Better follow redirection for HTTPClient

libraries/ESP8266HTTPClient/src/ESP8266HTTPClient.cpp

@@ -558,8 +558,17 @@ bool HTTPClient::setURL(const String& url)
 /**
  * set true to follow redirects.
  * @param follow
+ * @deprecated
  */
 void HTTPClient::setFollowRedirects(bool follow)
+{
+    _followRedirects = follow ? HTTPC_FOLLOW_REDIRECTS : HTTPC_DONT_FOLLOW_REDIRECTS;
+}
+/**
+ * set redirect follow mode. See `followRedirects_t` enum for avaliable modes.
+ * @param follow
+ */
+void HTTPClient::setFollowRedirects(followRedirects_t follow)
 {
     _followRedirects = follow;
 }
@@ -652,87 +661,100 @@ int HTTPClient::sendRequest(const char * type, const String& payload)
  */
 int HTTPClient::sendRequest(const char * type, const uint8_t * payload, size_t size)
 {
-    bool redirect = false;
-    int code = 0;
-    do {
-        // wipe out any existing headers from previous request
-        for(size_t i = 0; i < _headerKeysCount; i++) {
-            if (_currentHeaders[i].value.length() > 0) {
-                _currentHeaders[i].value.clear();
-            }
+    // wipe out any existing headers from previous request
+    for(size_t i = 0; i < _headerKeysCount; i++) {
+        if (_currentHeaders[i].value.length() > 0) {
+            _currentHeaders[i].value.clear();
         }
+    }
 
-        redirect = false;
-        DEBUG_HTTPCLIENT("[HTTP-Client][sendRequest] type: '%s' redirCount: %d\n", type, _redirectCount);
+    DEBUG_HTTPCLIENT("[HTTP-Client][sendRequest] type: '%s' redirCount: %d\n", type, _redirectCount);
 
-        // connect to server
-        if(!connect()) {
-            return returnError(HTTPC_ERROR_CONNECTION_REFUSED);
-        }
+    // connect to server
+    if(!connect()) {
+        return returnError(HTTPC_ERROR_CONNECTION_REFUSED);
+    }
 
-        addHeader(F("Content-Length"), String(payload && size > 0 ? size : 0));
+    addHeader(F("Content-Length"), String(payload && size > 0 ? size : 0));
 
-        // send Header
-        if(!sendHeader(type)) {
-            return returnError(HTTPC_ERROR_SEND_HEADER_FAILED);
-        }
+    // send Header
+    if(!sendHeader(type)) {
+        return returnError(HTTPC_ERROR_SEND_HEADER_FAILED);
+    }
 
-        // send Payload if needed
-        if (payload && size > 0) {
-            size_t bytesWritten = 0;
-            const uint8_t *p = payload;
-            size_t originalSize = size;
-            while (bytesWritten < originalSize) {
-                int written;
-                int towrite = std::min((int)size, (int)HTTP_TCP_BUFFER_SIZE);
-                written = _client->write(p + bytesWritten, towrite);
-                if (written < 0) {
-                     return returnError(HTTPC_ERROR_SEND_PAYLOAD_FAILED);
-                } else if (written == 0) {
-                     return returnError(HTTPC_ERROR_CONNECTION_LOST);
-                }
-                bytesWritten += written;
-                size -= written;
+    // send Payload if needed
+    if (payload && size > 0) {
+        size_t bytesWritten = 0;
+        const uint8_t *p = payload;
+        size_t originalSize = size;
+        while (bytesWritten < originalSize) {
+            int written;
+            int towrite = std::min((int)size, (int)HTTP_TCP_BUFFER_SIZE);
+            written = _client->write(p + bytesWritten, towrite);
+            if (written < 0) {
+                    return returnError(HTTPC_ERROR_SEND_PAYLOAD_FAILED);
+            } else if (written == 0) {
+                    return returnError(HTTPC_ERROR_CONNECTION_LOST);
             }
+            bytesWritten += written;
+            size -= written;
         }
+    }
 
