gcoap/fileserver: implement PUT/POST/DELETE functionality

dist/tools/doccheck/exclude_patterns

@@ -14281,6 +14281,8 @@ sys/include/net/coap\.h:[0-9]+: warning: Member COAP_OPT_BLOCK1 \(macro definiti
 sys/include/net/coap\.h:[0-9]+: warning: Member COAP_OPT_BLOCK2 \(macro definition\) of group net_coap is not documented\.
 sys/include/net/coap\.h:[0-9]+: warning: Member COAP_OPT_CONTENT_FORMAT \(macro definition\) of group net_coap is not documented\.
 sys/include/net/coap\.h:[0-9]+: warning: Member COAP_OPT_ETAG \(macro definition\) of group net_coap is not documented\.
+sys/include/net/coap\.h:[0-9]+: warning: Member COAP_OPT_IF_MATCH \(macro definition\) of group net_coap is not documented\.
+sys/include/net/coap\.h:[0-9]+: warning: Member COAP_OPT_IF_NONE_MATCH \(macro definition\) of group net_coap is not documented\.
 sys/include/net/coap\.h:[0-9]+: warning: Member COAP_OPT_MAX_AGE \(macro definition\) of group net_coap is not documented\.
 sys/include/net/coap\.h:[0-9]+: warning: Member COAP_OPT_LOCATION_PATH \(macro definition\) of group net_coap is not documented\.
 sys/include/net/coap\.h:[0-9]+: warning: Member COAP_OPT_LOCATION_QUERY \(macro definition\) of group net_coap is not documented\.

examples/gcoap_fileserver/main.c

@@ -27,7 +27,8 @@ static msg_t _main_msg_queue[MAIN_QUEUE_SIZE];
 
 /* CoAP resources. Must be sorted by path (ASCII order). */
 static const coap_resource_t _resources[] = {
-    { "/vfs", COAP_GET | COAP_MATCH_SUBTREE, gcoap_fileserver_handler, VFS_DEFAULT_DATA },
+    { "/vfs", COAP_GET | COAP_PUT | COAP_DELETE | COAP_MATCH_SUBTREE,
+      gcoap_fileserver_handler, VFS_DEFAULT_DATA },
 };
 
 static gcoap_listener_t _listener = {

sys/include/net/coap.h

@@ -35,8 +35,10 @@ extern "C" {
  * @name    CoAP option numbers
  * @{
  */
+#define COAP_OPT_IF_MATCH       (1)
 #define COAP_OPT_URI_HOST       (3)
 #define COAP_OPT_ETAG           (4)
+#define COAP_OPT_IF_NONE_MATCH  (5)
 #define COAP_OPT_OBSERVE        (6)
 #define COAP_OPT_LOCATION_PATH  (8)
 #define COAP_OPT_URI_PATH       (11)

sys/net/application_layer/gcoap/fileserver.c

@@ -32,14 +32,27 @@
 /** Maximum length of an expressible path, including the trailing 0 character. */
 #define COAPFILESERVER_PATH_MAX (64)
 
+/**
+ * @brief   Structure holding information about present options in a request
+ */
+struct requestoptions {
+    uint32_t etag;                  /**< Etag value in an Etag option */
+    uint32_t if_match;              /**< Etag value in an If-Match option */
+    char if_match_len;              /**< Length of the Etag in an If-Match option */
+    struct {
+        bool if_match        :1;    /**< Request carries an If-Match option */
+        bool if_none_match   :1;    /**< Request carries an If-None-Match option */
+        bool etag            :1;    /**< Request carries an Etag option */
+        bool block2          :1;    /**< Request carries a Block2 option */
+        bool block1          :1;    /**< Request carries a Block1 option */
+    } exists;                       /**< Structure holding flags of present request options */
+};
+
 /** Data extracted from a request on a file */
 struct requestdata {
     /** 0-terminated expanded file name in the VFS */
     char namebuf[COAPFILESERVER_PATH_MAX];
-    uint32_t blocknum2;
-    uint32_t etag;
-    bool etag_sent;
-    uint8_t szx2;
+    struct requestoptions options;
 };
 
