sd-dhcp: option_append - support falling back to 'sname' and 'file'

5 files changed, 140 insertions, 40 deletions

diff --git a/src/libsystemd-network/dhcp-internal.h b/src/libsystemd-network/dhcp-internal.h
index 56423a2cce..76d357a6ed 100644
--- a/src/libsystemd-network/dhcp-internal.h
+++ b/src/libsystemd-network/dhcp-internal.h
@@ -36,7 +36,7 @@ int dhcp_network_send_raw_socket(int s, const union sockaddr_union *link,
 int dhcp_network_send_udp_socket(int s, be32_t address, uint16_t port,
                                  const void *packet, size_t len);
 
-int dhcp_option_append(uint8_t options[], size_t size, size_t *offset,
+int dhcp_option_append(DHCPMessage *message, size_t size, size_t *offset, uint8_t overload,
                        uint8_t code, size_t optlen, const void *optval);
 
 typedef int (*dhcp_option_cb_t)(uint8_t code, uint8_t len,
@@ -46,7 +46,7 @@ int dhcp_option_parse(DHCPMessage *message, size_t len,
                       dhcp_option_cb_t cb, void *user_data);
 
 int dhcp_message_init(DHCPMessage *message, uint8_t op, uint32_t xid, uint8_t type,
-                      uint8_t options[], size_t optlen, size_t *optoffset);
+                      size_t optlen, size_t *optoffset);
 
 uint16_t dhcp_packet_checksum(void *buf, size_t len);
 
diff --git a/src/libsystemd-network/dhcp-option.c b/src/libsystemd-network/dhcp-option.c
index 24f678c100..b6110c5f16 100644
--- a/src/libsystemd-network/dhcp-option.c
+++ b/src/libsystemd-network/dhcp-option.c
@@ -26,8 +26,8 @@
 
 #include "dhcp-internal.h"
 
-int dhcp_option_append(uint8_t options[], size_t size, size_t *offset,
-                       uint8_t code, size_t optlen, const void *optval) {
+static int option_append(uint8_t options[], size_t size, size_t *offset,
+                         uint8_t code, size_t optlen, const void *optval) {
         assert(options);
         assert(offset);
 
@@ -39,7 +39,7 @@ int dhcp_option_append(uint8_t options[], size_t size, size_t *offset,
 
         case DHCP_OPTION_PAD:
         case DHCP_OPTION_END:
-                if (size - *offset < 1)
+                if (size < *offset + 1)
                         return -ENOBUFS;
 
                 options[*offset] = code;
@@ -47,14 +47,17 @@ int dhcp_option_append(uint8_t options[], size_t size, size_t *offset,
                 break;
 
         default:
-                if (size - *offset < optlen + 2)
+                if (size < *offset + optlen + 2)
                         return -ENOBUFS;
 
-                assert(optval);
-
                 options[*offset] = code;
                 options[*offset + 1] = optlen;
-                memcpy(&options[*offset + 2], optval, optlen);
+
+                if (optlen) {
+                        assert(optval);
+
+                        memcpy(&options[*offset + 2], optval, optlen);
+                }
 
                 *offset += optlen + 2;
 
@@ -64,6 +67,77 @@ int dhcp_option_append(uint8_t options[], size_t size, size_t *offset,
         return 0;
 }
 