-        // handle Server Response (Header)
-        code = handleHeaderResponse();
-
-        //
-        // We can follow redirects for 301/302/307 for GET and HEAD requests and
-        // and we have not exceeded the redirect limit preventing an infinite
-        // redirect loop.
-        //
-        // https://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html
-        //
-        if (_followRedirects &&
-                (_redirectCount < _redirectLimit) &&
-                (_location.length() > 0) &&
-                (code == 301 || code == 302 || code == 307) &&
-                (!strcmp(type, "GET") || !strcmp(type, "HEAD"))
+    // handle Server Response (Header)
+    int code = handleHeaderResponse();
+
+    //
+    // Handle redirections as stated in RFC document:
+    // https://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html
+    //
+    // Implementing HTTP_CODE_FOUND as redirection with GET method,
+    // to follow most of existing user agent implementations.
+    //
+    if (
+        _followRedirects != HTTPC_DONT_FOLLOW_REDIRECTS && 
+        _redirectCount < _redirectLimit &&
+        _location.length() > 0
+    ) {
+        switch (code) {
+            // redirecting using the same method
+            case HTTP_CODE_MOVED_PERMANENTLY:
+            case HTTP_CODE_TEMPORARY_REDIRECT: {
+                if (
+                    // allow to force redirections on other methods
+                    // (the RFC require user to accept the redirection)
+                    _followRedirects == HTTPC_FORCE_FOLLOW_REDIRECTS ||
+                    // allow GET and HEAD methods without force
+                    !strcmp(type, "GET") || 
+                    !strcmp(type, "HEAD")
                 ) {
-            _redirectCount += 1; // increment the count for redirect.
-            redirect = true;
-            DEBUG_HTTPCLIENT("[HTTP-Client][sendRequest] following redirect:: '%s' redirCount: %d\n", _location.c_str(), _redirectCount);
-            if (!setURL(_location)) {
-                // return the redirect instead of handling on failure of setURL()
-                redirect = false;
+                    _redirectCount += 1;
+                    DEBUG_HTTPCLIENT("[HTTP-Client][sendRequest] following redirect (the same method): '%s' redirCount: %d\n", _location.c_str(), _redirectCount);
+                    if (!setURL(_location)) {
+                        DEBUG_HTTPCLIENT("[HTTP-Client][sendRequest] failed setting URL for redirection\n");
+                        // no redirection
+                        break;
+                    }
+                    code = sendRequest(type, payload, size);
+                }
+                break;
+            }
+            // redirecting with method dropped to GET or HEAD
+            // note: it does not need `HTTPC_FORCE_FOLLOW_REDIRECTS` for any method
+            case HTTP_CODE_FOUND:
+            case HTTP_CODE_SEE_OTHER: {
+                _redirectCount += 1;
+                DEBUG_HTTPCLIENT("[HTTP-Client][sendRequest] following redirect (dropped to GET/HEAD): '%s' redirCount: %d\n", _location.c_str(), _redirectCount);
+                if (!setURL(_location)) {
+                    DEBUG_HTTPCLIENT("[HTTP-Client][sendRequest] failed setting URL for redirection\n");
+                    // no redirection
+                    break;
+                }
+                code = sendRequest("GET");
             }
-        }
 
-    } while (redirect);
-
-    // handle 303 redirect for non GET/HEAD by changing to GET and requesting new url
-    if (_followRedirects &&
-            (_redirectCount < _redirectLimit) &&
-            (_location.length() > 0) &&
-            (code == 303) &&
-            strcmp(type, "GET") && strcmp(type, "HEAD")
-            ) {
-        _redirectCount += 1;
-        if (setURL(_location)) {
-            code = sendRequest("GET");
+            default:
+                break;
         }
     }
 

libraries/ESP8266HTTPClient/src/ESP8266HTTPClient.h

@@ -130,6 +130,12 @@ typedef enum {
     HTTPC_TE_CHUNKED
 } transferEncoding_t;
 
+typedef enum {
+    HTTPC_FOLLOW_REDIRECTS,
+    HTTPC_DONT_FOLLOW_REDIRECTS,
+    HTTPC_FORCE_FOLLOW_REDIRECTS
+} followRedirects_t;
+
 #if HTTPCLIENT_1_1_COMPATIBLE
 class TransportTraits;
 typedef std::unique_ptr<TransportTraits> TransportTraitsPtr;
@@ -173,8 +179,12 @@ class HTTPClient
     void setAuthorization(const char * user, const char * password);
     void setAuthorization(const char * auth);
     void setTimeout(uint16_t timeout);
-    void setFollowRedirects(bool follow);
+
+    // Redirections
+    void setFollowRedirects(bool follow) __attribute__ ((deprecated));
+    void setFollowRedirects(followRedirects_t follow);
     void setRedirectLimit(uint16_t limit); // max redirects to follow for a single request
+
     bool setURL(const String& url); // handy for handling redirects
     void useHTTP10(bool usehttp10 = true);
 
@@ -252,7 +262,7 @@ class HTTPClient
     int _returnCode = 0;
     int _size = -1;
     bool _canReuse = false;
-    bool _followRedirects = false;
+    followRedirects_t _followRedirects = HTTPC_DONT_FOLLOW_REDIRECTS;
     uint16_t _redirectCount = 0;
     uint16_t _redirectLimit = 10;
     String _location;