httpd: simplify CGI headers handling, check "HTTP/1.1" prefix, not just "HTTP"

function                                             old     new   delta
cgi_io_loop_and_exit                                 477     498     +21
.rodata                                           106830  106821      -9
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/1 up/down: 21/-9)              Total: 12 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

2 files changed, 32 insertions, 28 deletions

diff --git a/include/platform.h b/include/platform.h
index a5b61757f..c449075b9 100644
--- a/include/platform.h
+++ b/include/platform.h
@@ -211,6 +211,7 @@
 # define IF_LITTLE_ENDIAN(...)
 /* How do bytes a,b,c,d (sequential in memory) look if fetched into uint32_t? */
 # define PACK32_BYTES(a,b,c,d) (uint32_t)((d)+((c)<<8)+((b)<<16)+((a)<<24))
+# define PACK64_LITERAL_STR(s) (((uint64_t)PACK32_BYTES((s)[0],(s)[1],(s)[2],(s)[3])<<32) + PACK32_BYTES((s)[4],(s)[5],(s)[6],(s)[7]))
 #else
 # define SWAP_BE16(x) bswap_16(x)
 # define SWAP_BE32(x) bswap_32(x)
@@ -221,6 +222,7 @@
 # define IF_BIG_ENDIAN(...)
 # define IF_LITTLE_ENDIAN(...) __VA_ARGS__
 # define PACK32_BYTES(a,b,c,d) (uint32_t)((a)+((b)<<8)+((c)<<16)+((d)<<24))
+# define PACK64_LITERAL_STR(s) (((uint64_t)PACK32_BYTES((s)[4],(s)[5],(s)[6],(s)[7])<<32) + PACK32_BYTES((s)[0],(s)[1],(s)[2],(s)[3]))
 #endif
 
 
diff --git a/networking/httpd.c b/networking/httpd.c
index 5101f86f7..e98da9c57 100644
--- a/networking/httpd.c
+++ b/networking/httpd.c
@@ -537,7 +537,7 @@ struct globals {
 #if ENABLE_FEATURE_HTTPD_PROXY
         Htaccess_Proxy *proxy;
 #endif
-        char iobuf[IOBUF_SIZE];
+        char iobuf[IOBUF_SIZE] ALIGN8;
 };
 #define G (*ptr_to_globals)
 #define verbose           (G.verbose          )
@@ -1425,7 +1425,7 @@ static NOINLINE void cgi_io_loop_and_exit(int fromCgi_rd, int toCgi_wr, int post
                 /*pfd[FROM_CGI].events = POLLIN; - moved out of loop */
                 /*pfd[FROM_CGI].revents = 0; - not needed */
 
-                /* gcc-4.8.0 still doesnt fill two shorts with one insn :( */
+                /* gcc-4.8.0 still doesn't fill two shorts with one insn :( */
                 /* http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47059 */
                 /* hopefully one day it will... */
                 pfd[TO_CGI].events = POLLOUT;
@@ -1507,8 +1507,6 @@ static NOINLINE void cgi_io_loop_and_exit(int fromCgi_rd, int toCgi_wr, int post
 
