httpd: optional support for partial downloads

3 files changed, 128 insertions, 17 deletions

diff --git a/networking/Config.in b/networking/Config.in
index d687dbed9..030b1c0de 100644
--- a/networking/Config.in
+++ b/networking/Config.in
@@ -83,6 +83,15 @@ config HTTPD
         help
           Serve web pages via an HTTP server.
 
+config FEATURE_HTTPD_RANGES
+        bool "Support 'Ranges:' header"
+        default n
+        depends on HTTPD
+        help
+          Makes httpd emit "Accept-Ranges: bytes" header and understand
+          "Range: bytes=NNN-[MMM]" header. Allows for resuming interrupted
+          downloads, seeking in multimedia players etc.
+
 config FEATURE_HTTPD_USE_SENDFILE
         bool "Use sendfile system call"
         default n
diff --git a/networking/httpd.c b/networking/httpd.c
index a8e5df98c..057416040 100644
--- a/networking/httpd.c
+++ b/networking/httpd.c
@@ -138,6 +138,7 @@ typedef struct Htaccess_IP {
 
 enum {
         HTTP_OK = 200,
+        HTTP_PARTIAL_CONTENT = 206,
         HTTP_MOVED_TEMPORARILY = 302,
         HTTP_BAD_REQUEST = 400,       /* malformed syntax */
         HTTP_UNAUTHORIZED = 401, /* authentication needed, respond with auth hdr */
@@ -165,6 +166,9 @@ enum {
 
 static const uint16_t http_response_type[] ALIGN2 = {
         HTTP_OK,
+#if ENABLE_FEATURE_HTTPD_RANGES
+        HTTP_PARTIAL_CONTENT,
+#endif
         HTTP_MOVED_TEMPORARILY,
         HTTP_REQUEST_TIMEOUT,
         HTTP_NOT_IMPLEMENTED,
@@ -192,7 +196,10 @@ static const struct {
         const char *info;
 } http_response[ARRAY_SIZE(http_response_type)] = {
         { "OK", NULL },
-        { "Found", "Directories must end with a slash" }, /* ?? */
+#if ENABLE_FEATURE_HTTPD_RANGES
+        { "Partial Content", NULL },
+#endif
+        { "Found", NULL },
         { "Request Timeout", "No request appeared within 60 seconds" },
         { "Not Implemented", "The requested method is not recognized" },
 #if ENABLE_FEATURE_HTTPD_BASIC_AUTH
@@ -214,13 +221,13 @@ static const struct {
 #endif
 };
 
+
 struct globals {
         int verbose;            /* must be int (used by getopt32) */
         smallint flg_deny_all;
 
         unsigned rmt_ip;        /* used for IP-based allow/deny rules */
         time_t last_mod;
-        off_t ContentLength;    /* -1 - unknown */
         char *rmt_ip_str;       /* for $REMOTE_ADDR and $REMOTE_PORT */
         const char *bind_addr_or_port;
 
@@ -237,6 +244,13 @@ struct globals {
         USE_FEATURE_HTTPD_CGI(char *referer;)
         USE_FEATURE_HTTPD_CGI(char *user_agent;)
 
+        off_t file_size;        /* -1 - unknown */
+#if ENABLE_FEATURE_HTTPD_RANGES
+        off_t range_start;
+        off_t range_end;
+        off_t range_len;
+#endif
+
 #if ENABLE_FEATURE_HTTPD_BASIC_AUTH
         Htaccess *g_auth;       /* config user:password lines */
 #endif
@@ -264,13 +278,18 @@ struct globals {
 #define home_httpd        (G.home_httpd       )
 #define found_mime_type   (G.found_mime_type  )
 #define found_moved_temporarily (G.found_moved_temporarily)
-#define ContentLength     (G.ContentLength    )
 #define last_mod          (G.last_mod         )
 #define ip_a_d            (G.ip_a_d           )
 #define g_realm           (G.g_realm          )
 #define remoteuser        (G.remoteuser       )
 #define referer           (G.referer          )
 #define user_agent        (G.user_agent       )
+#define file_size         (G.file_size        )
+#if ENABLE_FEATURE_HTTPD_RANGES
+#define range_start       (G.range_start      )
+#define range_end         (G.range_end        )
+#define range_len         (G.range_len        )
+#endif
 #define rmt_ip_str        (G.rmt_ip_str       )
 #define g_auth            (G.g_auth           )
 #define mime_a            (G.mime_a           )
@@ -283,9 +302,17 @@ struct globals {
         PTR_TO_GLOBALS = xzalloc(sizeof(G)); \
         USE_FEATURE_HTTPD_BASIC_AUTH(g_realm = "Web Server Authentication";) \
         bind_addr_or_port = "80"; \
-        ContentLength = -1; \
+        file_size = -1; \
 } while (0)
 