 /**
@@ -84,69 +97,75 @@ static unsigned _count_char(const char *s, char c)
 /** Build an ETag based on the given file's VFS stat. If the stat fails,
  * returns the error and leaves etag in any state; otherwise there's an etag
  * in the stattag's field */
-static int stat_etag(const char *filename, uint32_t *etag)
+static void stat_etag(struct stat *stat, uint32_t *etag)
 {
-    struct stat stat;
-    int err = vfs_stat(filename, &stat);
-    if (err < 0) {
-        return err;
-    }
-
     /* Normalizing fields whose value can change without affecting the ETag */
-    stat.st_nlink = 0;
+    stat->st_nlink = 0;
 #if defined(CPU_ESP32) || defined(CPU_ESP8266) || defined(CPU_MIPS_PIC32MX) || defined(CPU_MIPS_PIC32MZ)
-    memset(&stat.st_atime, 0, sizeof(stat.st_atime));
+    memset(&stat->st_atime, 0, sizeof(stat->st_atime));
 #else
-    memset(&stat.st_atim, 0, sizeof(stat.st_atim));
+    memset(&stat->st_atim, 0, sizeof(stat->st_atim));
 #endif
-
-    *etag = fletcher32((void *)&stat, sizeof(stat) / 2);
-
-    return 0;
+    *etag = fletcher32((void *)stat, sizeof(*stat) / 2);
 }
 
 /** Create a CoAP response for a given errno (eg. EACCESS -> 4.03 Forbidden
- * etc., defaulting to 5.03 Internal Server Error) */
-static size_t gcoap_fileserver_errno_handler(coap_pkt_t *pdu, uint8_t *buf, size_t len, int err)
+ * etc., defaulting to 5.03 Internal Server Error), or interpret a positive
+ * value for err as a CoAP response code */
+static size_t gcoap_fileserver_error_handler(coap_pkt_t *pdu, uint8_t *buf, size_t len, int err)
 {
-    uint8_t code;
-    switch (err) {
-    case -EACCES:
-        code = COAP_CODE_FORBIDDEN;
-        break;
-    case -ENOENT:
-        code = COAP_CODE_PATH_NOT_FOUND;
-        break;
-    default:
-        code = COAP_CODE_INTERNAL_SERVER_ERROR;
-    };
-    DEBUG("gcoap_fileserver: Rejecting error %d (%s) as %d.%02d\n", err, strerror(err),
-          code >> 5, code & 0x1f);
+    uint8_t code = err;
+    if (err < 0) {
+        switch (err) {
+            case -EACCES:
+                code = COAP_CODE_FORBIDDEN;
+                break;
+            case -ENOENT:
+                code = COAP_CODE_PATH_NOT_FOUND;
+                break;
+            default:
+                code = COAP_CODE_INTERNAL_SERVER_ERROR;
+        };
+        DEBUG("gcoap_fileserver: Rejecting error %d (%s) as %d.%02d\n", err, strerror(err),
+              code >> 5, code & 0x1f);
+    }
     return gcoap_response(pdu, buf, len, code);
 }
 
-static void _calc_szx2(coap_pkt_t *pdu, size_t reserve, struct requestdata *request)
+static void _calc_szx2(coap_pkt_t *pdu, size_t reserve, coap_block1_t *block2)
 {
     assert(pdu->payload_len > reserve);
     size_t remaining_length = pdu->payload_len - reserve;
     /* > 0: To not wrap around; if that still won't fit that's later caught in
      * an assertion */
-    while ((coap_szx2size(request->szx2) > remaining_length) && (request->szx2 > 0)) {
-        request->szx2--;
-        request->blocknum2 <<= 1;
+    while ((coap_szx2size(block2->szx) > remaining_length) && (block2->szx > 0)) {
+        block2->szx--;
+        block2->blknum <<= 1;
     }
 }
 