+int dhcp_option_append(DHCPMessage *message, size_t size, size_t *offset,
+                       uint8_t overload,
+                       uint8_t code, size_t optlen, const void *optval) {
+        size_t file_offset = 0, sname_offset =0;
+        bool file, sname;
+        int r;
+
+        assert(message);
+        assert(offset);
+
+        file = overload & DHCP_OVERLOAD_FILE;
+        sname = overload & DHCP_OVERLOAD_SNAME;
+
+        if (*offset < size) {
+                /* still space in the options array */
+                r = option_append(message->options, size, offset, code, optlen, optval);
+                if (r >= 0)
+                        return 0;
+                else if (r == -ENOBUFS && (file || sname)) {
+                        /* did not fit, but we have more buffers to try
+                           close the options array and move the offset to its end */
+                        r = option_append(message->options, size, offset, DHCP_OPTION_END, 0, NULL);
+                        if (r < 0)
+                                return r;
+
+                        *offset = size;
+                } else
+                        return r;
+        }
+
+        if (overload & DHCP_OVERLOAD_FILE) {
+                file_offset = *offset - size;
+
+                if (file_offset < sizeof(message->file)) {
+                        /* still space in the 'file' array */
+                        r = option_append(message->file, sizeof(message->file), &file_offset, code, optlen, optval);
+                        if (r >= 0) {
+                                *offset = size + file_offset;
+                                return 0;
+                        } else if (r == -ENOBUFS && sname) {
+                                /* did not fit, but we have more buffers to try
+                                   close the file array and move the offset to its end */
+                                r = option_append(message->options, size, offset, DHCP_OPTION_END, 0, NULL);
+                                if (r < 0)
+                                        return r;
+
+                                *offset = size + sizeof(message->file);
+                        } else
+                                return r;
+                }
+        }
+
+        if (overload & DHCP_OVERLOAD_SNAME) {
+                sname_offset = *offset - size - (file ? sizeof(message->file) : 0);
+
+                if (sname_offset < sizeof(message->sname)) {
+                        /* still space in the 'sname' array */
+                        r = option_append(message->sname, sizeof(message->sname), &sname_offset, code, optlen, optval);
+                        if (r >= 0) {
+                                *offset = size + (file ? sizeof(message->file) : 0) + sname_offset;
+                                return 0;
+                        } else {
+                                /* no space, or other error, give up */
+                                return r;
+                        }
+                }
+        }
+
+        return -ENOBUFS;
+}
+
 static int parse_options(const uint8_t options[], size_t buflen, uint8_t *overload,
                          uint8_t *message_type, dhcp_option_cb_t cb,
                          void *user_data) {
diff --git a/src/libsystemd-network/dhcp-packet.c b/src/libsystemd-network/dhcp-packet.c
index 10b645759e..3e2fb96c27 100644
--- a/src/libsystemd-network/dhcp-packet.c
+++ b/src/libsystemd-network/dhcp-packet.c
@@ -38,7 +38,7 @@
 #define DHCP_CLIENT_MIN_OPTIONS_SIZE            312
 
 int dhcp_message_init(DHCPMessage *message, uint8_t op, uint32_t xid,
-                      uint8_t type, uint8_t options[], size_t optlen, size_t *optoffset) {
+                      uint8_t type, size_t optlen, size_t *optoffset) {
         size_t offset = 0;
         int r;
 
@@ -50,8 +50,8 @@ int dhcp_message_init(DHCPMessage *message, uint8_t op, uint32_t xid,
         message->xid = htobe32(xid);
         message->magic = htobe32(DHCP_MAGIC_COOKIE);
 
-        r = dhcp_option_append(message->options, optlen, &offset,
-                                 DHCP_OPTION_MESSAGE_TYPE, 1, &type);
+        r = dhcp_option_append(message, optlen, &offset, 0,
+                               DHCP_OPTION_MESSAGE_TYPE, 1, &type);
         if (r < 0)
                 return r;
 
diff --git a/src/libsystemd-network/sd-dhcp-client.c b/src/libsystemd-network/sd-dhcp-client.c
index cee4ccf784..ac97e00772 100644
--- a/src/libsystemd-network/sd-dhcp-client.c
+++ b/src/libsystemd-network/sd-dhcp-client.c
@@ -268,7 +268,7 @@ static int client_message_init(sd_dhcp_client *client, DHCPMessage *message,
         assert(type == DHCP_DISCOVER || type == DHCP_REQUEST);
 
         r = dhcp_message_init(message, BOOTREQUEST, client->xid, type,
-                              message->options, optlen, optoffset);
+                              optlen, optoffset);
         if (r < 0)
                 return r;
 
@@ -284,7 +284,7 @@ static int client_message_init(sd_dhcp_client *client, DHCPMessage *message,
 
