udhcp: optionally support RFC3397 (by Gabriel L. Somlo <somlo@cmu.edu>)

6 files changed, 77 insertions, 21 deletions

diff --git a/networking/udhcp/Config.in b/networking/udhcp/Config.in
index f633473eb..9dd02c497 100644
--- a/networking/udhcp/Config.in
+++ b/networking/udhcp/Config.in
@@ -65,3 +65,11 @@ config FEATURE_UDHCP_DEBUG
           the background.
 
           See http://udhcp.busybox.net for further details.
+
+config FEATURE_RFC3397
+        bool "Support for RFC3397 domain search (experimental)"
+        default n
+        depends on APP_UDHCPD || APP_UDHCPC
+        help
+          If selected, both client and server will support passing of domain
+          search lists via option 119, specified in RFC3397.
diff --git a/networking/udhcp/Kbuild b/networking/udhcp/Kbuild
index dc2c01f61..57d2511f0 100644
--- a/networking/udhcp/Kbuild
+++ b/networking/udhcp/Kbuild
@@ -6,13 +6,14 @@
 #
 
 lib-y:=
-lib-$(CONFIG_APP_UDHCPC)        += common.o options.o packet.o pidfile.o \
-                                   signalpipe.o socket.o
-lib-$(CONFIG_APP_UDHCPD)        += common.o options.o packet.o pidfile.o \
-                                   signalpipe.o socket.o
-lib-$(CONFIG_APP_UDHCPC)        += dhcpc.o clientpacket.o clientsocket.o \
-                                   script.o
-lib-$(CONFIG_APP_UDHCPD)        += dhcpd.o arpping.o files.o leases.o \
-                                   serverpacket.o static_leases.o
-lib-$(CONFIG_APP_DUMPLEASES)    += dumpleases.o
+lib-$(CONFIG_APP_UDHCPC)        += common.o options.o packet.o pidfile.o \
+                                   signalpipe.o socket.o
+lib-$(CONFIG_APP_UDHCPD)        += common.o options.o packet.o pidfile.o \
+                                   signalpipe.o socket.o
+lib-$(CONFIG_APP_UDHCPC)        += dhcpc.o clientpacket.o clientsocket.o \
+                                   script.o
+lib-$(CONFIG_APP_UDHCPD)        += dhcpd.o arpping.o files.o leases.o \
+                                   serverpacket.o static_leases.o
+lib-$(CONFIG_APP_DUMPLEASES)    += dumpleases.o
 lib-$(CONFIG_APP_DHCPRELAY)     += dhcprelay.o
+lib-$(CONFIG_FEATURE_RFC3397)   += domain_codec.o
diff --git a/networking/udhcp/files.c b/networking/udhcp/files.c
index e35f50a17..ab6f4a3e4 100644
--- a/networking/udhcp/files.c
+++ b/networking/udhcp/files.c
@@ -104,6 +104,12 @@ static void attach_option(struct option_set **opt_list,
         if (!existing) {
                 DEBUG("Attaching option %s to list", option->name);
 
+#if ENABLE_FEATURE_RFC3397
+                if ((option->flags & TYPE_MASK) == OPTION_STR1035)
+                        /* reuse buffer and length for RFC1035-formatted string */
+                        buffer = dname_enc(NULL, 0, buffer, &length);
+#endif
+
                 /* make a new option */
                 new = xmalloc(sizeof(struct option_set));
                 new->data = xmalloc(length + 2);
@@ -117,12 +123,22 @@ static void attach_option(struct option_set **opt_list,
 
                 new->next = *curr;
                 *curr = new;
+#if ENABLE_FEATURE_RFC3397
+                if ((option->flags & TYPE_MASK) == OPTION_STR1035 && buffer != NULL)
+                        free(buffer);
+#endif
                 return;
         }
 
         /* add it to an existing option */
         DEBUG("Attaching option %s to existing member of list", option->name);
         if (option->flags & OPTION_LIST) {
+#if ENABLE_FEATURE_RFC3397
+                if ((option->flags & TYPE_MASK) == OPTION_STR1035)
+                        /* reuse buffer and length for RFC1035-formatted string */
+                        buffer = dname_enc(existing->data + 2,
+                                        existing->data[OPT_LEN], buffer, &length);
+#endif
                 if (existing->data[OPT_LEN] + length <= 255) {
                         existing->data = xrealloc(existing->data,
                                         existing->data[OPT_LEN] + length + 3);
@@ -137,6 +153,10 @@ static void attach_option(struct option_set **opt_list,
                         memcpy(existing->data + existing->data[OPT_LEN] + 2, buffer, length);
                         existing->data[OPT_LEN] += length;
                 } /* else, ignore the data, we could put this in a second option in the future */
+#if ENABLE_FEATURE_RFC3397
+                if ((option->flags & TYPE_MASK) == OPTION_STR1035 && buffer != NULL)
+                        free(buffer);
+#endif
         } /* else, ignore the new data */
 }
 
@@ -183,6 +203,9 @@ static int read_opt(const char *const_line, void *arg)
                         if (retval) retval = read_ip(val, buffer + 4);
                         break;
                 case OPTION_STRING:
+#if ENABLE_FEATURE_RFC3397
+                case OPTION_STR1035:
+#endif
                         length = strlen(val);
                         if (length > 0) {
                                 if (length > 254) length = 254;
diff --git a/networking/udhcp/options.c b/networking/udhcp/options.c
index bda6efc7e..a58adb9a9 100644
--- a/networking/udhcp/options.c
+++ b/networking/udhcp/options.c
@@ -11,7 +11,7 @@
 