-static ssize_t gcoap_fileserver_file_handler(coap_pkt_t *pdu, uint8_t *buf, size_t len,
-                                             struct requestdata *request)
+static ssize_t _get_file(coap_pkt_t *pdu, uint8_t *buf, size_t len,
+                         struct requestdata *request)
 {
+    int err;
     uint32_t etag;
-    int err = stat_etag(request->namebuf, &etag);
-    if (err < 0) {
-        return gcoap_fileserver_errno_handler(pdu, buf, len, err);
+    coap_block1_t block2 = { .szx = CONFIG_NANOCOAP_BLOCK_SIZE_EXP_MAX };
+    {
+        struct stat stat;
+        if ((err = vfs_stat(request->namebuf, &stat)) < 0) {
+            return gcoap_fileserver_error_handler(pdu, buf, len, err);
+        }
+        stat_etag(&stat, &etag);
     }
-
-    if (request->etag_sent && etag == request->etag) {
+    if (request->options.exists.block2 && !coap_get_block2(pdu, &block2)) {
+        return gcoap_fileserver_error_handler(pdu, buf, len, COAP_CODE_BAD_OPTION);
+    }
+    if (request->options.exists.if_match &&
+        memcmp(&etag, &request->options.if_match, request->options.if_match_len)) {
+        return gcoap_fileserver_error_handler(pdu, buf, len, COAP_CODE_PRECONDITION_FAILED);
+    }
+    if (request->options.exists.etag &&
+        !memcmp(&etag, &request->options.etag, sizeof(etag))) {
         gcoap_resp_init(pdu, buf, len, COAP_CODE_VALID);
         coap_opt_add_opaque(pdu, COAP_OPT_ETAG, &etag, sizeof(etag));
         return coap_opt_finish(pdu, COAP_OPT_FINISH_NONE);
@@ -154,7 +173,7 @@ static ssize_t gcoap_fileserver_file_handler(coap_pkt_t *pdu, uint8_t *buf, size
 
     int fd = vfs_open(request->namebuf, O_RDONLY, 0);
     if (fd < 0) {
-        return gcoap_fileserver_errno_handler(pdu, buf, len, fd);
+        return gcoap_fileserver_error_handler(pdu, buf, len, fd);
     }
 
     gcoap_resp_init(pdu, buf, len, COAP_CODE_CONTENT);
@@ -162,8 +181,8 @@ static ssize_t gcoap_fileserver_file_handler(coap_pkt_t *pdu, uint8_t *buf, size
     coap_block_slicer_t slicer;
     _calc_szx2(pdu,
                5 + 1 + 1 /* reserve BLOCK2 size + payload marker + more */,
-               request);
-    coap_block_slicer_init(&slicer, request->blocknum2, coap_szx2size(request->szx2));
+               &block2);
+    coap_block_slicer_init(&slicer, block2.blknum, coap_szx2size(block2.szx));
     coap_opt_add_block2(pdu, &slicer, true);
     size_t resp_len = coap_opt_finish(pdu, COAP_OPT_FINISH_PAYLOAD);
 
