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 fd2a61cc0..34adf35fe 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 adbcd77ac..77d7fd5d4 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 1c5afa6f9..28e34718a 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 c36d4180b..53e10d00e 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)