         /* Some DHCP servers will refuse to issue an DHCP lease if the Client
            Identifier option is not set */
-        r = dhcp_option_append(message->options, optlen, optoffset,
+        r = dhcp_option_append(message, optlen, optoffset, 0,
                                DHCP_OPTION_CLIENT_IDENTIFIER,
                                sizeof(client->client_id), &client->client_id);
         if (r < 0)
@@ -299,7 +299,7 @@ static int client_message_init(sd_dhcp_client *client, DHCPMessage *message,
            it MUST include that list in any subsequent DHCPREQUEST
            messages.
          */
-        r = dhcp_option_append(message->options, optlen, optoffset,
+        r = dhcp_option_append(message, optlen, optoffset, 0,
                                DHCP_OPTION_PARAMETER_REQUEST_LIST,
                                client->req_opts_size, client->req_opts);
         if (r < 0)
@@ -315,7 +315,7 @@ static int client_message_init(sd_dhcp_client *client, DHCPMessage *message,
          */
         max_size = htobe16(DHCP_IP_UDP_SIZE + DHCP_MESSAGE_SIZE +
                            DHCP_MIN_OPTIONS_SIZE);
-        r = dhcp_option_append(message->options, optlen, optoffset,
+        r = dhcp_option_append(message, optlen, optoffset, 0,
                                DHCP_OPTION_MAXIMUM_MESSAGE_SIZE,
                                2, &max_size);
         if (r < 0)
@@ -373,14 +373,14 @@ static int client_send_discover(sd_dhcp_client *client) {
            option to suggest the lease time it would like.
          */
         if (client->last_addr != INADDR_ANY) {
-                r = dhcp_option_append(discover->dhcp.options, optlen, &optoffset,
+                r = dhcp_option_append(&discover->dhcp, optlen, &optoffset, 0,
                                        DHCP_OPTION_REQUESTED_IP_ADDRESS,
                                        4, &client->last_addr);
                 if (r < 0)
                         return r;
         }
 
-        r = dhcp_option_append(discover->dhcp.options, optlen, &optoffset,
+        r = dhcp_option_append(&discover->dhcp, optlen, &optoffset, 0,
                                DHCP_OPTION_END, 0, NULL);
 
         /* We currently ignore:
@@ -424,13 +424,13 @@ static int client_send_request(sd_dhcp_client *client) {
                    filled in with the yiaddr value from the chosen DHCPOFFER.
                  */
 
-                r = dhcp_option_append(request->dhcp.options, optlen, &optoffset,
+                r = dhcp_option_append(&request->dhcp, optlen, &optoffset, 0,
                                        DHCP_OPTION_SERVER_IDENTIFIER,
                                        4, &client->lease->server_address);
                 if (r < 0)
                         return r;
 
-                r = dhcp_option_append(request->dhcp.options, optlen, &optoffset,
+                r = dhcp_option_append(&request->dhcp, optlen, &optoffset, 0,
                                        DHCP_OPTION_REQUESTED_IP_ADDRESS,
                                        4, &client->lease->address);
                 if (r < 0)
@@ -443,7 +443,7 @@ static int client_send_request(sd_dhcp_client *client) {
                    option MUST be filled in with client’s notion of its previously
                    assigned address. ’ciaddr’ MUST be zero.
                  */
-                r = dhcp_option_append(request->dhcp.options, optlen, &optoffset,
+                r = dhcp_option_append(&request->dhcp, optlen, &optoffset, 0,
                                        DHCP_OPTION_REQUESTED_IP_ADDRESS,
                                        4, &client->last_addr);
                 if (r < 0)
@@ -476,7 +476,7 @@ static int client_send_request(sd_dhcp_client *client) {
                 return -EINVAL;
         }
 
-        r = dhcp_option_append(request->dhcp.options, optlen, &optoffset,
+        r = dhcp_option_append(&request->dhcp, optlen, &optoffset, 0,
                                DHCP_OPTION_END, 0, NULL);
         if (r < 0)
                 return r;
diff --git a/src/libsystemd-network/test-dhcp-option.c b/src/libsystemd-network/test-dhcp-option.c
index 3dd7102d82..4482a6783c 100644
--- a/src/libsystemd-network/test-dhcp-option.c
+++ b/src/libsystemd-network/test-dhcp-option.c
@@ -92,7 +92,7 @@ static void test_message_init(void)
         message = malloc0(len);
 
         assert_se(dhcp_message_init(message, BOOTREQUEST, 0x12345678,
-                  DHCP_DISCOVER, message->options, optlen, &optoffset) >= 0);
+                  DHCP_DISCOVER, optlen, &optoffset) >= 0);
 
         assert_se(message->xid == htobe32(0x12345678));
         assert_se(message->op == BOOTREQUEST);
@@ -287,10 +287,6 @@ static void test_options(struct option_desc *desc)
                 printf("DHCP type %s\n", dhcp_type(res));
 }
 