+#if !ENABLE_FEATURE_HTTPD_RANGES
+enum {
+        range_start = 0,
+        range_end = MAXINT(off_t) - 1,
+        range_len = MAXINT(off_t),
+};
+#endif
+
 
 #define STRNCASECMP(a, str) strncasecmp((a), (str), sizeof(str)-1)
 
@@ -921,10 +948,26 @@ static void send_headers(int responseNum)
         }
 #endif
 
-        if (ContentLength != -1) {    /* file */
+        if (file_size != -1) {    /* file */
                 strftime(tmp_str, sizeof(tmp_str), RFC1123FMT, gmtime(&last_mod));
-                len += sprintf(iobuf + len, "Last-Modified: %s\r\n%s %"OFF_FMT"d\r\n",
-                        tmp_str, "Content-length:", ContentLength);
+#if ENABLE_FEATURE_HTTPD_RANGES
+                if (responseNum == HTTP_PARTIAL_CONTENT) {
+                        len += sprintf(iobuf + len, "Content-Range: bytes %"OFF_FMT"d-%"OFF_FMT"d/%"OFF_FMT"d\r\n",
+                                        range_start,
+                                        range_end,
+                                        file_size);
+                        file_size = range_end - range_start + 1;
+                }
+#endif
+                len += sprintf(iobuf + len,
+#if ENABLE_FEATURE_HTTPD_RANGES
+                        "Accept-Ranges: bytes\r\n"
+#endif
+                        "Last-Modified: %s\r\n%s %"OFF_FMT"d\r\n",
+                                tmp_str,
+                                "Content-length:",
+                                file_size
+                );
         }
         iobuf[len++] = '\r';
         iobuf[len++] = '\n';
@@ -1373,7 +1416,7 @@ static void send_file_and_exit(const char *url, int headers)
         const char *try_suffix;
         ssize_t count;
 #if ENABLE_FEATURE_HTTPD_USE_SENDFILE
-        off_t offset = 0;
+        off_t offset;
 #endif
 
         suffix = strrchr(url, '.');
@@ -1415,6 +1458,26 @@ static void send_file_and_exit(const char *url, int headers)
                 if (headers)
                         send_headers_and_exit(HTTP_NOT_FOUND);
         }
+#if ENABLE_FEATURE_HTTPD_RANGES
+        if (!headers)
+                range_start = 0; /* err pages and ranges don't mix */
+        range_len = MAXINT(off_t);
+        if (range_start) {
+                if (!range_end) {
+                        range_end = file_size - 1;
+                }
+                if (range_end < range_start
+                 || lseek(f, range_start, SEEK_SET) != range_start
+                ) {
+                        lseek(f, 0, SEEK_SET);
+                        range_start = 0;
+                } else {
+                        range_len = range_end - range_start + 1;
+                        send_headers(HTTP_PARTIAL_CONTENT);
+                        headers = 0;
+                }
+        }
+#endif
 
         if (headers)
                 send_headers(HTTP_OK);
@@ -1424,24 +1487,32 @@ static void send_file_and_exit(const char *url, int headers)
         signal(SIGPIPE, SIG_IGN);
 
 #if ENABLE_FEATURE_HTTPD_USE_SENDFILE
+        offset = range_start;
         do {
-                /* byte count (3rd arg) is rounded down to 64k */
-                count = sendfile(1, f, &offset, MAXINT(ssize_t) - 0xffff);
+                /* sz is rounded down to 64k */
+                ssize_t sz = MAXINT(ssize_t) - 0xffff;
+                USE_FEATURE_HTTPD_RANGES(if (sz > range_len) sz = range_len;)
+                count = sendfile(1, f, &offset, sz);
                 if (count < 0) {
-                        if (offset == 0)
+                        if (offset == range_start)
                                 goto fallback;
                         goto fin;
                 }
-        } while (count > 0);
+                USE_FEATURE_HTTPD_RANGES(range_len -= sz;)
+        } while (count > 0 && range_len);
         log_and_exit();
 