@@ -205,16 +224,162 @@ late_err:
     return coap_get_total_hdr_len(pdu);
 }
 
-static ssize_t gcoap_fileserver_directory_handler(coap_pkt_t *pdu, uint8_t *buf, size_t len,
-                                                  struct requestdata *request,
-                                                  const char *root, const char* resource_dir)
+static ssize_t _put_file(coap_pkt_t *pdu, uint8_t *buf, size_t len,
+                         struct requestdata *request)
 {
+    int ret, fd;
+    uint32_t etag;
+    struct stat stat;
+    coap_block1_t block1 = {0};
+    bool create = (vfs_stat(request->namebuf, &stat) == -ENOENT);
+    if (create) {
+        /* While a file 'f' is initially being created,
+           we save the partial content in '.f' and rename it afterwards */
+        if (!(ret = strlen(request->namebuf)) || (unsigned)ret >= sizeof(request->namebuf) - 1) {
+            /* need one more char '.' */
+            return gcoap_fileserver_error_handler(pdu, buf, len, -ENOBUFS);
+        }
+        char *file = strrchr(request->namebuf, '/');
+        memmove(file + 2, file + 1, strlen(file + 1));
+        *(file + 1) = '.';
+    }
+    if (request->options.exists.block1 && !coap_get_block1(pdu, &block1)) {
+        ret = COAP_CODE_BAD_OPTION;
+        goto unlink_on_error;
+    }
+    if (block1.blknum == 0) {
+        /* "If-None-Match only works correctly on Block1 requests with (NUM=0)
+           and MUST NOT be used on Block1 requests with NUM != 0." */
+        if (request->options.exists.if_none_match && !create) {
+            ret = COAP_CODE_PRECONDITION_FAILED;
+            goto unlink_on_error;
+        }
+    }
+    if (request->options.exists.if_match) {
+        stat_etag(&stat, &etag); /* Etag before write */
+        if (create || memcmp(&etag, &request->options.if_match, request->options.if_match_len)) {
+            ret = COAP_CODE_PRECONDITION_FAILED;
+            goto unlink_on_error;
+        }
+    }
+    ret = O_WRONLY;
+    ret |= (create ? O_CREAT | O_APPEND : 0);
+    if ((fd = vfs_open(request->namebuf, ret, 0)) < 0) {
+        ret = fd;
+        goto unlink_on_error;
+    }
+    if (create) {
+        if ((ret = vfs_lseek(fd, 0, SEEK_END)) < 0) {
+            goto close_on_error;
+        }
+        if (block1.offset != (unsigned)ret) {
+            /* expect block to be in the correct order during initial creation */
+            ret = COAP_CODE_REQUEST_ENTITY_INCOMPLETE;
+            goto close_on_error;
+        }
+    }
+    else {
+        if (block1.offset > (unsigned)stat.st_size) {
+            /* after initial file creation, random access is fine,
+                as long as it does not result in holes in the file */
+            ret = COAP_CODE_REQUEST_ENTITY_INCOMPLETE;
+            goto close_on_error;
+        }
+        if ((ret = vfs_lseek(fd, block1.offset, SEEK_SET)) < 0) {
+            goto close_on_error;
+        }
+    }
+    if ((ret = vfs_write(fd, pdu->payload, pdu->payload_len)) < 0 ||
+        (unsigned)ret != pdu->payload_len) {
+        goto close_on_error;
+    }
+    vfs_close(fd);
+    if (!block1.more) {
+        if ((ret = vfs_stat(request->namebuf, &stat)) < 0) {
+            goto unlink_on_error;
+        }
+        if (create) {
+            char path[COAPFILESERVER_PATH_MAX];
+            strcpy(path, request->namebuf);
+            char *file = strrchr(path, '/');
