httpd: a little bit more correct handling of CGI "HTTP/xxx" output

2 files changed, 50 insertions, 36 deletions

diff --git a/libbb/full_write.c b/libbb/full_write.c
index bceac6de5..7bbacb8ac 100644
--- a/libbb/full_write.c
+++ b/libbb/full_write.c
@@ -7,8 +7,6 @@
  * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
  */
 
-#include <stdio.h>
-#include <unistd.h>
 #include "libbb.h"
 
 /*
diff --git a/networking/httpd.c b/networking/httpd.c
index 6f4ca05a7..3524531e3 100644
--- a/networking/httpd.c
+++ b/networking/httpd.c
@@ -967,7 +967,7 @@ static int sendCgi(const char *url,
         int pid = 0;
         int inFd;
         int outFd;
-        int firstLine = 1;
+        int buf_count;
         int status;
         size_t post_read_size, post_read_idx;
 
@@ -994,7 +994,7 @@ static int sendCgi(const char *url,
                 dup2(toCgi[0], 0);  // replace stdin with the pipe
                 dup2(fromCgi[1], 1);  // replace stdout with the pipe
                 /* Huh? User seeing stderr can be a security problem...
-                 * and if cgi really wants that, it can always dup2(1,2)...
+                 * and if CGI really wants that, it can always dup2(1,2)...
                 if (!DEBUG)
                         dup2(fromCgi[1], 2);  // replace stderr with the pipe
                 */
@@ -1125,6 +1125,7 @@ static int sendCgi(const char *url,
 
         /* parent process */
 
+        buf_count = 0;
         post_read_size = 0;
         post_read_idx = 0; /* for gcc */
         inFd = fromCgi[0];
@@ -1162,10 +1163,11 @@ static int sendCgi(const char *url,
                 }
 
                 if (nfound <= 0) {
-                        if (waitpid(pid, &status, WNOHANG) <= 0)
+                        if (waitpid(pid, &status, WNOHANG) <= 0) {
                                 /* Weird. CGI didn't exit and no fd's
-                                 *  are ready, yet select returned?! */
+                                 * are ready, yet select returned?! */
                                 continue;
+                        }
                         close(inFd);
                         if (DEBUG && WIFEXITED(status))
                                 bb_error_msg("piped has exited with status=%d", WEXITSTATUS(status));
@@ -1190,7 +1192,7 @@ static int sendCgi(const char *url,
                 ) {
                         /* We expect data, prev data portion is eaten by CGI
                          * and there *is* data to read from the peer
-                         * (POST data?) */
+                         * (POSTDATA?) */
                         count = bodyLen > (int)sizeof(wbuf) ? (int)sizeof(wbuf) : bodyLen;
                         count = safe_read(config->accepted_socket, wbuf, count);
                         if (count > 0) {
@@ -1202,42 +1204,56 @@ static int sendCgi(const char *url,
                         }
                 }
 
-                if (FD_ISSET(inFd, &readSet)) {
-                        /* There is something to read from CGI */
-                        int s = config->accepted_socket;
-                        char *rbuf = config->buf;
 #define PIPESIZE PIPE_BUF
 #if PIPESIZE >= MAX_MEMORY_BUFF
 # error "PIPESIZE >= MAX_MEMORY_BUFF"
 #endif
-                        /* Must use safe_read, not full_read, because
-                         * cgi may output a few first lines and then wait
-                         * for POSTDATA without closing stdout.
-                         * With full_read we may wait here forever. */
-                        count = safe_read(inFd, rbuf, PIPESIZE);
-                        if (count == 0)
-                                break;  /* closed */
-                        if (count < 0)
-                                continue; /* huh, error, why continue?? */
-
-                        if (firstLine) {
+                if (FD_ISSET(inFd, &readSet)) {
+                        /* There is something to read from CGI */
+                        int s = config->accepted_socket;
+                        char *rbuf = config->buf;
+
+                        /* Are we still buffering CGI output? */
+                        if (buf_count >= 0) {
                                 static const char HTTP_200[] = "HTTP/1.0 200 OK\r\n\r\n";
-                                rbuf[count] = '\0';
-                                /* check to see if the user script added headers */
-                                /* (NB: buggy wrt cgi splitting "HTTP OK") */
-                                if (memcmp(rbuf, HTTP_200, 4) != 0) {
-                                        /* there is no "HTTP", do it ourself */
-                                        full_write(s, HTTP_200, sizeof(HTTP_200)-1);
+                                /* Must use safe_read, not full_read, because
+                                 * 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(inFd, rbuf + buf_count, PIPESIZE - 4);
+                                if (count <= 0) {
+                                        /* eof (or error) and there was no "HTTP",
+                                         * so add one and write out the received data */
+                                        if (buf_count) {
+                                                full_write(s, HTTP_200, sizeof(HTTP_200)-1);
+                                                full_write(s, rbuf, buf_count);
+                                        }
+                                        break;  /* closed */
                                 }
-                                /* Example of valid GCI without "Content-type:"
-                                 * echo -en "HTTP/1.0 302 Found\r\n"
-                                 * echo -en "Location: http://www.busybox.net\r\n"
-                                 * echo -en "\r\n"
-                                if (!strstr(rbuf, "ontent-")) {
-                                        full_write(s, "Content-type: text/plain\r\n\r\n", 28);
+                                buf_count += count;
+                                count = 0;
+                                if (buf_count >= 4) {
+                                        /* check to see if CGI added "HTTP" */
+                                        if (memcmp(rbuf, HTTP_200, 4) != 0) {
+                                                /* there is no "HTTP", do it ourself */
+                                                if (full_write(s, HTTP_200, sizeof(HTTP_200)-1) != sizeof(HTTP_200)-1)
+                                                        break;
+                                        }
+                                        /* example of valid CGI without "Content-type:"
+                                         * echo -en "HTTP/1.0 302 Found\r\n"
+                                         * echo -en "Location: http://www.busybox.net\r\n"
+                                         * echo -en "\r\n"
+                                        if (!strstr(rbuf, "ontent-")) {
+                                                full_write(s, "Content-type: text/plain\r\n\r\n", 28);
+                                        }
+                                         */
+                                        count = buf_count;
+                                        buf_count = -1; /* buffering off */
                                 }
-                                 */
-                                firstLine = 0;
+                        } else {
+                                count = safe_read(inFd, rbuf, PIPESIZE);
+                                if (count <= 0)
+                                        break;  /* eof (or error) */
                         }
                         if (full_write(s, rbuf, count) != count)
                                 break;