                 if (pfd[FROM_CGI].revents) {
                         /* There is something to read from CGI */
-                        char *rbuf = iobuf;
-
                         /* Still buffering CGI output? */
                         if (out_cnt >= 0) {
                                 /* HTTP_200[] has single "\r\n" at the end.
@@ -1523,34 +1521,34 @@ static NOINLINE void cgi_io_loop_and_exit(int fromCgi_rd, int toCgi_wr, int post
                                  * CGI may output a few first bytes and then wait
                                  * for POSTDATA without closing stdout.
                                  * With full_read we may wait here forever. */
-                                count = safe_read(fromCgi_rd, rbuf + out_cnt, IOBUF_SIZE);
+                                count = safe_read(fromCgi_rd, iobuf + out_cnt, IOBUF_SIZE);
                                 if (count <= 0) {
-                                        /* eof (or error) and there was no "HTTP" (tiny 0..3 bytes output),
-                                         * send "HTTP/1.1 200 OK\r\n", then send received 0..3 bytes */
+                                        /* EOF (or error, and out_cnt=0..7
+                                         * send "HTTP/1.1 200 OK\r\n", then send received 0..7 bytes */
                                         goto write_HTTP_200_OK;
                                         /* we'll read once more later, in "no longer buffering"
                                          * code path, get another EOF there and exit */
                                 }
                                 out_cnt += count;
                                 count = 0;
-                                /* "Status" header format is: "Status: 302 Redirected\r\n" */
-                                if (out_cnt >= 8 && memcmp(rbuf, "Status: ", 8) == 0) {
+                                if (out_cnt >= 8) {
 //FIXME: "Status: " is not required to be the first header! It can be anywhere!
 //FIXME: many servers also check "Location: ". If it exists but "Status: " does _not_, "302 Found" is assumed instead of "200 OK".
-                                        /* send "HTTP/1.1 " */
-                                        if (full_write(STDOUT_FILENO, HTTP_200, 9) != 9)
-                                                break;
-                                        /* skip "Status: " (including space, sending "HTTP/1.1  NNN" is wrong) */
-                                        rbuf += 8;
-                                        count = out_cnt - 8;
-                                        out_cnt = -1; /* buffering off */
-                                } else if (out_cnt >= 4) {
-//NB: Apache has no such autodetection. It always adds its own HTTP/ header,
+                                        /* "Status" header format is: "Status: 302 Redirected\r\n" */
+                                        //if (memcmp(iobuf, "Status: ", 8) == 0)
+                                        if (*(uint64_t*)iobuf == PACK64_LITERAL_STR("Status: ")) {
+                                                /* send "HTTP/1.1 " */
+                                                if (full_write(STDOUT_FILENO, HTTP_200, 9) != 9)
+                                                        break;
+                                                /* skip "Status: " (including space, sending "HTTP/1.1  NNN" is wrong) */
+                                                out_cnt -= 8;
+                                                memmove(iobuf, iobuf + 8, out_cnt);
+                                        }
+//NB: Apache has no such autodetection. It always adds its own HTTP/1.x header,
 //unless the CGI name starts with "nph-", in which case it passes its output verbatim to network.
-                                        /* Did CGI add "HTTP"? */
-                                        if (memcmp(rbuf, HTTP_200, 4) != 0) {
+                                        else if (memcmp(iobuf, HTTP_200, 8) != 0) { /* Did CGI send "HTTP/1.1"? */
  write_HTTP_200_OK:
-                                                /* there is no "HTTP", send "HTTP/1.1 200 OK\r\n" ourself */
+                                                /* no, send "HTTP/1.1 200 OK\r\n" ourself */
                                                 if (full_write(STDOUT_FILENO, HTTP_200, sizeof(HTTP_200)-1) != sizeof(HTTP_200)-1)
                                                         break;
                                         }
@@ -1562,17 +1560,16 @@ static NOINLINE void cgi_io_loop_and_exit(int fromCgi_rd, int toCgi_wr, int post
                                          */
                                         count = out_cnt;
                                         out_cnt = -1; /* buffering off */
-                                        /* NB: we mishandle CGI writing "Stat","us..." in two separate writes */
                                 }
                         } else {
-                                count = safe_read(fromCgi_rd, rbuf, IOBUF_SIZE);
+                                count = safe_read(fromCgi_rd, iobuf, IOBUF_SIZE);
                                 if (count <= 0)
-                                        send_EOF_and_exit();  /* eof (or error) */
+                                        send_EOF_and_exit();  /* EOF (or error) */
                         }
-//FIXME: many (most?) servers translate bare "\n" to "\r\n", often only in the headers, not body (the part after empty line)
-                        if (full_write(STDOUT_FILENO, rbuf, count) != count)
+//FIXME: many (most?) servers translate bare "\n" to "\r\n", only in the headers, not body (the part after empty line)
+                        if (full_write(STDOUT_FILENO, iobuf, count) != count)
                                 break;
-                        dbg("cgi read %d bytes: '%.*s'\n", count, count, rbuf);
+                        dbg("cgi read %d bytes: '%.*s'\n", count, count, iobuf);
                 } /* if (pfd[FROM_CGI].revents) */
         } /* while (1) */
         log_and_exit();
@@ -2948,7 +2945,12 @@ int httpd_main(int argc UNUSED_PARAM, char **argv)
         IF_FEATURE_HTTPD_SETUID(const char *s_ugid = NULL;)
         IF_FEATURE_HTTPD_SETUID(struct bb_uidgid_t ugid;)
         IF_FEATURE_HTTPD_AUTH_MD5(const char *pass;)
-
+#if 0 // PACK64_LITERAL_STR test
+        char testing[16] = "Status: ";
+        printf("0x%08llx\n", PACK64_LITERAL_STR("Status: "));
+        printf("0x%08llx\n", *(uint64_t*)testing);
+        exit(1);
+#endif
         INIT_G();
 
 #if ENABLE_LOCALE_SUPPORT