httpd: "HEAD" support. Closes bug 1530.

send_file_and_exit                                   629     645     +16
static.request_HEAD                                    -       5      +5
handle_incoming_and_exit                            2732    2737      +5
send_headers                                         594     597      +3
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 3/0 up/down: 29/0)               Total: 29 bytes
   text    data     bss     dec     hex filename
 796283     740    7484  804507   c469b busybox_old
 796312     740    7484  804536   c46b8 busybox_unstripped

1 files changed, 36 insertions, 26 deletions

diff --git a/networking/httpd.c b/networking/httpd.c
index bcd1126a6..5be53179f 100644
--- a/networking/httpd.c
+++ b/networking/httpd.c
@@ -340,7 +340,12 @@ enum {
 #define STRNCASECMP(a, str) strncasecmp((a), (str), sizeof(str)-1)
 
 /* Prototypes */
-static void send_file_and_exit(const char *url, int headers) ATTRIBUTE_NORETURN;
+enum {
+        SEND_HEADERS     = (1 << 0),
+        SEND_BODY        = (1 << 1),
+        SEND_HEADERS_AND_BODY = SEND_HEADERS + SEND_BODY,
+};
+static void send_file_and_exit(const char *url, int what) ATTRIBUTE_NORETURN;
 
 static void free_llist(has_next_ptr **pptr)
 {
@@ -957,7 +962,7 @@ static void send_headers(int responseNum)
         const char *infoString = NULL;
         const char *mime_type;
 #if ENABLE_FEATURE_HTTPD_ERROR_PAGES
-        const char *error_page = 0;
+        const char *error_page = NULL;
 #endif
         unsigned i;
         time_t timer = time(0);
@@ -1012,7 +1017,7 @@ static void send_headers(int responseNum)
                 full_write(1, iobuf, len);
                 if (DEBUG)
                         fprintf(stderr, "writing error page: '%s'\n", error_page);
-                return send_file_and_exit(error_page, FALSE);
+                return send_file_and_exit(error_page, SEND_BODY);
         }
 #endif
 
@@ -1480,10 +1485,10 @@ static void send_cgi_and_exit(
  * Send a file response to a HTTP request, and exit
  *
  * Parameters:
- * const char *url    The requested URL (with leading /).
- * headers            Don't send headers before if FALSE.
+ * const char *url  The requested URL (with leading /).
+ * what             What to send (headers/body/both).
  */
-static void send_file_and_exit(const char *url, int headers)
+static void send_file_and_exit(const char *url, int what)
 {
         static const char *const suffixTable[] = {
         /* Warning: shorter equivalent suffix in one line must be first */
@@ -1516,6 +1521,10 @@ static void send_file_and_exit(const char *url, int headers)
         off_t offset;
 #endif
 
+        /* If you want to know about EPIPE below
+         * (happens if you abort downloads from local httpd): */
+        signal(SIGPIPE, SIG_IGN);
+
         suffix = strrchr(url, '.');
 
         /* If not found, set default as "application/octet-stream";  */
@@ -1552,11 +1561,15 @@ static void send_file_and_exit(const char *url, int headers)
         if (f < 0) {
                 if (DEBUG)
                         bb_perror_msg("cannot open '%s'", url);
-                if (headers)
+                /* Error pages are sent by using send_file_and_exit(SEND_BODY).
+                 * IOW: it is unsafe to call send_headers_and_exit
+                 * if what is SEND_BODY! Can recurse! */
+                if (what != SEND_BODY)
                         send_headers_and_exit(HTTP_NOT_FOUND);
+                log_and_exit();
         }
 #if ENABLE_FEATURE_HTTPD_RANGES
-        if (!headers)
+        if (what == SEND_BODY)
                 range_start = 0; /* err pages and ranges don't mix */
         range_len = MAXINT(off_t);
         if (range_start) {
@@ -1571,18 +1584,14 @@ static void send_file_and_exit(const char *url, int headers)
                 } else {
                         range_len = range_end - range_start + 1;
                         send_headers(HTTP_PARTIAL_CONTENT);
-                        headers = 0;
+                        what = SEND_BODY;
                 }
         }
 #endif
 