+            memmove(file + 1, file + 2, strlen(file + 2) + 1);
+            if ((ret = vfs_rename(request->namebuf, path)) < 0) {
+                goto unlink_on_error;
+            }
+        }
+        stat_etag(&stat, &etag); /* Etag after write */
+        gcoap_resp_init(pdu, buf, len, create ? COAP_CODE_CREATED : COAP_CODE_CHANGED);
+        coap_opt_add_opaque(pdu, COAP_OPT_ETAG, &etag, sizeof(etag));
+    }
+    else {
+        gcoap_resp_init(pdu, buf, len, COAP_CODE_CONTINUE);
+        block1.more = true; /* resource is created atomically */
+        coap_opt_add_block1_control(pdu, &block1);
+    }
+    return coap_opt_finish(pdu, COAP_OPT_FINISH_NONE);
+
+close_on_error:
+    vfs_close(fd);
+unlink_on_error:
+    if (create) {
+        vfs_unlink(request->namebuf);
+    }
+    return gcoap_fileserver_error_handler(pdu, buf, len, ret);
+}
+
+static ssize_t _delete_file(coap_pkt_t *pdu, uint8_t *buf, size_t len,
+                            struct requestdata *request)
+{
+    int ret;
+    uint32_t etag;
+    struct stat stat;
+    if ((ret = vfs_stat(request->namebuf, &stat)) < 0) {
+        return gcoap_fileserver_error_handler(pdu, buf, len, ret);
+    }
+    if (request->options.exists.if_match && request->options.if_match_len) {
+        stat_etag(&stat, &etag);
+        if (memcmp(&etag, &request->options.if_match, request->options.if_match_len)) {
+            return gcoap_fileserver_error_handler(pdu, buf, len, COAP_CODE_PRECONDITION_FAILED);
+        }
+    }
+    if ((ret = vfs_unlink(request->namebuf)) < 0) {
+        return gcoap_fileserver_error_handler(pdu, buf, len, ret);
+    }
+    gcoap_resp_init(pdu, buf, len, COAP_CODE_DELETED);
+    return coap_opt_finish(pdu, COAP_OPT_FINISH_NONE);
+}
+
+static ssize_t gcoap_fileserver_file_handler(coap_pkt_t *pdu, uint8_t *buf, size_t len,
+                                             struct requestdata *request)
+{
+    switch (coap_get_code(pdu)) {
+        case COAP_METHOD_GET:
+            return _get_file(pdu, buf, len, request);
+        case COAP_METHOD_PUT:
+            return _put_file(pdu, buf, len, request);
+        case COAP_METHOD_DELETE:
+            return _delete_file(pdu, buf, len, request);
+        default:
+            return gcoap_fileserver_error_handler(pdu, buf, len, COAP_CODE_METHOD_NOT_ALLOWED);
+    }
+}
+
+static ssize_t _get_directory(coap_pkt_t *pdu, uint8_t *buf, size_t len,
+                              struct requestdata *request,
+                              const char *root, const char* resource_dir)
+{
+    int err;
     vfs_DIR dir;
     coap_block_slicer_t slicer;
-
-    int err = vfs_opendir(&dir, request->namebuf);
-    if (err != 0) {
-        return gcoap_fileserver_errno_handler(pdu, buf, len, err);
+    coap_block1_t block2 = { .szx = CONFIG_NANOCOAP_BLOCK_SIZE_EXP_MAX };
+    if (request->options.exists.block2 && !coap_get_block2(pdu, &block2)) {
+        return gcoap_fileserver_error_handler(pdu, buf, len, COAP_OPT_FINISH_NONE);
+    }
+    if ((err = vfs_opendir(&dir, request->namebuf)) < 0) {
+        return gcoap_fileserver_error_handler(pdu, buf, len, err);
+    }
+    if (request->options.exists.if_match && request->options.if_match_len) {
+        return gcoap_fileserver_error_handler(pdu, buf, len, COAP_CODE_PRECONDITION_FAILED);
     }
     DEBUG("gcoap_fileserver: Serving directory listing\n");
 
