATURE_UDHCP_RFC3397
-	{ OPTION_STR1035 | OPTION_LIST            , 0x77 }, /* DHCP_DOMAIN_SEARCH */
+	{ OPTION_DNS_STRING | OPTION_LIST         , 0x77 }, /* DHCP_DOMAIN_SEARCH */
+	{ OPTION_SIP_SERVERS                      , 0x78 }, /* DHCP_SIP_SERVERS   */
 #endif
 	{ OPTION_STATIC_ROUTES                    , 0x79 }, /* DHCP_STATIC_ROUTES */
 	{ OPTION_STRING                           , 0xfc }, /* DHCP_WPAD          */
@@ -106,22 +107,32 @@ const char dhcp_option_strings[] ALIGN1 =
 //	"userclass" "\0"   /* DHCP_USER_CLASS     */
 #if ENABLE_FEATURE_UDHCP_RFC3397
 	"search" "\0"      /* DHCP_DOMAIN_SEARCH  */
+// doesn't work in udhcpd.conf since OPTION_SIP_SERVERS
+// is not handled yet by "string->option" conversion code:
+	"sipservers" "\0"  /* DHCP_SIP_SERVERS    */
 #endif
-// "staticroutes" is only used to set udhcpc environment, it doesn't work
-// in udhcpd.conf since OPTION_STATIC_ROUTES is not handled yet
-// by "string->option" conversion code:
-	"staticroutes" "\0"/* DHCP_STATIC_ROUTES */
-	"wpad" "\0"        /* DHCP_WPAD          */
+// doesn't work in udhcpd.conf since OPTION_STATIC_ROUTES
+// is not handled yet by "string->option" conversion code:
+	"staticroutes" "\0"/* DHCP_STATIC_ROUTES  */
+	"wpad" "\0"        /* DHCP_WPAD           */
 	;
 
-/* Lengths of the different option types */
+/* Lengths of the option types in binary form.
+ * Used by:
+ * udhcp_str2optset: to determine how many bytes to allocate.
+ * xmalloc_optname_optval: to estimate string length
+ * from binary option length: (option[LEN] / dhcp_option_lengths[opt_type])
+ * is the number of elements, multiply in by one element's string width
+ * (len_of_option_as_string[opt_type]) and you know how wide string you need.
+ */
 const uint8_t dhcp_option_lengths[] ALIGN1 = {
 	[OPTION_IP] =      4,
 	[OPTION_IP_PAIR] = 8,
 //	[OPTION_BOOLEAN] = 1,
-	[OPTION_STRING] =  1,
+	[OPTION_STRING] =  1,  /* ignored by udhcp_str2optset */
 #if ENABLE_FEATURE_UDHCP_RFC3397
-	[OPTION_STR1035] = 1,
+	[OPTION_DNS_STRING] = 1,  /* ignored by both udhcp_str2optset and xmalloc_optname_optval */
+	[OPTION_SIP_SERVERS] = 1,
 #endif
 	[OPTION_U8] =      1,
 	[OPTION_U16] =     2,
@@ -332,7 +343,7 @@ static NOINLINE void attach_option(
 	if (!existing) {
 		log2("Attaching option %02x to list", option->code);
 #if ENABLE_FEATURE_UDHCP_RFC3397
-		if ((option->flags & OPTION_TYPE_MASK) == OPTION_STR1035) {
+		if ((option->flags & OPTION_TYPE_MASK) == OPTION_DNS_STRING) {
 			/* reuse buffer and length for RFC1035-formatted string */
 			allocated = buffer = (char *)dname_enc(NULL, 0, buffer, &length);
 		}
@@ -360,7 +371,7 @@ static NOINLINE void attach_option(
 		log1("Attaching option %02x to existing member of list", option->code);
 		old_len = existing->data[OPT_LEN];
 #if ENABLE_FEATURE_UDHCP_RFC3397
-		if ((option->flags & OPTION_TYPE_MASK) == OPTION_STR1035) {
+		if ((option->flags & OPTION_TYPE_MASK) == OPTION_DNS_STRING) {
 			/* reuse buffer and length for RFC1035-formatted string */
 			allocated = buffer = (char *)dname_enc(existing->data + OPT_DATA, old_len, buffer, &length);
 		}
@@ -426,7 +437,7 @@ int FAST_FUNC udhcp_str2optset(const char *const_str, void *arg)
 			break;
 		case OPTION_STRING:
 #if ENABLE_FEATURE_UDHCP_RFC3397
-		case OPTION_STR1035:
+		case OPTION_DNS_STRING:
 #endif
 			length = strnlen(val, 254);
 			if (length > 0) {
diff --git a/networking/udhcp/common.h b/networking/udhcp/common.h
index 1c5afa6..28e3471 100644
--- a/networking/udhcp/common.h
+++ b/networking/udhcp/common.h
@@ -71,7 +71,8 @@ enum {
 	OPTION_IP_PAIR,
 	OPTION_STRING,
 #if ENABLE_FEATURE_UDHCP_RFC3397
-	OPTION_STR1035,	/* RFC1035 compressed domain name list */
+	OPTION_DNS_STRING,  /* RFC1035 compressed domain name list */
+	OPTION_SIP_SERVERS,
 #endif
 //	OPTION_BOOLEAN,
 	OPTION_U8,
@@ -130,6 +131,7 @@ enum {
 //#define DHCP_USER_CLASS       0x4d /* RFC 3004. set of LASCII strings. "I am a printer" etc */
 #define DHCP_FQDN               0x51 /* client asks to update DNS to map its FQDN to its new IP */
 //#define DHCP_DOMAIN_SEARCH    0x77 /* RFC 3397. set of ASCIZ string, DNS-style compressed */
+//#define DHCP_SIP_SERVERS      0x78 /* RFC 3361. flag byte, then: 0: domain names, 1: IP addrs */
 //#define DHCP_STATIC_ROUTES    0x79 /* RFC 3442. (mask,ip,router) tuples */
 //#define DHCP_WPAD             0xfc /* MSIE's Web Proxy Autodiscovery Protocol */
 #define DHCP_END                0xff
diff --git a/networking/udhcp/dhcpc.c b/networking/udhcp/dhcpc.c
index c36d418..53e10d0 100644
--- a/networking/udhcp/dhcpc.c
+++ b/networking/udhcp/dhcpc.c
@@ -42,19 +42,24 @@
 
