X-Forwarded-For stunnel 4.54 patch

stunnel-4.54-xforwarded-for.diff

diff --git a/doc/stunnel.8 b/doc/stunnel.8
index b0204d6..7f46be0 100644
--- a/doc/stunnel.8
+++ b/doc/stunnel.8
@@ -739,6 +739,10 @@ This options has been renamed to \fInone\fR.
 .RE
 .RS 4
 .RE
+.IP "\fBxforwardedfor\fR = yes | no" 4
+.IX Item "xforwardedfor = yes | no"
+append an 'X-Forwarded-For:' HTTP request header providing the
+client's IP address to the server.
 .IP "\fBverify\fR = level" 4
 .IX Item "verify = level"
 verify peer certificate
diff --git a/src/client.c b/src/client.c
index 5fa5d15..a34c74a 100644
--- a/src/client.c
+++ b/src/client.c
@@ -48,6 +48,8 @@
 #define SHUT_RDWR 2
 #endif
 
+#define IPLEN 40
+
 static void client_try(CLI *);
 static void client_run(CLI *);
 static void init_local(CLI *);
@@ -75,6 +77,12 @@ CLI *alloc_client_session(SERVICE_OPTIONS *opt, int rfd, int wfd) {
     c=str_alloc(sizeof(CLI));
     str_detach(c);
     c->opt=opt;
+    /* some options need space to add some information */
+    if (c->opt->option.xforwardedfor)
+        c->buffsize = BUFFSIZE - BUFF_RESERVED;
+    else
+        c->buffsize = BUFFSIZE;
+    c->crlf_seen=0;
     c->local_rfd.fd=rfd;
     c->local_wfd.fd=wfd;
     return c;
@@ -501,6 +509,28 @@ static void win_new_chain(CLI *c) {
 }
 #endif
 
+/* Moves all data from the buffer <buffer> between positions <start> and <stop>
+ * to insert <string> of length <len>. <start> and <stop> are updated to their
+ * new respective values, and the number of characters inserted is returned.
+ * If <len> is too long, nothing is done and -1 is returned.
+ * Note that neither <string> nor <buffer> can be NULL.
+ */
+static int buffer_insert_with_len(char *buffer, int *start, int *stop, int limit, char *string, int len) {
+    if (len > limit - *stop)
+        return -1;
+    if (*start > *stop)
+        return -1;
+    memmove(buffer + *start + len, buffer + *start, *stop - *start);
+    memcpy(buffer + *start, string, len);
+    *start += len;
+    *stop += len;
+    return len;
+}
+
+static int buffer_insert(char *buffer, int *start, int *stop, int limit, char *string) {
+    return buffer_insert_with_len(buffer, start, stop, limit, string, strlen(string));
+}
+
 /****************************** transfer data */
 static void transfer(CLI *c) {
     int watchdog=0; /* a counter to detect an infinite loop */
@@ -519,7 +549,7 @@ static void transfer(CLI *c) {
     do { /* main loop of client data transfer */
         /****************************** initialize *_wants_* */
         read_wants_read=!(SSL_get_shutdown(c->ssl)&SSL_RECEIVED_SHUTDOWN)
-            && c->ssl_ptr<BUFFSIZE && !read_wants_write;
+            && c->ssl_ptr<c->buffsize && !read_wants_write;
         write_wants_write=!(SSL_get_shutdown(c->ssl)&SSL_SENT_SHUTDOWN)
             && c->sock_ptr && !write_wants_read;
 
@@ -528,7 +558,7 @@ static void transfer(CLI *c) {
         /* for plain socket open data strem = open file descriptor */
         /* make sure to add each open socket to receive exceptions! */
         if(sock_open_rd)
-            s_poll_add(c->fds, c->sock_rfd->fd, c->sock_ptr<BUFFSIZE, 0);
+            s_poll_add(c->fds, c->sock_rfd->fd, c->sock_ptr<c->buffsize, 0);
         if(sock_open_wr)
             s_poll_add(c->fds, c->sock_wfd->fd, 0, c->ssl_ptr);
         /* for SSL assume that sockets are open if there any pending requests */
@@ -655,7 +685,7 @@ static void transfer(CLI *c) {
         /****************************** read from socket */
         if(sock_open_rd && sock_can_rd) {
             num=readsocket(c->sock_rfd->fd,
-                c->sock_buff+c->sock_ptr, BUFFSIZE-c->sock_ptr);
+                c->sock_buff+c->sock_ptr, c->buffsize-c->sock_ptr);
             switch(num) {
             case -1:
                 if(parse_socket_error(c, "readsocket"))
@@ -692,7 +722,7 @@ static void transfer(CLI *c) {
         /****************************** update *_wants_* based on new *_ptr */
         /* this update is also required for SSL_pending() to be used */
         read_wants_read=!(SSL_get_shutdown(c->ssl)&SSL_RECEIVED_SHUTDOWN)
-            && c->ssl_ptr<BUFFSIZE && !read_wants_write;
+            && c->ssl_ptr<c->buffsize && !read_wants_write;
         write_wants_write=!(SSL_get_shutdown(c->ssl)&SSL_SENT_SHUTDOWN)
             && c->sock_ptr && !write_wants_read;
 
