upstream handler support for model names with forward slash (#298)

The upstream handler would break on model IDs that contained a forward
slash. Model IDs like "aaa/bbb" called at upstream/aaa/bbb would result
in an error. This commit adds support for model IDs with a forward slash
by iteratively searching the path for a match.

Fixes: #229

proxy/proxymanager.go

@@ -227,7 +227,7 @@ func (pm *ProxyManager) setupGinEngine() {
 	pm.ginEngine.GET("/upstream", func(c *gin.Context) {
 		c.Redirect(http.StatusFound, "/ui/models")
 	})
-	pm.ginEngine.Any("/upstream/:model_id/*upstreamPath", pm.proxyToUpstream)
+	pm.ginEngine.Any("/upstream/*upstreamPath", pm.proxyToUpstream)
 
 	pm.ginEngine.GET("/unload", pm.unloadAllModelsHandler)
 	pm.ginEngine.GET("/running", pm.listRunningProcessesHandler)
@@ -393,24 +393,52 @@ func (pm *ProxyManager) listModelsHandler(c *gin.Context) {
 }
 
 func (pm *ProxyManager) proxyToUpstream(c *gin.Context) {
-	requestedModel := c.Param("model_id")
+	upstreamPath := c.Param("upstreamPath")
 
-	if requestedModel == "" {
+	// split the upstream path by / and search for the model name
+	parts := strings.Split(strings.TrimSpace(upstreamPath), "/")
+	if len(parts) == 0 {
 		pm.sendErrorResponse(c, http.StatusBadRequest, "model id required in path")
 		return
 	}
 
-	processGroup, realModelName, err := pm.swapProcessGroup(requestedModel)
+	modelFound := false
+	searchModelName := ""
+	var modelName, remainingPath string
+	for i, part := range parts {
+		if parts[i] == "" {
+			continue
+		}
+
+		if searchModelName == "" {
+			searchModelName = part
+		} else {
+			searchModelName = searchModelName + "/" + parts[i]
+		}
+
+		if real, ok := pm.config.RealModelName(searchModelName); ok {
+			modelName = real
+			remainingPath = "/" + strings.Join(parts[i+1:], "/")
+			modelFound = true
+			break
+		}
+	}
+
+	if !modelFound {
+		pm.sendErrorResponse(c, http.StatusBadRequest, "model id required in path")
+		return
+	}
+
+	processGroup, realModelName, err := pm.swapProcessGroup(modelName)
 	if err != nil {
 		pm.sendErrorResponse(c, http.StatusInternalServerError, fmt.Sprintf("error swapping process group: %s", err.Error()))
 		return
 	}
 
 	// rewrite the path
-	c.Request.URL.Path = c.Param("upstreamPath")
+	c.Request.URL.Path = remainingPath
 	processGroup.ProxyRequest(realModelName, c.Writer, c.Request)
 }
-
 func (pm *ProxyManager) proxyOAIHandler(c *gin.Context) {
 	bodyBytes, err := io.ReadAll(c.Request.Body)
 	if err != nil {