  fallback:
 #endif
         while ((count = safe_read(f, iobuf, IOBUF_SIZE)) > 0) {
-                ssize_t n = count;
-                count = full_write(1, iobuf, count);
+                ssize_t n;
+                USE_FEATURE_HTTPD_RANGES(if (count > range_len) count = range_len;)
+                n = full_write(1, iobuf, count);
                 if (count != n)
                         break;
+                USE_FEATURE_HTTPD_RANGES(range_len -= count;)
+                if (!range_len)
+                        break;
         }
 #if ENABLE_FEATURE_HTTPD_USE_SENDFILE
  fin:
@@ -1781,6 +1852,23 @@ static void handle_incoming_and_exit(const len_and_sockaddr *fromAddr)
                                 credentials = checkPerm(urlcopy, tptr);
                         }
 #endif          /* FEATURE_HTTPD_BASIC_AUTH */
+#if ENABLE_FEATURE_HTTPD_RANGES
+                        if (STRNCASECMP(iobuf, "Range:") == 0) {
+                                // We know only bytes=NNN-[MMM]
+                                char *s = skip_whitespace(iobuf + sizeof("Range:")-1);
+                                if (strncmp(s, "bytes=", 6) == 0) {
+                                        s += sizeof("bytes=")-1;
+                                        range_start = BB_STRTOOFF(s, &s, 10);
+                                        if (s[0] != '-' || range_start < 0) {
+                                                range_start = 0;
+                                        } else if (s[1]) {
+                                                range_end = BB_STRTOOFF(s+1, NULL, 10);
+                                                if (errno || range_end < range_start)
+                                                        range_start = 0;
+                                        }
+                                }
+                        }
+#endif
                 } /* while extra header reading */
         }
 
@@ -1833,8 +1921,7 @@ static void handle_incoming_and_exit(const len_and_sockaddr *fromAddr)
         if (urlp[-1] == '/')
                 strcpy(urlp, "index.html");
         if (stat(tptr, &sb) == 0) {
-                /* It's a dir URL and there is index.html */
-                ContentLength = sb.st_size;
+                file_size = sb.st_size;
                 last_mod = sb.st_mtime;
         }
 #if ENABLE_FEATURE_HTTPD_CGI
diff --git a/shell/ash.c b/shell/ash.c
index 167232c33..492474110 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -2494,6 +2494,7 @@ pwdcmd(int argc, char **argv)
 #define DQSYNTAX   1    /* in double quotes */
 #define SQSYNTAX   2    /* in single quotes */
 #define ARISYNTAX  3    /* in arithmetic */
+#define PSSYNTAX   4    /* prompt */
 
 #if ENABLE_ASH_OPTIMIZE_FOR_SIZE
 #define USE_SIT_FUNCTION
@@ -9886,6 +9887,9 @@ readtoken1(int firstc, int syntax, char *eofmark, int striptabs)
         smallint dblquote;
         smallint oldstyle;
         smallint prevsyntax; /* syntax before arithmetic */
+#if ENABLE_ASH_EXPAND_PRMT
+        smallint pssyntax;   /* we are expanding a prompt string */
+#endif
         int varnest;         /* levels of variables expansion */
         int arinest;         /* levels of arithmetic expansion */
         int parenlevel;      /* levels of parens in arithmetic */
@@ -9910,6 +9914,11 @@ readtoken1(int firstc, int syntax, char *eofmark, int striptabs)
         dblquote = (syntax == DQSYNTAX);
         oldstyle = 0;
         prevsyntax = 0;
+#if ENABLE_ASH_EXPAND_PRMT
+        pssyntax = (syntax == PSSYNTAX);
+        if (pssyntax)
+                syntax = DQSYNTAX;
+#endif
         varnest = 0;
         arinest = 0;
         parenlevel = 0;
@@ -9948,6 +9957,12 @@ readtoken1(int firstc, int syntax, char *eofmark, int striptabs)
                                         if (doprompt)
                                                 setprompt(2);
                                 } else {
+#if ENABLE_ASH_EXPAND_PRMT
+                                        if (c == '$' && pssyntax) {
+                                                USTPUTC(CTLESC, out);
+                                                USTPUTC('\\', out);
+                                        }
+#endif
                                         if (dblquote &&
                                                 c != '\\' && c != '`' &&
                                                 c != '$' && (
@@ -10780,7 +10795,7 @@ expandstr(const char *ps)
 
         /* XXX Fix (char *) cast. */
         setinputstring((char *)ps);
-        readtoken1(pgetc(), DQSYNTAX, nullstr, 0);
+        readtoken1(pgetc(), PSSYNTAX, nullstr, 0);
         popfile();
 
         n.narg.type = NARG;