 /* supported options are easily added here */
 const struct dhcp_option dhcp_options[] = {
-        /* name[10]     flags                                   code */
+        /* name[12]     flags                                   code */
         {"subnet",      OPTION_IP | OPTION_REQ,                 0x01},
         {"timezone",    OPTION_S32,                             0x02},
         {"router",      OPTION_IP | OPTION_LIST | OPTION_REQ,   0x03},
@@ -43,6 +43,9 @@ const struct dhcp_option dhcp_options[] = {
         {"tftp",        OPTION_STRING,                          0x42},
         {"bootfile",    OPTION_STRING,                          0x43},
         {"userclass",   OPTION_STRING,                          0x4D},
+#if ENABLE_FEATURE_RFC3397
+        {"search",      OPTION_STR1035 | OPTION_LIST | OPTION_REQ, 0x77},
+#endif
         /* MSIE's "Web Proxy Autodiscovery Protocol" support */
         {"wpad",        OPTION_STRING,                          0xfc},
         {"",            0x00,                                   0x00}
@@ -54,6 +57,9 @@ const unsigned char option_lengths[] = {
         [OPTION_IP_PAIR] = 8,
         [OPTION_BOOLEAN] = 1,
         [OPTION_STRING] =  1,
+#if ENABLE_FEATURE_RFC3397
+        [OPTION_STR1035] = 1,
+#endif
         [OPTION_U8] =      1,
         [OPTION_U16] =     2,
         [OPTION_S16] =     2,
diff --git a/networking/udhcp/options.h b/networking/udhcp/options.h
index 588504e5d..11f013fd4 100644
--- a/networking/udhcp/options.h
+++ b/networking/udhcp/options.h
@@ -9,6 +9,9 @@ enum {
         OPTION_IP=1,
         OPTION_IP_PAIR,
         OPTION_STRING,
+#if ENABLE_FEATURE_RFC3397
+        OPTION_STR1035, /* RFC1035 compressed domain name list */
+#endif
         OPTION_BOOLEAN,
         OPTION_U8,
         OPTION_U16,
@@ -33,5 +36,9 @@ uint8_t *get_option(struct dhcpMessage *packet, int code);
 int end_option(uint8_t *optionptr);
 int add_option_string(uint8_t *optionptr, uint8_t *string);
 int add_simple_option(uint8_t *optionptr, uint8_t code, uint32_t data);
+#if ENABLE_FEATURE_RFC3397
+char *dname_dec(const uint8_t *cstr, int clen, const char *pre);
+uint8_t *dname_enc(const uint8_t *cstr, int clen, const char *src, int *retlen);
+#endif
 
 #endif
diff --git a/networking/udhcp/script.c b/networking/udhcp/script.c
index d2b0bb05b..dc8ff7a1c 100644
--- a/networking/udhcp/script.c
+++ b/networking/udhcp/script.c
@@ -19,6 +19,9 @@ static const int max_option_length[] = {
         [OPTION_IP] =           sizeof("255.255.255.255 "),
         [OPTION_IP_PAIR] =      sizeof("255.255.255.255 ") * 2,
         [OPTION_STRING] =       1,
+#if ENABLE_FEATURE_RFC3397
+        [OPTION_STR1035] =      1,
+#endif
         [OPTION_BOOLEAN] =      sizeof("yes "),
         [OPTION_U8] =           sizeof("255 "),
         [OPTION_U16] =          sizeof("65535 "),
@@ -53,21 +56,23 @@ static int mton(struct in_addr *mask)
 }
 
 
-/* Fill dest with the text of option 'option'. */
-static void fill_options(char *dest, uint8_t *option,
-                        const struct dhcp_option *type_p)
+/* Allocate and fill with the text of option 'option'. */
+static char *alloc_fill_opts(uint8_t *option, const struct dhcp_option *type_p)
 {
-        int type, optlen;
+        int len, type, optlen;
         uint16_t val_u16;
         int16_t val_s16;
         uint32_t val_u32;
         int32_t val_s32;
-        int len = option[OPT_LEN - 2];
-
-        dest += sprintf(dest, "%s=", type_p->name);
+        char *dest, *ret;
 
+        len = option[OPT_LEN - 2];
         type = type_p->flags & TYPE_MASK;
         optlen = option_lengths[type];
+
+        dest = ret = xmalloc(upper_length(len, type) + strlen(type_p->name) + 2);
+        dest += sprintf(ret, "%s=", type_p->name);
+
         for (;;) {
                 switch (type) {
                 case OPTION_IP_PAIR:
@@ -103,13 +108,21 @@ static void fill_options(char *dest, uint8_t *option,
                 case OPTION_STRING:
                         memcpy(dest, option, len);
                         dest[len] = '\0';
-                        return;  /* Short circuit this case */
+                        return ret;      /* Short circuit this case */
+#if ENABLE_FEATURE_RFC3397
+                case OPTION_STR1035:
+                        /* unpack option into dest; use ret for prefix (i.e., "optname=") */
+                        dest = dname_dec(option, len, ret);
+                        free(ret);
+                        return dest;
+#endif
                 }
                 option += optlen;
                 len -= optlen;
                 if (len <= 0) break;
                 dest += sprintf(dest, " ");
         }
+        return ret;
 }
 
 
@@ -155,9 +168,7 @@ static char **fill_envp(struct dhcpMessage *packet)
                 temp = get_option(packet, dhcp_options[i].code);
                 if (!temp)
                         continue;
-                envp[j] = xmalloc(upper_length(temp[OPT_LEN - 2],
-                        dhcp_options[i].flags & TYPE_MASK) + strlen(dhcp_options[i].name) + 2);
-                fill_options(envp[j++], temp, &dhcp_options[i]);
+                envp[j++] = alloc_fill_opts(temp, &dhcp_options[i]);
 
                 /* Fill in a subnet bits option for things like /24 */
                 if (dhcp_options[i].code == DHCP_SUBNET) {