@@ -702,12 +732,70 @@ static void transfer(CLI *c) {
                  * writesocket() above made some room in c->ssl_buff */
                 (read_wants_write && ssl_can_wr)) {
             read_wants_write=0;
-            num=SSL_read(c->ssl, c->ssl_buff+c->ssl_ptr, BUFFSIZE-c->ssl_ptr);
+            num=SSL_read(c->ssl, c->ssl_buff+c->ssl_ptr, c->buffsize-c->ssl_ptr);
             switch(err=SSL_get_error(c->ssl, num)) {
             case SSL_ERROR_NONE:
                 if(num==0)
                     s_log(LOG_DEBUG, "SSL_read returned 0");
-                c->ssl_ptr+=num;
+                if (c->buffsize != BUFFSIZE && c->opt->option.xforwardedfor) { /* some work left to do */
+                    int last = c->ssl_ptr;
+                    c->ssl_ptr += num;
+
+                    /* Look for end of HTTP headers between last and ssl_ptr.
+                    * To achieve this reliably, we have to count the number of
+                    * successive [CR]LF and to memorize it in case it's spread
+                    * over multiple segments. --WT.
+                    */
+                    while (last < c->ssl_ptr) {
+                        if (c->ssl_buff[last] == '\n') {
+                            if (++c->crlf_seen == 2)
+                                break;
+                        } else if (last < c->ssl_ptr - 1 &&
+                                    c->ssl_buff[last] == '\r' &&
+                                    c->ssl_buff[last+1] == '\n') {
+                            if (++c->crlf_seen == 2)
+                                break;
+                            last++;
+                        } else if (c->ssl_buff[last] != '\r')
+                            /* don't refuse '\r' because we may get a '\n' on next read */
+                            c->crlf_seen = 0;
+                        last++;
+                    }
+                    if (c->crlf_seen >= 2) {
+                        /* X-Forwarded-For: xxxx \r\n\0 */
+                        char xforw[17 + IPLEN + 3];
+
+                        /* We have all the HTTP headers now. We don't need to
+                        * reserve any space anymore. <ssl_ptr> points to the
+                        * first byte of unread data, and <last> points to the
+                        * exact location where we want to insert our headers,
+                        * which is right before the empty line.
+                        */
+                        c->buffsize = BUFFSIZE;
+
+                        /* We will insert our X-Forwarded-For: header here.
+                         * We need to write the IP address, but if we use
+                         * sprintf, it will pad with the terminating 0.
+                         * So we will pass via a temporary buffer allocated
+                         * on the stack.
+                         */
+                        memcpy(xforw, "X-Forwarded-For: ", 17);
+                        if (getnameinfo(&c->peer_addr.sa,
+                            c->peer_addr_len,
+                            xforw + 17, IPLEN, NULL, 0,
+                            NI_NUMERICHOST) == 0) {
+                            strcat(xforw + 17, "\r\n");
+                            buffer_insert(c->ssl_buff, &last, &c->ssl_ptr,
+                                c->buffsize, xforw);
+                        }
+                        /* last still points to the \r\n and ssl_ptr to the
+                         * end of the buffer, so we may add as many headers
+                         * as wee need to.
+                         */
+                    }
+                }
+                else
+                   c->ssl_ptr+=num;
                 watchdog=0; /* reset watchdog */
                 break;
             case SSL_ERROR_WANT_WRITE:
diff --git a/src/common.h b/src/common.h
index 4f85e2f..f9f1335 100644
--- a/src/common.h
+++ b/src/common.h
@@ -52,6 +52,9 @@
 /* I/O buffer size - 18432 is the maximum size of SSL record payload */
 #define BUFFSIZE 18432
 
+/* maximum space reserved for header insertion in BUFFSIZE */
+#define BUFF_RESERVED 1024
+
 /* how many bytes of random input to read from files for PRNG */
 /* OpenSSL likes at least 128 bits, so 64 bytes seems plenty. */
 #define RANDOM_BYTES 64
diff --git a/src/options.c b/src/options.c
index 3073e3a..5b217c5 100644
--- a/src/options.c
+++ b/src/options.c
@@ -1032,6 +1032,33 @@ static char *parse_service_option(CMD cmd, SERVICE_OPTIONS *section,
     }
 #endif
 
+    /* xforwardedfor */
+    switch(cmd) {
+    case CMD_BEGIN:
+        section->option.xforwardedfor=0;
+        break;
+    case CMD_EXEC:
+        if(strcasecmp(opt, "xforwardedfor"))
+            break;
+        if(!strcasecmp(arg, "yes"))
+            section->option.xforwardedfor=1;
+        else if(!strcasecmp(arg, "no"))
+            section->option.xforwardedfor=0;
+        else
+            return "argument should be either 'yes' or 'no'";
+        return NULL; /* OK */
+    case CMD_END:
+        break;
+    case CMD_FREE:
+        break;
+    case CMD_DEFAULT:
+        break;
+    case CMD_HELP:
+        s_log(LOG_NOTICE, "%-22s = yes|no append an HTTP X-Forwarded-For header",
+            "xforwardedfor");
+        break;
+    }
+
     /* exec */
     switch(cmd) {
     case CMD_BEGIN:
diff --git a/src/prototypes.h b/src/prototypes.h
index 3181323..2a3cbdc 100644
--- a/src/prototypes.h
+++ b/src/prototypes.h
@@ -204,6 +204,7 @@ typedef struct service_options_struct {
         unsigned int accept:1;          /* endpoint: accept */
         unsigned int client:1;
         unsigned int delayed_lookup:1;
+        unsigned int xforwardedfor:1;
 #ifdef USE_LIBWRAP
         unsigned int libwrap:1;
 #endif
@@ -433,6 +434,8 @@ typedef struct {
     FD *ssl_rfd, *ssl_wfd; /* read and write SSL descriptors */
     int sock_bytes, ssl_bytes; /* bytes written to socket and SSL */
     s_poll_set *fds; /* file descriptors */
+    int buffsize;  /* current buffer size, may be lower than BUFFSIZE */
+    int crlf_seen; /* the number of successive CRLF seen */
 } CLI;
 
 CLI *alloc_client_session(SERVICE_OPTIONS *, int, int);