@@ -222,8 +387,8 @@ static ssize_t gcoap_fileserver_directory_handler(coap_pkt_t *pdu, uint8_t *buf,
     coap_opt_add_format(pdu, COAP_FORMAT_LINK);
     _calc_szx2(pdu,
                5 + 1 /* reserve BLOCK2 size + payload marker */,
-               request);
-    coap_block_slicer_init(&slicer, request->blocknum2, coap_szx2size(request->szx2));
+               &block2);
+    coap_block_slicer_init(&slicer, block2.blknum, coap_szx2size(block2.szx));
     coap_opt_add_block2(pdu, &slicer, true);
     buf += coap_opt_finish(pdu, COAP_OPT_FINISH_PAYLOAD);
 
@@ -236,8 +401,8 @@ static ssize_t gcoap_fileserver_directory_handler(coap_pkt_t *pdu, uint8_t *buf,
     while (vfs_readdir(&dir, &entry) > 0) {
         const char *entry_name = entry.d_name;
         size_t entry_len = strlen(entry_name);
-        if (entry_len <= 2 && memcmp(entry_name, "..", entry_len) == 0) {
-            /* Up pointers don't work the same way in URI semantics */
+        if (*entry_name == '.') {
+            /* Exclude everything that starts with '.' */
             continue;
         }
         bool is_dir = entry_is_dir(request->namebuf, entry_name);
@@ -246,7 +411,6 @@ static ssize_t gcoap_fileserver_directory_handler(coap_pkt_t *pdu, uint8_t *buf,
             buf += coap_blockwise_put_char(&slicer, buf, ',');
         }
         buf += coap_blockwise_put_char(&slicer, buf, '<');
-
         buf += coap_blockwise_put_bytes(&slicer, buf, resource_dir, resource_dir_len);
         buf += coap_blockwise_put_bytes(&slicer, buf, root_dir, root_dir_len);
         buf += coap_blockwise_put_char(&slicer, buf, '/');
@@ -263,15 +427,65 @@ static ssize_t gcoap_fileserver_directory_handler(coap_pkt_t *pdu, uint8_t *buf,
     return (uintptr_t)buf - (uintptr_t)pdu->hdr;
 }
 
+static ssize_t _put_directory(coap_pkt_t *pdu, uint8_t *buf, size_t len,
+                              struct requestdata *request)
+{
+    int err;
+    vfs_DIR dir;
+    if ((err = vfs_opendir(&dir, request->namebuf)) == 0) {
+        vfs_closedir(&dir);
+        if (request->options.exists.if_match && request->options.if_match_len) {
+            return gcoap_fileserver_error_handler(pdu, buf, len, COAP_CODE_PRECONDITION_FAILED);
+        }
+        gcoap_resp_init(pdu, buf, len, COAP_CODE_CHANGED);
+    }
+    else {
+        if (request->options.exists.if_match) {
+            return gcoap_fileserver_error_handler(pdu, buf, len, COAP_CODE_PRECONDITION_FAILED);
+        }
+        if ((err = vfs_mkdir(request->namebuf, 0)) < 0) {
+            return gcoap_fileserver_error_handler(pdu, buf, len, err);
+        }
+        gcoap_resp_init(pdu, buf, len, COAP_CODE_CREATED);
+    }
+    return coap_opt_finish(pdu, COAP_OPT_FINISH_NONE);
+}
+
+static ssize_t _delete_directory(coap_pkt_t *pdu, uint8_t *buf, size_t len,
+                                 struct requestdata *request)
+{
+    int err;
+    if (request->options.exists.if_match && request->options.if_match_len) {
+        return gcoap_fileserver_error_handler(pdu, buf, len, COAP_CODE_PRECONDITION_FAILED);
+    }
+    if ((err = vfs_rmdir(request->namebuf)) < 0) {
+        return gcoap_fileserver_error_handler(pdu, buf, len, err);
+    }
+    gcoap_resp_init(pdu, buf, len, COAP_CODE_DELETED);
+    return coap_opt_finish(pdu, COAP_OPT_FINISH_NONE);
+}
+
+static ssize_t gcoap_fileserver_directory_handler(coap_pkt_t *pdu, uint8_t *buf, size_t len,
+                                                  struct requestdata *request,
+                                                  const char *root, const char* resource_dir)
+{
+    switch (coap_get_code(pdu)) {
+        case COAP_METHOD_GET:
+            return _get_directory(pdu, buf, len, request, root, resource_dir);
+        case COAP_METHOD_PUT:
+            return _put_directory(pdu, buf, len, request);
+        case COAP_METHOD_DELETE:
+            return _delete_directory(pdu, buf, len, request);
+        default:
+            return gcoap_fileserver_error_handler(pdu, buf, len, COAP_CODE_METHOD_NOT_ALLOWED);
+    }
+}
+
 ssize_t gcoap_fileserver_handler(coap_pkt_t *pdu, uint8_t *buf, size_t len,
                                  coap_request_ctx_t *ctx) {
     const char *root = coap_request_ctx_get_context(ctx);
     const char *resource = coap_request_ctx_get_path(ctx);
-    struct requestdata request = {
-        .etag_sent = false,
-        .blocknum2 = 0,
-        .szx2 = CONFIG_NANOCOAP_BLOCK_SIZE_EXP_MAX,
-    };
+    struct requestdata request = {0};
 