 /* get a rough idea of how long an option will be (rounding up...) */
 static const uint8_t len_of_option_as_string[] = {
-	[OPTION_IP] =		sizeof("255.255.255.255 "),
-	[OPTION_IP_PAIR] =	sizeof("255.255.255.255 ") * 2,
-	[OPTION_STATIC_ROUTES]= sizeof("255.255.255.255/32 255.255.255.255 "),
-	[OPTION_STRING] =	1,
+	[OPTION_IP              ] = sizeof("255.255.255.255 "),
+	[OPTION_IP_PAIR         ] = sizeof("255.255.255.255 ") * 2,
+	[OPTION_STATIC_ROUTES   ] = sizeof("255.255.255.255/32 255.255.255.255 "),
+	[OPTION_STRING          ] = 1,
 #if ENABLE_FEATURE_UDHCP_RFC3397
-	[OPTION_STR1035] =	1,
+	[OPTION_DNS_STRING      ] = 1, /* unused */
+	/* Hmmm, this severely overestimates size if SIP_SERVERS option
+	 * is in domain name form: N-byte option in binary form
+	 * mallocs ~16*N bytes. But it is freed almost at once.
+	 */
+	[OPTION_SIP_SERVERS     ] = sizeof("255.255.255.255 "),
 #endif
-//	[OPTION_BOOLEAN] =	sizeof("yes "),
-	[OPTION_U8] =		sizeof("255 "),
-	[OPTION_U16] =		sizeof("65535 "),
-//	[OPTION_S16] =		sizeof("-32768 "),
-	[OPTION_U32] =		sizeof("4294967295 "),
-	[OPTION_S32] =		sizeof("-2147483684 "),
+//	[OPTION_BOOLEAN         ] = sizeof("yes "),
+	[OPTION_U8              ] = sizeof("255 "),
+	[OPTION_U16             ] = sizeof("65535 "),
+//	[OPTION_S16             ] = sizeof("-32768 "),
+	[OPTION_U32             ] = sizeof("4294967295 "),
+	[OPTION_S32             ] = sizeof("-2147483684 "),
 };
 
