curl: add --follow

Makes curl follow redirects an act on the response code and change a
custom method accordingly, contrary to --location.

Potential future command line to send QUERY and following a redirect
according to the status code:

    curl -d "request-body" -X QUERY --follow https://example.com

add test 794,796,797

Assisted-by: Daniel Böhmer <post@daniel-boehmer.de>

Closes #16543

src/config2setopts.c

@@ -512,8 +512,7 @@ static CURLcode http_setopts(struct OperationConfig *config,
 {
   long postRedir = 0;
 
-  my_setopt_long(curl, CURLOPT_FOLLOWLOCATION,
-                 config->followlocation);
+  my_setopt_long(curl, CURLOPT_FOLLOWLOCATION, config->followlocation);
   my_setopt_long(curl, CURLOPT_UNRESTRICTED_AUTH,
                  config->unrestricted_auth);
   my_setopt_str(curl, CURLOPT_AWS_SIGV4, config->aws_sigv4);

src/tool_cfgable.h

@@ -224,6 +224,7 @@ struct OperationConfig {
   long happy_eyeballs_timeout_ms; /* happy eyeballs timeout in milliseconds.
                                      0 is valid. default: CURL_HET_DEFAULT. */
   unsigned long timecond;
+  long followlocation;      /* follow http redirects mode */
   HttpReq httpreq;
   long proxyver;             /* set to CURLPROXY_HTTP* define */
   long ftp_ssl_ccc_mode;
@@ -264,7 +265,6 @@ struct OperationConfig {
   BIT(show_headers);        /* show headers to data output */
   BIT(no_body);             /* do not get the body */
   BIT(dirlistonly);         /* only get the FTP dir list */
-  BIT(followlocation);      /* follow http redirects */
   BIT(unrestricted_auth);   /* Continue to send authentication (user+password)
                                when following redirects, even when hostname
                                changed */

src/tool_getparam.c

@@ -144,6 +144,7 @@ static const struct LongShort aliases[]= {
   {"fail-early",                 ARG_BOOL, ' ', C_FAIL_EARLY},
   {"fail-with-body",             ARG_BOOL, ' ', C_FAIL_WITH_BODY},
   {"false-start",                ARG_BOOL, ' ', C_FALSE_START},
+  {"follow",                     ARG_BOOL, ' ', C_FOLLOW},
   {"form",                       ARG_STRG, 'F', C_FORM},
   {"form-escape",                ARG_BOOL, ' ', C_FORM_ESCAPE},
   {"form-string",                ARG_STRG, ' ', C_FORM_STRING},
@@ -2098,12 +2099,6 @@ static ParameterError opt_bool(struct OperationConfig *config,
   case C_LIST_ONLY: /* --list-only */
     config->dirlistonly = toggle; /* only list the names of the FTP dir */
     break;
-  case C_LOCATION_TRUSTED: /* --location-trusted */
-    config->unrestricted_auth = toggle;
-    FALLTHROUGH();
-  case C_LOCATION: /* --location */
-    config->followlocation = toggle; /* Follow Location: HTTP headers */
-    break;
   case C_MANUAL: /* --manual */
     if(toggle)   /* --no-manual shows no manual... */
       return PARAM_MANUAL_REQUESTED;
@@ -2166,6 +2161,19 @@ static ParameterError opt_bool(struct OperationConfig *config,
   case C_MPTCP: /* --mptcp */
     config->mptcp = toggle;
     break;
+  case C_LOCATION_TRUSTED: /* --location-trusted */
+    config->unrestricted_auth = toggle;
+    FALLTHROUGH();
+  case C_LOCATION: /* --location */
+    if(config->followlocation == CURLFOLLOW_OBEYCODE)
+      warnf(global, "--location overrides --follow");
+    config->followlocation = toggle ? CURLFOLLOW_ALL : 0;
+    break;
+  case C_FOLLOW: /* --follow */
+    if(config->followlocation == CURLFOLLOW_ALL)
+      warnf(global, "--follow overrides --location");
+    config->followlocation = toggle ? CURLFOLLOW_OBEYCODE : 0;
+    break;
   default:
     return PARAM_OPTION_UNKNOWN;
   }

src/tool_getparam.h

@@ -90,6 +90,7 @@ typedef enum {
   C_FAIL_EARLY,
   C_FAIL_WITH_BODY,
   C_FALSE_START,
+  C_FOLLOW,
   C_FORM,
   C_FORM_ESCAPE,
   C_FORM_STRING,

src/tool_listhelp.c

@@ -201,6 +201,9 @@ const struct helptxt helptext[] = {
   {"    --false-start",
    "Enable TLS False Start",
    CURLHELP_DEPRECATED},
+  {"    --follow",
+   "Follow redirects per spec",
+   CURLHELP_HTTP},
   {"-F, --form <name=content>",
    "Specify multipart MIME data",
    CURLHELP_HTTP | CURLHELP_UPLOAD | CURLHELP_POST | CURLHELP_IMAP |

src/tool_setopt.c

@@ -150,6 +150,14 @@ const struct NameValue setopt_nv_CURL_NETRC[] = {
   NVEND,
 };
 
+const struct NameValue setopt_nv_CURLOPT_FOLLOWLOCATION[] = {
+  NV(0L),
+  NV(CURLFOLLOW_ALL),
+  NV(CURLFOLLOW_OBEYCODE),
+  NV(CURLFOLLOW_FIRSTONLY),
+  NVEND,
+};
+
 /* These options have non-zero default values. */
 static const struct NameValue setopt_nv_CURLNONZERODEFAULTS[] = {
   NV1(CURLOPT_SSL_VERIFYPEER, 1),

src/tool_setopt.h

@@ -54,6 +54,7 @@ extern const struct NameValue setopt_nv_CURLFTPSSL_CCC[];
 extern const struct NameValue setopt_nv_CURLUSESSL[];
 extern const struct NameValueUnsigned setopt_nv_CURLSSLOPT[];
 extern const struct NameValue setopt_nv_CURL_NETRC[];
+extern const struct NameValue setopt_nv_CURLOPT_FOLLOWLOCATION[];
 extern const struct NameValueUnsigned setopt_nv_CURLAUTH[];
 extern const struct NameValueUnsigned setopt_nv_CURLHSTS[];