-static uint8_t result[64] = {
-        'A', 'B', 'C', 'D',
-};
-
 static uint8_t options[64] = {
         'A', 'B', 'C', 'D',
         160, 2, 0x11, 0x12,
@@ -304,24 +300,34 @@ static uint8_t options[64] = {
 
 static void test_option_set(void)
 {
+        DHCPMessage *result;
         size_t offset = 0, len, pos;
         unsigned i;
 
-        assert_se(dhcp_option_append(result, 0, &offset, DHCP_OPTION_PAD,
-                                  0, NULL) == -ENOBUFS);
+        result = malloc0(sizeof(DHCPMessage) + 11);
+        assert_se(result);
+
+        result->options[0] = 'A';
+        result->options[1] = 'B';
+        result->options[2] = 'C';
+        result->options[3] = 'D';
+
+        assert_se(dhcp_option_append(result, 0, &offset, 0, DHCP_OPTION_PAD,
+                                     0, NULL) == -ENOBUFS);
         assert_se(offset == 0);
 
         offset = 4;
-        assert_se(dhcp_option_append(result, 1, &offset, DHCP_OPTION_PAD,
-                                    0, NULL) >= 0);
+        assert_se(dhcp_option_append(result, 5, &offset, 0, DHCP_OPTION_PAD,
+                                     0, NULL) == -ENOBUFS);
+        assert_se(offset == 4);
+        assert_se(dhcp_option_append(result, 6, &offset, 0, DHCP_OPTION_PAD,
+                                     0, NULL) >= 0);
         assert_se(offset == 5);
 
         offset = pos = 4;
-        len = 60;
-        while (pos < 64 && options[pos] != DHCP_OPTION_END) {
-                offset = pos;
-
-                assert_se(dhcp_option_append(result, len, &offset,
+        len = 11;
+        while (pos < len && options[pos] != DHCP_OPTION_END) {
+                assert_se(dhcp_option_append(result, len, &offset, DHCP_OVERLOAD_SNAME,
                                              options[pos],
                                              options[pos + 1],
                                              &options[pos + 2]) >= 0);
@@ -331,14 +337,34 @@ static void test_option_set(void)
                 else
                         pos += 2 + options[pos + 1];
 
-                assert_se(offset == pos);
+                if (pos < len)
+                        assert_se(offset == pos);
         }
 
-        for (i = 0; i < pos; i++) {
+        for (i = 0; i < 9; i++) {
                 if (verbose)
-                        printf("%2d: 0x%02x(0x%02x)\n", i, result[i],
+                        printf("%2d: 0x%02x(0x%02x) (options)\n", i, result->options[i],
                                options[i]);
-                assert_se(result[i] == options[i]);
+                assert_se(result->options[i] == options[i]);
+        }
+
+        if (verbose)
+                printf("%2d: 0x%02x(0x%02x) (options)\n", 9, result->options[9],
+                       DHCP_OPTION_END);
+
+        assert_se(result->options[9] == DHCP_OPTION_END);
+
+        if (verbose)
+                printf("%2d: 0x%02x(0x%02x) (options)\n", 10, result->options[10],
+                       DHCP_OPTION_PAD);
+
+        assert_se(result->options[10] == DHCP_OPTION_PAD);
+
+        for (i = 0; i < pos - 8; i++) {
+                if (verbose)
+                        printf("%2d: 0x%02x(0x%02x) (sname)\n", i, result->sname[i],
+                               options[i + 9]);
+                assert_se(result->sname[i] == options[i + 9]);
         }
 
         if (verbose)