-        if (headers)
+        if (what & SEND_HEADERS)
                 send_headers(HTTP_OK);
 
-        /* If you want to know about EPIPE below
-         * (happens if you abort downloads from local httpd): */
-        signal(SIGPIPE, SIG_IGN);
-
 #if ENABLE_FEATURE_HTTPD_USE_SENDFILE
         offset = range_start;
         do {
@@ -1756,13 +1765,13 @@ static void handle_incoming_and_exit(const len_and_sockaddr *fromAddr) ATTRIBUTE
 static void handle_incoming_and_exit(const len_and_sockaddr *fromAddr)
 {
         static const char request_GET[] ALIGN1 = "GET";
-
         struct stat sb;
         char *urlcopy;
         char *urlp;
         char *tptr;
         int ip_allowed;
 #if ENABLE_FEATURE_HTTPD_CGI
+        static const char request_HEAD[] ALIGN1 = "HEAD";
         const char *prequest;
         char *cookie = NULL;
         char *content_type = NULL;
@@ -1827,9 +1836,12 @@ static void handle_incoming_and_exit(const len_and_sockaddr *fromAddr)
 #if ENABLE_FEATURE_HTTPD_CGI
         prequest = request_GET;
         if (strcasecmp(iobuf, prequest) != 0) {
-                prequest = "POST";
-                if (strcasecmp(iobuf, prequest) != 0)
-                        send_headers_and_exit(HTTP_NOT_IMPLEMENTED);
+                prequest = request_HEAD;
+                if (strcasecmp(iobuf, prequest) != 0) {
+                        prequest = "POST";
+                        if (strcasecmp(iobuf, prequest) != 0)
+                                send_headers_and_exit(HTTP_NOT_IMPLEMENTED);
+                }
         }
 #else
         if (strcasecmp(iobuf, request_GET) != 0)
@@ -1964,17 +1976,14 @@ static void handle_incoming_and_exit(const len_and_sockaddr *fromAddr)
                         /* Try and do our best to parse more lines */
                         if ((STRNCASECMP(iobuf, "Content-length:") == 0)) {
                                 /* extra read only for POST */
-                                if (prequest != request_GET) {
+                                if (prequest != request_GET && prequest != request_HEAD) {
                                         tptr = iobuf + sizeof("Content-length:") - 1;
                                         if (!tptr[0])
                                                 send_headers_and_exit(HTTP_BAD_REQUEST);
-                                        errno = 0;
                                         /* not using strtoul: it ignores leading minus! */
-                                        length = strtol(tptr, &tptr, 10);
+                                        length = bb_strtou(tptr, NULL, 10);
                                         /* length is "ulong", but we need to pass it to int later */
-                                        /* so we check for negative or too large values in one go: */
-                                        /* (long -> ulong conv caused negatives to be seen as > INT_MAX) */
-                                        if (tptr[0] || errno || length > INT_MAX)
+                                        if (errno || length > INT_MAX)
                                                 send_headers_and_exit(HTTP_BAD_REQUEST);
                                 }
                         }
@@ -2096,7 +2105,7 @@ static void handle_incoming_and_exit(const len_and_sockaddr *fromAddr)
                 }
         }
 #endif
-        if (prequest != request_GET) {
+        if (prequest != request_GET && prequest != request_HEAD) {
                 send_headers_and_exit(HTTP_NOT_IMPLEMENTED);
         }
 #endif  /* FEATURE_HTTPD_CGI */
@@ -2123,7 +2132,8 @@ static void handle_incoming_and_exit(const len_and_sockaddr *fromAddr)
          * }
          */
 
-        send_file_and_exit(tptr, TRUE);
+        send_file_and_exit(tptr,
+                (prequest != request_HEAD ? SEND_HEADERS_AND_BODY : SEND_HEADERS));
 }
 
 /*