     /** Index in request.namebuf. Must not point at the last entry as that will be
      * zeroed to get a 0-terminated string. */
@@ -284,75 +498,108 @@ ssize_t gcoap_fileserver_handler(coap_pkt_t *pdu, uint8_t *buf, size_t len,
         strncpy(request.namebuf, root, sizeof(request.namebuf));
         namelength = strlen(root);
     }
-
     bool is_directory = true; /* either no path component at all or trailing '/' */
-    coap_optpos_t opt = {
-        .offset = coap_get_total_hdr_len(pdu),
-    };
-    uint8_t *value;
-    ssize_t optlen;
-    while ((optlen = coap_opt_get_next(pdu, &opt, &value, 0)) != -ENOENT) {
-
-        if (optlen < 0) {
-            errorcode = COAP_CODE_BAD_REQUEST;
+    {
+        coap_optpos_t opt = { .offset = coap_get_total_hdr_len(pdu) };
+        uint8_t *value;
+        ssize_t optlen;
+        while ((optlen = coap_opt_get_next(pdu, &opt, &value, 0)) != -ENOENT) {
+            if (optlen < 0) {
+                errorcode = COAP_CODE_BAD_REQUEST;
+                goto error;
+            }
+            switch (opt.opt_num) {
+                case COAP_OPT_IF_MATCH:
+                    /* support only one if-match option, although it is repeatable */
+                    if (request.options.exists.if_match) {
+                        errorcode = COAP_CODE_NOT_IMPLEMENTED;
+                        goto error;
+                    }
+                    if (optlen > 8) {
+                        errorcode = COAP_CODE_BAD_OPTION;
+                        goto error;
+                    }
+                    if (optlen && optlen != sizeof(request.options.if_match)) {
+                        errorcode = COAP_CODE_PRECONDITION_FAILED;
+                        goto error;
+                    }
+                    memcpy(&request.options.if_match, value,
+                           request.options.if_match_len = optlen);
+                    request.options.exists.if_match = true;
+                    break;
+                case COAP_OPT_IF_NONE_MATCH:
+                    if (optlen || request.options.exists.if_none_match) {
+                        errorcode = COAP_CODE_BAD_OPTION;
+                        goto error;
+                    }
+                    request.options.exists.if_none_match = true;
+                    break;
+                case COAP_OPT_URI_PATH:
+                    if (strip_remaining != 0) {
+                        strip_remaining -= 1;
+                        continue;
+                    }
+                    if ((is_directory = (optlen == 0))) { /* '/' */
+                        continue;
+                    }
+                    if (memchr(value, '\0', optlen) != NULL ||
+                        memchr(value, '/', optlen) != NULL) {
+                        /* Path can not be expressed in the file system */
+                        errorcode = COAP_CODE_PATH_NOT_FOUND;
+                        goto error;
+                    }
+                    size_t newlength = namelength + 1 + optlen;
+                    if (newlength > sizeof(request.namebuf) - 1) {
+                        /* Path too long, therefore can't exist in this mapping */
+                        errorcode = COAP_CODE_PATH_NOT_FOUND;
+                        goto error;
+                    }
+                    request.namebuf[namelength] = '/';
+                    memcpy(&request.namebuf[namelength] + 1, value, optlen);
+                    namelength = newlength;
+                    break;
+                case COAP_OPT_ETAG:
+                    if (optlen != sizeof(request.options.etag)) {
+                        /* Can't be a matching tag, no use in carrying that */
+                        continue;
+                    }
+                    if (request.options.exists.etag) {
+                        /* We can reasonably only check for a limited sized set,
+                        * and it size is 1 here (sending multiple ETags is
+                        * possible but rare) */
+                        continue;
+                    }
+                    request.options.exists.etag = true;
+                    memcpy(&request.options.etag, value, sizeof(request.options.etag));
+                    break;