 /* note: ip is a pointer to an IP in network order, possibly misaliged */
@@ -80,16 +85,13 @@ static NOINLINE char *xmalloc_optname_optval(uint8_t *option, const struct dhcp_
 {
 	unsigned upper_length;
 	int len, type, optlen;
-	uint16_t val_u16;
-	uint32_t val_u32;
-	int32_t val_s32;
 	char *dest, *ret;
 
 	/* option points to OPT_DATA, need to go back and get OPT_LEN */
 	len = option[OPT_LEN - OPT_DATA];
 	type = type_p->flags & OPTION_TYPE_MASK;
 	optlen = dhcp_option_lengths[type];
-	upper_length = len_of_option_as_string[type] * (len / optlen);
+	upper_length = len_of_option_as_string[type] * ((unsigned)len / (unsigned)optlen);
 
 	dest = ret = xmalloc(upper_length + strlen(opt_name) + 2);
 	dest += sprintf(ret, "%s=", opt_name);
@@ -113,24 +115,20 @@ static NOINLINE char *xmalloc_optname_optval(uint8_t *option, const struct dhcp_
 		case OPTION_U8:
 			dest += sprintf(dest, "%u", *option);
 			break;
-		case OPTION_U16:
+//		case OPTION_S16:
+		case OPTION_U16: {
+			uint16_t val_u16;
 			move_from_unaligned16(val_u16, option);
 			dest += sprintf(dest, "%u", ntohs(val_u16));
 			break;
-//		case OPTION_S16: {
-//			int16_t val_s16;
-//			move_from_unaligned16(val_s16, option);
-//			dest += sprintf(dest, "%d", ntohs(val_s16));
-//			break;
-//		}
-		case OPTION_U32:
-			move_from_unaligned32(val_u32, option);
-			dest += sprintf(dest, "%lu", (unsigned long) ntohl(val_u32));
-			break;
+		}
 		case OPTION_S32:
-			move_from_unaligned32(val_s32, option);
-			dest += sprintf(dest, "%ld", (long) ntohl(val_s32));
+		case OPTION_U32: {
+			uint32_t val_u32;
+			move_from_unaligned32(val_u32, option);
+			dest += sprintf(dest, type == OPTION_U32 ? "%lu" : "%ld", (unsigned long) ntohl(val_u32));
 			break;
+		}
 		case OPTION_STRING:
 			memcpy(dest, option, len);
 			dest[len] = '\0';
@@ -180,7 +178,7 @@ static NOINLINE char *xmalloc_optname_optval(uint8_t *option, const struct dhcp_
 			return ret;
 		}
 #if ENABLE_FEATURE_UDHCP_RFC3397
-		case OPTION_STR1035:
+		case OPTION_DNS_STRING:
 			/* unpack option into dest; use ret for prefix (i.e., "optname=") */
 			dest = dname_dec(option, len, ret);
 			if (dest) {
@@ -189,8 +187,35 @@ static NOINLINE char *xmalloc_optname_optval(uint8_t *option, const struct dhcp_
 			}
 			/* error. return "optname=" string */
 			return ret;
+		case OPTION_SIP_SERVERS:
+			/* Option binary format:
+			 * type: byte
+			 * type=0: domain names, dns-compressed
+			 * type=1: IP addrs
+			 */
+			option++;
+			len--;
+			if (option[-1] == 0) {
+				dest = dname_dec(option, len, ret);
+				if (dest) {
+					free(ret);
+					return dest;
+				}
+			} else
+			if (option[-1] == 1) {
+				const char *pfx = "";
+				while (1) {
+					len -= 4;
+					if (len < 0)
+						break;
+					dest += sprint_nip(dest, pfx, option);
+					pfx = " ";
+					option += 4;
+				}
+			}
+			return ret;
 #endif
-		}
+		} /* switch */
 		option += optlen;
 		len -= optlen;
 		if (len <= 0)