+                case COAP_OPT_BLOCK2:
+                    if (optlen > 4 || request.options.exists.block2) {
+                        errorcode = COAP_CODE_BAD_OPTION;
+                        goto error;
+                    }
+                    request.options.exists.block2 = true;
+                    break;
+                case COAP_OPT_BLOCK1:
+                    if (optlen > 4 || request.options.exists.block1) {
+                        errorcode = COAP_CODE_BAD_OPTION;
+                        goto error;
+                    }
+                    request.options.exists.block1 = true;
+                    break;
+                default:
+                    if (opt.opt_num & 1) {
+                        errorcode = COAP_CODE_BAD_OPTION;
+                        goto error;
+                    }
+                    break;
+            }
+        }
+        if (request.options.exists.if_match &&
+            request.options.exists.if_none_match) {
+            errorcode = COAP_CODE_PRECONDITION_FAILED;
             goto error;
         }
-
-        switch (opt.opt_num) {
-            case COAP_OPT_URI_PATH:
-                if (strip_remaining != 0) {
-                    strip_remaining -= 1;
-                    continue;
-                }
-                if ((is_directory = (optlen == 0))) { /* '/' */
-                    continue;
-                }
-                if (memchr(value, '\0', optlen) != NULL ||
-                    memchr(value, '/', optlen) != NULL) {
-                    /* Path can not be expressed in the file system */
-                    errorcode = COAP_CODE_PATH_NOT_FOUND;
-                    goto error;
-                }
-                size_t newlength = namelength + 1 + optlen;
-                if (newlength > sizeof(request.namebuf) - 1) {
-                    /* Path too long, therefore can't exist in this mapping */
-                    errorcode = COAP_CODE_PATH_NOT_FOUND;
-                    goto error;
-                }
-                request.namebuf[namelength] = '/';
-                memcpy(&request.namebuf[namelength] + 1, value, optlen);
-                namelength = newlength;
-                break;
-            case COAP_OPT_ETAG:
-                if (optlen != sizeof(request.etag)) {
-                    /* Can't be a matching tag, no use in carrying that */
-                    continue;
-                }
-                if (request.etag_sent) {
-                    /* We can reasonably only check for a limited sized set,
-                     * and it size is 1 here (sending multiple ETags is
-                     * possible but rare) */
-                    continue;
-                }
-                request.etag_sent = true;
-                memcpy(&request.etag, value, sizeof(request.etag));
-                break;
-            case COAP_OPT_BLOCK2:
-                /* Could be more efficient now that we already know where it
-                 * is, but meh */
-                coap_get_blockopt(pdu, COAP_OPT_BLOCK2, &request.blocknum2, &request.szx2);
-                break;
-            default:
-                if (opt.opt_num & 1) {
-                    errorcode = COAP_CODE_BAD_REQUEST;
-                    goto error;
-                }
-                else {
-                    /* Ignoring elective option */
-                }
-        }
     }
-
     request.namebuf[namelength] = '\0';
 
     DEBUG("request: '%s'\n", request.namebuf);
@@ -360,13 +607,9 @@ ssize_t gcoap_fileserver_handler(coap_pkt_t *pdu, uint8_t *buf, size_t len,
     /* Note to self: As we parse more options than just Uri-Path, we'll likely
      * pass a struct pointer later. So far, those could even be hooked into the
      * resource list, but that'll go away once we parse more options */
-    if (is_directory) {
-        return gcoap_fileserver_directory_handler(pdu, buf, len, &request, root, resource);
-    }
-    else {
-        return gcoap_fileserver_file_handler(pdu, buf, len, &request);
-    }
-
+    return is_directory
+        ? gcoap_fileserver_directory_handler(pdu, buf, len, &request, root, resource)
+        : gcoap_fileserver_file_handler(pdu, buf, len, &request);
 error:
     return gcoap_response(pdu, buf, len, errorcode);
 }